旱作和灌溉条件下小麦籽粒淀粉粒粒度的分布特征

Starch Granule Size Distribution in Wheat Grains under Irrigated and Rainfed Conditions

在灌溉和旱作2种栽培条件下,以籽粒淀粉含量不同的小麦品种鲁麦21和德99-3为试验材料,研究了籽粒淀粉粒的分布特征及基因型差异。结果表明,与灌溉栽培相比,旱作栽培条件下2个小麦品种籽粒B型淀粉粒（2.0-9.8μm和〈9.8μm）的体积、表面积百分比显著增加,而粒径〉18.8μm的A型淀粉粒的体积、表面积百分比明显减少。水分亏缺降低了2个品种的籽粒直链淀粉和总淀粉含量,而增加了籽粒蛋白质含量、峰值黏度和最终黏度,这表明旱作栽培有利于小麦籽粒品质的改善。相关分析表明,2个品种籽粒的直链淀粉和总淀粉含量均与2.0-9.8μm和〈9.8μm的淀粉粒体积百分比呈负相关,与9.8-18.8μm的淀粉粒体积百分比呈正相关,籽粒蛋白质含量与2.0-9.8μm和〈9.8μm的淀粉粒呈显著和极显著正相关,而与9.8-18.8μm的淀粉粒呈负相关。表明小淀粉粒（2.0-9.8μm和〈9.8μm）的直链淀粉和总淀粉含量较低、蛋白质含量较高,而大淀粉粒（9.8-18.8μm和〉9.8μm）具有较高的直链淀粉和总淀粉含量。

Starch granules comprise A and B types in mature wheat （Triticum aestivum L.） grains, which are different in chemical composition and functional properties. The granule size distribution of wheat starch is affected by both genotype and environment factors. Currently little information is available about the different distribution of starch granule size in wheat under different cultivation conditions. We used two wheat cultivars, Lumai 21 （starch content 68.9%） and De 99-3 （starch content 64.6%）, to investigate the distribution of grain starch granule size under irrigated and rainfed conditions at Tai＇an and Dezhou of Shandong Province in 2004-2005 growth season. The irrigated treatment received 3 irrigations with the total water amount of 2 250 m^2 ha^-1 during the whole growth period （750 m^3 ha^-1 each at before sowing, pre-wintering, and jointing stages, respectively）, while the rainfed treatment had no irrigation. In mature grains, the diameter of starch granules ranged from 0.37 to 52.60 pro, and the percent volume distribution showed a 2-peak curve with the mean granule diameter of 5 （B type） and 25 μm （A type） at each peak. The volume percentages of A and B types were 56.1-65.5% and 34.5-43.9%, respectively. A 2-peak curve was also shown in percent surface area distribution of starch granules, but only one peak in percent number, because the number of B-type granules accounted for over 99% of the total starch granules. As compared with irrigated treatment, rainfed treatment affected the distribution of starch granules in grains of both cultivars through increasing the percent volume and percent surface area of 2.0-9.8 μm and 〈9.8 μm starch granules and decreasing those of 〉18.8 μm starch granules. The soil water deficit also decreased the contents of amylose and starch in grains and increased protein content, peak viscosity and final viscosity, suggesting that rianfed treatment may improve wheat grain quality. The contents of amylose, starch, and protein in grains were significantly correlated with the percent volume of starch granules with different diameter ranges. For starch, the r was -0.560^＊, -0.831^＊＊ （2.0-9.8 μm） and -0.597^＊, -0.812^＊＊ （〈9.8 μm）; and for protein, the r was 0.799^＊＊, 0.603^＊, （2.0-9.8 μm） and 0.799^＊＊, 0.578^＊ （〈9.8 μm）, respectively. The result suggested that small s.tarch granules （2.0-9.8 μm and 〈9.8 μm） are low in contents of amylose and starch, and high in protein content, whereas big starch granules （9.8-18.8 μm and 〉9.8 μm） high in contents of amylose and starch.