基施氮肥及灌浆前期喷施锌肥对小麦籽粒富锌及蛋白组分含量的影响

Effects of Basal Nitrogen and Foliar Zinc Application at the Early Filling Stage on Zinc Enrichment and Protein Components Content in Wheat Grain

【目的】叶面喷锌(Zn)是提高小麦籽粒锌含量进而解决人体缺锌问题的有效农艺措施。探明不同施氮(N)量下叶面喷锌后小麦全粒及面粉中的富锌效果及对蛋白组分含量的影响。【方法】基于长期定位试验,于2018-2020年连续进行了两年裂区田间试验。以基施不同用量氮肥(N_(0)、N_(120)、N_(240),施N量分别为0、120、240 kg·hm^(-2))为主区,副区为灌浆前期喷施锌肥处理(Zn_(0)、Zn_(1),分别为喷H_(2)O、喷0.4%ZnSO_(4)·7H_(2)O),测定了灌浆前期和成熟期各部位锌含量、叶片等营养器官中锌向籽粒的转移量及分配、籽粒和面粉中蛋白质及其组分含量。【结果】与N_(0)相比,N_(120)和N_(240)处理籽粒产量显著提高,增幅达88%-114%,但N_(120)和N_(240)处理之间并无显著差异。叶面喷锌均能显著提高小麦籽粒和面粉锌含量且籽粒达富锌标准,而不受施氮量的影响,其中,N_(120)、N_(240)处理小麦籽粒锌含量分别比N_(0)处理提高0.95和1.12倍。与N_(0)相比,施用氮肥均提高了小麦灌浆前期叶片等营养器官中氮、锌向籽粒的转移量,但降低了二者的转移比例,其中氮转移比例由60.2%下降至48.6%,锌由55.4%下降至42.3%。无论喷锌与否,氮、锌向籽粒的转移量及成熟期籽粒中氮、锌含量均呈显著线性正相关,且喷锌时氮、锌协同效应更为显著。与灌浆前期相比,成熟期小麦籽粒和面粉中储藏蛋白(醇溶蛋白和谷蛋白)含量显著增加,约占蛋白含量的80%-84%。施氮对籽粒和面粉中醇溶蛋白和谷蛋白含量提升幅度高于清蛋白和球蛋白,且以谷蛋白最大,而喷锌不影响籽粒和面粉中蛋白质及其组分含量,但在Zn_(1)条件下,施氮对籽粒和面粉中谷蛋白含量的提高幅度高于Zn_(0)条件下,分别提升37.5%和38.1%。【结论】叶面喷锌能够实现籽粒富锌,但不影响籽粒和面粉中蛋白质及其组分含量,表明籽粒和面粉中存在足够的用于锌储存的蛋白质库。因此在潜在缺锌石灰性土壤上,通过合理施用氮肥结合小麦灌浆前期叶面喷锌,能在保证小麦高产稳产的同时提高籽粒氮、锌营养品质。

【Objective】Foliar zinc(Zn)application is an effective agronomic biofortification strategy to realize Zn enrichment of wheat grains and to combat the human Zn malnutrition.The aim of this study was to investigate the effects of spraying Zn with different nitrogen(N)inputs on Zn enrichment and content of protein and protein components in wheat whole grain and flour.【Method】Based on the long-term positioning experiment,the spraying experiment of Zn in wheat for two consecutive seasons was conducted during 2018-2020.A split plot design was used with soil N rates of 0(N_(0)),120(N_(120))and 240·hm^(-2)(N_(240))as the main plot factor,and the foliar application of distilled water(Zn_(0))and 0.4%ZnSO_(4)·7H_(2)O(Zn_(1))as subplot.The indexes were analyzed for this study,including Zn content of various nutritional organs,Zn mobilization and distribution from leaf and other vegetative organs to grain,and protein and protein component content in grains and flour at the early filling stage and maturation stage.【Result】Compared with N_(0),the grain yield under N_(120)and N_(240)treatments was significantly increased by 88%-114%,but there was no significant difference between N_(120)and N_(240).Regardless of the N inputs,the foliar Zn application could significantly increase the Zn concentration in grains and flour and the grain Zn content reached the biofortification standard.Among those treatments,the Zn concentration of wheat grains under N_(120)and N_(240)was increased by 0.95 and 1.12 times than that under N_(0),respectively.Compared with N_(0),the N inputs increased the translocation of N and Zn transferred from leaf and other vegetative organs to grain at early grain filling stage,but reduced the transfer ratio of N and Zn:N decreased from 60.2%to 48.6%and Zn decreased from 42.3%to 26.5%.A significant positive linear correlation was found between the amount of N and Zn mobilization and the content of N and Zn in grain at maturity,and the synergistic effect of N and Zn was more significant at Zn_(1).Compared with the early filling stage,the content of storage protein(gliadin and glutenin)in grains and flour at the mature stage increased significantly,accounting for about 80%-84%of the protein content.The content of gliadin and glutenin in grain and flour was increased by N application more than that of albumin and globulin,and the gluten was the largest.The content of protein and protein components in grain and flour were not affected by spraying Zn.However,in terms of Zn_(1),the increase of gluten content in grain and flour was higher than that under the condition of Zn_(0) with the increase of N dosage,which was 37.5%and 38.1%,respectively.【Conclusion】Foliar Zn application could achieve Zn-rich grains but did not affect the content of protein and protein components in grains and flour,indicating that there was sufficient protein pool for Zn storage in grains and flour.Therefore,a reasonable amount of soil N combined with foliar Zn application could increase the N,Zn content and nutritional quality of the grains by ensuring high and stable yield on potentially Zn-deficient calcareous soils.