Key Laboratory of Crop Ecophysiology and Farming Systems in Southwest China, Ministry of Agriculture/Crop Ecophysiology and Cultivation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China.
Carbohydr Polym. 2021 Jan 15;252:117212. doi: 10.1016/j.carbpol.2020.117212. Epub 2020 Oct 14.
Chalkiness is a major concern in rice production and its acceptance and is increased by shade stress. However, the relationship between rice chalkiness and the structural and thermal properties of starch is unclear. Here, we investigated the effect of shade stress on rice starch properties. The chalky grain rate and chalkiness degree significantly decreased with the amylose content, Mn, and ΔH and increased with surface area- and volume-weighted mean diameters, branching degree, ratio of 1022/995 cm, and molecular weight polydispersity. Shade stress significantly increased the volume- and surface area-weighted mean diameters and Mw and decreased the amylose content, A chain proportion of amylopectin, Mn, and regularity of starch. These effects led to an increase in the molecular weight polydispersity and branching degree and a decrease in the crystallinity degree and 1045/1022 cm ratio, thereby reducing starch ΔH and uniformity. These factors contributed to increased chalkiness of rice under shade stress.
垩白度是稻米生产和接受过程中的一个主要关注点，其会受到遮阴胁迫的影响而增加。然而，稻米垩白度与淀粉结构和热性质之间的关系尚不清楚。在这里，我们研究了遮阴胁迫对稻米淀粉性质的影响。垩白粒率和垩白度随直链淀粉含量、Mn 和 ΔH 的增加而显著降低，随表面积和体积加权平均粒径、分支度、1022/995cm 比值和分子量多分散性的增加而增加。遮阴胁迫显著增加了体积和表面积加权平均粒径以及 Mw，降低了直链淀粉含量、支链淀粉中 A 链的比例、Mn 和淀粉的规整度。这些作用导致分子量多分散性和分支度增加，结晶度和 1045/1022cm 比值降低，从而降低了淀粉的 ΔH 和均匀性。这些因素导致稻米在遮阴胁迫下的垩白度增加。
