大田长期水氮处理对土壤氮素及小麦籽粒淀粉糊化特性的影响

土壤氮素和水分含量对小麦产量和品质有重要影响。为优化水肥管理实现优质高效栽培,2014—2015和2015—2016小麦生长季在河南省温县大田水氮长期定位试验地块,以中筋品种豫麦49-198为材料进行灌水与施氮两因子裂区试验。主区为灌水处理,设全生育期不灌水(W0)、拔节期750 m3 hm-2(W1)和拔节期750 m3 hm-2+开花期750 m3 hm-2(W2)3个水平,副区为氮素处理,设不施氮(N0)及总氮量180(N1)、240(N2)和300 kg hm-2(N3)4个水平。与W0处理相比,2个灌水处理均显著降低耕层土壤(0~20 cm)中的硝态氮含量,灌水处理的籽粒支链淀粉含量、总淀粉含量、淀粉峰值黏度、谷值黏度和最终黏度均显著高于不灌水处理。灌水还增加了籽粒中小淀粉粒(粒径5.0μm)的体积百分比,2014—2015年度增幅显著,W1、W2处理分别较W0处理增加3.4%和4.8%。施氮提高耕层土壤硝态氮含量,但籽粒直链淀粉含量和小淀粉粒体积百分比低于不施氮处理。在0~240 kg hm–2施氮量范围内,籽粒支链淀粉含量、总淀粉含量及峰值黏度、谷值黏度、最终黏度均随施氮量增加而增加。相关分析表明,耕层土壤硝态氮含量与总淀粉含量、峰值黏度、谷值黏度和最终黏度间呈极显著正相关。拔节期灌1水、施氮量240 kg hm–2条件下,耕层土壤硝态氮含量为19.64~20.55 mg kg–1,小麦籽粒黏度值较高,同时改善了淀粉品质。

Effects of Long-Term Irrigation and Nitrogen Regimes on Soil Nitrogen Content and Paste Property of Wheat Grain

Nitrogen (N) and water contents in soil are primary elements affecting grain yield and quality of wheat. For optimizing the water and fertilizer management in high-quality and high-efficiency wheat production, a split-plot experiment was carried out in the long-term fertilization fields in Wenxian county, Henan province in the 2014-2015 and 2015-2016 winter wheat seasons. The main-plot factor was irrigation in three levels (W0 for no irrigation, W1 for 750 m ³ ha ^-1 at jointing, and W2 for 750 +750 m ³ ha ^-1 at jointing + anthesis), and the split-plot factor was N rate in four levels (0, 180, 240, and 300 kg ha ^-1). Yumai 49-198, a medium-gluten variety, was the unique variety used in the experiment. The soil NO₃ ^--N content in the 0-20 cm soil layer was significantly lower, whereas, the amylopectin and starch contents, starch peak viscosity and final viscosity were significantly higher in W1 and W2 treatments than in W0 treatment. Under irrigation conditions, the volume of small starch granule (<5.0 μm) increased as compared with that under W0 condition, with the increase of 3.4% in W1 and 4.8% in W2 in the 2014-2015 wheat season. Nitrogen application improved soil NO₃ ^--N content but negatively affected amylose content and the percentage of small starch granules. Amylopectin and starch contents, peak viscosity, through viscosity, and final viscosity increased with N application ranging from 0 to 240 kg ha ^-1. The correlation analysis revealed positive correlations (P < 0.01) of NO₃ ^--N with starch yield, peak viscosity, through viscosity, and final viscosity. Results showed that under N 240 kg ha ^-1 and W1 condition the nitrate content in topsoil layer was 19.64-20.55 mg kg ^-1 having higher grain yield and good starch property.