Effect of Deep Nitrogen Fertilizer Application on Grain Protein Content and Quality of Bread Wheat

In dry agricultural areas, plant uptake of nitrogen (N) stored in topsoil is limited as soil excessively dries up, especially in the late period of wheat growth. Deep N application is often suggested to ensure effectively use of water stored in the subsoil. This experiment was carried out in two different fields with different soils at Transitional Zone Agricultural Research Institute (TZARI) between 2012–2015 in the fallow-wheat rotation system. Efficiency of six different applications (1- deep Autumn 40 kg N ha−1(A40), 2- deep Autumn 20 kg N ha−1 (A20), 3-deep Spring 40 kg N ha−1(S40), 4- deep Spring 20 kg N ha−1(S20), 5- Traditional (T), 6- Control (C)) was investigated in Mufitbey and Bezostaja1 cultivars. The highest grain yield (4861 kg ha−1) was obtained in deep application of 20 kg N ha−1 in autumn, and the lowest grain yield (3969 kg ha−1) was obtained in control. Also, the highest protein content of 12.65% was obtained with deep N applications of 20 kg N ha−1 in autumn, while the lowest GPC (11.37%) was found in the control. Significant and high correlations occurred between nitrate content at 60 cm soil depth in the grain filling period and spike N uptake (r = 0.85, P < .001), GPC (r = 0.84 P < .001), farinograph number (r = 0.85, P < .05), development time (r = 0.83 P < .05) and yield (r = 0.96, P < .001). Significant occurred between Bezostaja1 and Müfitbey in rheological (dough) properties. The data showed that climate and soil conditions should be taken into account in deep N application in dryland wheat farming.

在干旱农区，由于土壤过度干旱，尤其是在小麦生长后期，作物对表层土壤储存氮素（Nitrogen, N）的吸收会受到限制。深施氮肥常被建议用于保障对亚表层土壤储存水分的有效利用。本试验于2012-2015年在过渡带农业研究所（Transitional Zone Agricultural Research Institute, TZARI）的两个不同土壤类型田块中开展，采用休闲-小麦轮作制度。本试验针对穆菲特贝（Müfitbey）与贝佐斯塔亚1号（Bezostaja1）两个小麦品种，研究了六种不同施肥处理的施用效果：1- 秋季深施40 kg·ha⁻¹氮肥（A40）、2- 秋季深施20 kg·ha⁻¹氮肥（A20）、3- 春季深施40 kg·ha⁻¹氮肥（S40）、4- 春季深施20 kg·ha⁻¹氮肥（S20）、5- 传统施肥（T）、6- 空白对照（C）。结果显示，秋季深施20 kg·ha⁻¹氮肥处理的籽粒产量最高，达4861 kg·ha⁻¹；空白对照处理的籽粒产量最低，为3969 kg·ha⁻¹。此外，秋季深施20 kg·ha⁻¹氮肥处理的籽粒蛋白质含量（Grain Protein Content, GPC）最高，达12.65%；空白对照处理的GPC最低，为11.37%。籽粒灌浆期60 cm土层硝态氮含量与穗部氮素吸收量（相关系数r=0.85，P<0.001）、GPC（r=0.84，P<0.001）、粉质仪参数（Farinograph Number, farinograph number）（r=0.85，P<0.05）、面团形成时间（r=0.83，P<0.05）及籽粒产量（r=0.96，P<0.001）均呈显著高度相关。贝佐斯塔亚1号与穆菲特贝两个品种的流变学（面团）特性存在显著差异。试验数据表明，旱地小麦氮肥深施应综合考虑气候与土壤条件。