论文部分内容阅读
Granule size distribution of wheat starch is an important characteristic that may affect the functionality of wheat products.Temperature is one of the main factors affecting grain and starch quality.Two winter wheat cultivars were grown in natural environment and treated by heat stresss at middle stage of grain filling,from 17 days to 20 days after anthesis (daa) in climate-controlled greenhouse with a maximum daytime temperature of 37 ℃ from 11∶00 am to 16∶00 pm for 4 days,to evaluate the effect of post-anthesis high temperature on starch granule size distribution and starch components in wheat grains at maturity by pot experiment.Starch was isolated from the two wheat and Granule size/volume distributions of the isolated starches were analyzed using a laser diffraction particle size analyzer.Heat stress caused a marked drop in starch yield and led to a significant reduction in the proportion (both by volume and by surface area) of A-type starch granules(>9.9 mm),with an increase in those of B-type starch granules (≤9.9 mm).This suggest that the production of A-type starch granules was more sensitive to heat stress than that of B-type starch granules in middle stage of grain-filling.However,heat stress had little effect on the proportional number of A-type starch granules.This may suggest that the limited substrate for starch accumulation was mainly partitioned towards hypertrophy (larger granules) not hyperplasia (more) of starch granules.Furthermore,Granule size distribution had a close association with starch component content leading to affect the starch quality.