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Salinity stress is a major threat to cotton growth and productivity worldwide. This study evaluated a diverse collection of fifty cotton genotypes at critical seedling stage using analysis of variance and principal component analysis. The seedlings were subjected to 10dSm-1 and 17dSm-1 salt stress levels starting from the 10th day after sowing until the 42nd days. Data was collected on morphological (root length, shoot length, fresh and dry weights of root and shoot, fresh and dry weight of whole plant) and biochemical (K+, Na+, K+/Na+) parameters. Significant variations were observed among the cotton genotypes for the evaluated traits under control and salt stress conditions. The results revealed that salinity stress had detrimental effects on various growth parameters, including root length, shoot length, fresh root weight, fresh shoot weight, dry shoot weight, dry root weight, and whole plant dry weight. Additionally, sodium levels exhibited a substantial increase under NaCl-induced stress, whereas potassium levels experienced reductions in the leaves. Based on multivariate analysis, the genotypes NIAB - 545, FH- Kehkshan, FH-490, and GH-Mubarak displayed notable salt tolerance likely due to mechanisms such as ion exclusion, osmotic adjustment and tissue tolerance at both 10 dSm-1 and 17 dSm-1 levels. Conversely, the genotypes FH-303, FH-532, FH-542, and SB-149 were deemed salt-sensitive. These findings underscore the challenges associated with selection for salt tolerance in cotton due to the potential masking effects of environmental factors on genetic expression. This study discovers potential salt-tolerant cotton genotypes for use in breeding programs to increase yields under saline stress. However, all genotype-environment interactions must be explored. Overall, these findings provide useful information about salt stress responses in cotton seedlings. [ABSTRACT FROM AUTHOR]

The tillering phase of wheat (Triticum aestivum) crops is extremely susceptible to drought. We explored the potential of silver nanoparticles (AgNPs) in protecting wheat genotypes from drought injury during this sensitive stage. After treating with AgNPs (60 ppm), the plants were submitted to different water levels; i.e. 100% field capacity (FC), 75% FC (mild drought), 50% FC (moderate drought) and 25% FC (severe drought) from 15 to 41 days after sowing (tillering phase). Leaf physiological data were collected at stress termination, while yield attributes were recorded at crop maturity. We found that increasing drought intensity significantly impaired leaf physiology and grain yield of both studied genotypes. Compared with control, moderately and severely drought-stressed plants produced 25% and 45% lesser grain yield per spike, respectively (averaged across genotypes and years of study). Likewise, moderate and severe drought reduced photosynthesis by 49% and 76%, respectively, compared with control. In contrast, AgNPs significantly restored leaf physiological functioning and grain yield formation at maturity. For example, under moderate and severe drought, AgNPs-treated plants produced 22% and 17% more grains per plant, respectively, than their respective water-treated plants. Our study suggests that exogenous AgNPs can protect wheat crops from drought during early development stages. Wheat (Triticum aestivum) crops suffer significant grain yield losses when water supplies are affected during the early developmental phases. This study shows varying levels of drought stress impaired carbon assimilation, tiller formation and final grain yield of wheat genotypes. In contrast, exogenously applied silver nanoparticles (AgNPs) restored plant growth and grain yield formation, suggesting their potential to protect wheat crops from drought-induced injury. [ABSTRACT FROM AUTHOR]

Wheat crops are highly sensitive to high temperatures during reproductive and grain filling phases. This study explored how hydrogen peroxide (H2O2) protects grain yield formation in wheat crops exposed to heat during different developmental phases. Two wheat genotypes, Ujala-16 and Anaj-17, of varying heat tolerances, were subjected to heat stress (32 °C/20 °C) at pre-anthesis, anthesis, and post-anthesis stages under glasshouse and field conditions. Before heat stress treatment, the plants were sprayed with 60-ppm hydrogen peroxide (H2O2). Post-stress changes in leaf physiology were studied to understand the heat recovery mechanism. Despite significant genotypic variations, high temperature damaged leaf physiology and grain yield of both studied wheat genotypes. On average, high temperatures during any developmental phase caused more damage to Anaj-17 than to Ujala-16. Compared with the control, the plants heated during pre-anthesis, anthesis, and post-anthesis produced 44%, 35%, and 25% lesser grains yield per spike (averaged across genotypes and experiments), respectively. In contrast, post-anthesis-stressed plants produced the smallest grains compared to those heated during pre-anthesis or at anthesis. Compared with the control, H2O2-treated plants sustained significantly higher leaf chlorophyll and net photosynthetic rate by protecting cellular membranes from heat injury. Under hot conditions, hydrogen peroxide-treated plants yielded 17% more grains (averaged across the developmental phases and genotypes) than control plants. Our study suggests wheat performance can be improved through exogenous H2O2 application, particularly during terminal heat stress. [ABSTRACT FROM AUTHOR]

High temperature stress at reproductive stages of cotton crop severely affects the yield and quality of cotton crop under changing climatic conditions. To alleviate the adverse effects of high temperature stress on cotton crop, the regulatory effects of potassium (K), zinc (Zn), and boron (B) were assessed by applying different temperature regimes at three reproductive stages of cotton crop under field and glass house conditions. Cotton plants were subjected to low (32/20 °C ± 2), medium (38/24 °C ± 2), and high (45/30 °C ± 2) temperatures under glasshouse, but sown at specific dates in field to provide different temperatures at three reproductive stages. High-temperature stress at squaring, flowering and boll formation stages in both field studies increased relative cell injury (RCI), total soluble proteins (TSP), reactive oxygen species and reduced fiber yield attributes i.e. total number of bolls per plant (TNBPP), number of sympodial branches per plant (NSBPP) and quality traits. For example, RCI, TNBPP and fiber fineness were reduced by 73%, 42% and 29%, respectively under supra thermal regime (SupTR) of glass house study over the optimal thermal regime (OpTR). Foliar application of K and Zn followed by B increased TSP, RWC, TNBPP, NSBPP, fiber fineness, fiber length and fiber strength. Further, foliar spray of K and Zn followed by B also reduced H2 O2 under SupTR and SubTR over the OpTR. The findings of the present study clearly demonstrate that foliar spray of Zn, K and B alleviated adverse effects of high temperature stress at squaring, flowering and boll formation stages and increased seed cotton yield and quality of cotton crop. [ABSTRACT FROM AUTHOR]

Among all the abiotic stresses, high temperature stress, especially at flowering, is the major factor causing substantial reduction in cotton yield. To check the effect of foliar applied chitosan (CH), a derivative of chitin, for inducing thermo-tolerance during flowering stage in cotton crop, a field experiment was conducted during 2016 and repeated in 2017. Heat stress was imposed at flowering stage for 4 and 8 days and varied chitosan concentrations (0, 0.2, 0.4, 0.6 and 0.8 g L-1) were applied foliarly after imposing heat stress. Heat was imposed by making the plastic tunnels using perforated transparent polythene sheet. High temperature stress reduced leaf total phenolic contents, total soluble proteins, turgor potential, relative leaf water contents and seed cotton yield. Application of chitosan @ 0.8 g L-1 induced thermo-tolerance by improving all the recorded parameters under high temperature stress while application of chitosan @ 0.6 g L-1 improved the bio-chemical, physiological and yield components under ambient conditions. Conclusively, high temperature stress adversely affected the recorded response while foliar application of high dose of chitosan ameliorated the adverse effects of heat stress at bio-chemical and physiological levels. [ABSTRACT FROM AUTHOR]