测墒补灌和施氮对冬小麦产量及氮素吸收分配的影响

采用田间试验裂区设计方法,研究了测墒补灌和施氮对冬小麦产量及氮素吸收分配的影响。补灌设3个水平,在冬小麦拔节期0—40cm土层补灌至土壤目标相对含水量的60%(W_1),70%(W_2)和80%(W_3)。施氮设3个水平:不施氮(N_0)、施纯氮195kg/hm~2(N_(195))和255kg/hm~2(N_(255))。结果表明:(1)不同补灌和施氮对冬小麦关键生育期株高、叶面积影响效果较为显著,同一补灌处理下,其冬小麦株高、叶面积均表现为N_(255)N_(195)N0(p0.05)。N_(195)、N_(255)处理显著高于N_0处理,但N_(195)及N_(255)处理间无显著性差异(p0.05),同一施氮处理下,W_2(569.4m~3/hm~2)、W_3(873.45m~3/hm~2)处理显著高于W_1(265.2m~3/hm~2)处理,但W_2及W_3处理间无显著性差异(p0.05)。说明过量施氮和补灌对冬小麦株高、叶面积无显著性作用。(2)同一施氮水平下,补灌对冬小麦的增产效应随施氮量的增加呈下降趋势,说明施氮和补灌对冬小麦产量存在一定的临界值,超过临界值,产量下降。当施氮量为195kg/hm~2,补灌量为田间持水量的70%(569.4m~3/hm~2)时达最高产8 500kg/hm~2。(3)冬小麦成熟期,施氮处理的植株氮素积累量显著高于不施氮处理(p0.05),但在W_2、W_3处理下,N_(255)相较于N_(195)显著下降(p0.05),特别是在W_3(873.45m~3/hm~2)水平下,N_(255)甚至低于N_0处理;在N_0、N_(195)处理下,植株氮素积累量随补灌量的增加显著增加(p0.05),但在N_(255)处理下并无显著差异(p0.05),说明适量补灌、施氮可提高冬小麦的吸氮能力,但过量补灌、施氮并不利于植株对氮素的吸收。(4)拔节期补灌量的增加虽提高了冬小麦的吸氮能力,促进冬小麦吸收较多的氮素,却抑制了冬小麦体的氮素向籽粒的转移和分配。综合考虑冬小麦生长状况及氮素风险状况,建议施氮量为195kg/hm~2、补灌至田间持水量的70%(569.4m~3/hm~2),作为该区域适宜的水、肥用量。

Effects of Supplemental Irrigation Based on Soil Moisture Content Measuring and Nitrogen Fertilizer Application on Winter Wheat Yield, Nitrogen Absorption and Distribution

In this study,a field experiment was performed by using split-plot to investigate the effects of supplemental irrigation and nitrogen fertilizer application on winter wheat yield,nitrogen absorption and distribution.Based on measured of soil moisture content in 0-40 cm soil layers at the jointing stage of wheat,three irrigation levels were designed in main plots,which could make the moisture content of target soil reach 60％ (W1),70％ (W2),and 80％ (W3).In the sub-plots,three nitrogen levels were designed,0 kg/hm2 (N0),195 kg/hm2 (N195),and 255 kg/hm2 (N255).The results were as follows:(1) Supplemental irrigation and nitrogen application had significant effects on plant height and leaf area of winter wheat.For the same irrigation treatments,plant height and leaf area all followed the order of N255＞N195＞N0 (p＜0.05),under the same nitrogen application treatments,plant height and leaf area in W2 (569.4 m3/hm2) and W3 (873.45 m3/hm2) were significantly higher than that in W1 (265.2 m3/hm2) (p＜0.05),but the differences between W2 and W3 were not significant (p＞0.05),indicating that excessive nitrogen application and irrigation had no significant influence on the plant height and leaf area of winter wheat.(2) Under the same nitrogen application treatments,the threshold response of wheat yield was observed under different ratios of N application and irrigation,the highest yield (8 500 kg/hm2) was reached under the N195 and W2 (569.4 m3/hm2).(3) During the maturity stage of winter wheat,under W2 and W3,nitrogen accumulation under N255 was significantly lower than that under N1g5 (p＜0.05);especially for N255,nitrogen application had no significant influence on nitrogen accumulation,indicating that appropriate irrigation and nitrogen application could increase wheat's ability to absorb nitrogen.(4) Though wheat nitrogen absorption increased with increasing amount of water irrigation,nitrogen distribution proportion in the grain was reduced.Considering the growth status of winter wheat and nitrogen risk status,a N level of 195 kg/hm2 and an irrigation rate of 70％ field capacity (569.4 m3/hm2) is suitable for water and fertilizer application in this region.