The inexorable process of climate change in terms of the rise in minimum (nighttime) temperature delineates its huge impact on crop plants. It can affect the yield and quality of various crops. We investigated the effect of high night temperature (HNT) (+2.3 °C over ambient) from booting to physiological maturity on the yield parameters, grain growth rate (GGR), starch content, composition, and flour rheological properties in early (HI 1544, HI 1563) and late-maturing (HD 2932) wheat genotypes. The change in yield under HNT was highly correlated with grain number per plant (r = 0.740 ***) and hundred-grain weight (r = 0.628 **), although the reduction in grain weight was not significantly different. This was also reflected as an insignificant change in starch content (except in HI 1544). Under HNT, late-sown genotypes (HI 1563 and HD 2932) maintained high GGR compared to the timely sown (HI 1544) genotype during the early period of grain growth (5 to 10 days after anthesis), which declined during the later phase of grain development. The increased rheological properties under HNT can be attributed to a significant reduction in the amylose to amylopectin (AMY/AMP) ratio in early-maturity genotypes (HI 1544 and HI 1563). The AMY/AMP ratio was positively correlated to flour rheological parameters (except setback from peak) under HNT. Our study reports the HNT-induced change in the amylose/amylopectin ratio in early maturing wheat genotypes, which determines the stability of flour starches for specific end-use products.
Keywords: amylopectin; amylose; high night temperature; rheological properties; wheat.