中文摘要：

调查分析了陕西榆林2块19500kg·hm-2以上超高产春玉米田的产量构成、干物质分配和0～100cm土层根系分布及土壤理化性状指标.结果表明：其种植密度为105000～123000株·hm-2、成穗率97.7%～102.2%、千粒重320g以上,果穗干物质积累量占整株干物质积累量的60.2%～65.5%.0～100cm土壤平均容重为1.28～1.33g·cm-3,层间（每层20cm）土壤容重、孔隙度和田间持水量均呈＂M＂型变化.玉米根系主要分布在0～60cm,0～20cm土层根系量占根系总量的64.8%～72.1%,20～60cm土层根系量占根系总量的23.30%～28.17%.根系分布与土壤理化性状关系密切,0～20cm土层玉米的根系量与土壤有机质、全氮和全磷含量呈显著正相关,20～60cm土层根系量与土壤容重和田间持水量显著相关.因此,选择通透性和保水保肥能力良好的土壤,实行宽窄行双株密植栽培是获得玉米高产的关键.

英文摘要：

An investigation was made on the yield component,dry matter allocation,root distribution in 0-100 cm soil layer,and soil physical and chemical properties in two high yielding（19500 kg·hm-2） spring maize fields of Yulin,Shaanxi Province.In the two fields,the planting density was from 105000 plants·hm -2 to 123000 plants·hm -2,spike rate was from 97.7% to 102.2%,1000-grain weight was 320 g,and the dry matter allocation in ears occupied 60.2%-65.5% of the total.The average bulk density in 0-100 cm soil layer was from 1.28 g·cm -3 to 1.33 g·cm -3,and the soil bulk density,porosity,and field water-holding capacity along the profile all changed in M type.Maize roots were mainly distributed in 0-60 cm soil layer,and those in 0-20 cm and 20-60 cm accounted for 64.8% -72.1% and 23.30% -28.17% of the total,respectively.There was a close relationship between root distribution and soil physical-chemical properties.Root dry mass in 0-20 cm soil layer had a significant positive correlation with soil organic matter,total nitrogen,and total phosphorus,while that in 20-60 cm soil layer was significantly correlated with soil bulk density and field water-holding capacity.Therefore,to select soils with good permeability and high maintenance capacity of water and nutrients would be the key in obtaining high maize yield.