Heat stress at reproductive stages of cotton crop is the main cause for instability in yield than other abiotic stresses of crops. An experiment was conducted to observe the impacts of heat stress at squaring and flowering stages of cotton and potential of exogenously applied ascorbic acid to alleviate this stress. The experiment was planted for two consecutive years, that is 2013 and 2014, in randomized complete block design with split plot arrangement having three replications. Treatments were comprised of heat stress in main plots, viz. H0 = no heat imposition; H1 = heat imposition at square initiation; H2 = heat imposition at flower initiation and foliar‐applied ascorbic acid in subplots, viz. A0 = control or water spray; A1 = 20 mg/L; A2 = 40 mg/L; and A3 = 60 mg/L. Results showed that heat stress badly affected plant water relations (relative water contents and osmotic potential), total chlorophyll contents and activities of antioxidant enzymes that led to a corresponding decrease in seed cotton yield. Foliar application of ascorbic acid (40–60 mg/L) ameliorated adverse effects of heat and thus helped the crop to improve its water relations, stay green and antioxidant enzymes resulting into better crop yield.

Effective use of salt affected soils needs the development of the most efficient and suitable reclamation technology to optimize farm management and better crop yields. Different chemical methods and amendments are used to reclaim the salt affected soils and after reclamation such soils may be used for sustainable agricultural production. Choice of a chemical amendment depends on its availability, cost, handling and time of application. Application of sulfur is very effective technique to suppress the uptake of undesired toxic elements and to improve the quantity and quality of produce in salt affected soils. So, a three-year field experiment was carried out to evaluate the comparative reclamation efficiency of two sulfur sources, i.e elemental sulfur and gypsum to improve the soil conditions by reducing the salinity/sodicity impact and yield characteristics of rice and wheat crop. A saline-sodic field {(EC e = 6.10 dS m -1 , pH s = 9.21 and SAR = 41.67 (mmol L -1 ) 1/2 , SO 4 -S = 16.0 (mg kg -1 ) and soil gypsum requirement (SGR) of 9.10 t ha -1 for 0-15 cm soil depth} was selected. The treatments included were: control, gypsum application @ 100 SGR, S application @ 25, 50, 57, 100 and 125 % of SGR. Statistical analysis of three-year pooled data showed that varying levels of sulfur and gypsum significantly improved soil properties and rice-wheat yield than control, however, gypsum @ 100% of soil GR was at par with S @ 125 and 100% of SGR in term terms of improving yield component of both test crops and reducing soil pH s , EC e and SAR. Efficiency of treatment could be arranged as gypsum @ 100% SGR = S @ 125 % of SGR= S @ 100% of SGR> S @ 75 % of SGR> S @ 50 % of SGR> S @ 25% of SGR>control.

High temperature during reproductive stages of cotton is a major constraint to achieve potential yield of cotton. The aim of the present study was to determine comparative thermo-sensitivity of squaring and flowering, to optimize exogenous selenium for heat-stressed cotton, and to explore correlation among physiochemical and morphological attributes. The experiment was conducted during 2013 and repeated during 2014. The experiment was laid out in randomized complete block design under split plot arrangement and replicated thrice. Treatments were comprised of heat stress (H 0 = no heat imposition; H 1 = heat imposition at squaring; and H 2 = heat imposition at flowering) in main plot and varying foliar selenium concentrations (Se 0 = water spray/control; Se 50 = 50; Se 100 = 100; and Se 150 = 150 mg L-1 selenium) in split plot. Significantly, more antioxidants, chlorophyll contents, water relation attributes, seed cotton yield, and lesser hydrogen peroxide were recorded with 150 mg L-1 foliar selenium compared with other concentrations under H 0. While under H 1 and H 2 , statistically similar and significantly more antioxidants, chlorophyll contents, water relation attributes, seed cotton yield, and lesser hydrogen peroxide were observed for 100 and 150 mg L-1 selenium compared with other selenium concentrations. Conclusively, H 2 proved more thermolabile compared with H 1 , and application of 150 mg L-1 foliar selenium effectively alleviated adverse effects of heat. Moreover, we observed strong and significant associations of all physiochemical attributes with seed cotton yield.

No abstract