Abstract
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.