播种密度对秸秆覆盖旱地冬小麦产量和土壤水分的影响

为了解秸秆覆盖下作物群体对土壤水分和小麦产量的影响，于2012年6月至2013年6月在渭北旱塬研究秸秆覆盖与常规耕作模式下播种密度对土壤储水量、冬小麦群体动态变化、小麦产量及水分利用效率的影响。秸秆覆盖与常规耕作相比休闲期在0~3.6 m土层多蓄水105 mm，主要于小麦拔节后利用。不同播种密度主要影响小麦抽穗前的群体大小，抽穗后群体差异不显著。小麦籽粒产量为2 841~3 496 kg/hm, 不同密度水平或覆盖均没有显著影响小麦产量，但是高密度处理较中、低密度显著降低小麦收获指数。另外，秸秆覆盖小麦较常规增加20%耗水量，小麦水分利用效率降低11%。因此，在休闲期降雨丰富，生育期特旱的气候条件下播种密度对秸秆覆盖小麦产量没有影响，显著增加耗水量，降低水分利用效率。播种密度、秸秆覆盖及其交互效应还有待于在其他气候年型下进一步研究观测以便综合评价这些因素的影响效应，进而建立旱地小麦高产高效用水的管理措施。

Effect of Seeding Rate on Winter Wheat Yield and Soil Water Dynamics under Straw Mulching on Dryland

The objective of this research was to investigate effects of different seeding rates on soil water storage, development of winter wheat population, grain yield and water use efficiency under straw mulching and conventional conditions on dryland in Weibei Plateau from June 2012 to June 2013. The results showed that water storage at 0-3.6 m soil layer was 105 mm higher under straw mulching than under conventional treatment at wheat sowing time, which was used by wheat after the jointing stage. In addition, wheat population size before heading stage was significantly influenced by seeding rate, but no differences were observed after heading. Wheat grain yield ranged from 2 841 kg/hm to 3 496 kg/hm, both seeding rate and mulching had no prominent effects on grain yield. However, a significant lower harvest index was observed under high seeding rate than middle and low seeding rates. The water use efficiency was lower by 11% under straw mulching than under conventional, which due to the significant higher water use by 20%. Therefore, seeding rate and mulching had no pronounced effects on wheat yield under tested weather condition, further studies are needed to comprehensively evaluate these effects under other weather conditions to establish rational management practice for dryland wheat.