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The red and far-red light photoreceptor phytochrome B (phyB) transmits light signals following cytosol-to-nuclear translocation to regulate transcriptional networks therein. This necessitates changes in protein-protein interactions of phyB in the cytosol, about which little is presently known. Via introduction of a nucleus-excluding G767R mutation into the dominant, constitutively active phyBY276H (YHB) allele, we explore the functional consequences of expressing a cytosol-localized YHBG767R variant in transgenic Arabidopsis seedlings. We show that YHBG767R elicits selective constitutive photomorphogenic phenotypes in dark-grown phyABCDE null mutants, wild type and other phy-deficient genotypes. These responses include light-independent apical hook opening, cotyledon unfolding, seed germination and agravitropic hypocotyl growth with minimal suppression of hypocotyl elongation. Such phenotypes correlate with reduced PIF3 levels, which implicates cytosolic targeting of PIF3 turnover or PIF3 translational inhibition by YHBG767R. However, as expected for a cytoplasm-tethered phyB, YHBG767R elicits reduced light-mediated signaling activity compared with similarly expressed wild-type phyB in phyABCDE mutant backgrounds. YHBG767R also interferes with wild-type phyB light signaling, presumably by formation of cytosol-retained and/or otherwise inactivated heterodimers. Our results suggest that cytosolic interactions with PIFs play an important role in phyB signaling even under physiological conditions.

Mutants lacking functional HYD2 homoeologs showed improved seedling growth, but comparable or increased susceptibility to salt stress in tillering plants, suggesting a developmentally restricted role of HYD2 in salt response. Salinity stress threatens global food security by reducing the yield of staple crops such as wheat (Triticum ssp.). Understanding how wheat responds to salinity stress is crucial for developing climate resilient varieties. In this study, we examined the interplay between carotenoid metabolism and the response to salt (NaCl) stress, a specific form of salinity stress, in tetraploid wheat plants with mutations in carotenoid β-hydroxylase 1 (HYD1) and HYD2. Our investigation encompassed both the vulnerable seedling stage and the more developed tillering stage of wheat plant growth. Mutant combinations lacking functional HYD2 homoeologs, including hyd-A2 hyd-B2, hyd-A1 hyd-A2 hyd-B2, hyd-B1 hyd-A2 hyd-B2, and hyd-A1 hyd-B1 hyd-A2 hyd-B2, had longer first true leaves and slightly enhanced root growth during germination under salt stress compared to the segregate wild-type (control) plants. Interestingly, these mutant seedlings also showed decreased levels of neoxanthin and violaxanthin (xanthophylls derived from β-carotene) and an increase in β-carotene in roots. However, tillering hyd mutant and segregate wild-type plants generally did not differ in their height, tiller count, and biomass production under acute or prolonged salt stress, except for decreases in these parameters observed in the hyd-A1 hyd-B1 hyd-A2 hyd-B2 mutant that indicate its heightened susceptibility to salt stress. Taken together, these findings suggest a significant, yet developmentally restricted role of HYD2 homoeologs in salt-stress response in tetraploid wheat. They also show that hyd-A2 hyd-B2 mutant plants, previously demonstrated for possessing enriched nutritional (β-carotene) content, maintain an unimpaired ability to withstand salt stress.

Numerous studies have shown reduced performance in plants that are surrounded by neighbours of the same species1,2, a phenomenon known as conspecific negative density dependence (CNDD)3. A long-held ecological hypothesis posits that CNDD is more pronounced in tropical than in temperate forests4,5, which increases community stabilization, species coexistence and the diversity of local tree species6,7. Previous analyses supporting such a latitudinal gradient in CNDD8,9 have suffered from methodological limitations related to the use of static data10-12. Here we present a comprehensive assessment of latitudinal CNDD patterns using dynamic mortality data to estimate species-site-specific CNDD across 23 sites. Averaged across species, we found that stabilizing CNDD was present at all except one site, but that average stabilizing CNDD was not stronger toward the tropics. However, in tropical tree communities, rare and intermediate abundant species experienced stronger stabilizing CNDD than did common species. This pattern was absent in temperate forests, which suggests that CNDD influences species abundances more strongly in tropical forests than it does in temperate ones13. We also found that interspecific variation in CNDD, which might attenuate its stabilizing effect on species diversity14,15, was high but not significantly different across latitudes. Although the consequences of these patterns for latitudinal diversity gradients are difficult to evaluate, we speculate that a more effective regulation of population abundances could translate into greater stabilization of tropical tree communities and thus contribute to the high local diversity of tropical forests.

Introduction: Changes in the rhizosphere microbiome and metabolites resulting from crop intercropping can significantly enhance crop growth. While there has been an increasing number of studies on various crop combinations, research on the intercropping of tobacco and maize at seedling stage remains limited. Methods: This study is the first to explore rhizosphere effects of intercropping between tobacco and maize seedling stages, we analyzed the nitrogen, phosphorus and potassium nutrients in the soil, and revealed the important effects on soil microbial community composition and metabolite profiles, thereby regulating crop growth and improving soil balance. Results and discussion: Compared with mono-cropping, intercropping increased the biomass of the two crops and promoted the nutrient absorption of nitrogen, phosphorus and potassium. Under intercropping conditions, the activities of sucrase, catalase and nitrate reductase in tobacco rhizosphere soil and the content of available potassium, the activities of nitrate reductase and acid phosphatase in maize rhizosphere soil were significantly increasing. Rhizosphere soil bacterial and fungal communities such as Sphingomonas, Massilia, Humicola and Penicillium respond differently to crop planting patterns, and soil dominant microbial communities are regulated by environmental factors such as pH, Organic Matter, Available Potassium, Nitrate Reductase, and Urease Enzyme. Network analysis showed that soil microbial communities were more complex after intercropping, and the reciprocal relationship between bacteria and fungi was enhanced. The difference of metabolites in soil between intercropping and monocropping system was mainly concentrated in galactose metabolism, starch and sucrose metabolism pathway, and the content of carbohydrate metabolites was significantly higher than that of monocropping soil. Key metabolites such as D-Sucrose, D-Fructose-6-Phosphate, D-Glucose-1-Phosphatel significantly influence the composition of dominant microbial communities such as Sphingomonas and Penicillium. This study explained the effects of intercropping between flue-cured tobacco and maize on the content of soil metabolites and soil microbial composition in rhizosphere soil, and deepened the understanding that intercropping system can improve the growth of flue-cured crops seedlings through rhizosphere effects. [ABSTRACT FROM AUTHOR]

Brown circular stem canker symptom was observed on common bean plants in Mahallat county, Markazi province, Iran, in the summer of 2022. Five identical associated fungal isolates were recovered from the infected plants. Morphological and molecular characterization of the representative isolate (UTR38) using the partial sequence of beta-tubulin, and as well as RNA polymerase II second largest subunit loci was done. The associated fungus was identified as Paramyrothecium roridum. Pathogenicity of the isolate UTR38 was conducted on six-week-old seedling stems of the P. vulgaris cultivar Sunray. The inoculated fungus was also reisolated from the inoculated plants to fulfill the Koch's postulates. According to the results, this is the first report of P. roridum as the causal agent of stem canker disease in P. vulgaris in Iran and worldwide. [ABSTRACT FROM AUTHOR]

Zinc oxide nanoparticle (ZnO NPs) has been used as a fertilizer alternative, although some applications technique and metal-microbial effects should be studied. This research evaluated the bioefficiency of synthetic ZnO NPs in soybean seedlings combined with different water status and with or without PcO6 bacteria. ZnO NPs performed in sand inhibited growth and fluorescence parameters. Still, when soybean seeds were exposed to ZnO NPs seed priming the root mass was increased, mainly in non-drought conditions. Soybean plants cultivated in drought conditions will have compromised development, although was demonstrate soybeans seed inoculation with PcO6 may decrease undesired effects from drought. Also, PcO6 soybean inoculation mitigate metal ZnO toxicity. Here, one of the first positive report about soybean interaction with PcO6 by drought and metal mitigation of toxicity. In addition, the best way to apply ZnO was through seed priming, while sand application was toxic and foliar application had no effects. [ABSTRACT FROM AUTHOR]

High-quality seedlings are one of the key factors in achieving high yield and precocity of blueberries. The inoculation of arbuscular mycorrhizal fungi (AMF) can enhance the development of seedlings in the nursery, ensuring more vigorous seedlings in a shorter time. This study evaluated the effect of inoculation of arbuscular mycorrhizal fungi on the development of 'PowderBlue'blueberryseedlings. The treatments were arranged in a 4 x 2 factorial scheme, in which the first factor was the arbuscular mycorrhizal fungi Gigaspora rosea, Glomus clarum, G. rosea + G. clarum, and a control level without mycorrhizae, while the second factor consisted of usingindole-3-butyric acid(IBA) and a control level without IBA. Semi-hardwood cuttings were planted in pots containing sterilized soil and kept in a greenhouse for 660 days. The percentage of rooted cuttings, plant height, root system length, shoot dry mass, root dry mass, total dry mass, peroxidase (POD) and superoxide dismutase (SOD) enzyme activities, SPAD index, mycorrhizal efficiency and dependence, number of spores, and soil basal respiration were evaluated. Plants inoculated with G. clarum without IBA and inoculated with G. rosea with IBA showed higher dry matter and SOD and POD enzyme activities, but the use of IBA had a negative effect on the fungus. The inoculation of blueberry cuttings with G. clarummay help seedlingdevelopment, thus improving biometric and biochemical parameters. Furthermore, the plant regulator IBAwas essential in establishing the symbiosis between blueberry and the AMF G. rosea. [ABSTRACT FROM AUTHOR]

Background: Spatial clumping of plants results in intense competition. Aims: We analysed the extent of clumping of Proteaceae seedlings across the Cape Floristic Region after fire. Methods: To demonstrate the extent of clumping in 23 species, we analysed the seedling and adult densities in 290 post-fire surveys each of 100 × 1 m2 plots using standard indices of clumping. Key results: We detected clumping of Cape Proteaceae seedlings, whereas parent plants were less clumped. The clumping is not due to limited safe sites for seedlings because the number of plots at a site with at least one seedling was positively related to the number of seedlings at the site. Sites with seedlings were enriched in nutrients relative to those without. Conclusions: The possible benefits of clumping are saturation of granivores and co-location of buried seeds with nutrient-rich patches of fire-derived ash and debris. A cause of clumping is seeds sticking together. Clumping, which is strongly intraspecific, has implications for trait evolution and the dominance of reseeders over resprouters. Strong clumping reduces the usefulness of the widely used seedling:parent index to determine whether fires were favourable or not. Implications: Clumping has implications for understanding seed dispersal distances, seedling versus adult traits, fire responses and demography. Seedlings of Cape Proteaceae tend to occur in clumps and these clumps thin out with time to produce adult stands that are less clumped. We analysed seedling and adult densities and discuss the implications for trait evolution and dominance of reseeders over resprouters of strongly intra-specific clumping. [ABSTRACT FROM AUTHOR]

Daily changes in the content of phytohormones accumulating in the hypocotyls of young sunflower seedlings that grow under a 14/10-h light-to-dark (LD) photoperiod were followed using LC–MS. The objective of the work was to investigate whether the presence of light and light transitions lead to visible changes visible in phytohormone levels on the sixth day after the onset of germination. The LC–MS technique used allowed the simultaneous detection of more than one hundred individual phytohormone derivatives, of which the daily accumulation patterns were determined for nearly fifty members. The daily changes in phytohormone levels followed specific patterns for each phytohormone. There were differences between the daytime and nighttime levels, most likely reflecting the effects of light on phytohormone metabolism. A significant difference was found between cytokinins (CKs) and all other phytohormones, so that CK group of phytohormones may be considered to have a separate role in hypocotyl elongation. Prolonged daytime (postponed dusk) resulted in a rapid disruption of rhythmic hypocotyl elongation and it triggered an acute light stress response that was evident in increased levels of a number of important phytohormones from all groups except CKs. However, this light stress, termed ARELD (Acute Response to Extended Light Duration), was not present in control plants grown under continuous light conditions. The data suggest that sunflower has means to adapt to the potentially stressful conditions of continuous light (LL). The qPCR-RT study of the isoforms of circadian clock-associated genes HaLHY, HaTOC1, HaELF3, and HaPIF3 revealed diurnal rhythms under both LD and LL conditions in which the peaks were synchronized and shifted toward the subjective dawn. [ABSTRACT FROM AUTHOR]

Key message: Cistus ladanifer L. shows an extraordinary plasticity of germination and growth. Fire promotes the regeneration of C. ladanifer by triggering its germination through thermal shock as well as by enhancing its seedling growth through the addition of ashes. On the contrary, stacking of Pinus pinaster Ait. leaf litter may hinder seedling establishment, at least in the first months after germination. Context: Pinus pinaster Ait. is affected by forest fires in the Mediterranean basin. Its extreme flammability is due to the high spatial continuity together with the massive accumulation of leaf litter. Cistus ladanifer L. is a species which is widely distributed in the west Mediterranean region where it can form vast shrublands and flourish under these pinewoods. Although high temperatures associated with the occurrence of fire trigger germination of C. ladanifer, knowledge on how other factors, such as the presence of litter on the forest floor or the ash left after the fire, influence germination and seedling growth is essential to improve land management plans. Aims: The main objective of this study was to determine the effects of different loads of litter from P. pinaster and ash from their combustion on the germination and growth of seedlings of C. ladanifer. Methods: Two experiments were carried out to assess the effect of heat shock (100 °C for 10 min) and two loads of litter and ash from P. pinaster (control, high and low loads of litter, high and low loads of ash) on the germination and growth after 2 and 4 months of C. ladanifer. Results: Heat shock significantly increased the germination of C. ladanifer. In contrast, the addition of litter and ash had no effect on total germination but affected the growth of the seedlings coming from seeds exposed to heat shock. Litter treatments reduced biomass of 2 months seedlings and ash increased biomass of 4 months seedlings. Conclusion: C. ladanifer is a species favoured by fire in different ways depending on the stage of regeneration. Germination is promoted by heat shock while seedling growth is favoured by ash nutrients. In contrast, pine leaf litter hinders seedling growth, although this effect disappears 4 months after germination. Alternative forest management practices to prescribed fires are recommended if preventing the spread of Cistus is a priority. [ABSTRACT FROM AUTHOR]

Climate changes threat global food security and food production. Soil salinization is one of the major issues of changing climate, causing adverse impacts on agricultural crops. Germination and seedlings establishment are damaged under these conditions, so seeds must be safeguard before planting. Here, we use recycled organic tree waste combined with cold (low-pressure) plasma treatment as grain coating to improve the ability of wheat seed cultivars (Misr-1 and Gemmeza-11) to survive, germinate and produce healthy seedlings. The seeds were coated with biofilms of lignin and hash carbon to form a protective extracellular polymeric matrix and then exposed them to low-pressure plasma for different periods of time. The effectiveness of the coating and plasma was evaluated by characterizing the physical and surface properties of coated seeds using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), nuclear magnetic resonance (NMR) spectroscopy, and wettability testing. We also evaluated biological and physiological properties of coated seeds and plants they produced by studying germination and seedling vigor, as well as by characterizing fitness parameters of the plants derived from the seeds. The analysis revealed the optimal plasma exposure time to enhance germination and seedling growth. Taken together, our study suggests that combining the use of recycled organic tree waste and cold plasma may represent a viable strategy for improving crop seedlings performance, hence encouraging plants cultivation in stressed ecosystems. [ABSTRACT FROM AUTHOR]

Ascorbic acid (AsA), an essential non-enzymatic antioxidant in plants, regulates development growth and responses to abiotic and biotic stresses. However, research on AsA's role in cold tolerance remains largely unknown. Here, our study uncovered the positive role of AsA in improving cold stress tolerance in tomato seedlings. Physiological analysis showed that AsA significantly enhanced the enzyme activity of the antioxidant defense system in tomato seedling leaves and increased the contents of proline, sugar, abscisic acid (ABA), and endogenous AsA. In addition, we found that AsA is able to protect the photosynthetic system of tomato seedlings, thereby relieving the declining rate of chlorophyll fluorescence parameters. qRT-PCR analysis indicated that AsA significantly increased the expression of genes encoding antioxidant enzymes and involved in AsA synthesis, ABA biosynthesis/signal transduction, and low-temperature responses in tomato. In conclusion, the application of exogenous AsA enhances cold stress tolerance in tomato seedlings through various molecular and physiological responses. This provides a theoretical foundation for exploring the regulatory mechanisms underlying cold tolerance in tomato and offers practical guidance for enhancing cold tolerance in tomato cultivation. [ABSTRACT FROM AUTHOR]

Ecuadorian cocoa possesses important organoleptic characteristics such as aroma and flavor, called fine and aromatic cocoa. The objective of this study was to evaluate the initial growth responses of young cocoa seedlings to glyphosate in a dose progression in 45 cocoa plants (5 months old), which were transplanted into pots with substrate adjusted to pH 6.0–6.5. Glyphosate doses (0 to 904 g e.e. ha−1) were applied every two weeks, evaluating the impact at 30 and 60 days post-application. Data on shikimate accumulation parameters, chlorophyll content and PSII quantum efficiency were subjected to multivariate analysis using a three-dimensional scatter plot. The results indicated that high concentrations of glyphosate contributed to higher shikimate concentration and lower PSII quantum efficiency. The findings for the variables crop damage, stem height and stem diameter were evaluated by ANOVA. Similarities were reported between the results of the variables height and diameter, and significant differences (p < 0.05) in the variable crop damage for all treatments were also reported. In terms of phytotoxic reaction and growth parameters, the most efficient treatment was DO4, since the seedlings with this dosage showed a low percentage of damage (10%) and the best indices in terms of height and diameter. The least efficient treatment was D15. The control plants (DO1) showed a crop damage of >50% because the absence of control favored weed proliferation. These indications highlight the need to adjust glyphosate doses according to the specific needs of each crop and the development stage of the plant in order to reduce negative effects and maximize potential benefits. [ABSTRACT FROM AUTHOR]

Plant responses to different light and water availability are variable among species and their respective phenotypic plasticity, and the combination between these two abiotic factors can alleviate or intensify stressful effects. This study aimed to evaluate the impacts of exposure time of Cedrela fissilis Vell. seedlings to different water and light availability considering natural radiation variations and the interaction of these factors. Seedlings were submitted to combinations of three shading levels—SH (0, 30 and 70%) and three water regimes based on the water holding capacity (WHC) in the substrate, constituting nine cultivation conditions: T1—0% SH + 40% WHC; T2—0% SH + 70% WHC; T3—0% SH + 100% WHC; T4—30% SH + 40% WHC; T5—30% SH + 70% WHC; T6—30% SH + 100% WHC; T7—70% SH + 40% WHC; T8—70% SH + 70% WHC; T9—70% SH + 100% WHC. C. fissilis seedlings are sensitive to water deficit, here represented by 40% WHC, regardless of exposure time, and when cultivated in full sun even though there are variations in radiation, the stressful effects were enhanced, acting in a synergistic manner. The condition that provided better gas exchange performance and greater total dry mass accumulation for C. fissilis seedlings was 30% shading combined with 100% WHC. C. fissilis seedlings have physiological plasticity and resilience to survive under different water and light conditions. [ABSTRACT FROM AUTHOR]

Rice grown in cadmium (Cd)-contaminated soil, is a potential threat to human health, but exogenous selenium (Se) application on rice can mitigate Cd toxicity. However, the mechanisms underlying Se mitigation of Cd stress in ratoon rice (RR) are still poorly understood. We conducted a pot experiment with moderate Cd-contaminated yellow–brown paddy soil on two rice varieties 'Taoyouxiangzhan' (TX) and 'Liangyou 6326'(LY). For all treatments, 1.0 mg kg−1 sodium selenite solution was added to soil. Treatment T1 was sodium selenite only, and in the other treatments 100 mg L−1 Se solution was sprayed on the leaves at seedling stage (T2), at tillering stage (T3), and in early anthesis stage (T4). Se treatments decreased Cd accumulation in rice grains and herbage. Under foliar spraying 100 mg L−1 Se at the seedling + 1.0 mg kg−1 Se in soil (T2), leaf Cd content decreased 16.95% in the current season and grains content decreased 46.67% in the subsequent season. Furthermore, grain Se content increased 0.94 mg kg−1 for the TX variety combined with the analysis of Cd bio-accumulation factor in grains, and Se treatments effectively decreased Cd grain concentrations due to reduced Cd translocation from roots to grains. TX variety rice showed a more pronounced response to Se treatments than LY. [ABSTRACT FROM AUTHOR]

ABSTRACT Stomata are channels through which plants exchange H2O and CO2 with the external environment. The regulation of stomatal movement has significant impacts on plant growth, development and stress adaptation. Here, we present a maize R2R3−MYB transcription factor, ZmMYB56, which regulates high CO2‐induced stomatal closure in maize seedlings. ZmMYB56 is highly expressed in stomatal guard cells and is negatively regulated by CO2 and HCO3−. Loss of ZmMYB56 function leads to insensitivity to high CO2. As a transcription factor, ZmMYB56 binds to a cis‐acting element in the ZmHLT1 promoter and regulates its expression. ZmHLT1 plays a key role in CO2‐ induced maize stomatal movement, and its absence causes a severe weakening of maize's response to ambient CO2. ZmHLT1 expression is negatively regulated by bicarbonate, which does not occur in Zmmyb56 mutants, highlighting the significance of this regulatory relationship in plant responses to CO2 and HCO3−. Taken together, these results show that ZmMYB56‐regulated ZmHLT1 expression is important for high CO2‐induced stomatal closure in maize. Our findings provide insight into genetic pathways that could be manipulated to improve maize growth and stress tolerance, especially under increasing atmospheric CO2 concentrations. [ABSTRACT FROM AUTHOR]

The neighborhood effect has become an important framework with which to study the mechanisms that maintain the coexistence of tree species. Phylogenetic relatedness among neighboring plants directly affects species coexistence and the maintenance of tree diversity. And some studies have reported that seedling performance is negatively correlated with phylogenetic relatedness, which termed phylogenetic negative density dependence. Soil-borne fungal pathogens affected seedling performance of phylogenetically related host species, i.e., phylogenetic Janzen–Connell effect. Seedlings may be particularly vulnerable to habitat and neighbor characteristics. Although previous studies have demonstrated the influence of neighborhood effects, phylogenetic relatedness, and habitat filtering on seedling survival, growth, and mortality, the effect of variation in these factors on seedling abundance remains unclear. To address this question, we used a 4-ha (200 m × 200 m) and monitored four-year (2020–2023) seedling dataset from a mid-montane humid evergreen broad-leaved subtropical forest in the Gaoligong Mountains, Yunnan, Southwestern China, and which consisted of 916 seedlings belonging to 56 species. The results of generalized linear mixed models showed no significant effect of conspecific adult neighbors on seedling abundance at any of the intervals evaluated. In contrast, we found evidence of phylogenetic distance density dependence in the forests of the Gaoligong Mountains. Specifically, there was a significant positive effect of the relative average phylogenetic distance between heterospecific adult neighbors and focal seedlings on focal seedling abundance in 2020; however, the relative average phylogenetic distance between heterospecific seedling neighbors and focal seedlings had a significant negative effect on seedling abundance over the four-year period (2020–2023). Among the habitat factors, only light (canopy opening) had a negative effect on seedling abundance in all four years. Light resources may be a limiting factor for seedlings, and determine seedling dynamics in subtropical forests. Overall, our results demonstrated that phylogenetic density dependence and habitat filtering affected subtropical seedling abundance. Our findings provide new evidence of the impact of phylogenetic density dependence on seedling abundance in a subtropical mid-montane humid evergreen broad-leaved forest and highlight the need to incorporate the neighborhood effect, phylogenetic relatedness, and habitat factors in models assessing seedling abundance. [ABSTRACT FROM AUTHOR]

The use of high‐quality seeds is essential for reforestation and ecosystem restoration; however, few Andean species have been assessed to determine factors influencing seed quality. Most Andean native tree species used for restoration are propagated from naturally regenerated seedlings or cuttings. We evaluated the seed quality (germination, viability, vigor, and physical characteristics) of a central Peruvian population of the keystone high Andean tree species Polylepis incana (quinual) in relation to the mother tree and microsite characteristics. Our analysis, using 12,912 seeds categorized by weight, included germination tests in incubator, tetrazolium tests, and vigor test (germination in nursery conditions). Results showed a mean germination rate of 30.9 ± 22.4%, with a significant proportion of damaged (38.7%), empty (19.1%), and non‐viable (12.7%) seeds. Heavier seeds exhibited the highest germination, while dasometric variables of the mother tree were not related to seed performance. However, solar incidence and slope negatively impacted germination. We conclude that seed quality may be higher than previously estimated, supporting the need to re‐evaluate and promote the use of seeds for propagating P. incana. Furthermore, since the characteristics of mother trees seem not to be relevant for this species and only solar incidence and terrain slope seem to negatively affect seed quality, we consider it important to change the paradigm from identifying individual seed trees to identifying seed forests. Conservation of natural forests as primary seed sources should be the foundation of future reforestation and restoration efforts in the high Andes. [ABSTRACT FROM AUTHOR]

[Objectives] This paper aimed to clarify the change of nutrient content in Leguminous green manure crops and its impact on soil fertility with none extra chemical fertilizer. [Methods] The experiments were conducted to study the growth and development of four Leguminous green manure crops from October 2021 to May 2022 in field. They were Chinese milk vetch(Astragalus sinicus L.), hairy vetch (Vicia villosa Roth.), broad bean (Vicia faba L.) and common vetch (Vicia sativa L.), respectively. The nutrient contents of nitrogen(N), phosphorus(P)and potassium (K) in green manure crops as well as the soil nutrient content were measured. [Results] The changes in N, P, K nutrient content of different Leguminous green manure crops during the seedling stage and later growth stage were similar. Four Leguminous green manure crops had significantly higher nutrient content at the later growth stage than at the seedling stage, with biomass of dry weight of over 1800 kg·hm-2, making them suitable for flipping. In later growth period, the total N content (3.34%) and total P content (0.29%) of hairy vetch were significantly higher than the others, while the total K content of Chinese milk vetch (3.58%) was the highest and the difference displayed a significant level. The accumulation of N, P and K nutrients in Chinese milk vetch and hairy vetch was relatively high, while that in broad bean and common vetch was relatively low. The pH value of soil did not change with green manure application. After growing Leguminous green manure, the organic carbon content in soil as well as total N, available P and available K contents increased, with a range of 2.71%-29.50%. Among them, the application of Chinese milk vetch to the field could significantly improve soil fertility, and the organic carbon, total N, available P and available K contents increased by 4.04%, 3.40%, 29.50% and 8.22% compared to fallow cultivation, respectively. [Conclusions] Under the condition of disappeared application of chemical fertilizer, Chinese milk vetch was conducive to improving soil fertility. [ABSTRACT FROM AUTHOR]

The interspecific trade‐off between growth versus mortality rates of tree species is thought to be driven by functional biology and to contribute to species ecological niche differentiation. Yet, functional trait variation is often not strongly correlated with growth and mortality, and few studies have investigated the relationships of both traits and niches, specifically encompassing above and belowground resources, to the trade‐off itself. These relationships are particularly relevant for seedlings, which must often survive resource limitation to reach larger size classes.We investigated the functional basis of the interspecific growth–mortality trade‐off and its relationship with ecological niches for seedlings of 14 tree species in a tropical forest in southwest China.We found evidence for an interspecific growth–mortality trade‐off at the seedling stage using 15 functional traits and 15 ecological niche variables. None of the organ‐level traits correlated with growth, mortality, nor the trade‐off, whereas specific stem length (SSL), a biomass allocation trait, was the only trait to have a significant correlation (positive). Moreover, light‐defined niches were not correlated with growth, mortality or the trade‐off, but soil‐defined niches did. Species at the faster growth/higher mortality end of the trade‐off were associated with higher fertility defined by lower soil bulk density and slope, and higher soil organic matter concentration and soil total nitrogen.Our findings indicate the importance of stem elongation and soil fertility for growth, mortality and their trade‐off at the seedling stage in this Asian tropical forest. Our findings contrast with analogous studies in neotropical forests showing the importance of photosynthesis‐related leaf traits related to insolation. Therefore, the functional drivers of demographic rates and trade‐offs, as well as their consequences for ecological niches, can vary among forests, likely owing to differences in biogeography, canopy disturbance rates, topography and soil properties. Moreover, the effects of functional trait variation on demographic rates and trade‐offs may be better revealed when biomass allocation is accounted for in a whole‐plant context. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The efficient conversion of tissues into reproductive success is a crucial aspect affecting the evolution of life histories. Masting, the interannually variable and synchronous seed production in perennial plants, is a strategy that can enhance reproductive efficiency by mitigating seed predation and pollen limitation. However, evaluating benefits is insufficient to establish whether efficiency has improved, as such assessments neglect the associated costs of masting, particularly during the critical seed‐to‐seedling stage. We conducted a parentage analysis of seedlings and adults in a population of 209 Sorbus aucuparia trees, monitored over 23 years, providing pioneering documentation of the effects of masting on the fitness of individual trees beyond the seed stage. Our results show high costs of interannual variation that can be mitigated by high synchrony and reveal the existence of phenotypes that appear to reap the benefits of masting while avoiding its costs through regular reproduction. [ABSTRACT FROM AUTHOR]

The Sideritis genus includes over 150 species primarily found in the Mediterranean basin, including the S. clandestina subsp. pelopponesiaca from the Peloponnese and S. scardica from North and Central Greece. In vitro seed germination has proven effective for conserving and amplifying the genetic diversity of endangered species such as Sideritis. This study aimed to optimize in vitro germination and seedling growth of S. scardica and S. clandestina subsp. pelopponesiaca under different lighting conditions at 22 °C, including white fluorescent lamps (WFL-BG-40) and LEDs (LED-BGYOR-40, LED-BR-40, LED-BR-80, LED-BR-120) all under a 16-h light/8-h dark photoperiod (WFL: white fluorescent light, B:blue, G:green, Y:yellow, O:orange, R:red, 40–80–120 μmol m−2 s−1), along with a 24-h dark treatment. The results indicated that LED-BR-80 combined with 250 mg L−1 GA3 in the MS medium promoted best germination (40%, day 55) and shoot proliferation in S. clandestina subsp. pelopponesiaca. Conversely, 5-year-old cold stratified S. scardica seeds showed higher germination rates (80%) and robust seedling growth under LED-BGYOR-40 with 250 mg L−1 GA3, particularly thriving in LED-BR-120 for increased shoot height and root number. This is the first report of the efficacy of LED technology in optimizing in vitro conditions for Sideritis species, crucial for their conservation and sustainable commercial cultivation. [ABSTRACT FROM AUTHOR]

Seedling growth is one of the most important stages for the establishment of natural and artificial regeneration. For the first time, the initial growth and biomass allocation of seedlings germinated from cryostored seeds of Parkia nitida were analyzed. P. nitida is an economically and ecologically important timber tree species distributed in Central and South America. Cryostored seeds germinated quickly after priming by scarifying a part of the seedcoat with emery paper, reaching a germination percentage of 94%. Thirteen weeks after germination, the seedlings grew to a height of 16.5 to 60.0 cm. The results of our study, under different day/night alternating culture temperatures, showed that culture temperature had a direct correlation with seedling growth, total biomass allocation, and biomass partitioning. The greatest growth (height, diameter, and number of node sections) and greatest biomass allocation (leaf, stem, and root weight) were recorded under alternating temperatures of 30/25 °C, and these decreased with decreasing culture temperatures to 25/20 °C and 20/15 °C. Shoot:Root (S:R) ratios also decreased with decreasing culture temperatures, but a statistically significant difference (p < 0.05) was only observed between 20/15 °C and 30/25 °C. However, significant differences were not observed in Photosynthetic:Non-photosynthetic organ ratios among the different alternating culture temperatures. This study provides fundamental information for the production of good-quality seedlings of the fast-growing tropical trees of the legume family. [ABSTRACT FROM AUTHOR]

The growth status of winter wheat seedlings during the greening period is called the seedling situation. Timely and accurate determinations of the seedling situation type are important for subsequent field management measures and yield estimation. To solve the problems of low-efficiency artificial classification, subjective doping, inaccurate classification, and overfitting in transfer learning in classifying the seedling condition of winter wheat seedlings during the greening period, we propose an improved ConvNeXt winter wheat seedling status classification and identification network based on the pre-training–fine-tuning model addressing over-fitting in transfer learning. Based on ConvNeXt, a SETFL-ConvNeXt network (Squeeze and Excitation attention-tanh ConvNeXt using focal loss), a winter wheat seedling identification and grading network was designed by adding an improved SET attention module (Squeeze and Excitation attention-tanh) and replacing the Focal Loss function. The accuracy of the SETFL-ConvNeXt reached 96.68%. Compared with the classic ConvNeXt model, the accuracy of the Strong class, First class, and Third class increased by 1.188%, 2.199%, and 0.132%, respectively. With the model, we also compared the effects of different optimization strategies, five pre-training-fine-tuning models, and the degree of change in the pre-trained model. The accuracy of the fine-tuning models trained in the remaining layers increased by 0.19–6.19% using the last three frozen blocks, and the accuracy of the pre-trained model increased by 3.1–8.56% with the least degree of change method compared with the other methods. The SETFL-ConvNeXt network proposed in this study has high accuracy and can effectively address overfitting, providing theoretical and technical support for classifying winter wheat seedlings during the greening period. It also provides solutions and ideas for researchers who encounter overfitting. [ABSTRACT FROM AUTHOR]

The production of lettuce has increased significantly due to the use of hydroponic systems that rely on substrates. Disposal and acquisition costs present problems, necessitating the identification of sustainable alternatives. The present study aimed to evaluate the use of Eichhornia crassipes (water hyacinth) dry matter in a substrate for the formation of lettuce seedlings. Water plants were collected to obtain their dry matter, and twelve mixtures were formed with Sphagnum and perlite. Mixtures with more water hyacinth dry matter exhibited greater water retention. However, these mixtures also lost water at a faster rate than those containing primarily Sphagnum dry matter did. Higher percentages of germination were detected in the mixtures with water hyacinth dry matter, but these seedlings also presented higher concentrations of proline, such as 16.0 µg mL−1. The mixtures with water hyacinth dry matter presented the highest ion concentrations, mainly at high levels of humidity. Mixtures with a high proportion of water hyacinth dry matter had a greater water retention capacity and a high percentage of lettuce seed that germinated. The mixtures with a higher proportion of Sphagnum led to greater root length, greater concentrations of chlorophyll in cotyledonary leaves, and better morphological development of the seedlings. [ABSTRACT FROM AUTHOR]

Salt–alkaline stress is one of the most stressful occurrences, causing negative effects on plant development and agricultural yield. Identifying and utilizing genes that affect alkaline tolerance is an excellent approach to accelerate breeding processes and meet the needs for remediating saline–alkaline soil. Here, we employed a mapping population of 176 recombinant inbred lines (RILs) produced from a cross between alkali-tolerant Longdao5 and alkali-sensitive Zhongyouzao8 to identify the quantitative trait loci (QTLs) determining alkali tolerance at the seedling stage. For the evaluation of alkali tolerance, the recovered seedling's average alkali tolerance index (ATI), root number (RN), root length (RL), seedling dry weight (SW), root dry weight (RW), and seedling height (SH) were assessed, together with their relative alkaline damage rate. Under alkaline stress, the ATI was substantially negative connected with the root number, seedling height, seedling dry weight, and root dry weight; however, it was considerably positive correlated with the relative alkaline damage rate of the root number and root dry weight. A total of 13 QTLs for the root number, root length, seedling height, seedling dry weight, root dry weight, and alkali tolerance index under alkaline stress were identified, which were distributed across chromosomes 1, 2, 3, 4, 5, 7, and 8. All of these QTLs formed two QTL clusters for alkali tolerance on chromosome 5 and chromosome 7, designated AT5 and AT7, respectively. Nine QTLs were identified for the relative alkaline damage rate of the root number, root length, seedling height, seedling dry weight, and root dry weight under alkali stress. These QTLs were located on chromosome 2, 4, 6, 7, 8, 9, and 12. In conclusion, these findings further strengthen our knowledge about rice's genetic mechanisms for alkaline tolerance. This research offers clues to accelerate breeding programs for new alkaline-tolerance rice varieties. [ABSTRACT FROM AUTHOR]

The production of oak seedlings in intensive crops involves the modification of natural conditions, namely the degree of humidity, through artificial irrigation, which favors the appearance of the pathogen Erysiphe alphitoides, responsible for the Oak Powdery Mildew (OPM) disease. Thus, it is necessary to identify new substances and technologies to control OPM. In this sense, new products approved by the European Union (EU) and Forest Stewardship Council (FSC) were identified, both synthetic and, a great novelty, biological (based on chito-oligosaccharides-oligogalacturonans: COS-OGA). In order to quantify the results, a correlation was made with climatic factors, by sampling data related to temperature and relative humidity with Data Logger devices. The obtained results suggest that OPM has a high virulence in the temperature range of 20 to 30 °C; at a relative humidity above 75%. The data obtained from the field experiments show that the synthetic products controlled OPM with an effectiveness between 70% and 95%, and the biological product behaved almost similarly, between 60% and 90%, which creates high opportunities for environmentally friendly control of forest pathogens. [ABSTRACT FROM AUTHOR]

Carica papaya is a significant fruit crop solely grown from seeds for commercial purposes. Atmosphere, temperature, water, light, and substrate utilized are some of the variables that might affect a seed's ability to germinate. Papaya seed germination is frequently described as unpredictable, sluggish and partial. For papaya growers, increasing the degree of germination to enhance the production of healthier seedlings is a challenge owing to the higher seed cost. The present experiment aimed to determine the effect of various growing media combinations in Red Lady-786 using a completely randomized design (CRD). The experiment comprised nine treatment combinations. Four different growing media: soil, vermicompost, coco peat and perlite were used in different treatment combinations viz. T1: control; T2: soil + vermicompost (80% + 20%); T3: soil + vermicompost (60% + 40%); T4: soil + vermicompost + cocopeat (80%+10%+10%); T5: soil + vermicompost + cocopeat (60%+20%+20%); T6: soil + vermicompost + perlite (80%+10%+10%); T7: soil + vermicompost + perlite (60%+20%+20%); T8: soil + vermicompost + cocopeat + perlite (70%+10%+10%+10%+10%) and T9: soil + vermicompost + cocopeat + perlite (40%+20%+20%+20%). T9 was the most significant combination for early germination among all the treatment combinations. The application of T9 recorded maximum root length (7.70 cm), maximum shoot length (13.35 cm), maximum per cent initiation of germination (92.5%), high seed vigour (1947.75) and maximum height of the seedlings (21.05). The study revealed that for better germination and seedling growth, the application of treatment combination T9, which influenced the germination properties of papaya seedlings, can be exploited commercially. [ABSTRACT FROM AUTHOR]

Rootstocks/scions with potential for commercial growing, either for the industry or fresh market, have been one of the main objectives of the fruit breeding programs. Fruit crop breeding has impediments like polyembryony (PE) which is otherwise desirable for clonal plant propagation. In nature PE exist in some fruit crops like citrus, mango, jamun, rose apple, almond etc. In polyembryonic crops, there is an occurrence of the more than one embryo in seed and subsequently numerous seedlings emerge from that single seed. The mother type seedlings are considered nucellar are often vigorous in nature as compared to zygotic ones. In this review, the classification, genetic basis and mechanism of PE has been discussed. In current review, morphogenetic authentication of seedling from polyembronic seed has been discussed in the light of recent research. Transcriptional pathway along with the inheritance pattern and molecular breeding aspects of PE has also been summarized. [ABSTRACT FROM AUTHOR]

In order to explore the effect of chemical treatment on adventitious bud formation of P. koraiensis top pruned seedlings, 5-year-old P. koraiensis bare root seedlings were used as experimental materials. After top pruning at the beginning of the growing season, different chemicals were sprayed every 15 days (GA3 (200, 500, 1 000 mg/L), 6-BA (100, 300, 500 mg/L), KMnO4 (0. 1%, 0. 2%, 0. 3%)). Using spray water treatment as a control, the formation of adventitious buds of P. koraiensis seedlings treated with different chemicals was investigated. The results showed that the chemical treatment (except 1 000 mg/L GA3 and 0. 1% KMnO4) increased the incidence of adventitious buds of P. Koraiensis top pruned seedlings. Compared with the control, the sprouting rate increased by 5. 72% to 48. 58%, and the number of sprouting strip increased by 15. 37% to 175. 94%. The suitable concentration of GA3 to promote P. koraiensis top pruned seedlings was 200 mg/L, which can increase the sprouting rate by 34. 28%, and the number of sprouting strip by 33. 63%. The suitable concentration of 6-BA to promote P. koraiensis truncated seedlings was 500 mg/L, which can increase the sprouting rate by 48. 58%, and the number of sprouting strip by 175. 94%. The suitable concentration of KMnO4 to promote P. koraiensis top pruned seedlings was 0. 2%, which can increase the sprouting rate by 42. 85%, and the number of sprouting strip by 95. 18%. The better effect of promoting adventitious bud formation can be obtained by using 500mg/L 6-BA to treat P. koraiensis top pruned seedlings. [ABSTRACT FROM AUTHOR]

Apples often exhibit bitter pits in response to metabolic disorders during ripening and storage; however, the mechanisms underlying the bitter pit (BP) development remain unclear. Here, metabolome and transcriptome analyses were performed to investigate BP pulp of 'Fuji'. Two auxin-response genes, MdGH3.1 and MdSAUR36, were screened. Their expression as well as the auxin content in BP pulp were found to be higher than those in healthy pulp (P < 0.01). In the field, excess CO(NH2)2 increased the incidence of BP. Moreover, the auxin content and MdGH3.1 expression increased in apples after nitrogen fertilization. On Day 30 before harvest, the two genes were transiently transferred to the fruit, and 20.69% and 23.21% of BP fruits were harvested. After 10 μmol.L-1 auxin was infiltrated at low pressure into postharvest fruit, the increase in MdGH3.1 expression occurred earlier than that in MdSAUR36. MdGH3.1 increased the expression of MdSAUR36, but MdSAUR36 did not increase expression of MdGH3.1. Therefore, we suggest that MdGH3.1 acts upstream of MdSAUR36 during BP formation and that these genes induce BP formation by regulating auxin and phenylpropanoid biosynthesis. [ABSTRACT FROM AUTHOR]

Self-rooted apple stock is widely used for apple production. However, the shallowness of the adventitious roots in self-rooted apple stock leads to poor performance in the barren orchards of China. This is because of the considerable difference in the development of a gravitropic set-point angle (GSA) between self-rooted apple stock and seedling rootstock. Therefore, it is crucial to study the molecular mechanism of adventitious root GSA in self-rooted apple stock for breeding self-rooted and deep-rooted apple rootstock cultivars. An apple auxin response factor MdARF19 functioned to establish the adventitious root GSA of self-rooted apple stock in response to gravity and auxin signals. MdARF19 bound directly to the MdPIN7 promoter, activating its transcriptional expression and thus regulating the formation of the adventitious root GSA in 12-2 self-rooted apple stock. However, MdARF19 influenced the expression of auxin efflux carriers (MdPIN3 and MdPIN10) and the establishment of adventitious root GSA of self-rooted apple stock in response to gravity signals by direct activation of MdFLP. Our findings provide new information on the transcriptional regulation of MdPIN7 by auxin response factor MdARF19 in the regulation of the adventitious root GSA of self-rooted apple stock in response to gravity and auxin signals. [ABSTRACT FROM AUTHOR]

Papaya (Carica papaya L.) is a widely cultivated and consumed fruit. When forming papaya seedlings, the combination of the ideal substrate to obtain quality seedlings is essential. The objective of this study was to evaluate the effect of a combination of substrates formulated with coconut fiber and doses of calcareous algae on the initial growth of papaya seedlings (Carica papaya L.). The experimental design was completely randomized in a 3 × 5 factorial arrangement, with five replications. The treatments consisted of the following substrate formulations: full coconut fiber + Gypsum; coconut fiber powder + NPK (15-10-10); coconut fiber powder + Gypsum; and doses of calcareous algae (0, 15, 30, 45 and 60 mg dm−3) applied as cover. The plant height, stem diameter, leaf area, number of leaves, shoot dry mass, root length and dry mass, and relative chlorophyll content (Chlorophyll A and Chlorophyll B) at 40 days of application of calcareous algae were evaluated. Substrates formulated with coconut fiber powder plus gypsum associated with calcareous algae doses are a great alternative in the production of papaya seedlings, stimulating plant height, stem diameter, number of leaves, and root dry mass. [ABSTRACT FROM AUTHOR]

Finding methods, which may alleviate drought stress on the growth and biochemical properties of safflower (Carthamus tinctorius L.), as one of the important medicinal plants, is of significance. The objective was to alleviate drought stress on seed germination, seedling growth, and biochemical properties of different genotypes of safflower using 24-epibrassinosteroid (EBR). The experiments, conducted in the greenhouse in 2014 and 2015, were factorial on the basis of a complete randomized block design with three replicates. Drought stress (85 (S1), 65 (S2) and 45% (S3) of field capacity), genotype (Goldasht, Faraman and Sina), and the foliar application of 24-epibrassinosteroid (EBR) (0 and 10−7 M) were tested. Seed germination indices, seedling growth and biochemical properties were determined. The results indicated the significant effects of drought stress on the measured parameters including seed germination, which was the most sensitive stage. The use of EBR significantly increased seed germination and seedling growth, nutrient uptake and grain protein and oil contents, at different levels of stress. EBR significantly enhanced grain N (7.3%) and P (0.5%) uptake, as well as protein percentage (38.7%), even at the highest level of stress (S3), to the levels which were comparable with S1 and S2. The use of EBR may improve seed germination and the growth of safflower seedlings under drought stress conditions by affecting the physiological properties, mainly related to the mechanisms of protein production. [ABSTRACT FROM AUTHOR]

Water deficit stress is one of the key determinants causing crop yield losses globally. The present study was conducted to effectively screen Desi chickpea genotypes based on early dehydration tolerance-related traits as a tool for further evaluation in field experiments. Sixty-four genotypes of Desi chickpea were assessed under progressive water deficit stress, resulting in high variability in early growth characteristics and traits. The clustering analysis with UPGMA, separated the genotypes into three major groups, in accordance with biplot analysis grouping. The highest root length density was observed in the MCC438 genotype with an 18.6-fold increase compared to MCC884 which showed the lowest root length density among all analyzed chickpea genotypes. The genotypes MCC32 and MCC539 produced the higher shoot and root dry weight, while MCC884 showed the lowest value (with 12- and 32.5-fold differences, respectively). Ten genotypes showed differences in terms of their overall response to the water deficiency stress, including eight tolerant genotypes (MCC320, MCC418, MCC425, MCC438, MCC539, MCC540, MCC560, MCC576) and two susceptible ones (MCC433 and MCC897), were selected for further investigation of various growth and physio-biochemical traits based on drought response indices. A clear distinction was observed among ten analyzed genotypes for some physio-biochemical traits, indicating their tolerant responses to drought stress. Drought-tolerant candidate genotypes showed higher indices of seedling growth parameters, proline content, RWC, membrane stability, and root-to-shoot ratio in comparison to drought-susceptible candidate genotypes. The genotypes MCC425, MCC438, MCC418, and MCC539 were found more drought tolerant in the seedling stages, whereas genotype MCC433 was more sensitive. These results were consistent with what was obtained in our preliminary study. However, these results should be addressed further in the field conditions. [ABSTRACT FROM AUTHOR]

The stress-protective effect of melatonin (N-acetyl-5-methoxytryptamine) on plant cells is mediated by key signaling mediators, in particular calcium ions and reactive oxygen species (ROS). However, the links between changes in calcium and redox homeostasis and the formation of adaptive responses of cultivated cereals (including wheat) to the action of high temperatures have not yet been studied. In the present study, we investigated the possible involvement of ROS and calcium ions as signaling mediators in developing heat resistance in wheat (Triticum aestivum L.) seedlings and activating their antioxidant system. Treatment of 3-day-old etiolated seedlings with melatonin solutions at concentrations 0.01–10 µM increased their survival after exposure to 45 °C for 10 min. The most significant stress-protective effect was exerted by melatonin treatment at 1 µM concentration. Under the influence of melatonin, a transient enhancement of superoxide anion radical (O2•–) generation and an increase in hydrogen peroxide content were observed in roots, with a maximum at 1 h. Four hours after treatment with melatonin, the activity of catalase and guaiacol peroxidase increased in roots, while the activity of superoxide dismutase did not change significantly. After exposure to 45 °C, the activity of catalase and guaiacol peroxidase was higher in the roots of melatonin-treated wheat seedlings, and the indices of ROS generation, content of the lipid peroxidation product malonic dialdehyde, and cell membrane damage were lower than in control seedlings. Melatonin-induced changes in root ROS generation and antioxidant enzyme activities were eliminated by pretreatment with the hydrogen peroxide scavenger dimethylthiourea (DMTU), NADPH oxidase inhibitor imidazole, and calcium antagonists (the extracellular calcium chelator EGTA and phospholipase C inhibitor neomycin). Treatment with DMTU, imidazole, EGTA, and neomycin also abolished the melatonin-induced increase in survival of wheat seedlings after heat stress. The role of calcium ions and ROS, generated with the participation of NADPH oxidase, as signaling mediators in the melatonin-induced antioxidant system and heat stress resistance of wheat seedlings have been demonstrated. [ABSTRACT FROM AUTHOR]

In order to establish protocols that can contribute to the propagation of medicinal plants, this study evaluated the effect of hydropriming and substrates on the emergence and production of Calendula officinalis L. seedlings. Seeds were submitted or not to hydropriming for 24 hours, and subsequent sowing in four substrates: S1) 100% Dystroferric Red Latosol -- DRL, S2) DRL + coarse sand (1:1 v/v), S3) DRL + Tropstrato® commercial substrate (1:1 v/v) and S4) 100% Tropstrato®, and kept in greenhouse with 50% shading. Higher emergence percentage in substrates with the presence of DRL was observed. Seed hydropriming impaired seedling emergence, but contributed to root growth, biomass production and seedling quality. The 100% Tropstrato® substrate favored higher dry mass production and seedling quality. Positive linear correlation (≥ 0.70) was observed between shoot and root growth characteristics with biomass production and Dickson's quality index. Principal component analysis explained 78.95% of the experimental variance, excluding the first count and the shoot/root ratio with low representativeness. In the cluster analysis of Euclidean distances, seedlings with the greatest similarity were those produced with 100% DRL and DRL + Tropstrato® with and without hydropriming, respectively. Dystroferric Red Latosol is recommended pure or combined with Tropstrato® for the production of C. officinalis L seedlings, and the hydropriming impaired seedling emergence characteristics. [ABSTRACT FROM AUTHOR]

This study determined how temperature affected the early growth of seedlings of Calobota sericea (Thunb.) Boatwr. & B.-E.van Wyk. One-month-old C. sericea seedlings were grown at constant temperatures of 2.5, 5, 10 and 20 °C for 30 days. After 30 days the plants were removed and shoot length, root length, stem thickness, number of leaves, middle leaflet length, leaf width, petiole length, shoot fresh and dry mass, and cell membrane stability through electrolyte leakage from the leaves, and shoot water content were measured. Results showed that the optimum temperature for C. sericea seedling growth was approximately 10 °C. Significant seedling mortality was observed at 20 °C, while no mortality was observed between 2.5 and 5 °C, and less than 4% of seedlings died at 10 °C. The majority of measured morphological variables in this study increased significantly from 2.5 °C and 5 °C, reaching a maximum at 10 °C before decreasing significantly at 20 °C. Electrolyte leakage from leaves was significantly more at 2.5 °C and at 20 °C, suggesting that seedlings were more stressed at these temperatures. In conclusion, even though C. sericea has a wide optimum germination temperature range, early seedling growth requires a narrow temperature range for optimum growth and development. [ABSTRACT FROM AUTHOR]

Melatonin (MT) is a multifunctional hormone that enhances crop resilience against various abiotic stresses. However, its regulatory mechanism of osmotic tolerance in forage oats (Avena sativa) plants under water-limited scenarios is still unclear. This study aimed to delineate the impact of MT pretreatment on the morphological, physiological, and biochemical functions of oat seedlings under osmotic stress. Our findings demonstrated that exogenous treatment of MT noticeably elevated leaf area while decreasing the root/shoot ratio of oat seedlings subjected to osmotic stress. Osmotic-induced 38.22% or 48.37% decrease in relative water content could be significantly alleviated by MT pretreatment on day 7 or day 14, respectively. MT treatment also significantly mitigated osmotic-induced decreases in photosynthetic parameters including net photosynthetic rate, stomatic conductance, and intercellular CO2 concentration as well as various chlorophyll fluorescence parameters, which could contribute to enhanced accumulations of free proline and soluble sugars in seedlings after being subjected to a prolonged duration of osmotic stress. Furthermore, MT markedly improved antioxidant enzyme activities including superoxide dismutase, ascorbate peroxidase, catalase, and peroxidase along with the accumulation of ascorbic acid contributing to a significant reduction in reactive oxygen species under osmotic stress. In addition, the MT application induced a 978.12%, 33.54%, or 30.59% increase in endogenous MT, indole acetic acid, or gibberellic acid content under osmotic stress but did not affect the accumulation of abscisic acid. These findings suggest that an optimal concentration of MT (100 μmol·L−1) could relieve osmotic stress via improvement in osmotic adjustment, the enzymatic antioxidant defense system, and endogenous hormonal balance, thereby contributing to enhanced photosynthetic functions and growth of oat seedlings under water-limited conditions. [ABSTRACT FROM AUTHOR]

Cold acclimation before winter has been shown to enhance the cold tolerance of evergreen conifers, including Pinus massoniana Lamb., a characteristic heteroblastic foliage tree in the conifer. In the initial growing season of P. massoniana, both primary needle seedlings (PNSs) and secondary needle seedlings (SNSs) are generated. While previous research has highlighted differences in the morphological structure and photosynthetic physiological functions of primary and secondary needles, their response to cold acclimation remains poorly understood. This study aimed to investigate the changes in morpho-anatomical structure, starch grain accumulation, and lignin deposition in the roots, stems, and leaves of PNSs and SNSs during cold acclimation using solid potassium iodide and hydrochloric acid phloroglucinol double-staining techniques. The results revealed that, during cold acclimation, the leaves and stems of PNSs exhibited sensitivity to low-temperature stress, resulting in noticeable shrinkage and fracture of mesophyll and cortical parenchyma cells. Furthermore, the early stages of cold acclimation promoted the accumulation of starch grains and lignin in the seedling tissues. In contrast to PNSs, the leaves and stems of SNSs exhibited a shorter cold acclimation period, attributed to the hydrolysis of starch grains in the epidermal cell walls and the transformation of xylem lignin, which supports cell structure stability and enhances cold resistance. In conclusion, these findings suggest that SNSs displayed a superior cold resistance potential compared to PNSs following cold acclimation, providing a significant theoretical basis for the further screening of cold-tolerant germplasm resources of P. massoniana and the analysis of cold resistance traits in heteroblastic foliage. [ABSTRACT FROM AUTHOR]

A monoacylglycerol, α-(7Z,10Z,13Z)-hexadeca-7,10,13-trienoic acid monoglyceride, extracted from leaves of Japanese radish (Raphanus sativus) has been reported as an anti-bolting compound (ABC); however, the mechanism how ABC inhibits the plant bolting has been remained to be elucidated. In this paper, it was found that exogenous applications of ABC led Arabidopsis thaliana seedlings decrease transcriptional levels of AtKO and increase those of AtGA2ox to reduce endogenous levels of gibberellins (GAs) to retard A. thaliana growth, whose physiological phenomena were counteracted by exogenous applications of ent-kaurenoic acid and GA3, respectively. Furthermore, α-oleanolic acid monoglyceride having both activities of supressing KO and enhancing GA2ox inductions retarded A. thaliana growth post germination, although α-palmitic acid monoglyceride having only the effect of supressing KO induction was not enough to suppress the growth. These experimental data supported the idea that dual function was essential for ABC to show biological activity. [ABSTRACT FROM AUTHOR]

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Scots pine (Pinus sylvestris L.) has higher early growth rates than Norway spruce (Picea abies (L.) H. Karst.). To help efforts to understand possible reasons for this difference and identify appropriate regeneration methods, we labeled seedlings with 15N in the nursery to probe nitrogen (N) uptake and retranslocation in Scots pine and Norway spruce seedlings at both harsh and fertile sites in southern and northern Sweden. For this, 15N dilution was measured during the first two years after planting. We also examined the potential N2-fixation capacity in fine roots after 5–7 growing seasons. Use of 15N-labeled seedlings enabled clear discernment of contributions of uptake of new N and retranslocation of old N to new foliage. Scots pine seedlings had higher proportions of N derived from uptake (Ndfu) than Norway spruce seedlings, and higher growth. Scots pine seedlings were less responsive to site preparation treatments compared to Norway spruce that has a greater need for appropriate silvicultural measures to grow well. After the second growing season, the contribution of N derived from retranslocation (Ndfr) to N in new foliage had diminished to 10–20% at all except the harshest site, where both species were more dependent on Ndfr. The potential N2-fixation capacity in fine roots of the two species differed, but in both cases the contribution of N2-fixation to N-acquisition was negligible. [ABSTRACT FROM AUTHOR]

Previous studies examining the influence of understory shrubs and light transmittance through the canopy (LT) (%) on seedling establishment of desired species and litter decomposition have reported inconsistent findings. Uncertainty still also remains about the effects of understory junipers (Juniperus oxycedrus L. subsp. oxycedrus) and LT on survival and growth of black pine (Pinus nigra Arnold.) seedlings as well as on litter decomposition across species' geographical range. Thus, this study aimed to examine the influence of understory junipers and LT on the growth and survival of black pine seedlings. Moreover, how junipers and LT affect litter decomposition was also monitored for eighteen months. Survival and growth of seedlings were most significantly affected by LT and understory junipers. LT and junipers negatively affected the survival of black pine seedlings. LT increased root-collar diameter (RCD) growth of the seedlings, while the RCD growth rate decreased with the presence of understory junipers. Moreover, the influences of LT and junipers on litter mass loss were mainly statistically significant; the presence of junipers and increasing LT in understory retarded litter decomposition. The findings may help our knowledge of ecological processes such as litter decomposition and seedling establishment in black pine forests. The results would also provide important guidance for evaluating the effects of overstory thinning (i.e., providing light to understory) and removing junipers on the ecological processes associated with litter decomposition and seedling recruitment in a black pine stand. [ABSTRACT FROM AUTHOR]

Aiming at the current peanut pickup combine harvester seedling vines crushing mechanism operation qualified seedling length rate is low, the impurity rate is high, and the seedling vines crushing mechanism is optimized design. On the basis of the material characteristics of peanut seedling vines, taking the crushing mechanism as the research carrier, the interaction mechanism of the seedling vine mechanism was analyzed. Establish the mechanical model and motion trajectory model in the crushing process, simulate the peanut seedling vines crushing process based on the discrete element method, analyze the influence of the cutter shaft rotational speed, movement speed, and bending angle on the crushing of peanut seedling vines, and establish the regression model, and the results of the research show that the influence factors in the main order of priority are: knife shaft speed > movement speed > bending angle The optimal parameter combination is knife shaft speed 2171.94 r/min, movement speed 0.79 m/s, and bending angle 45°. According to the field test conditions, it is determined that the knife shaft rotational speed of 2170 r/min, movement speed of 0.8 m/s, and bending angle of 45° can make the peanut seedling vines crushing mechanism of the work performance to achieve a qualified seedling length rate of 97.292%, the rate of impurity content of 2.746%, and the error with the predicted value is less than 2%, which indicates that this study can provide a reference for the optimal design of the seedling vines crushing mechanism of the peanut pickup combine harvester. [ABSTRACT FROM AUTHOR]

Timely and accurate acquisition of cotton seedling information is crucial for seedling replenishment, yield increase, and effective cotton field management. This study proposes a cotton seedling recognition model and weed removal method for high-resolution UAV (Unmanned Aerial Vehicle) remote sensing images. First, the image information of cotton seedlings is enhanced by calculating the remote sensing index and using threshold segmentation. Second, the recognition model is constructed based on the spatial morphological characteristics of cotton seedlings, with weed interference removed using the straight-line method. Finally, the growth condition of cotton seedlings in farmland is comprehensively evaluated by calculating the seedling emergence rate and coverage rate. The experimental results show that: (1) the combination of the GLI (Green Leaf Index) and Otsu threshold segmentation algorithm effectively distinguishes cotton seedlings from the soil background and accurately portrays cotton seedling contours, further enhancing image information; (2) the proposed recognition model achieves an average overall accuracy of 95.75%, making it a practical method for cotton seedling recognition; and (3) the overall growth condition of cotton seedlings in the study area is good, enabling farmers to apply appropriate seedling replenishment and fertilizer based on the comprehensive cotton evaluation map to further improve the final cotton yield. This study aims to provide new research ideas for crop seedling identification and serve as a reference for the practical application of UAVs in crop monitoring. [ABSTRACT FROM AUTHOR]

Accurate segmentation of the stem of pumpkin seedlings has a great influence on the modernization of pumpkin cultivation, and can provide detailed data support for the growth of pumpkin plants. We collected and constructed a pumpkin seedling point cloud dataset for the first time. Potting soil and wall background in point cloud data often interfere with the accuracy of partial cutting of pumpkin seedling stems. The stem shape of pumpkin seedlings varies due to other environmental factors during the growing stage. The stem of the pumpkin seedling is closely connected with the potting soil and leaves, and the boundary of the stem is easily blurred. These problems bring challenges to the accurate segmentation of pumpkin seedling point cloud stems. In this paper, an accurate segmentation algorithm for pumpkin seedling point cloud stems based on CPHNet is proposed. First, a channel residual attention multilayer perceptron (CRA-MLP) module is proposed, which suppresses background interference such as soil. Second, a position-enhanced self-attention (PESA) mechanism is proposed, enabling the model to adapt to diverse morphologies of pumpkin seedling point cloud data stems. Finally, a hybrid loss function of cross entropy loss and dice loss (HCE-Dice Loss) is proposed to address the issue of fuzzy stem boundaries. The experimental results show that CPHNet achieves a 90.4% average cross-to-merge ratio (mIoU), 93.1% average accuracy (mP), 95.6% average recall rate (mR), 94.4% F1 score (mF1) and 0.03 plants/second (speed) on the self-built dataset. Compared with other popular segmentation models, this model is more accurate and stable for cutting the stem part of the pumpkin seedling point cloud. [ABSTRACT FROM AUTHOR]

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Generally, orchids highly depend on specific fungi for seed germination and subsequent seedling development in nature. For medicinal orchids, obtaining compatible fungi is prerequisite for imitation of wild cultivation and conservation. In this study, the two important traditional Chinese medicinal orchids, Pleione bulbocodioides and Bletilla striata, were studied to screen out effective fungi for seed germination and seedling development. P. bulbocodioides seeds germinated and formed protocorms in all fungal and control treatments, but seedlings only developed in fungal Serendipita officinale (SO) and S. indica (SI) treatments and nutrient-rich medium MS treatment. At 90 days after incubation, the percentages of seedlings were 34.83 ± 3.4% and 27.59 ± 3.5% in SO and SI treatments, which were significantly higher than the MS treatment (18.39 ± 2.0%; all P < 0.05). At this stage, most seedlings in SO and SI treatments bore two leaves (Stage 5), and pelotons inside the basal cells of seedlings were clearly observed. For B. striata, seeds germinated up to seedlings with or without fungus, but seedlings developed rapidly in SI treatment. At 90 days after incubation, the percentage of seedlings in SI treatment reached 77.90 ± 4.1%, but was significantly lower than the nutrient-poor medium OMA treatment (85.18 ± 3.7%; P < 0.01), however, the seedlings in SI treatment were stronger than the seedlings in OMA treatment. The results suggested that P. bulbocodioides rely on compatible fungi for seeds germinated up to seedlings, and fungus SO could effectively promote seed germination and support seedling development; while B. striata can germinate up to seedling without any fungus, but compatible fungus S. indica can greatly speed up seed germination and promote seedling development. We suggest that S. officinale and S. indica fungi can be used in conservation practices or imitation of wild cultivation of these two important medicinal orchids, respectively. [ABSTRACT FROM AUTHOR]

To determine the effect of uniconazole (S3307 ) on the growth of hybrid Cymbidium seedlings,a new self-bred strain GZ1-11 was employed as the test material, and different concentrations of S3307 were used for root irrigation treatment. S3307 at the appropriate concentration efficiently inhibited the height, leaf length, and root length of new seedlings, increased leaf width and root thickness, but had no effect on the longitudinal and transverse diameters of pseudobulbs. The dwarfing effect of S3307 on plants increased with application concentration, with 30 mL concentration of 10. 00 mg / L S3307 having the strongest dwarfing effect. However, given the phenotypic traits and expense of hybrid orchids, such as plant height and leaf morphology, a 30 mL dosage of 2. 50 mg / L S3307 is recommended in production. [ABSTRACT FROM AUTHOR]