不同水氮水平冬小麦干物质积累特征及产量效应

为了阐明灌水施氮对冬小麦干物质积累和产量形成的影响机制,通过2012-2014年在关中平原进行的3个灌水水平、4个施氮水平的田间试验,采用Richards生长曲线对干物质积累过程进行拟合,定量分析了干物质积累过程的动态特征和产量效应。结果表明灌越冬水和拔节水均能显著延长干物质积累的总时间,使最大干物质量由雨养下的10 831提高到灌两水条件下的13 813 kg/hm~2。氮肥显著提高了干物质积累过程的平均速率和最大速率,缩短了达到最大速率的时间,使最大干物质量由8 001(不施氮)提高到14 112 kg/hm~2(施氮210 kg/hm~2)。年份主要通过控制进入快速生长期和达到最大速率的时间来影响干物质量积累过程。灌水的产量效应年际变异较大,在2013和2014年分别通过增加千粒质量和每平方米粒数来影响产量,2013年千粒质量由雨养下的35.8提高到灌两水下的41.7 g,2014年每平方米粒数由雨养下的13 833增加到灌两水条件下的15 749粒/m~2。氮肥主要是通过增加每平方米粒数来提高产量,由不施氮下的10 414增大到施氮210 kg/hm~2条件下的15 911粒/m~2,继续增施氮肥对产量及产量构成要素影响不大。产量和每平方米粒数均与干物质积累过程的平均速率和最大速率呈显著正相关性,表明在该研究地区小麦产量主要受氮肥限制。该研究为干旱半干旱地区合理调控水肥措施,实现作物高产高效提供科学依据。

Effects of irrigation and nitrogen regimes on dry matter dynamic accumulation and yield of winter wheat

Abstract: Wheat yield formation is mainly dependent on dry matter accumulation, which is influenced by irrigation and nitrogen input. It will be very helpful for improving yield to understand how irrigation and nitrogen affect wheat dry matter accumulation. Field experiments over 2 years with three-level irrigation and four-level nitrogen input for winter wheat were conducted during 2012-2014 in Guanzhong Plain located in Shaanxi Province, China. Dry matter accumulation with growing degree day was fitted by Richards function, and 5 derived characteristic parameters were analyzed using the univariate analysis of variance (ANOVA) and the multivariate analysis of variance (MANOVA), the result of which was more appropriate when there were significant correlations among dependent variables. None of the 5 derived characteristic parameters of dry matter accumulation was significantly influenced by the interaction of irrigation and nitrogen fertilization. None of irrigation, nitrogen and year had a significant effect on the function parameter b and c. Irrigation significantly prolonged the thermal time required for the entire dry matter accumulation process and then led to an increase of dry matter at maturity from 10 831 kg/hm2 under rainfed condition to 13 813 kg/hm2 with irrigation at wintering and jointing stages. Nitrogen fertilization significantly enhanced the average and maximum rate of dry matter accumulation, and shortened the thermal time achieving the maximum rate of dry matter accumulation since sowing. Dry matter at maturity significantly increased from 8 001 to 14 112 kg/hm2 under the nitrogen input from 0 to 210 kg/hm2 in this study. No more dry matter was gained from more nitrogen input. Weather conditions over 2 years had a significant effect on the thermal time entering the rapid growth stage and achieving the maximum growth rate since sowing, but had no significant effect on the maximum of dry matter. The effect of irrigation on yield and yield components varied with weather conditions in study period. Irrigation significantly increased the yield and the weight of 1 000 grains in 2012-2013, however, it had no significant effect on those in 2013-2014. The weight of 1 000 grains evolved from 35.8 under rainfed condition to 41.7 g with irrigation at wintering and jointing in 2012-2013, which resulted that the corresponding yield increased from 4.74 to 6.29 t/hm2. In 2013-2014, irrigation significantly enhanced the grain number per square meter from 13 833 under rainfed to 15 749 with irrigation at winter and jointing. Yield and grain number per square meter were significantly influenced by nitrogen, while nitrogen had no effect on the weight of 1 000 grains over 2 years. Grain number per square meter increased from 10 414 to 15 911 as nitrogen input increased from 0 to 210 kg/hm2, which contributed to the corresponding increase of yield from 4.42 to 6.96 t/hm2. No more yield and grain number were gained from more nitrogen input, which indicated the nitrogen rate of 210 kg/hm2 would be sufficient for wheat growth and yield formation. The interaction of irrigation and nitrogen had no effect on yield and yield components during 2012-2014. The yield had a higher correlation with grain number per square meter than with the weight of 1 000 grains, which indicated that yield was largely determined by grain number. Both of yield and grain number per square meter had a strong correlation with the average and maximum rate of dry matter accumulation, which indicated improving the rate of dry matter accumulation would be a promising measure to raise yield in the future. This also indicated that nitrogen was the limited factor to wheat grain yield improvement in this study area. The results obtained in this research provide scientific basis and valuable information for selecting the optimum irrigation and nitrogen regimes in semi-arid regions of China.