RESPONSE OF YIELD AND QUALITY OF WHEAT TO HEAT STRESS AT DIFFERENT GRAIN FILLING STAGES

Abstract

Changes in the yields and quality and the physiological response of winter wheat (Triticum aestivum cv. 'Ji′nan17' and 'Lumai21') grown under heat stress during different filling stages were studied. Winter wheat growing in flowerpots was transferred to temperature-controlled open top chambers (OTC) after anthesis. Heat stress treatments of 25 ℃/35 ℃ (night/day) were applied at early filling stage (1-10 days after anthesis), middle filling stage (11-20 days after anthesis), and late filling stage (21-30 days after anthesis). The controls were grown at temperatures of 20 ℃/30 ℃ (night/day). Protein accumulation rate, nitrogen accumulation and distribution, kernel weight and yield, test weight, protein composition, protein content, wet gluten content, glutenin macropolymer (GMP) content, and starch and protein quality traits were measured. The results showed that protein accumulation rate in wheat kernels grown in the 25 ℃/35 ℃ (night/day) chambers were higher than those in the control chambers (p0.05); however, nitrogen accumulation was reduced and the nitrogen harvest index (NHI) declined under heat stress (p0.05). There were differences in starch and protein quality responses to heat stress during the different filling stages. Protein and starch quality traits improved at the early filling stage but declined at the middle and late filling stages under heat stress; however, the protein content increased at late filling stage under heat stress. Protein content increased but kernel weight decreased under higher temperatures, which suggested that the starch accumulation rate decreased more sharply than protein accumulation rates under higher temperature. The two varieties, 'Ji'nan17' and 'Lumai21', showed similar responses to heat stress at the different filling stages.