Effect of foliar application of bioregulators for improving high temperature tolerance of wheat (Triticum aestivum L.)

Aim: The aim of the present study was to evaluate the effect of sowing at different thermal environments and its interaction with foliar spray of bioregulators on yield and yield contributing traits in wheat. Methodology: The present study was conducted by using split plot design with four replications consisting of 24 treatments, namely, main plots: three sowing at different thermal environments (22 degrees C, 20 degrees C and 18 degrees C) and sub plots: eight foliar spray of bioregulators (control, water spray, salicylic acid @ 100 ppm, salicylic acid @ 200 ppm, thio salicylic acid @ 100 ppm, thio salicylic acid @ 200 ppm, thioglycolic acid @ 100 ppm and thioglycolic acid @ 200 ppm). Results: The results indicated that sowing at 20 degrees C recorded the maximum yield parameters viz, effective tillers/m row length, length of ear, no. of grains per ear, test weight, days to maturity and grain, straw and biological yield of wheat over sowing at 22 degrees C and 18 degrees C temperature. Sowing at different thermal environment treatments was found to be non-significant with harvest index of wheat. Among the foliar spray of bioregulators, the treatment B-4 (SA @ 200 ppm) significantly increased the yield components and yield, while remaining at par with B-6 (TSA @ 200 ppm) and B-8(TGA @ 200 ppm) proved superior in comparison to rest of the treatments. However, the significantly higher harvest index was obtained under B-4(SA @ 200 ppm) treatment and was statistically at par with all other treatments, except B-1 and B-2. Interpretation: It is concluded that salicylic acid @ 200 ppm at tittering (40-45 DAS) and ear emergence (60-65 DAS) stage may be sprayed on 20 degrees C temperature sown crop is a viable option to improve wheat yield under semi-arid environment.