Background Today, stress moderators are employed to mitigate crop loss due to the adverse effects of environmental stress. The current research aimed to investigate the impacts of time and stress moderator types on agro-physiological responses of cotton on conventional and double-cropping systems during 2017 and 2018 under saline conditions. A split-plot factorial experiment was carried out in a randomized complete block design with three replications. Cultivation system [conventional (recommended planting date) and double-cropping systems (sowing after harvest of wheat)] were considered as the main plots, and stress moderator type at four levels [water control, 2 mmol·L–1 Salicylic acid (SA), 100 mmol·L–1 Glycine betaine (GB), and 100 μmol·L–1 sodium nitroprusside (SNP)] and application time (flowering and flowering + bolling stages) were regarded as subplots. Results Plant height, reproductive branch number, the number of bolls, 10-boll weight, 1 000-seed weight, biological yield, seed cotton yield, lint yield, chlorophyll a, chlorophyll b, carotenoids, total chlorophyll, sodium, potassium, and proline content were less in double-cropping system comparing with conventional system. Spraying with the stress moderators alleviated soil salinity effects on yield, yield components, and biochemical traits of cotton. SNP spraying led to maximum plant height, branch number, the number of bolls per plant, 10-boll weight and seed cotton yield. SA spraying yielded the highest 1 000-seed weight, biological yield, lint percentage and lint yield. The highest chlorophyll a, chlorophyll b, carotenoids, and total chlorophyll content resulted from SNP spraying. Yield, yield components, and biochemical traits did not respond to the stress moderator types in double-cropping system. However, the highest chlorophyll a, carotenoids, proline content, the number of bolls per plant, and seed cotton yield resulted from SNP spraying in conventional system. No statistically significant differences were observed between spraying with SNP and SA in most studied traits. Conclusions The results suggest that the optimum cotton planting time and SNP spraying could be recommended for producing the most suitable yield under saline conditions. Highlights External application of stress modulators increases salinity stress tolerance. Spraying with sodium nitroprusside has more moderating effect. Agro-physiological response of cotton to moderators is stronger in early sowing. Maximum seed cotton yield was achieved at early sowing and spraying sodium nitroprusside. Delayed cultivation reduces cotton yield.

Background: Today, stress moderators are employed for mitigating the negative effects of environmental stress as the main cause of reduced yields of crops. In this study, the impacts of time and types of stress moderators on agrophysiological responses of cotton under saline conditions on different planting dates were investigated during 2017 and 2018. A split-plot factorial experiment was carried out in a randomized complete block design with 3 replications. Sowing dates (early and late) were considered as the main plots and stress moderator type at 4 levels (control, 2mM Salicylic acid (SA), 100 mM Glycine betaine (GB), and 100 μM sodium nitroprusside (SNP)) and application time (flowering and flowering+bolling stages) were regarded as the sub plots. Results: The delayed planting reduced plant height, reproductive branch number, number of bolls, boll weight, 1000-seed weight, biological yield, seed cotton yield, lint yield, chlorophyll a, chlorophyll b, carotenoids, total chlorophyll, sodium, potassium and proline content. Spraying with the stress moderators alleviated soil salinity effects on yield, yield components and biochemical traits of cotton. SA spraying led to maximum height, 1000-seed weight, biological yield, seed cotton percentage, seed cotton yield, and potassium content. SNP spraying yielded the greatest number of bolls per plant, boll weight, lint yield, and proline content. The highest plant height, chlorophyll a, chlorophyll b, carotenoids and total chlorophyll content resulted from GB spraying. Yield, yield components, and biochemical traits did not respond to the stress moderator types in the delayed sowing date, while the highest chlorophyll a, carotenoids, proline content, the number of bolls per plant and seed cotton yield was resulted from spraying with SNP in early planting. No statistically significant differences were observed between spraying with SNP and SA in most studied traits. Conclusions: The result suggests that cotton planting at an appropriate date and SNP spraying could be recommended for producing the most suitable yield under saline conditions.