施氮水平对小麦籽粒谷蛋白大聚合体粒径分布的调控效应

GMP particles size distribution in grains of wheat in relation to application of nitrogen fertilizer

谷蛋白大聚合体(GMP)是决定小麦品质形成的重要因素,在小麦籽粒发育过程中,GMP以球形颗粒形式贮藏在小麦籽粒胚乳中,其含量及颗粒大小受亚基组成及环境条件的影响。以不同穗型冬小麦品种为材料,通过大田试验探讨了施氮水平与小麦籽粒谷蛋白大聚合体含量及其颗粒粒径分布的关系。结果表明,在0—240kg/hm2范围内增施氮肥能显著提高小麦籽粒中GMP的含量,施氮量继续增加则不利于小麦籽粒GMP积累。小麦籽粒GMP颗粒粒径分布范围为0.375—256μm;GMP颗粒的体积和表面积分布均呈双峰曲线,数目分布呈单峰曲线。在0—240kg/hm2范围内增施氮肥能显著提高>10μm GMP颗粒数目百分比和体积百分比,表明施氮能促进大颗粒GMP的形成。不同品种对施用氮肥的反应呈现差异。大穗型品种泰山9818籽粒GMP含量及颗粒粒径分布对氮肥的反应较为敏感。

Glutenin macropolymer is an important characteristic that affect significantly processing quality of wheat flour.It is determined by glutenin subunit composition and influenced by field environment during grain development.Application of nitrogen fertilizer is one of the most important measure to increase grain yield and protein content in winter wheat production.However,misuse of nitrogen fertilizer will not only affect grain yield,but also cause the decline of quality.To evaluate effects of nitrogen rates on GMP contents and GMP particles distribution in grains,a fertilizer experiment was designed with four treatments： without applying N fertilizer（N0）,nitrogen rates of 160 kg/hm2（N1）,240 kg/hm2（N2）,and 320 kg/hm2（N3）,ratios of base fertilizer to topdressing of 1∶1,using two wheat cultivars differing in spike type.The plot area was 3 m×4 m = 12 m2.At the three-leaf stages,the seedings were thinned to a density of 225 plants per m2 for Taishan9818（the large-spike cultivar）,while for Shannong15（the small-spike cultivar） that was 180 plants per m2. The results showed that application of nitrogen fertilizer increased markedly the GMP content in both cultivars,but,there were different patterns in response to nitrogen application between the two cultivars.Nitrogen application generally increased GMP content at nitrogen rate ranging from 0 to 240 kg/hm2,and decreased when excessive nitrogen of 320 kg/hm2 was applied in Shannong 15,while in Taishan9818,the content of GMP was increased within the nitrogen rates from 0 to 160 kg/hm2,and decreased with the increasing nitrogen supply.This indicated that appropriate N fertilizer rate generally increased GMP content of wheat grain,while at the excessive nitrogen rate,the contents of GMP decreased.Taishan9818,the large-spike cultivar,was more sensitive to nitrogen in GMP content as compared with small-spike cultivar Shannong15.At maturity,the diameter of GMP particles changed in the range of 0.375-256 m.Volume and surface area distribution of GMP particles exhibited the typical two populations,while number distribution showed single peak curves.The D4,3（weighted average volume） of Shannong15 was higher than Taishan9818,this contribution mainly came from the higher percentage of 100 μm GMP particle volume distribution in Shannong15.At the rage of 0-240 kg/hm2,the percentage of 10 μm GMP particle volume distribution was decreased with the increasing nitrogen supply.It indicated that appropriate nitrogen fertilizer rate generally increased the percentage of lager particles volume distribution.The surface area percentage of 10-100μm and 100 μm GMP particle and the D3,2（weighted average surface area） were increased within the nitrogen rates from 0 to 240 kg/hm2,and decreased when excessive nitrogen of 320 kg/hm2was applied,nitrogen application also increased the percentages of number of 10 m GMP particles.These indicated that appropriate nitrogen application promoted the formation of lager particles.The analysis of correlation showed that the content and proportions of GMP in total protein were positively correlated with the volume of 100 m GMP particles and sensitively with the D4,3.It suggested that the higher proportion of larger GMP granules was consistent with higher content of GMP in grains of wheat.