密度、施肥对旱地春小麦产量、水分利用效率和籽粒养分含量的补偿效应

为了探明旱作条件下无机营养对作物产量和水分利用效率的补偿效应，我们在宁南黄土高原半干旱地区开展了为期两年的春小麦密度与肥料试验。通过4种播种密度和5种肥力水平的综合研究结果表明，在不同处理的籽粒产量和水分利用效率排序中，播种密度为500粒／m^2时，以施肥量90kg／hm^2N和135kg／hm^2P2O5处理的产量和水分利用效率为最大。与不施肥的对照相比，增施肥料与籽粒产量和水分利用效率的提高成显著的正相关关系，相关系数分别达到0．959和0．894，而播种密度则与产量和水分利用效率的相关性不显著。增施肥料虽然能够提高可育小花数，但随着播种密度的增大，穗粒数和千粒重反而呈下降趋势，表明可育小花数对肥料水平反应敏感，而穗粒数和千粒重主要受播种密度的影响。施肥能够促进春小麦根系的生长发育，特别是促进浅层根量的增加，增强了作物的水分养分吸收。另外，不同种类肥料配施的结果表明，单施P肥或者N、P、K配合施用，可使春小麦产量分别提高44．6％和55．4％。N、P、K配合施肥还能够提高品质，使籽粒中的P、N、K含量分别提高18．5％、18．4％和8．1％。上述研究结果说明，控制播种密度、改善土壤肥力对于促进旱地春小麦高效利用有限水分具有明显的补偿效应。

Compensation effects of planting density and fertilization on grain yield,water use efficiency and seeds nutrient contents of dry land spring wheat

To assess the compensation effects of input fertilizers on the crop yield and water use efficiency (WUE),two-year experiments of spring wheat planting density and fertilization influence yield formation were conducted in the semiarid field conditions of loess hilly area in Ningxia Uh autonomous region.A comparison of wheat yield and WUE sequences under four planting densities with five fertilization levels shows that maximum yield and highest WUE were achieved under the optimum fertilizer input of 90 kg N and 135 ckg P2O5 per hm2 with 500 seeds/m2.Increase soil fertilization was positively correlated with grain yield and water use efficiency of spring wheat,with a correlation coefficient were 0.959 and 0.894,planting density,however,showed poor correlation with both.Increasing fertilizer level significantly increased fertile spikelets number,kernels per spike and kernel weight.These components were decreased with the increase in planting density.Fertile spikelets number was sensitive to fertilization,whereas kernel number and weight was mainly affected by plant density.Fertilization applied in spring wheat improved root system development and especially enhanced roots growth in the cultivated soil layer of 0～20 cm.Ameliorated root system was able to improve crop water use and nutrient absorption,and hence,crop yield and water use efficiency was increased.Grain yield of spring wheat was increased by 44.6% and 55.4% when P and P+N+K were applied,respectively.A significant increase in yield was also obtained with N application but not with K.P or P+N promoted spike development and hence,increased seed production.N+P+K improved the quality of seeds,and the content of N,P and K in seed increased by 18.5%,18.4% and 8.1%,respectively,compared with no nutrient treatment.This study highlights the compensation effects of improving soil fertility to high efficient use of limited water in dry land spring wheat production.