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Emergence heterogeneity caused by epicotyl dormancy contributes to variations in seedling quality during large-scale breeding. However, the mechanism of epicotyl dormancy release remains obscure. We first categorized the emergence stages of Chinese cork oak (Quercus variabilis) using the BBCH-scale. Subsequently, we identified the key stage of the epicotyl dormancy process. Our findings indicated that cold stratification significantly released epicotyl dormancy by increasing the levels of gibberellic acid 3 (GA 3) and GA 4. Genes associated with GA biosynthesis and signaling also exhibited altered expression patterns. Inhibition of GA biosynthesis by paclobutrazol (PAC) treatment severely inhibited emergence, with no effect on seed germination. Different concentrations (50 μM, 100 μM, and 200 μM) of GA 3 and GA 4+7 treatments of germinated seeds demonstrated that both can promote the emergence, with GA 4 exhibiting a more pronounced effect. In conclusion, this study provides valuable insights into the characterization of epicotyl dormancy in Chinese cork oak and highlights the critical role of GA biosynthesis in seedling emergence. These findings serve as a basis for further investigations on epicotyl dormancy and advancing large-scale breeding techniques. • BBCH-scale was used to describe Q. variabilis seed germination and emergence. • Cold stratification effectively breaks epicotyl dormancy of Q. variabilis seeds. • GA biosynthesis is essential for epicotyl dormancy release in Q. variabilis. • The promoting effect of GA 4 on seedling emergence is superior to that of GA 3. [ABSTRACT FROM AUTHOR]

• Priming with karrikinolide (KAR 1) enhanced seed germination in aged marrow, cabbage and pepper seeds. • Repair mechanism of seed aging by the treatments operated through repairing cell structure reducing solute leakage lower electrical conductivity and less K leakage in treated seeds. • Treatments with smoke extract affected ROS enzyme activity i.e. catalase, ascorbate peroxidase and superoxide dismutase activity of aged seeds. • Smoke extract treatments can be an efficient tool for enhancing seedling quality in marrow, cabbage and pepper seeds. The aging process induces the deterioration of seed vigor and viability. Priming methods have been shown to regenerate and rejuvenate aged crop seeds. Several studies have established that plant-derived smoke from burning plant material enhances germination and post-germination. Karrikinolide (KAR 1), which has been identified as a molecule derived from smoke, can improve the germination of seeds of a range of plant species. However, the effect of KAR 1 on aged seeds is not well known. Therefore, this study was carried out to determine the impact of KAR 1 and hydropriming on germination and repair mechanism in unaged and artificially aged pepper, marrow, and cabbage seeds. Aged seeds were artificially produced at 40 ± 1 °C and 100% relative humidity for 48 h in cabbage and 72 h in marrow and pepper. KAR 1 (10−7 M) was applied by dipping seeds in solution at a weight ratio of 1:5 seed: solution for 16 h at 20 °C. Hydropriming was applied under the same conditions using distilled water. Following the treatments, germination, seedling emergence, electrical conductivity, potassium leaching, and enzyme analysis were determined. Results showed that KAR 1- treated seeds had the lowest electrical conductivity and potassium leakage in unaged and artificially aged seeds in all three species. The influence of KAR 1 was more prominent on catalase activity in both artificially aged and unaged seeds. Additionally, KAR 1 treatment improved germination and fresh and dry weights of seedlings in all three species. The results of the present study show that the application of KAR 1 can help improve the performance of marrow, cabbage and pepper seeds in artificially aged (low-quality) seed germination. [ABSTRACT FROM AUTHOR]

Araucaria angustifolia is a conifer endemic to southern South America that is threatened with extinction, necessitating strategies to enhance its reforestation success. We assessed the effects of inoculation with plant growth-promoting bacteria (PGPB) on araucaria seedlings to determine whether PGPB increases their quality. The experiment was carried on in a three-way factorial scheme and an additional control, with six replications. A volume of 50 mL of diluted inoculant (Azospirillum brasilense Abv5 + Abv6 or Bacillus subtilis BRM2084 + B. megaterium (renamed Prestia megaterium) BRM119) was applied at planting (to seeds or to the substrate) or at through irrigation after seedling emergence, at concentrations of 0.2 %, 0.4 %, 0.8 %, or 1.6 % (v/v, inoculant/water). Destructive sampling was conducted (1) when seedlings only had the stem, (2) when the first branch was formed, and (3) when the second branch was established. The inoculants increased taproot growth and shoot P and N contents at the stem phase, but not later stages. Improved seedling mass, nutrient content and Dickson Quality Index were associated to inoculation with A. brasilense in the substrate and through irrigation. The most promising inoculant concentration was 0.9 %. Thus, inoculation with PGPB increases araucaria seedlings quality, which could be beneficial for seedling establishment in the field and should be further explored as a restoration strategy. • Plant growth-promoting bacteria increased araucaria seedling quality. • Inoculants for annual crops may be suitable for forest species. • Inoculants may be applied directly to substrate or through irrigation. [ABSTRACT FROM AUTHOR]

• A new trichomeless mutant was found, whose trichomeless trait is controlled by a single recessive gene BrTRI1. • A new unique allele BraA06g038610.3.5C with 108 bp insertion in the promoter region and transposable element insertion in the third exon was confirmed. • All reported variants of BrTRI1 and BrTTG1 were detected among 342 DH and high inbred lines. Only the identical material sources Y358-10 and Y358P1 concomitantly conformed to BrTRI1-PI and BrTRI1-TE. The trichome is a specialized structure developed from the epidermal cells of plants. It serves as a protective tissue covering the surface of plants, playing a crucial role in shielding plants against biotic and abiotic stresses. The trichomeless trait is a necessary quality trait of seedling Chinese cabbage, contributing to the enrichment of Chinese cabbage germplasm resources. This study analyzed the trichomeless mutant Y358-10 and identified the trichomeless trait as being controlled by the recessive gene BrTRI1. Through BSA-seq (Bulked sergeant analysis) and KASP (Kompetitive allele-specific PCR) techniques, the BrTRI1 gene was located on chromosome A06 at 24.91–24.95 Mb. Functional annotation analysis revealed that BraA06g038610.3.5C is a homologous gene of Arabidopsis AtGL1 and induces trichome formation, which may be a candidate gene for BrTRI1. Sequence analysis revealed a 108 bp insertion in the promoter region and transposable element (TE) insertion in the third exon of BraA06g038610.3.5C , differing from the previously published mutation. The InDel markers BrTRI1-PI and BrTRI1-TE were developed and validated in the F 2 population and 342 DH (Double haploid) and high inbred lines. We identified all reported variants of BrTRI1 and BrTTG1 among 342 DH and high inbred lines, which covered the widest variation range and the most germplasm resources. The results demonstrated that only the identical source Y358-10 and Y358P1 concomitantly conformed to BrTRI1-PI and BrTRI1-TE. RNA-seq and qRT-PCR analyses indicated that variations in BraA06g038610.3.5C and the differential expression of other genes involved in trichome development in Y358-10 resulted in the inhibition of trichome formation. This provides a new perspective for studying the molecular mechanism of Chinese cabbage trichome formation and genetic improvement. [ABSTRACT FROM AUTHOR]

Nitrogen is an environmental factor affecting anthocyanin synthesis, and rational application of nitrogen can improve the ornamental value and economic value of garden plants. Malus spectabilis are widely used in gardens and have contributed to the breeding of Malus varieties in the world. In the Malus spectabilis industry, nitrogen will not only affect the production quality of its seedlings, but also directly affect its ornamental value in the garden. However, the underlying mechanism of low nitrogen affecting Malus spectabilis anthocyanin synthesis is still unclear. Here, low nitrogen caused anthocyanin accumulation in leaves of Malus spectabilis , and anthocyanin accumulation decreased with the increase of IBA concentration. Through transcriptome analysis of Malus spectabilis leaves under low nitrogen and conventional nitrogen conditions, a differentially expressed lateral organ boundaries domain (LBD) transcription factor MsLBD41-like was identified, which may be related to anthocyanin synthesis. Subsequently, multiple experiments confirmed that MsLBD41-like negatively regulates anthocyanin synthesis by inhibiting the MsF3'H promoter under low nitrogen conditions. The yeast one-hybrid assays analysis preliminarily confirmed the interaction between MsARF5 and MsLBD41-like promoter. Subsequently, the activation effect of MsARF5 on the MsLBD41-like promoter was further validated through Dual luciferase assays and GUS staining assay in tobacco leaves. The regulatory effect of MsARF5–MsLBD41-like–MsF3'H module on anthocyanins under low nitrogen conditions was verified through transient transformation in apple peel and leaves of Malus spectabilis. Altogether, our data reveal that low nitrogen-induced anthocyanin biosynthesis is mediated at least in part by MsARF5 and MsLBD41-like regulatory proteins, providing a theoretical basis for the rational application of nitrogen to regulate plant leaf coloring in landscaping applications. • Low nitrogen induced anthocyanin synthesis in leaves of Malus varieties. • Identified MsARF5, MsLBD41-like, are negative regulators of anthocyanin biosynthesis under low nitrogen conditions. • MsARF5 directly binds to the promoter of MsLBD41-like. • MsLBD41-like directly binds to MsF3'H promoter to inhibit anthocyanin synthesis. • The MsARF5-MsLBD41-like–MsF3'H transcriptional cascade involved in anthocyanin accumulation. [ABSTRACT FROM AUTHOR]

• Alternating temperature enhanced seed germination in four cultivars of aubergine. • The most effective treatment tested was a temperature regime of 35/20°C at 16/8 h. • Endogenous hormone analysis showed decreased ABA in seeds with higher germination. • Increased germination and emergence correlated well with increase lipase levels. • There was a corresponding increase observed in SOD with increased germination. High seed quality is important for obtaining high quality seedlings for commercial vegetable production. The rate of seed germination affects seedling quality since seeds which tend to germinate more slowly generally result in low-quality seedlings, especially in aubergine seeds. Alternating temperatures play a crucial role in determining the rate of seed germination in many plant species. This study investigated the effect of alternating temperatures on aubergine seed germination, emergence rates, and physiological changes regulating dormancy. Seeds from four open-pollinated aubergine cultivars were incubated for 14 days under the following temperature regimes: 35/20°C-24/24h, 35/20°C-16/8h, 35/20°C-8/16h, 30/20°C-24/24h, 30/20°C-16/8h, 30/20°C-8/16h, or at constant 25°C. The highest mean germination was 92%, with a corresponding highest mean emergence of 88%, which was found with the 35/20°C-16/8h treatment. All alternating temperature treatments displayed faster germination and emergence compared to the control (25°C), as well as high catalase, superoxide dismutase and ascorbate peroxidase antioxidant enzyme activities, and high auxin and salicylic acid levels. In contrast, lipase enzyme activity, abscisic acid and jasmonic acid content decreased. In conclusion, these findings showed that alternating temperatures improved aubergine seed germination rate, and seedling emergence, and also demonstrated positive correlations with enzymatic and hormonal fluctuations within the seeds. [ABSTRACT FROM AUTHOR]

• Additional far-red light could promote wound callus cell production, healing and seedling quality of DRC grafted watermelon seedlings. • Additional far-red light improves antioxidant enzymes and osmotic regulation substances, but inhibits the accumulation of ROS and MDA. • The qRT-PCR analyses revealed that additional of far-red light significantly induced the expression level of graft healing related genes. Graft healing is an important factor that determines the survival of the double-root-cutting (DRC) grafted plants. Recent studies have shown that adding far-red light (FR) to change the red/far-red (R/FR) ratio plays a crucial role in plant growth and development. However, there have been few studies on how R/FR ratio affects the grafting union healing process of DRC grafted seedling. In this study, we applied four light quality treatments: dark (D), white (R/FR=6.0, W), R/FR ratios of 3 (H) and 0.3 (L). The effects of different ratios of R/FR on the survival rate, photosynthetic fluorescence characteristics, graft union healing and growth of DRC grafted watermelon seedlings during the healing period were analyzed using darkness (D) as a control. The results showed that compared with the control L treatment could significantly improve the survival rate, growth indicators and photosynthetic capacity of grafted seedlings, significantly increased the activities of SOD and POD, and contents of soluble sugar and protein in the graft union, and significantly reduced the accumulation of O2−, H 2 O 2 and MDA, which was conducive to the production of callus cell and the healing of grafted union. Meanwhile, qRT-PCR results showed that the expression levels of graft healing-related genes, ClaIAA, ClaSOD, ClaPOD, ClaWOX4, ClaGH9B14 and ClaGH9B1 were significantly induced L treatment. The current study can contribute to speeding up the development of industrialized production with high-quality watermelon grafted seedlings. [ABSTRACT FROM AUTHOR]

• Composting increased the proportion of pig manure digestate in seedling substrate. • Composting stabilize the physiochemical properties of pig manure digestate. • Perlite and sawdust improve the physiochemical properties of PMBD in composting. • Both PMBD and CPMBD improved plant growth performance, especially CPMBD. • Tomato was more sensitive than Lettuce to the seedling substrate properties. Anaerobic digestion of organic residues has the potential to significantly contribute to a shift from fossil to renewable energy, while the remaining biogas digestate need to be treated or used for a second time. In this study, the pig manure biogas digestate (PMBD) was evaluated as a potential part of seedling substrates and composting was considered a pretreating method to improve its characters. Composting was carried out firstly in a forced aeration composting system (100 L), in which perlite and sawdust were used as additives in different proportions separately or together. Based on the comparison of the physicochemical characters of different seedling substrates formulas mixed with PMBD or pig manure biogas digestate pretreated by composting (CPMBD), selected seedling substrates were analyzed by bioassay experiment. The results showed that pretreatment by composting and the additives (perlite and sawdust) used in composting decreased the pH value of PMBD and make it suitable for seedling substrates, especially composted with perlite and sawdust. Both PMBD and CPMBD with low proportion in the substrates improved plant growth of lettuce and tomato, while CPMBD was better than PMBD. However, when the proportions of PMBD was increased more than 20% and CPMBD was increased more than 40%, plant growth inhibition was observed. Tomato was more sensitive than lettuce to the physicochemical characters of the substrate. In summary, PMBD pretreated by composting not only increases the uses of digestate, but also enhances plant growth and hence yield. [ABSTRACT FROM AUTHOR]

Populus species are fast growing with high N requirements; an optimum level of fertilization is necessary for high seedling quality and subsequent plantation productivity. In this study, the morphological and physiological responses of two poplar clones (XH and BL3) to exponential and conventional N dosages were investigated, with a specific focus on leaf traits, the photorespiratory N cycle, and the interconversion of amino acids within leaves. Results show that shoot height and leaf number exponentially increased with plant growth. Leaf area, chlorophyll concentration, and net photosynthetic rate significantly increased for both clones during N fertilization, with a significant difference only in leaf area of clone XH between exponential and conventional dosages. Leaf concentrations of free amino acids and soluble sugars were not different but soluble proteins and fatty acids were significantly different for clone XH between N dosages; the amino acids glutamate, alanine, and aspartic acid concentrations increased in exponentially fertilized seedlings compared to controls. Amino acids, including the composition concentration and activity of glutamic-oxalacetic and -pyruvic transaminase, and soluble sugars were significantly higher for clone BL3 in fertilized seedlings. Photorespiration (glycine and glycolate oxidase) and glutathione redox (oxidized glutathione) were affected by fertilization. The activities of key enzymes (glycolate oxidase, catalase, and γ-glutamate cysteine ligase) involved in photorespiration and glutathione metabolism were lower for clone XH with exponential fertilization. Phenylalanine catabolism was influenced by fertilization and the interaction, clone × fertilization, showing accumulation of phenylalanine and tyrosine but decreases in phenylalanine ammonialyase activity and flavonoid concentrations in leaves of fertilized seedlings. The results indicate that leaf area and the interconversion of amino acids through deamidation/transamination are key regulatory hubs in poplar acclimation to soil N availability. • N application significantly improved poplar growth and physiological status. • The efficacy of N addition is determined by a combination of poplar clone and fertilization model. • Exponential N addition is a preferable fertilization strategy for clone XH. • Leaf area is significantly higher for clone XH under exponential than conventional N addition. • Photorespiratory N cycle, and leaf interconversion of amino acids are significant in poplar response to N fertilizations. • Phe catabolism through PAL to flavonoid is implicated in poplar acclimation to different N additions. [ABSTRACT FROM AUTHOR]

Rapeseed (Brassica napus L.) is an important oil crop worldwide, and the Yangtze River Basin (YRB) region is one of the most vital rapeseeds producing areas in China. However, the uneven distribution of annual precipitation during the rapeseed seedling stage in this region often leads to droughts and waterlogging, resulting in declined rapeseed seedling quality and yield. Therefore, this study aimed to assess the impact of micro-ridge-furrow planting (MR) and conventional flat cropping planting (FC) under straw returning on rapeseed seedling growth and yield during two growing seasons: wet year (WY) and dry year (DY). In MR planting, rapeseed was sown either on the ridge surface (RS) or in the ridge furrow (RF). We found that MR planting had stronger regulation of soil temperature and humidity compared to FC. The average soil volume water content in RS was 19.2 % lower than FC, while in RF, it was 9.0 % higher than FC. Under MR planting, the daily temperature fluctuations in RF were smaller than in FC, whereas in RS, they were larger than in FC. Through the adjustment of temperature and humidity, MR increased the activities of β-glucosidase (β-Glu) and cellulose disaccharide hydrolase (CBH) in the soil, thereby accelerating rice straw decomposition. Importantly, MR led to improved root growth, seedling quality, precipitation water use efficiency (WUE P), and yield of rapeseed during both the WY and DY seasons. Notably, root morphological traits were significantly altered under straw returning (RT) in MR, particularly with an 11.0 % increase in root surface area, which showed a significant correlation with the indoleacetic acid and jasmonic acid contents in the root system. Furthermore, RT increased antioxidant enzymes activity in rapeseed roots. The H 2 O 2 and ∙OH contents in MR were lower than in FC, indicating that the roots of MR were capable of self-protection and reducing the accumulation of superoxide radicals and peroxides by adapting actively to the soil water environment under straw returning. The yield and WUE P of MR were higher by 11.9 % and 21.0 %, respectively, compared to FC. In conclusion, MR planting has the potential to enhance seedling quality and increase rapeseed yield when combined with rice straw returning. This finding provides technical support for realizing the full and strong seedling establishment and improving the cultivation of direct-seeded rapeseed in the YRB region. • The micro-ridge-furrow (MR) planting technology in the Yangtze River basin be used. • MR technology have realized mechanization matching and widely applied. • MR improved the seedling quality and yield of rapeseed by regulating soil moisture. • MR regulated soil humiture and enzyme activity to promote straw decomposition. • MR induced lateral root proliferation of rapeseed by increasing JA content. [ABSTRACT FROM AUTHOR]

• An online monitoring system for the uprightness of transplanting machines based on machine vision and deep learning is constructed is constructed. • A seedling planting status dataset is constructed and an efficient algorithm YOLO-RDS for the detection of the planting posture of seedlings is proposed. • Improved traditional (HBB) object detection box, the introduction of angular predictor headers, and the RWBF detection head constructed. • Integrated development of a seedling quality monitoring system and field experiments conducted. During the mechanized transplanting process, the planting angle and standing posture of seedlings are essential factors in evaluating the survival of the planting, and the uprightness of the planting is an essential indicator in evaluating the planting quality. With the gradual expansion of mechanization, the traditional method of manually checking the uprightness of mechanized planting has gradually become inapplicable. To address this problem, an online monitoring system for the uprightness of transplanting machines based on machine vision and deep learning is constructed. The system mainly consists of an image acquisition device, a vehicle-mounted computer, and an interactive interface. Furthermore, to improve the identification errors caused by the unstructured environment in the field, a field planting uprightness monitoring device was designed to integrate LED light sources, photoelectric sensors, a CCD camera, and light hoods. An efficient algorithm YOLO-RDS for the detection of the planting posture of seedlings is proposed using a single-stage detection paradigm. First, the traditional (HBB) target detection box is improved and the circle smooth label is introduced to adapt to different seedling planting inclined postures. Secondly, the RWBF detection head network was constructed, and the stem incline angle was extracted using adaptive rotation to calculate the actual incline angle of the seedlings in three-dimensional space. Experimental results show that YOLO-RDS is better than the classic rotating target detection method, the average accuracy (mAP) is 97%, and FPS is 22. By encapsulating the algorithm, a seedling planting uprightness monitoring system was integrated and developed. Field experiments show that the average relative error rate of uprightness identification monitored by the system is 3.09%, the accuracy rate is 92.56%, and the absolute angle error is 0°-3°. The system has good accuracy and stability, meets the requirements for seedling uprightness monitoring, and can provide technical support for the quality evaluation of seedling transplanter operations. [ABSTRACT FROM AUTHOR]

Vietnam is one of the most dynamic furniture industries in the world. However, the domestic raw wood is struggling to meet the demands of the booming furniture industry in quantity and quality. Long-rotation plantations are expected to be a potential solution to improve local livelihoods and mitigate climate change impacts. In this study, we used binary logistic regression to analyze four groups of factors that affect the adoption of long-rotation plantations, including household characteristics, socio-economic factors, biophysical and technical factors, and institutional and policy factors using data collected from 315 households in Vinh Linh and Cam Lo districts, Quang Tri province, Vietnam. We also developed a Bayesian Network model to identify key drivers influencing small-scale forest planters' adoption of long-rotation plantations. The study results indicated that FSC participation, assurance of seedling source, understanding of the long-rotation timber market, and distance from house to plantation site positively influence households' decision on long-rotation plantation. In contrast, the lack of capital in years 4 to 5 and the typhoon impact rate negatively affect long-rotation plantations. The research findings suggest that supporting policies that provide forest planters with better access to FSC projects, low-interest credit systems, and better-quality planting material and equipment could encourage local households to adopt long-rotation plantations in the coming years. • This research aimed to contribute to sustainable timber supply and forest management. • Our conceptual model explains Vietnam households' long-rotation decisions. • We built BNs to identify long-rotation plantation drivers. • Long-rotation adoption influenced by FSC, seedling source while hindered by typhoons. • Policies supporting FSC, low-interest credit, and quality seedlings are recommended. [ABSTRACT FROM AUTHOR]

• Proper seed source selection is key for tropical forest restoration/reforestation. • Piecewise structural equation models assessed phenotypic effects on seedling quality. • Scarification, not tree phenotype, drives germination success in Coulteria platyloba. • Provenance, rather than tree phenotype, affects seedling quality in C. platyloba. • Both natural and managed populations should be used as seed sources for this species. A major obstacle faced by reforestation/restoration programs is an insufficient supply of high-quality seed. Seed collection is commonly based on opportunistic strategies that only consider availability and distance to seed sources, but not seed quality. Although for commercial timber species from temperate ecosystems the selection of individuals with above-average phenotypes often results in high-quality seeds and seedlings, the validity of this criterion has not been assessed in tropical dry forests (TDF). By using the abundant TDF tree Coulteria platyloba as study model and piecewise structural equation modelling (pSEM), we examined the associations between germination success and seedling growth, and various tree, fruit and seed characteristics, for seeds from two provenances (natural vs. managed populations), that were either scarified or not. Unexpectedly, phenotypic attributes of trees, fruits and seeds had no effect on germination success, as this response variable depended on scarification only. Also, fruit quality was unrelated to tree size, but it was related to provenance. According to pSEM, the best supported path resulting in high quality seedlings established a relationship between managed populations, high quality fruits and seedlings with better roots systems, but only for seeds that were scarified and did not germinate very rapidly. Overall, the assessed relationships were complex, weak, and sometimes difficult to interpret. Nonetheless, these results provide guidance to improve seed source selection efforts that consider operation costs of nurseries and the success of future plantations. In TDF, selecting trees with above-average phenotypes as seed sources does not necessarily favour the quality of seedlings used to restore degraded areas. In these ecosystems, we recommend a seed collection strategy that combines managed and natural populations as seed sources to maximize genetic variability in future plantations, while improving nursery operation efficacy. [ABSTRACT FROM AUTHOR]

• OW and EW reduced the boron and sodium content in leaves of capsicum seedlings. • OW (0.4 ppm) showed a higher ratio of root mass versus root length. • Catalase activity increased under OW and EW treatments but kept the TBARS levels. • Sanitizer treatments cause microbial load reduction; OW higher than EW. Ozonated water has been extensively used in the food industry as an effective sanitizer to prolong the shelf life of fruit and vegetables during the postharvest. Recently, the disinfection of water used in primary production has been a critical point in preventing plant losses during the growing of the crop, especially in the nursery crop. In this study two different irrigation treatments have been used: ozonated water (OW, 750 mV), and electrolyzed water (EW, 495 mV), compared to a control treatment using water without any sanitizer treatment, in capsicum seedling plants grown under greenhouse conditions. The results showed the control to have the highest Ca, Mg, and Zn values with respect to the OW and EW treatments. However, no significant differences were observed in these minerals in the vegetal plant tissue. Capsicum leaves, irrigated with EW and OW, showed a minor content in B and Na. Moreover, the sanitizing treatments provided plants with a higher number of leaves. Sanitizer treatments did not affect the net photosynthesis or antioxidant compounds, total phenolic compounds, nor the vitamin C. At day 49 lower DHAA and lipid peroxidation were observed in treated samples. A higher catalase activity was measured in OW and EW irrigation treatments compared to the control, preventing the lipid peroxidation. Additionally, OW and EW reduced the microbial load in the water (E. coli and total Enterobacteriae) and OW reduced the mould and yeast of water and the mesophilic load of capsicum seedlings. [ABSTRACT FROM AUTHOR]

Highlights • Lighting environment at seedling stage influenced mature lettuce yield. • Nitrate content of lettuce was not affected by light treatment at seedling stage. • Broad spectrum LED with red to blue ratio of 2.2 was suitable for seedling growth. • Daily light integral of 11.5 mol m−2 d−1 was appropriate for seedling growth. Abstract In order to obtain high-quality lettuce seedlings, effects of photosynthetic photon flux density (PPFD), photoperiod and light quality at seedling stage on growth and quality of hydroponic lettuce were investigated at different growth stages. Hydroponic lettuce (Lactuca sativa L. cv. Frill ice) seedlings were grown under 12 combinations of two levels of PPFD (200 and 250 μmol m−2 s-1) and two photoperiods (14 and 16 h d-1) under three light quality: light-emitting diodes (LEDs) with red to blue ratio (R:B ratio) of 1.2 and 2.2, and fluorescent lamps with R:B ratio of 1.8 as control. After the 20-day treatment during seedling stage, lettuce seedlings were transplanted to a homogeneous lighting environment for another 20 days before harvest. Results showed that leaf length and ratio of leaf length to leaf width at 20 days after sowing decreased in a logarithmic way with increasing daily light integral and fluorescent lamps resulted in larger seedlings with bigger leaves and higher leaf and root dry weights compared to LEDs. Leaf and root fresh weights of harvested lettuces were higher in the seedlings grown under PPFD at 200 μmol m−2 s-1 with a 16 h d-1 photoperiod, regardless of light quality at seedling stage. Generally, vitamin C content of mature lettuce was lower in seedlings grown under LEDs with R:B ratio of 1.2 and no significant differences were observed in nitrate content among the three lighting sources. In consideration of mature yield and quality, lighting efficiency and electrical consumption of lighting sources, PPFD of 200 μmol m−2 s-1 with a photoperiod of 16 h d-1 provided by LEDs with R:B ratio of 2.2 was suitable for hydroponic lettuce (cv. Frill ice) seedling production. [ABSTRACT FROM AUTHOR]

Highlights • Composting of biogas residues and spent mushroom substrate lasted 118 days. • Plant growth was used to evaluate the compost maturity. • Compost as tomato substrate showed better seedling quality than commercial seedling. • TOC, C/N, NH 4 +-N, NO 3 −-N, AK and lignocellulose can be used to evaluate compost maturity. Abstract Recycling of BR and SMS are crucial for the development of biogas industry and commercial mushroom cultivation. The seed germination test is limited to examine the maturity of compost because of lacking the effect of insoluble part on plant growth. The aim of this study was to evaluate the maturity of compost by analysis the relationship between agronomic parameters of plant growth with physicochemical parameters of compost. The thermophilic period (over 50 °C) was lasted 52 days. TOC, C/N, AP and NH4+-N was decreased along with composting process, while TK, TP, AK and NO 3 −-N showed an opposite trend. As for seedling quality, the raw material (T0) showed the worst plant growth but the 100% compost (T1) showed better seedling quality compared with commercial seedlings. According to the analysis of Spearman correlation, the results indicated that TOC, C/N, NH 4 +-N, NO 3 −-N, AK and lignocellulose can be used to evaluate compost maturity. [ABSTRACT FROM AUTHOR]

Highlights • Temperatures and summer aridity are increasing in southern forests of Pinus nigra. • The species' regeneration niche is consequently leaning upslope in these forests. • A significant seedling bank useful to restock harvested stands is present. • Water, irradiation and factors acting at the microhabitat scale affect recruitment. • Continuous cover forestry is recommended. Abstract Although typically considered shade-intolerant, Mediterranean pine species may form seedling banks due to the existence of facilitative interactions between seedlings and canopy trees. Consequently, seedling banks could be considered as part of the seedling pool that should restock managed Mediterranean pinewoods, thus increasing the resistance of these forests to climate change. The study investigated the characteristics of the seedling bank in a silviculturally undisturbed forest of Pinus nigra subsp. salzmanii exposed to increasingly arid conditions. The study site was located in the southernmost range limit of the species. The dynamics of the seedling bank was studied by comparing current seedling (height < 1.30 m, age < 2 yr) and pole tree (height ≥ 1.30 m and diameter at breast height < 12.5 cm) altitudinal distributions, using altitude as a proxy of aridity. Aridity was proved to have increased in the study area along the last four decades. These climatic trends were identified by means of Mann-Kendall tests for trend. Additionally, the effects of summer drought, light availability, soil compaction, litter layer and micro-slope as explanatory variables of the recruitment outcome were analysed by means of Generalized Linear Mixed Models and survival analysis. Altitude affected positively seedling establishment, but had no effect on the current abundance of pole trees, indicating a recent upwards displacement of the regeneration niche due to increasingly arid conditions. Water and light availability, the latter at intermediate levels of irradiance, affected tree recruitment positively, whereas the effects of soil compaction, litter layer depth and micro-slope were negative. Implementing extended rotation periods and maintaining intermediate values of tree cover are proposed as important management recommendations to achieve successful natural regeneration in Mediterranean pinewoods. [ABSTRACT FROM AUTHOR]

• HorBlock-decoupled head more accurately locates and completely model missing stolon. • Stem Block module increases feature expression ability and unifies feature channels. • Stolon-YOLO among all methods achieves the best performance. • The study provides a technical reference for related stolon detection research. Stolons are an essential nutritional organ of strawberry seedlings, whose quantity and vigorous growth directly impact the quality of the seedling cultivation. Accurately detecting stolon is essential for increasing productivity in seedling factories. To alleviate these issues of low recognition accuracy of stolon caused by complex backgrounds, diverse growth types and low proportion of effective information in the bounding box, we propose a Stolon-YOLO for visual recognition of stolon for the first time. In our method, improvements are focused on two aspects: HorBlock-decoupled head and Stem Block feature enhancement module. Firstly, a new decoupled head is designed by introducing the HorBlock, which enables the interaction of high-order spatial information and enhances the precision for locating stolons. Sequential gnConv of the HorBlock realizes better global modeling for incomplete and curved stolon to improve detection efficiency. Then, the Stem Block is used to reinforce feature expression and reduce dimensionality. We fuse the processing results of the Stem Block with the output of HorBlock in a residual form. Experimental results demonstrate that the Stolon-YOLO achieves 92.5% in precision, 89.7% in recall rate, 91.1% in F1 score and 88.5% in average precision for stolon detection, which outperforms the standard YOLOv7 by 3% in recall rate and 3.4% in average precision. Compared with YOLOX, SSD, CenterNet and Faster R-CNN, the Stolon-YOLO increases recall rate by 8.3%, 27.4%, 17%, and 3.5%, and increases AP by 12.2%, 28.9%, 2.4%, and 7.5%, respectively. Meanwhile, the Stolon-YOLO achieves a frame rate of 50.25 FPS, meeting real-time detection demands. The above results highlight that this study provides a fast and effective method for identifying the stolon of strawberry seedlings in glass greenhouses. [ABSTRACT FROM AUTHOR]

Camellia oleifera is an important industrial crop whose leaf, flower, pericarp, and seed have multiple application values. Grafting is the main means of C. oleifera propagation, and the quality of grafted seedlings is directly related to the propagation coefficient and yield promotion. However, the research on C. oleifera grafting is lacking, and there is little comprehensive understanding of the growth characteristics, metabolic patterns, and molecular mechanisms of different grafting combinations of C. oleifera. In this study, the phenotypic, metabolomic, and transcriptomic profiles of four grafting combinations [ C. oleifera (Co), C. yuhsienensis (Cy), C. chekiangoleosa (Cc), and C. gigantocarpa (Cg) four kinds of scions grafted onto one rootstock, C. oleifera (Co)] were investigated. The phenotypic analysis showed that hetero-grafting inhibited the growth vigor of grafted unions. The abundance of shikimic acid and phenylethylamine in hetero-grafting was lower than in auto-grafting based on the differential metabolite analysis, and the exogenous addition of both metabolites promoted the growth of grafted unions. Multi-omics analysis revealed that hetero-grafting could significantly affect the differential expression of hub genes (aroD , aroE , aroK , pheA , tyrB) in the biosynthesis of shikimic acid and phenylethylamine and that AP2/ERF , MYB , and GRAS transcription factors were involved in regulating the expression of the above hub genes. These findings innovatively characterized the important role of shikimic acid and phenethylamine in the growth of C. oleifera grafted seedlings and provided new insights for promoting the propagation and industry development of C. oleifera. [Display omitted] • Hetero-grafting inhibited the growth vigor of Camellia oleifera. • Shikimic acid and phenylethylamine have positive effects on grafted C. oleifera. • The hub genes involved in shikimic acid and phenylethylamine accumulation were screened. • The transcriptional regulation model of the hub genes was established. [ABSTRACT FROM AUTHOR]

• Procedures, standards and attributes used to control seedling quality vary greatly across Europe. • All countries monitor the origin of FRM as a potential genetic quality indicator. • Morphological attribute standards differ among countries. • The use of physiological attributes is very limited to a few countries of northern Europe. • European countries in general do not apply the "target plant concept", except for the origin of FRM. • This indicates the need to review seedling quality attributes and standards based on scientific knowledge and the need to harmonize some of them between EU countries. The relationship between the quality of forest seedlings and their outplanting survival and growth has long been recognized. Various attributes have been proposed to measure the quality of planted seedlings in forest regeneration projects, ranging from simple morphological traits to more complex physiological and performance attributes, or a combination thereof. However, the utility and meaning of seedling quality attributes can differ significantly among regions, nursery practices, site planting conditions, species and the establishment purpose. Here, forest scientists compiled information using a common agreed questionnaire to provide a review of current practices, experiences, legislation and standards for seedling quality across 23 European countries. Large differences exist in measuring seedling quality across countries. The control of the origin of seed and vegetative material (genetic component of plant quality), and control of pests and diseases are common practices in all countries. Morphological attributes are widely used and mandatory in most cases. However, physiological attributes are hardly used at the operative level and mainly concentrated to Fennoscandia. Quality control legislation and seedling quality standards are less strict in northern European countries where seedling production is high, and quality control relies more on the agreements between producers and local plant material users. In contrast, quality standards are stricter in Southern Europe, especially in the Mediterranean countries. The control of seedling quality based on plantation and reforestation success is uncommon and depends on the conditions of the planting site, the traditional practices and the financial support provided by each country. Overall, European countries do not apply the "target seedling concept" for seedling production except for seed origin. Seedling production in many countries is still driven by traditional "know-how" and much less by scientific knowledge progress, which is not adequately disseminated and transferred to the end-users. Our review highlights the need for greater harmonization of seedling quality practices across Europe and the increased dissemination of scientific knowledge to improve seedling quality in forest regeneration activities. [ABSTRACT FROM AUTHOR]

Highlights • An algorithm was developed for image correction of skewness plug trays. • An algorithm was developed to identify the seedling quality in each cell. • The evaluation accuracy was compared in the angle correction situation. Abstract The acquisition of quality information for plug seedlings is the foundation for automatic seedling transplanting. Machine vision technology is an extensively used method for this task. In the visual inspection of plug seedlings, the skewness of the images of dense-cell seedlings and the accuracy of target extraction affect the quality evaluation of plug seedlings. This study proposed a skewness correction algorithm on the basis of Canny operator and Hough transform for the images of a plug tray to improve the visual inspection method for transplanting equipment. Watershed algorithm was used to segment overlapping leaves, and gravity center method was applied to distinguish transboundary leaves. The leaf area and number of seedling leaves in the images of plug trays were extracted and used for quality evaluation. Two-week-old seedlings of Salvia splendens in 200-cell plug trays in a greenhouse were the objects of this study. Industrial cameras were used to capture images of the plug trays. These images underwent grayscale conversion in 2b–g–r channel, median filtering, Canny contour detection, and Hough transform to complete contour detection and skewness correction. The corrected angle deviation of the trays was less than 0.85°. Pre-treatment with grayscale conversion in 2g–r–b channel, binarization, and watershed algorithms were adopted to extract the target of the seedlings in the images. The image of the plug tray was divided into 200 small square areas in accordance with the cell area. The gravity center of the seedling leaves in the cell was calculated to locate the seedling. The number of the leaves and the area of seedlings in each cell were obtained and used as criteria to discriminate the quality of each seedling. The skewness angle of the plug tray during the actual delivery of plug seedlings was within the range of ±3°. Four sets of plug trays with skewness of ±1°, ±2°, and ±3° were obtained. Subsequently, the quality of seedlings in the four sets of plug trays was identified. The evaluation accuracy in the tray skewness and the angle correction situations were determined. Results showed that the average accuracy of seedling evaluation is 98% after angle correction. In contrast to the uncorrected images, the corrected ones can increase by 1.1–9.4 percentage points, thereby improving the evaluation accuracy for automatic seedling transplanting. [ABSTRACT FROM AUTHOR]

Highlights • Oak sprouts were most successful in pine stands with 25% canopy cover. • As implemented, the two prescribed fires did not benefit oak regeneration. • Browsing, frosts, and red maple competition synergistically limited oak success. Abstract Overstory and understory treatments were established in natural oak stands and red pine plantations in Michigan in 1991 to test the hypotheses that (1) oak seedling survival and growth would be greater in pine than oak stands and (2) removal of competitors would enhance oak seedling performance. Late spring prescribed fires were implemented in 2002 and 2008 to investigate their effectiveness in controlling understory red maple. Performance of planted northern red oaks has been monitored since 1991 and the abundance of naturally regenerating oak and red maple seedlings and sprouts in different size classes has been documented since 2001. A subset of oaks has been protected against deer browsing since planting. Results suggest partial competitor removal enhances oak seedling and sprout performance, whereas complete removal increases mortality from browsing and frost. Increases in red maple abundance and decreases in oak abundance were documented after the prescribed fires in 2015. Greater growth and survival of planted oaks was observed in the pine stands, provided they were protected from browsing. Based on these results, the most viable management scenario for maximizing survival and growth of oak seedlings and sprouts in the study region would include protecting oak seedlings from deer in 25% canopy cover shelterwoods in pine plantations. Opportunities exist for developing systems involving alternating rotations and mixtures of oak and pine. [ABSTRACT FROM AUTHOR]

Genes that control “Domestication Syndrome” traits were direct targets of selection, like those controlling increased seed size in the common bean. However, selection for this trait brought about unintentional selection on genes controlling seedling growth. We hypothesized that wild and domesticated plants have different early seedling growth patterns as an indirect consequence of selection for a larger seed size during domestication, and those differences resulted from changes in gene expression patterns of the wild ancestor. Large seeds pose a challenge to reserve remobilization during early heterotrophic growth, particularly during a transition towards more fertile alluvial soils. To address our hypothesis, we characterized the patterns of gene expression of cotyledon, root, and leaf tissues of 7-day old seedlings of a wild and a landrace accession of the common bean. Differential expression analyses detected genes with contrasting patterns of expression between the two genotypes in all three tissues. Some of the differentially expressed genes with contrasting genotypic patterns are known to have domestication-related signatures of selection. Among these genes were some transcription factors associated with key roles in development. These genes may represent targets of indirect selection and ultimately explain the growth phenotypic differences between wild and domesticated seedlings. [ABSTRACT FROM AUTHOR]

Argentinean peanut provides a significant source of food worldwide, therefore is essential to preserve the quality of seeds during the storage period in order to ensure the yield of this crop. In this study in situ effect of a formulation based on microencapsulated boldo ( Peumus boldus ) essential oil (EO) was evaluated on in-pod stored peanut ( Arachis hipogaea ) to preserve the seed quality. Statistically significant ( p <  0.05) fungitoxic effects were observed at the end of the storage period. Seed damages caused by insects was very low during the 5 months, however, reductions of seed germinations were produced by the formulation. Low levels of residual boldo oil were recorded at the end of the assay. The application of boldo oil microcapsules is useful to preserve stored peanuts avoiding its deterioration, but not when it is intended for seed, but for another purposes as by-product elaboration. [ABSTRACT FROM AUTHOR]

• Designed a transient multi-indicator detection system for plug seedling sorting in high-speed transplanting. • Build a lightweight YOLOv5s model to detection weak seedlings, no seedlings, strong seedlings, and damaged seedlings. • The mAP and FPS values for the lightweight YOLOv5s are reached 94.23 % and 54. Quality sorting of plug seedlings is an important part of factory nurseries, and deep learning is starting to become a core technology in this field. In response to the key problems of existing sorting systems with a single perspective and insufficient detection indicators, this paper innovatively proposes a lightweight multi-indicator detection model for plug seedlings, and an integrated transient sorting system for high-speed transplanting is designed. The new YOLOv5s model is composed of the ShuffleNet-V2 backbone, a channel attention mechanism neck, and a head block, and it can effectively extract image features of different seedling qualities. We built a dataset for pepper and tomato plug seedlings, and the experimental results showed that the model was highly accurate in detecting no seedlings, weak seedlings, damaged seedlings and strong seedlings, with an mAP of 94.23 %. Finally, in the verification of different operating speeds, the transplanting-sorting-replanting multifunctional system had the best integrated efficiency of 4200 plants per hour, and the average treatment time for single plug seedlings was only 0.86 s. Our method effectively can improve the performance of seedling quality sorting systems and provide technical support for factory nurseries. [ABSTRACT FROM AUTHOR]

The formulation from R. coriaria aqueous crude 35% concentrate, Emereen 1820 (5%) and water (60%) was prepared. An in vitro analysis was conducted, to determine the effectiveness of the strategy, for managing Fusarium oxysporum (Acc. Number KM039054) and Colletotrichum boninense (Acc. Number KM039057), two of the most harmful bacteria, as well as Xanthomonas vesicatoria (Acc. Number KU661975), and Ralstonia solanacearum (Acc. Number KT783476), two well-documented bacteria. Plants treated with formulation prior to infection by bacteria and fungi were seen to exhibit moderate resistance against these pathogenic bacteria and fungi with 5 and 10% concentrations. The results derived from a comparison with the control sample, revealed that the application of both the concentrations, substantially decreased the total AUDPC, for all the investigated diseases. The most significant decrease in disease intensity (82.58, 70.38, 64.93 and 64.80% for X. vesicatoria, R. solanacearum, F. oxysporum and C. boninense respectively), is attributed to the application of nanoemulsion formulations, at a concentration of 10%. The remedial measures employed, served to greatly enhance the shoot height and root length, increase the dry shoot and dry root occurrence, boost the chlorophyll content, and expand the leaf surface area. In view of these outcomes, the sumac biopesticide formulation can be considered a more cost effective and eco-friendly alternative, to chemical pesticides, for the curbing of diseases affecting tomato plants. • The formulation was stable and effective as well as efficient. • Rhus coriaria nanoemulsion was effective to manage tomato pathogens. • Nanoemulsion can improve the quality of tomato seedlings and promote growth. • Nanoemulsion considered biocontrol candidate for tomato disease management. [ABSTRACT FROM AUTHOR]

Intake of food containing high levels of selenium (Se) poses a safety risk to human health. Sulfur (S) fertilizer exerts different regulatory effects on Se uptake in crops. In this study, field experiments were conducted in 2012–2013 and 2013–2014 to clarify the effects of different S species [60 kg ha −1 S applied as elemental sulfur or magnesium sulfate] on the Se uptake and quality of seeds in rapeseed ( Brassica napus L.) treated with Se [60 g ha −1 Se applied as sodium selenite or sodium selenate]. The results showed that the application of sulfur or sulfate significantly reduced the Se concentrations of seeds in plants treated with selenite or selenate. The two S fertilizers caused consistent reductions in seed Se concentrations, approximately 25% for the selenite treatment and 40% for the selenate treatment. The seed Se concentrations of selenate-treated plants were approximately 3.0–5.0 times those of selenite-treated plants. More than 99% of the Se accumulated in seeds of selenite- or selenate-treated plants was concentrated in rapeseed meal, with less than 1% of the Se being found in rapeseed oil. The application of selenite or selenate significantly reduced the erucic acid content and increased the oleic acid content of seeds. Applying S fertilizer on the basis of Se fertilizer further reduced the erucic acid content while increasing the oleic acid content of seeds. This study indicated that Se was accumulated mainly in the rapeseed meal of seeds in B. napus treated with selenite or selenate. Application of sulfur or sulfate in combination with Se fertilizer could significantly reduce the Se concentration while improving the quality of seeds in B. napus . [ABSTRACT FROM AUTHOR]

• Seedling development models are calibrated and assessed under experimental conditions. • Wang and Engel's model was superior in predicting the seedling development. • Development models simulate the seedling duration under current and future climates. • Projected air temperature increases will modify the development rates of both species. • Changing the sowing date and the seedling production environment will be necessary. Development models are tools that couple environmental effects on development, allowing to predict development dynamics and to quantify the seedling phase duration for forest species under current and future climate conditions. Unfortunately, studies on forest species are scarce, even for commercially important species. This study calibrates and evaluates two development models under current climate conditions, and identifies possible changes in future climate conditions on the development of Corymbia citriodora (Hook.) (K.D. Hill & L.A.S. Johnson) and Eucalyptus urophylla (S.T. Blake), which are widely used in Brazilian forest plantations. The Phyllochron (Phyl) and Wang and Engel (WE) development models estimate the daily cumulative leaf number (CLN), and when integrated over time, gives the seedling phase duration (SPD). Field experiments were conducted using eleven sowing dates (SD) during 2014 and 2015 growing seasons in Itajubá, Minas Gerais, Brazil to evaluate the performance and calibrate the model coefficients for predicting the development of the two species. Subsequently, the best model was simulated for current climate conditions (1980–2005) and projected for future climates (2021–2050 and 2071–2100) under two radiative forcing scenarios (RCP 4.5 and 8.5) considering eleven SDs. Data from nine Earth System Models from the NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP), that are derived from Coupled Model Intercomparison Project Phase 5 (CMIP5) were used. The Phyl and WE models were capable of predicting the CLN and SPD developmental dynamics for both species. However, the cumulative errors in CLN from the Phyl model, generated less accurate estimates for SPD. By contrast, the WE model was excellent (superior to the Phyl) at estimating CLN and SPD, with an error of less than 2.6 leaves, and 6 days, respectively. Additionally, the projected increases of up to 4 °C throughout the 21st century may modify the development rates, increase the SPD (∼+ 15 days), thus interfering with the permanence time of the two species at forest nursery, the date of sale, and seedling quality. Since the climate change time ranges exert greater influence on the SPD of both species, changing the sowing date and artificially controlling seedling production environments are the most viable adaptation measures to cope future climate change threats. [ABSTRACT FROM AUTHOR]

• BC 1 F 3 hybrid seedlings exhibited the largest total growth and incremental height growth. • Seedlings from the BC 3 F 3 generation had intermediate Cryphonectria parasitica resistance. • Phytophthora root rot contributed to mortality in planted chestnut seedlings. • High performing and poor performing BC 3 F 3 families could be identified. • Using larger size seedlings at planting will reduce time needed to obtain desired tree size. The American chestnut (Castanea dentata) is imperiled due primarily to two diseases caused by nonnative pathogens, notably chestnut blight and Phytophthora root rot (PRR) caused by Cryphonectria parasitica and Phytophthora cinnamomi , respectively. Field reintroduction trials are important to test trees bred for blight resistance under forest conditions to quantify survival and field performance in managed stands that represent future restoration sites. We planted 513 pedigreed bare-root (1–0) nursery seedlings into an even-aged regeneration harvest in the Blue Ridge Mountains of eastern Tennessee, USA to test effects of breeding, genetics, and seedling size class on field performance, including survival, total growth, incremental growth (a measure of growth efficiency), and height growth patterns. Mortality was highest in the first two years after planting, and PRR symptoms coupled with soil and root assays that tested positive for P. cinnamomi suggested this disease was a significant contributor to mortality. Chinese chestnut (C. mollissima), known to be resistant to P. cinnamomi and C. parasitica , had the highest survival (96 percent) compared to American chestnut (34 percent) and hybrid generations, including the BC 3 F 3 generation (41 percent). Less advanced hybrid generations, such as the BC 1 F 3 and BC 2 F 3 , had the greatest total height and ground-line diameter (GLD) and height growth efficiencies. BC 3 F 3 generation seedlings were associated with higher-than-expected rates of nominal height growth patterns (i.e., flat growth rates over time or early mortality) compared to Chinese chestnut seedlings. Results, however, indicated the breeding program was successfully integrating desired American chestnut growth traits into the hybrid genome while transferring an intermediate level of resistance from the Chinese chestnut. We identified superior and inferior BC 3 F 3 families that can help inform breeding and restoration efforts. Visually grading seedlings before planting affected survival and growth of generations and genetic families differently, indicating that refinement of nursery production and restoration plantings should consider genetic effects. Across generations, seedling size grading improved total height and GLD growth that would save resources necessary for competition control and animal browsing protection, but large-size seedlings also exhibited lower C. parasitica resistance rankings over time, probably owing to earlier bark fissuring. PRR probably affected outcomes, particularly for hybrid and American chestnut seedlings that have very low levels of P. cinnamomi resistance. Managers could expect advanced breeding generations to perform similarly to American chestnut in growth through the critical stage of early stand development. More durable resistance to C. parasitica and mitigation of PRR through better site selection and/or resistance screening will improve future restoration efforts. [ABSTRACT FROM AUTHOR]

Industrial seedling quality assessment, such as attempting to find abnormal seedlings, is a challenging task where assessment methods must contend with the natural variability of seedlings, as well as the subjective nature of expert judgements. Furthermore, obtaining expert judgements is expensive and time-consuming, so machine learning approaches which rely on fewer judgements would be useful in practice. We investigate autoencoders, operating on 3D point clouds obtained from 6732 seedlings to address this challenge, exploiting such systems' ability to work with partially labelled data. Point clouds from tomato seedlings are recorded using a 3D data capture platform, MARVIN™, and the quality of each seedling is determined by expert judgement. An existing system is used to establish baseline performance scores using a rule-based expert system and machine learning with handcrafted features. Autoencoders are trained on the point clouds to learn representations for subsequent use in classification. We examine scenarios where large amounts of partially labelled data are available, and compare with the case where fully labelled data is available. To improve performance, we compare the architectural subcomponents based on PointNet and PointNet++, as well as the effect of different training strategies. We find, with 13.6% of training data labelled, our model has correct classification rates of 97.7% and 82.7% for normals and abnormals respectively. With further improvements and fully labelled data, we find that correct classification rates of 97.6% and 96.1% can be reached. The results demonstrate that semi-supervised learning supported by partially labelled data has the potential to greatly reduce the cost of data curation, with minimal impact on overall accuracy. • A dataset of 6732 tomato seedling 3D point clouds is collected and labelled by experts. • Autoencoders perform abnormality detection on 3D point clouds of plants. • Partially labelled data can be used, lowering the labelling burden substantially. • Accuracy is 97.7% (normals) and 82.7% (abnormals) with 13.6% of data labelled. • Accuracy of 97.6% (normals) and 96.1% (abnormals) possible with fully labelled data. [ABSTRACT FROM AUTHOR]

Lack of sufficient studies on seed ecology of endemic species poses practical hurdles in their habitat restoration programs. Here, we studied the seed ecology traits and regeneration potential of Actaea kashmiriana – an endemic plant species to Kashmir Himalaya. We conducted population sampling of the species at four different sites in Kashmir Himalaya. The seeds showed profuse covering with brownish membranous wings, indicating wind dispersal in the species. The percentage of seed set varied from 67(±0.7) to 72(±0.6) and seed viability from 76(±2.4) to 86(±2.4), with highest being at low-altitude site. We observed a gradual reduction in viability of the seeds over time, and 4 °C temperature optimum for maintaining long-term viability. Gibberellic acid (GA 3) treatment (3 mM) showed highest percentage of seed germination and seedling survival. The treatments involving GA 3 (2 mM), GA 3 (2.5 mM), and GA 3 (3 mM) showed highest number of seeds germinated per day as well as seedling vigour index. Mean germination time was significantly reduced to 45 ± 0.92 days under GA 3 (3 mM) as compared to the other treatments. For breaking the epicotyl dormancy, 24–25 °C temperature was effective for the emergence of cotyledon. Faster seed germination initiated within 38 and40 days under treatments with GA 3 (3 mM) and GA 3 in combination with Thiourea respectively. Our results indicate non-deep morpho-physiological dormancy in the species and GA 3 likely serves as a substitute for cold stratification. Based on our findings, we outline a protocol for production of quality seedlings in A. kashmiriana , which can steer restoration of the species in this Himalayan biodiversity hotspot and enlighten the restoration of endemic biodiversity elsewhere. • Seed ecology of Actaea kashmiriana , an endemic species to the Himalaya, is studied. • We report the presence of non-deep morpho-physiological dormancy in the species. • For long term viability of the seeds, optimum temperature of 4 °C proved effective. • The temperature of 24–25 °C was found effective for breaking the seed dormancy. • Protocol for production of quality seedlings developed for the species restoration. [ABSTRACT FROM AUTHOR]

• Paclobutrazole (PBZ) applied in the molting phase promotes morphological and biochemical changes after transplantation. • Water stress promotes morphophysiological and biochemical changes in Passiflora edulis Sims plants. • The PBZ optimizes the exhaust mechanism under water stress. • Under excess water, low concentrations of PBZ result in greater water absorption and storage capacity in the tissues. • Low concentrations of the regulator protect isohydric expression under water restriction. • The growth restriction imposed by the regulator reduces the potential for biomass accumulation under water restriction. Water status such as drought or excess water, have led to great socio-economic impacts on sour passion fruit (Passiflora edulis Sims) crops. Relevant studies have highlighted the impact of growth regulators on the activation and modulation of plant escape mechanisms to water stress. This study aimed to analyze whether PBZ affect morphophysiology and biochemistry of sour passion-fruit seedlings inducing a better adaptation to water stress after transplanting. In general, the irrigation regime was the factor that promoted the most expressive effect for all the evaluated characteristics, while the PBZ concentration factor affected only the morphology. The interaction between these factors was observed for leaf water potential (ѱ w) and mass accumulation, characterized by increases as a function of increasing water availability. The 40 and 80 mg L−1 PBZ concentration induced the maintenance of higher ѱ w throughout the variation of water regime evaluated in this study, when it was determined at 140 days after emergence. The shifting from the quadratic model to the linear model of morphological characteristics as a function of the irrigation regimes, corroborates regulator effect to becoming it more directly associated with water availability, without interactions with other factors not addressed. The relationship between mass accumulation and PBZ concentrations were evidenced for the water excess regimes (90 and 120% pot capacity), characterized by decreases. Under water excess, 40 mg L−1 of PBZ results greater water uptake and storage capacity, increasing the plants' vigor. Although the anticipation of the escape mechanisms optimizes the plant's water status, the growth restriction imposed by the regulator reduced the biomass accumulation potential of the plants under water restriction. [ABSTRACT FROM AUTHOR]

We studied the influence of seed priming with beta-amino butyric acid (BABA) on the growth, physiological and biochemical parameters of seedlings with varied abiotic stress tolerance, which were raised and grown under unstressed and stressed (NaCl/PEG-6000) conditions. Under stressed conditions, the growth of rice seedlings was less when compared to control plants. After BABA priming, the seedling growth increased both under unstressed and stressed conditions as compared to the respective controls. BABA priming of rice seeds caused increase in the photosynthetic pigment content of the leaves, modified the chlorophyll a fluorescence related parameters and also enhanced the photosystem activities of seedlings when compared to their respective non-primed controls. BABA priming also caused increased mitochondrial activities of the rice seedlings. Moreover, BABA priming significantly reduced malondialdehyde content in the seedlings and also resulted in accumulation of proline especially in the NaCl tolerant variety Vyttila 6. BABA seed priming also enhanced the activity of nitrate reductase enzyme and activities of antioxidant enzymes like guaiacol peroxidase and superoxide dismutase. The presence of BABA was detected by high performance thin layer chromatography analysis in the rice seeds whereas in the seedlings it was not detected. Thus, it can be inferred that the seed priming effect of BABA mainly occurred within the seeds, which was further carried to the seedlings. It is concluded that BABA priming of seeds improved the drought and salinity stress tolerance of all the three rice varieties and it was significantly evident in the drought tolerant variety Vaisakh and NaCl tolerant variety Vyttila 6, when compared to the stress sensitive variety Neeraja. [ABSTRACT FROM AUTHOR]

Playas have a high potential for producing dust, sand, and salt storms, which can influence human health and agricultural land in the near future. Growing vegetation is an effective way to control wind erosion, but events like soil salinity and dust storms prevent vegetation from settling in these areas. In this study, the effects of two halotolerant plant growth-promoting rhizobacterial strains, Bacillus pumilus HR and Zhihengliuella halotolerans SB, on morpho-physiological and nutritional status of the desert halophyte Nitraria schoberi under the stress of salinity (0, 300, and 600 mM NaCl) and dust (0 and 1.5 g m−2 month−1) were examined. The results showed that salinity, dust and the combination of the two stresses had a negative effect on most morphological and physiological traits of the plant. Salinity stress reduced potassium, iron, and manganese of N. schoberi by 28, 30, and 21 %, and increased anthocyanins, proline, and peroxidase by 21, 92, and 16 %, respectively. Both bacterial strains and their combination improved plant growth against such stresses. The effect of B. pumilus HR strain was more than that of Z. halotolerans SB strain on the plant. HR strain and SB strain increased chlorophyll a by 62 and 25 %, total dry biomass by 66 and 31 % at 300 mM NaCl level, respectively, and significantly increased seedling quality index by 72 and 76 %, respectively, under dust stress. The results of principal component analysis (PCA) showed that the presence of bacterial strains decreased antioxidant compounds (negative correlation) and increased mineral elements, chlorophyll, total dry biomass, and seedling quality index. This information can help us in the optimal afforestation of this plant species and the fixation of salt dust in the playa under the conditions of climate change in arid and semi-arid ecosystems. [ABSTRACT FROM AUTHOR]

• A portable smartphone application for stem-base width and plant height measurement. • An easy-to-attain reference object for scale factor determination. • Combing an application and a reference object to measure actual morphological traits. The measurements of stem-base width and plant height in rice seedlings are significantly associated with the assessment of in-field seedling growth quality, the determination of optimal seedling transplanting time, and the decision-making of later fertilization use. At present, the measurements of such two morphological traits heavily rely on the inefficient manual measurement method. Herein, we develop a smartphone application to accomplish these tedious and repetitive measurement tasks. Using the developed smartphone application, the reference object and rice seedling were taken into an entire image and then were performed image pre-processing, thereby segmenting the foreground from the background. The reference object image and rice seedling image in the foreground were respectively separated via a comparison in heights of the foreground contours. The reference object image was used for obtaining a scale factor, while the rice seedling image was used for measuring actual stem-base width and plant height by employing the obtained scale factor. The results of automatic measurements resulted from different conditions were compared with those of manual measurements, accomplishing the assessment of measurement accuracy. Collectively, the smartphone application achieved R2 values of 0.9832 and 0.9796 in measuring stem-base width and plant height respectively, and corresponding RMSE values were 0.0307 mm and 1.2311 mm respectively, when tests were performed in various conditions including three camera resolutions, three photographing heights, and three sunlight conditions. The mean runtime for processing an individual image was about 1796.164 ms when a total of 350 rice seedlings were measured under various conditions. This work not only demonstrates that the smartphone application allows low-cost, fast, and accurate measurements of stem-base width and plant height in rice seedling, which can be used as a reasonable alternative to the traditional manual measurement method; but also offers a valuable reference for farmers or researchers in terms of evaluating in-field seedling growth quality, determining optimal seedling transplanting time, as well as guiding follow-up in-field fertilizer expenditures; and further provides methodological support for relevant researches in other crops or domains. [ABSTRACT FROM AUTHOR]

Highlights: [•] Polybag size, substrate, and fertiliser showed little interaction on oil palm seedling growth. [•] Polybag size affected seedling growth more than substrate or fertiliser. [•] In the Benin context, the recommended forest soil is not a suitable nursery substrate. [•] Current pricing for oil palm seedlings in Benin compromises seedling quality. [•] Plant height or root-collar diameter are good, non-destructive proxies of seedling biomass. [Copyright &y& Elsevier]

Highlights: [•] No-tillage increased soil compaction (penetration resistance) limiting the seedling emergence. [•] Crop yield and seed quality (sunflower) were extremely low under no-tillage. [•] Reduced-tillage (chiselling) solved these constraints without resorting to soil inversion. [ABSTRACT FROM AUTHOR]

Highlights: [•] Seed dispersal of Quercus liaotungensis forest was monitored for two cycles in three regions in Shaanxi Province, China. [•] The accumulated seed rain density was ranged 43–123 seeds/m2 in the three study regions. [•] Seed dispersal in the three regions has a roughly similar trend. [•] Arborous species richness has a positive effect on seed rain density, send weight and seed volume. [•] Promoting arborous species richness could enhance seedling establishment. [ABSTRACT FROM AUTHOR]

Highlights: [•] Seedling response is related to the spatial pattern of topographic factors. [•] Topography described by LiDAR was closely linked to seedling response. [•] These models help to select areas with a higher survival and growth potential. [ABSTRACT FROM AUTHOR]

Abstract: Increasingly, trembling aspen (Populus tremuloides Michx.) is being planted in stressful situations such as forest land reclamation, afforestation and forest restoration in North America. This is due to its fast potential for growth and high resiliency, but its indeterminate growth strategy provides a special challenge in creating suitable planting stock for these sites. Clues from naturally established aspen seedlings suggest that root total non-structural carbohydrate (TNC) reserves and root:shoot ratio could be strongly related to subsequent seedling establishment and growth. Carbon allocation in plants is generally partitioned between reserve accumulation and growth and development. Under conditions in controlled nurseries, the allocation of carbohydrates to reserves could be manipulated in order to produce seedlings designed for specific environmental conditions. To manipulate seedling characteristics we attempted to induce premature bud set during nursery culture while allowing continued photosynthesis. Treatments included applying different fertilizer regimes, light intensities, reducing photoperiod and use of a shoot growth inhibitor. The shoot growth inhibitor was the most reliable treatment and resulted in complete bud set, while blackout was successful only when seedlings were grown outside. Low nutrient treatments also resulted in early bud set; however, leaves were abscised much earlier. There was a distinct trade-off between growth and reserve accumulation with the late bud set. A longer period of height growth reduced root and total TNC reserves, while early bud set allowed for continued photosynthesis and produced the highest levels of root and total TNC reserves in seedlings. Increased TNC reserves of aspen planting stock was positively related to height growth after outplanting, with root TNC reserves as high as 33% of dry weight and root:shoot ratios greater than 2 associated with the best growth. [Copyright &y& Elsevier]

Abstract: Container longleaf pine (Pinus palustris) seedlings often survive and grow better after outplanting than bareroot seedlings. Because of this, most longleaf pine are now produced in containers. Little is known about nursery fertilization effects on the quality of container longleaf pine seedlings and how that influences outplanting performance. We compared various fertilization rates (0.5, 1, 2, 3, or 4mg nitrogen (N) per week for 20weeks) for two crops (2004 and 2005) of container longleaf pine, grown inside a fully-controlled greenhouse (2004 and 2005) or in an outdoor compound (2005). Seedlings grew larger in the nursery with increasing amounts of N. After 20weeks of fertilizer treatment, seedlings received two additional fertigations at the same treatment rate to promote hardening, N concentrations declined sharply, and seedlings shifted biomass production toward roots. Overall, shoots showed more plasticity to N rate than did roots. Survival of either crop after outplanting was unaffected by nursery N rate. For both crops, no seedlings emerged from the grass stage during the first year after outplanting, and during the second year, more seedlings exited the grass stage and were taller as N rate increased up to 3mg per week. By the third field season, nearly all seedlings in the 2004 crop had exited the grass stage, whereas 44% of 2005 crop grown at 1mgN had yet to initiate height growth, either because of differences in seed source between the two crop years or because of droughty conditions. Our data suggests that an application rate of about 3mgN per week for 20weeks plus two additional applications during hardening yields satisfactory nursery growth as well as field response for the container type we used. The potential for improving field performance by using more robust fall fertilization during nursery production should be investigated. [Copyright &y& Elsevier]

Abstract: We experimentally managed silage fields to provide abundant seed as a conservation measure for wintering birds. Buntings Emberiza strongly selected seeded ryegrass plots, where they fed predominantly on ryegrass Lolium seed and maintained body weights similar to those on high-quality arable wintering habitats. Bunting usage of seeded plots was positively related to Lolium seedhead density, peaking at October seedhead densities above 400seedheadsm−2. Perennial ryegrass Lolium perenne swards could only provide one early silage crop (cut by mid-late May) if sufficient seed was to be produced, while Italian ryegrass Lolium multiflorum was able to provide two silage cuts and a large seed crop. Mats of lodged seedheads ensured the continuity of seed provision, resulting in high bird usage during late winter, when most seed has been depleted from existing wild bird seed measures. The estimated cost of the measure was comparable to small-plot measures in current English agri-environment schemes. A rotational seeded ryegrass measure should constitute an effective, affordable and widely applicable conservation measure for seed-eating farmland birds in grassland-dominated farmland across NW Europe. [Copyright &y& Elsevier]

Abstract: The performance of planted seedlings in drylands is affected by seedling morphological and physiological traits. Recent studies support a positive relationship between seedling size and field performance. However, exceptions to this paradigm suggest that this relationship may be dependent on species and degree of stress. To test the hypothesis that small seedlings would be favored under harsh semi-arid conditions over large seedlings, we produced seedlings of five Mediterranean woody species (Pistacia lentiscus, Quercus coccifera, Rhamnus lycioides, Rhamnus alaternus and Tetraclinis articulata) under contrasted fertilization regimes, and evaluated their performance after planting in a semi-arid area. Seedlings were cultivated under full sunlight and received either slow release fertilizer or bi-weekly applications of complete nutrient solution, diluted fertirrigation, or nutrient solutions containing no nitrogen or no phosphorus. Fertilization had a strong effect on nutrient status, above and belowground biomass accumulation, and biomass allocation patterns. Root: shoot ratio was higher in nitrogen- and phosphorus-deficient seedlings than in seedlings receiving complete nutrient solution or slow-release fertilizer. One year after planting, seedling survival was negatively correlated with plant size for all species. The effect of nutritional regime on field survival decreased over the 2 following years. Our results show that nutrient-deprived seedlings are more likely to establish under semi-arid conditions than well-fertilized seedlings, suggesting that morphological and functional characteristics associated with nutrient deficiency may outbalance the scarcity of nutrient reserves in seedling tissues. [Copyright &y& Elsevier]

Abstract: A properly selected stocktype can greatly enhance reforestation success through increased survival and growth following outplanting. Implementing a robust stocktype trial using stocktypes of equal quality can ensure results lead to the best choice. Six container types, differing primarily in depth and volume, were used to evaluate the performance of ponderosa pine (Pinus ponderosa Laws. var. ponderosa) seedlings outplanted on two sites that varied in volumetric soil moisture content (θ), average temperature, and total precipitation (mesic and xeric). Seedlings in each container type were cultured specifically to achieve uniform seedling quality. After two growing seasons, seedlings planted at the mesic site showed high survival (>99%) and incremental growth gains of 147, 100, and 794% for height, root-collar diameter (RCD), and stem volume, respectively; container types exhibited differences in total height, RCD, and stem volume with larger containers generally yielding the largest seedlings. Seedlings planted at the xeric site experienced 83% survival, smaller growth gains (25, 46, and 220% for height, RCD, and stem volume, respectively), and also exhibited differences in height, RCD, and stem volume. Regression analysis revealed that for each site, initial seedling morphological characteristics were better at predicting absolute height, RCD and stem volume after the first year than after the second year, with initial seedling height offering the best predictive power (R 2 =0.66, mesic site; and R 2 =0.70, xeric site). Second-year absolute growth prediction was poorest on the mesic site (R 2 <0.21). Regression analysis indicates that initial seedling characteristics lost predictive value with time, especially on the mesic site, as seedlings grew out of their initial, container-induced characteristics and become more limited by current environmental and genetic factors. Conversely, on a xeric site, where absolute growth was reduced, traits determined by the container type persisted longer. Selecting stocktypes for mesic site conditions may only be limited by the minimum growth gains desired. Conversely, xeric sites may benefit from deep-planted quality seedlings or carefully planted long-rooted, large container seedlings. [Copyright &y& Elsevier]

Abstract: Grafting is a unique horticultural technology that allows the grower to select an alternate, compatible root system with natural disease resistance for their desired crop. Short-term storage of grafted seedlings under low temperature may extend the production window of grafted seedlings, reduce the labor input and increase production of grafted seedlings with a small propagation capacity. To evaluate the low temperature storage conditions, Cucumis melo ‘Olympic Gold’ seedlings were grafted onto Cucurbita maxima x Cucurbita moschata ‘Tetsukabuto’ rootstock and stored for a period of 2 or 4 weeks at 9, 12, or 15°C under 12μmolm−2 s−1 photosynthetic photon flux (PPF). The study demonstrated that grafted seedlings could be stored at 12°C for 4 weeks without significant dry mass accumulation or effects on post-storage growth and development. Grafted seedlings stored at 15°C for 4 weeks had a significant increase in dry mass and stem elongation; this was not observed for the non-grafted seedlings stored under the same conditions, suggesting that the rootstock enhanced the scion growth at lower temperatures than optimal for muskmelon. Storing muskmelon seedlings at 9°C caused chilling damage but the damage was pronounced for non-grafted seedlings than grafted seedlings. ‘Tetsukabuto’ rootstock, an interspecific squash, presumably has a chilling tolerance and increased the storability of muskmelon seedlings. Further optimization is needed but there is potential for using this technique as a tool for mass production of grafted muskmelon seedlings. [Copyright &y& Elsevier]

Abstract: To date, little is known about the effect of certain cultivation practices on German chamomile (Matricaria chamomilla L.) in Belgium. The objective of the present study was to examine the effects of planting date and seedling age on agro-morphological characteristics, essential oil content and composition of German chamomile grown in Belgium. Treatments consisted of 4 different planting dates (15 April, 1 May, 15 May, 30 May) in combination with 5 seedling ages (30, 45, 60, 75 and 90 days) replicated thrice in a randomized complete block design. Planting date had significant effects on all of the agro-morphological characteristics. The highest values for them were obtained from the first date of planting whereas values decreased with later planting dates. Days after sowing (DAS) and transplanting (DAT) to flowering were significantly influenced by planting date and decreased with a later planting date. For 30-days-old seedlings, (E)-β-farnesene, α-bisabolol oxide A, α-bisabolone oxide and spathulenol were the compounds which were significantly influenced by planting date whereas the highest amounts were obtained for the latest planting date. Plant height and plant spread were the only agro-morphological characteristics which were significantly influenced by age of seedling at transplanting. Seedling age significantly increased DAS to flowering whereas the effect was age-dependent. For the first date of planting, spathulenol was the only compound which was significantly influenced by seedling age at transplanting whereas the highest amount was obtained for 90-days-old seedlings. The results of this study provide new knowledge to produce chamomile flowers of adequate quality in Belgium. [Copyright &y& Elsevier]

In the current study, Arabidopsis seedlings were hydroponically grown on MS media containing cadmium (Cd) of 0¿2.0mgL¿1 for 60h of treatment. Gene expression profiles were used to relate exposure to Cd with some altered biological responses and/or specific growth effects. RT-PCR analysis was used to quantitate mRNA expression for seven genes known to be involved in DNA mismatch repair (MMR) system and cell division. Results indicated that Cd concentrations of 0.25¿2.0mgL¿1 cause increased total soluble protein levels in shoots of Arabidopsis seedlings in an inverted U-shaped dose¿response manner. Exposure to 0.25 and 0.5mgL¿1 of Cd dramatically induced expression of four genes (i.e. proliferating cell nuclear antigen 2 (atPCNA 2), MutL1 homolog (atMLH1), MutS 2 homolog (atMSH2) and atMSH3) and five genes (i.e. atPCNA1,2, atMLH1 and atMSH2,7), respectively, in shoots of Arabidopsis seedlings; Exposure to 1.0mgL¿1 of Cd significantly elevated expression of only two genes (atMSH6,7), but caused prominent inhibition in expression of three genes (atPCNA2, atMLH1 and atMSH3) in shoots of Arabidopsis seedlings. The expression alterations of the above genes were independent of any biological effects such as survival, fresh weight and chlorophyll level of shoots. However, shoots of Arabidopsis seedlings exposed to 2.0mgL¿1 of Cd exhibited statistically prominent repression in expression of these seven genes, and showed incipient reduction of fresh weight and chlorophyll level. This research provides data concerning sensitivity of expression profiles of atMLH1, atMSH2,3,6,7 and atPCNA1,2 genes in Arabidopsis seedlings to Cd exposure, as well as the potential use of these gene expression patterns as representative molecular biomarkers indicative of Cd exposure and related biological effects. [Copyright &y& Elsevier]

Zinc (Zn) is a necessary element for plants, but excess Zn can be detrimental. To investigate Zn toxicity, rapeseed (Brassica napus) seedlings were treated with 0.07–1.12mM Zn for 7d. Inhibition of plant growth along with root damage, chlorosis and decreased chlorophyll (a and b) content in newly expanded leaves (the second and third leaves formed following cotyledons) were found under Zn stress. The Zn content increased in plants under external Zn stress, while concentrations of phosphorus, copper, iron, manganese and magnesium reduced significantly, especially in roots. Meanwhile, increased lipid peroxidation was detected biochemically and histochemically. Compared with controls, NADH oxidase and peroxidase (POD) activity increased in leaves and roots of plants under high Zn, but superoxide dismutase (SOD), catalase and ascorbate peroxidase activities decreased. The changes in glutathione S-transferase activity and in ascorbic acid, dehydroascorbate, non-protein thiols and glutathione contents were also measured under Zn stress. Isoforms of SOD and POD were separated using non-denaturing polyacrylamide gel electrophoresis and their activities were analyzed. Our results suggested that excess Zn exerts its toxicity partially through disturbing nutrient balance and inducing oxidative stress in plants. These data will be helpful for better understanding of toxicity of Zn and the adaptive mechanism in Zn non-hyperaccumulator plants. [Copyright &y& Elsevier]

• The proportion of shoot in the dry weight of the whole plant was almost more than 80%. • The shoot dry weight accumulation of tomato seedlings can be well fitted by DE- logical regression. • The PPFD of the maximum curvature point in the SDW curve was the highest significance level, among which the efficiency of increasing the dry weight per unit PPFD was the highest. • The tomato seedlings quality of optimized PPFD was the best with the lowest root - shoot ratio. The subsequent plant growth is determined by tomato seedling quality which is affected by light intensity. The present study proposes a method for obtaining the regulatory target value by using the U-chord length curvature method based on the dry weight model-fitted curve characteristics to obtain the optimum light intensity at the seedling stage. Tomato seedlings were selected as the experimental material, and six photosynthetic photon flux densities (PPFDs) were set under completely artificial side lighting. Depending on the scattering trend, the tomato shoot dry weights (SDWs) were fitted by the polynomial, logarithmic, and half logistic function models after optimization of parameters by using the differential evolution algorithm (DE-HLFM). According to the curve variation characteristics, the discrete curvature values corresponding to the models calculated using the U-chord length curvature method were 335, 108, and 241.3 µmol· m −2· s −1, respectively. Physiological tomato growth indicators exhibited that L4 had the smallest root–shoot ratio and the highest level of seedling index and SDW significance. Moreover, L4 had the highest SDW per PPFD improvement efficiency. Thus, tomato seedlings under L4 exhibited the best quality and highest efficiency among those under the six PPFDs. DE-HLFM optimization was closest to the optimal PPFD L4 (243.17 ± 4.37 µmol· m −2· s −1), indicating that DE-HLFM is the most suitable model with a coefficient of determination (R2) of 0.99897 and root-mean-square error of 0.00554. Thus, the PPFD corresponding to the maximum curvature point of the appropriate model exhibited physiological and production regulation significance. In conclusion, based on the curve characteristics, the curve feature point obtained using the U-chord curvature method can be used as the control target value for the precise control of the artificial controllable light environment. [ABSTRACT FROM AUTHOR]

• L4 (243.17 ± 4.37 μmol m-2 s-1) is the best PPFD with the highest light-adaption, and the highest total soluble sugar. • The closer the light environment is to the plant growth, the faster the light adaptation. • The larger the PPFD, the greater the curve deviation and the data discretization degree, and the higher the photoinhibition. • It is more efficient to analyze the results by extracting the parameters of high correlation degree. • The fluorescence parameter analysis can achieve the same effect as destructive detection of seedling health status. Seedling quality greatly affects the subsequent survival, quality and yield of tomatoes. To explore the response of tomato seedlings on vertical light, we investigated the continuous trends of chlorophyll fluorescence parameters in six vertical light intensities and Pearson's correlation analysis of them. The results showed that the dark fluorescence parameters of F m , F v /F m highly correlated with the photosynthetic photon flux density (PPFD) while NPQ, Y(NPQ), Y(NO) were highly correlated with the day of light processing (DLP). With increasing PPFD, the F v /F m decreased, the residual sum of curves increased and the scaling factor (S) was decreased. The photoinhibition phenomenon was relieved to different degrees on DLP 4. L4 (243.17 ± 4.37 μmol m-2 s-1) was the fastest light adaptation, L5 (295.34 ± 5.42 μmol m-2 s-1) was the second. Φ PSII accumulation was greatest in L4 and second in L5. Both L4 and L5 seedling health index and dry weight were significantly higher than L1 (53.20 ± 1.55 μmol m-2 s-1). L4 had the highest Chl a/b and total soluble sugar. It can be concluded that L4 was the best vertical PPFD with the highest light-adaption. The larger the PPFD, the greater the curve deviation, the greater the degree of data discretization, and the higher the photoinhibition. The more appropriate the light intensity is, the faster the seedlings light-adapted are. Therefore, the rapid and proper adjustment of light intensity is the key to obtain high quality tomato seedlings. [ABSTRACT FROM AUTHOR]