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Aims: In this study, a novel plant growth regulator 2,4-dichloroformamide cyclopropane acid (B2) was used to explore its effects on wheat stalk morphology, chemical composition, anatomical structure, crushing strength and their relationship with lodging resistance. The effects of stem quality change on grain filling and yield were further discussed. Methods: We conducted a series of experiments, including determinations of internode morphology and breaking resistance, analyses of chemical composition and hormone content, observation of internode anatomy, and measurement of grain filling rate, to explore the effects of internode developmental changes induced by B2 treatment on grain filling. Results: Spraying 150 μmol·L−1 B2 at jointing stage significantly decreased plant height, height of center of gravity, basal internode and cell length, while increased stem diameter, wall thickness of basal second internode, cortex thickness, vascular bundle transverse section area and cell cross-sectional area, which resulted in higher breaking strength and culm lodging resistance index. B2 also significantly reduced the content of gibberellin in the second basal internode, and increased the accumulation of lignin and cellulose, thus forming a shorter and stronger stalk. Correlation analysis showed that stem outer diameter, stem wall thickness, cellulose and lignin content were significantly and positively correlated with stem breaking strength. The improvement of stalk structure, especially vascular bundle area, increased bleeding sap, which contributed to grain filling and final yield formation. Conclusions: Lodging resistance and average grain-filling rate can be enhanced by spraying B2 at wheat jointing stage due to the improvement of culm structure, which is conducive to further increase of yield. [ABSTRACT FROM AUTHOR]

In recent years, Spodoptera frugiperda (S. frugiperda, Smith) has invaded China, seriously threatening maize production. To explore an effective method to curb the further expansion of the harm of the S. frugiperda, this experiment used maize seedlings of the Zhengdan 958 three-leaf stage (V3) of maize as the material to study the effect of coronatine (COR) on the ability of maize to resist insects (S. frugiperda) at the seedling stage. The results showed that when maize was sprayed with 0.05 μM COR, the newly incubated larvae of S. frugiperda had the least leaf feeding. It was found that 0.05 μM COR significantly increased the contents of abscisic acid (ABA) and jasmonate (JA) in maize leaves through the determination of hormone content. Moreover, transcriptome sequencing revealed that the expression of six genes (ZmBX1, ZmBX2, ZmBX3, ZmBX4, ZmBX5 and ZmBX6), which are associated with the synthesis of benzoxazinoid, were upregulated. Nine genes (ZmZIM3, ZmZIM4, ZmZIM10, ZmZIM13, ZmZIM18, ZmZIM23, ZmZIM27, ZmZIM28 and ZmZIM38) of JA-Zim Domain (JAZ) protein in the JA signal pathway, and seven genes (ZmPRH19, ZmPRH18, Zm00001d024732, Zm00001d034109, Zm00001d026269, Zm00001d028574 and Zm00001d013220) of ABA downstream response protein Group A Type 2C Protein Phosphatase (PP2C) were downregulated. These results demonstrated that COR could induce anti-insect factors and significantly improve insect resistance in seedling maize, which laid a theoretical foundation for further study of the mechanism of COR improving insect resistance in seedling maize, and provided data references for the use of COR as an environmentally friendly pest control method. [ABSTRACT FROM AUTHOR]

Soil salinity is one of the most critical factors limiting plant growth and development. Carex leucochlora is an important turfgrass species with a wide distribution in northern China that is highly sensitive to salt stress, which impairs its development. Recently, melatonin has emerged as a nontoxic biomolecule that regulates growth and enhances salt tolerance in plants. In this study, the mechanism of melatonin's regulation of plant growth and anatomical characteristics in C. leucochlora seedlings under continuous salt stress was explored. Our results indicated that salt stress strongly suppressed plant growth and leaf cell activity, inhibited root morphology and root activity, and negatively affected leaf and root anatomic structures in the seedlings. Conversely, melatonin (150 μmol L−1) pretreatment improved the detrimental effect of salt stress by restoring the morphology of the leaf, alleviating damage to the cell membrane, improving root activity, and altering the root architecture and plant growth attributes. Moreover, after 12 days of salt stress, anatomical observations of the leaf showed that the thickness of the leaf blade, vascular bundle area of the leaf main vein, vesicular cell area, thickness of the upper epidermis, and thickness of the lower epidermis were increased by 30.55, 15.63, 12.60, 16.76 and 27.53%, respectively, with melatonin under salinity. Melatonin treatment also showed an increase of 5.91, 7.59, 15.57, and 20.51% in epidermal thickness, vascular cylinder diameter, xylem vessel diameter, and pith cell diameter, respectively, compared with salt stress after 12 days. These results suggest that melatonin alleviated salt stress through augmenting seedling growth, leaf cell activity, and root characteristics, maintained the stability of anatomic traits to maintain chloroplast cell homeostasis, and also protected the vascular tissues to promote the radial transport of water and ions in the C. leucochlora seedlings. These modifications induced by the exogenous application of melatonin may help C. leucochlora to acclimate successfully to saline soils. [ABSTRACT FROM AUTHOR]

Miscanthus × giganteus has attracted much attention and occupied a significant niche as a bioenergy crop to meet the world's energy demand and in the fight against climate change. In this study, a field experiment was conducted to evaluate the yield and biomass characteristics of M. × giganteus over a period of three years from 2013 to 2015 in Beijing, China. M. × giganteus plants showed higher tiller density and litter leaf weight in the third year, whereas no significant difference in plant height was observed among the years. In contrast, a larger number of nodes per plant were recorded in the first year. Biomass yield potential was the highest in the third year (42.3 t ha−1). In addition, plant height (r =.594, p =.042), tiller density (r =.854, p <.01), and number of nodes per plant (r = ‐.589, p =.044) were significantly correlated with biomass yield. Contents of cellulose and lignin were higher in stems, while that of hemicellulose and ash were higher in leaves. M. × giganteus biomass may be used for cellulosic ethanol conversion due to high cellulose and hemicellulose contents and low lignin content and for direct combustion and co‐combustion due to high calorific value (18.5 MJ kg−1). To conclude, our findings indicate that M. × giganteus can be cultivated in northern China as an excellent herbaceous bioenergy crop. Rational utilization of the agronomic characteristics would be helpful to screening and breeding bioenergy grass for promoting bioenergy production in China. Core ideas: Miscanthus × giganteus is suitable for cultivation in northern China.Agronomic traits were significantly correlated with biomass yield.Biomass yield of M. × giganteus increased over a period of three years.Biomass quality exhibited better suitability for ethanol production.High calorific value may be used for direct combustion and co‐combustion. [ABSTRACT FROM AUTHOR]

Bacillus thuringensis (Bt) transgenic (insect-resistant) cotton cultivars senesce prematurely under potassium (K+) deficiency, more often than conventional cultivars, in the North China Plain. To verify if Bt-transgenic cotton was more susceptible to K+ deficit, two transgenic cultivars, 'CCRI 41' and 'DP 99B', and two conventional cultivars, 'CCRI 35' and 'CCRI 36', selected from widely used cultivars in China, were used in a seedling hydroponic study. The culture solution K+ concentration was 0.5 mM for high K+ and 0.02 mM for low K+ conditions. Seedlings of all four cultivars accumulated more dry matter and K+ when grown at high K+ than low K+ conditions. However, under low K+ condition, the dry weight and K+ content of Bt-transgenic cultivars CCRI 41 and DP 99B were lower than those of the conventional cultivars CCRI 36 and CCRI 35. The results indicated that Bt-transgenic cultivars CCRI 41 and DP 99B were more sensitive to K+ deficiency than conventional cultivars CCRI 36 and CCRI 35, which could be the reason for premature senescence symptoms observed from fields of Bt-transgenic cotton under K+ deficiency. Seedlings of all four cultivars had a higher K+ use efficiency (KUE) under low K+ than high K+ conditions, but the KUE did not account for the differential responses between Bt-transgenic and conventional cultivars at the low K+ concentration. The K+ depletion results did not reveal the mechanism for the above differential responses in Vmax and Km of the seedlings either. Further experiments with more cultivars are needed to clarify the differential mechanisms in these genotypes. [ABSTRACT FROM AUTHOR]

Conserving irrigation water resources is a most important measure for sustainable wheat production in the North China Plain. In the present study, the effect of phosphorus (P) application for saving irrigation water was evaluated. The application of fertilizer P increased nitrogen and phosphorus uptake, shoot biomass, head number, seed number and, consequently, grain yield, and increased soil water use and seasonal evapo-transpiration. The lower the volume of irrigation water applied, the more obvious were these effects. When winter wheat was basally fertilized with 88.5 kg P 2 O 5 /ha and irrigated with 90 mm at the jointing stage, the highest fertilizer P use efficiency, apparent P recovery and net profit (due to irrigation and/or fertilizer P) were obtained. The results suggested that fertilizer P should be used for saving irrigation water resources in the North China Plain. [ABSTRACT FROM AUTHOR]

Rice crab co-culture is a new integrated farming model in China. The application of triazole plant growth regulators (PRGs) is often used as an advantageous option to combat rice lodging. However, there is still a gap regarding the toxicity of these PRGs on the growth and development of the Chinese mitten crab (Eriocheir sinensis, E. sinensis). Here the effect of triazoles (paclobutrazol and uniconazole) on the molting mechanism of E. sinensis was investigated. Monitoring of regulatory genes associated with molting showed that the two PRGs were found to inhibit the expression of ecdysteroid hormone (EH), ecdysteroid receptors gene (EcR), and retinoid X receptors gene (RXR) and induce secretion of molt-inhibiting hormone (MIH) gene. In addition, the activities of chitinase (CHIA) and N-acetyl-β- d -aminoglucosidase (β-NAGase) were also inhibited by exposure to PRGs. Exposure to PRGs also elevated the mRNA expression of the growth-related myostatin gene (MSTN). These results revealed that there is a long-term risk of exposure to triazoles PRGs that may inhibit molting and affect normal development and immune system of E. sinensis. [Display omitted] • Effects of triazole plant growth regulators (RPGs) on E. sinensis were researched. • Paclobutrazol and uniconazole were not significantly acutely toxic to E. sinensis. • Triazole RPGs show endocrine disruptive ability in inhibiting molting in E. sinensis. [ABSTRACT FROM AUTHOR]

Ethephon is plant growth regulator widely used to control maize lodging at the early stage of jointing. However, the function and efficacy of ethephon due to differences of cultivars and maize growing areas remains elusive, necessitating the evaluation of each cultivar's sensitivities prior to the application of ethylene. In this study, we collected ten maize cultivars from the largest planted area in China and cultivated in three typical growing areas to evaluate their sensitivity to ethephon. The results showed that ethephon reduced maize plant height, ear height, length of base internode, and generally increased the crushing strength of maize base internode. These traits may enhance maize lodging resistance by reducing the center of gravity of the plant structure. The effect of ethephon varied across growing areas, and cultivars within the same region exhibited distinct sensitivity levels to ethephon. The crushing strength of the eighth internode in maize exhibits a wide range of change and small coefficient of variation. Hence, this index's change range could be utilized to assess the sensitivity of maize cultivars to ethephon in various regions. In addition to agronomic traits, we detected shifts in transcriptional levels related to the signaling pathways of phytohormones, particularly ethylene and gibberellin. These changes reveal the association between transcriptional signaling levels of key factors and the sensitivity to ethylene in ten maize cultivars. The results contribute to our understanding of the lodging resistance in different maize cultivars and evaluation the sensitivity of maize cultivar to ethephon in different growing areas, with implications for comparable pedo-climatic conditions elsewhere. [Display omitted] • The sensitivity of same cultivar to ETH differed in different growing areas, and within the same growing area. • The sensitivity of different cultivars to ETH can be evaluated by the crushing strength of maize eighth internode. • The sensitivity of different cultivars to ETH correlated to the expression level of ETH receptor. [ABSTRACT FROM AUTHOR]

Maize yield is limited by water deficit in the arid and semiarid regions of China. Conserving water and enhancing crop water productivity are inevitable requirements for the sustainable development of water efficient agriculture. Plant growth regulators (PGRs) play important roles in maize water stress tolerance. In this study, we investigated the effect of plant growth regulator-brazide, a functional analog of brassinolide (BR), on maize water stress resistance through a two-year (2020–2021) field experiment. The experiment included four water treatments (I100: 4012 m3 ha−1; I80: 3210 m3 ha−1; I60: 2407 m3 ha−1; I40: 1605 m3 ha−1), four PGR concentrations (CK: water; Bra: 0.1 μmol L−1 14-hydroxylated brassinosteroid; B1: 0.1 μmol L−1 brazide; B2: 1 μmol L−1 brazide; B3: 10 μmol L−1 brazide). The results showed that deficit irrigation (I60 and I40) decreased soil water content (SWC), photosynthetic rate (Pn), leaf area index (LAI), aboveground biomass (AB) and yield, but improved crop water productivity (WP c). Under deficit irrigation conditions, 1 μmol L−1 brazide application also increased dry matter accumulation and grain yield, a result attributed to improvement of the photosynthetic rate and increases in the root bleeding saps, water productivity. 1 μmol L−1 Brazide application reduced bare tip length, increasing kernel number per ear, thereby increased the yield of I60 and I40 by 15.1% and 11.4% (p ≤ 0.05; 2020), 16.4% and 20.4% (p ≤ 0.001; 2021), respectively. Path analysis showed brazide improved final yields by increasing thousand grain weight (TGW), photosynthetic rate (Pn) and WP c under deficit irrigation. The increase in TGW with brazide treatment was primarily attributed to the increase of Pn. Overall, Brazide increased maize drought resistance mainly by increasing Pn and WP c , with 1 μmol L−1 brazide as an optimal concentration. • A new plant growth regulator, Brazide, was evaluated in maize. • Brazide increased photosynthetic rate and WUE under deficit irrigation. • Application of brazide improved maize growth and grain yield under deficit irrigation. • 1 μmol L−1 brazide as an optimal concentration for maize in arid region of Northwest China. [ABSTRACT FROM AUTHOR]

Maize (Zea mays L.) is a major global crop, but lodging leads to yield loss. Ethephon can regulate maize growth, reduce plant height, and improve lodging resistance. The application of small crop protection unmanned aerial vehicles (UAV) to replace electric knapsack sprayers (EKS) for the mechanization of agriculture in China has been widely developed. However, there are no reports on the application of ethephon to control maize growth by UAV. In the present study, the effects of spraying by UAV (15 L ha−1 and 30 L ha−1) and EKS (450 L ha−1) on the droplet deposition distribution and dynamic degradation process of ethephon (60 g a.i. ha−1) were studied. The control of maize growth by different ethephon dosages was also investigated, i.e., 48, 60, and 90 g a.i. ha−1 for UAV and 60 g a.i. ha−1 for EKS. The droplet deposition rates of 15 L ha−1 and 30 L ha−1 by UAV were 11.2% and 15.2%, significantly higher than those of EKS. Furthermore, the degradation half-life under UAV application was longer than that under EKS. The 20% dosage reduction of ethephon applied by UAV (48 g a.i. ha−1) had the same maize growth control effect as EKS (60 g a.i. ha−1), and the UAV treatment was better than EKS when the dosage was the same (60 g a.i. ha−1). Considering the input cost and yield, we recommend that 48 a.i. g ha−1 ethephon is applied by UAV when the lodging risk is low and 90 a.i. g ha−1 when the lodging risk is high, at a spray volume of 15 L ha−1. The application cost of ethephon can be reduced by 47.91–71.81% compared to EKS under these conditions. • Application of UAV increased droplet deposition rate than EKS on maize leaves. • Degradation half-life of ethephon applied by UAV was longer than by EKS. • Application of ethephon by UAV had stronger maize lodging resistance than by EKS. • Ethephon applied by UAV increased maize yield when lodging occurred seriously. [ABSTRACT FROM AUTHOR]

Tricyclazole is used as a common fungicide to control rice blast. However, studies on the toxicity of tricyclazole to crabs in the rice-crab co-culture system are still extremely rare. Here, the environmental dissipation of tricyclazole was monitored in this model, and the potential toxicity of tricyclazole to E. sinensis at environmental concentrations as well as the dietary risk was evaluated. The results showed that tricyclazole had no significant acute toxicity to E. sinensis (LC 50  > 100 mg/L), while it promoted body weight gain. Tricyclazole in the hepatopancreas had a higher persistent bioaccumulation risk than in the muscle. Tricyclazole suppressed the immune response of E. sinensis under prolonged exposure and there should be gender differences, with females being more sensitive. Lipid metabolism enzymes were also significantly inhibited. While tricyclazole stimulated males molting but prolonged molting duration, both molting and duration of females were also disturbed. The dietary risk assessment indicated that tricyclazole intake from current crab consumption was low risk. This evidence demonstrated that tricyclazole may have potential risks to individual development, nutritional quality, and economic value on E. sinensis and should be used with caution in rice-crab co-culture system whenever possible., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)