中文摘要：

在大田条件下,选用3个不同类型优质小麦品种：豫麦47（强筋品种）、山农8355（中筋品种）和豫麦50（弱筋品种）,设置3个氮肥水平：施N 01、5和30 g/m2,研究了小麦子粒淀粉的粒度分布、直支链淀粉组成、糊化特性及其对氮素水平的响应。结果表明,优质小麦子粒中淀粉粒的粒径分布范围为14~5μm,其数目分布呈单峰或双峰曲线变化,体积和表面积分布均呈双峰曲线变化,峰谷位于10μm处 据此可将淀粉粒分为两种类型：A型大淀粉粒（104~5μm）和B型小淀粉粒（11~0μm）。优质小麦子粒淀粉粒组成存在显著的基因型差异。强筋品种豫麦47子粒中B型淀粉粒的比例较高,弱筋品种豫麦50子粒中A型淀粉粒的比例较高,中筋品种山农8355居中。施氮水平对优质小麦子粒中淀粉的粒度分布存在显著影响。在本试验条件下,随氮素水平的提高,强筋品种豫麦47子粒中A型淀粉粒的比例提高,而B型淀粉粒的比例下降 增施氮肥后弱筋品种豫麦50和中筋品种山农8355子粒中B型淀粉粒的比例增大,而A型淀粉粒的比例降低,且前者变化的幅度较大。适量增施氮肥提高优质小麦子粒中的淀粉含量,氮肥用量进一步增大后,淀粉含量降低 增施氮肥后优质小麦子粒中直链淀粉含量降低。增施氮肥对优质小麦子粒淀粉的糊化特性存在较大影响,且此影响的趋势因基因型和施氮量而异。其中强筋品种豫麦47表现为低谷粘度、最终粘度、反弹值、糊化温度和峰值时间提高,而高峰粘度和稀懈值降低 当氮肥用量增大至30 g/m2时,糊化温度和峰值时间降低,而以粘度为单位的参数均提高。弱筋品种豫麦50表现为增施氮肥后,RVA参数呈下降趋势,与之相对应中筋品种山农8355的呈上升趋势。相关性分析表明,B型淀粉粒的数目、体积和表面积比例与高峰粘度和稀懈值存在显著正相关 与低谷粘度、最终粘度和反弹

英文摘要：

In field conditions,3 typical cultivars,YM47（strong-gluten）,SN8355（medium-gluten） and YM50（weak-gluten） were used to investigate the starch granule distribution,composition of amylose and amylopection,and pasting characteristics of wheat starch under three nitrogen application rates（N 0,15 and 30 g/m2）.The results indicate that the range of starch granule diameters in wheat endosperm is from 1 to 45 μm.Wheat endosperm has a unimodal or bimodal curve in starch granule number distribution,and both starch granule volume and surface area distribution have a bimodal curve.The nadir of those bimodal curves is on the point of 10 μm,and therefore the starch granules in wheat endosperm could be divided into two groups,A-type granules（1-10 μm） and B-type granules（10-45 μm）.The composition of wheat starch granules in high quality wheat cultivars varies significantly with genotypes.The strong-gluten wheat YM47 has a much higher ratio of Btype starch granules,while the weak-gluten wheat YM50 has a higher ratio of A-type starch granules,and the distribution of starch granules in the medium-gluten wheat SN8355 has a central tendency.The N rates influence the distribution of starch granules in high quality wheat endosperm significantly.In the conditions of this study,increasing N fertilization improves the ratio of A-type starch granules and decreases the ratios of B-type starch granules in the endosperm of strong-gluten wheat YM47.The B-type starch granule ratios in the weak-gluten wheat YM50 and medium-gluten wheat SN8355 are increased under the N fertilization,on the contrary,the A-type starch ratios of those two cultivars are declined after using more N,and the amplitude of the variation of the weak-gluten wheat YM50 is much higher than that of the medium-gluten wheat SN8355.Increasing N fertilization appropriately could heighten the starch content in wheat grain,but as the amount of N continued to increase,grain starch content might decrease.The amylose content in wheat grain or in isolated wheat