2019-2020年以中熟品种陕单650品种和晚熟品种东单60为材料，设置6.0、7.5、9.0和10.5×104株 hm-2四个种植密度，研究了密度对玉米品种籽粒灌浆特性、干物质积累、叶片衰老、籽粒脱水速率和产量的影响。结果表明，增加密度提高不同熟期玉米品种的产量，其中陕单650在密度为9.0×104株 hm-2时最优产量18083.5kg hm-2，东单60在密度7.5×104株 hm-2时最优产量17472.9 kg hm-2。2个品种籽粒灌浆速率、粒重、籽粒含水率随密度的增大而减小，陕单650达到最大灌浆速率的天数、平均灌浆速率较东单60均早4 d和高0.06g d-1；陕单650籽粒平均脱水速率为0.98 % d-1，东单60平均脱水速率为0.93% d-1，且陕单650生理成熟4 d后籽粒含水率迅速降至25%。当密度为9.0×104株 hm-2时，陕单650的物质转运率明显高于东单60，其叶片转运率较东单60高99.6%。与东单60相比，密植下陕单650有较高产量和低水分含量，在于其群体籽粒灌浆速率高，生物量大；灌浆后期叶片衰老快及物质转运率高，促进籽粒脱水。通过适度增密提高籽粒产量、缩短生育期降低籽粒水分的技术途径，协同实现陕西春玉米密植高产机械籽粒收获生产。

A field experiment was conducted using the medium maturity maize hybrid Shaandan 650 and late maturity maize hybrid Dongdan 60with four plant densities of 6.0×104, 7.5×104, 9.0×104and 10.5×104plants hm-2 from 2019 to 2020. The effects of planting density on grain filling characteristics, dry matter accumulation, leaf senescence, grain dehydration rate and yield of maize hybrid were studied. The results showed that increasing density could increase the grain yield with different maturity maize hybrids. Among them, the optimized yield of Shaandan 650 was 18083.49kghm-2 when the density was 9.0×104 plants hm-2, while that of Dongdan 60 was 17472.9 kghm-2 when the density was 7.5×104plants hm-2. The grain filling rate, grain weight and grain moisture content of the two hybrid decreased with the increase of density. The days of Shaandan 650 reach the maximum grain filling rate and the average grain filling rate were 4 d earlier and 0.06 d-1 higher than those of Dongdan 60. the average grain dehydration rate of Shaandan 650 was 0.98% d-1, while the average dehydration rate of Dongdan 60 was 0.93% d-1, and the grain moisture content of Shaandan 650 decreased rapidly to 25% after 4 d of physiological maturity. When the density was 9.0×104 plants hm-2, the material translocation rate of Shaandan 650 (16.8%) was significantly higher than that of Dongdan 60 (12.7%), especially the leaf translocation rate was 99.6% higher than that of Dongdan 60. In summary, compared with the late maturity maize hybrid Dongdan 60, the medium maturity maize hybrid Shaandan 650 under dense planting had higher yield and low moisture content, which was mainly due to its higher grain filling rate, larger grain dry matter accumulation and faster matter transport in the later grain filling stage, especially high leaf translocation rate promote grain dehydration. Therefore, through the technical approach of moderate densification to increase grain yield and shorten the growth period to reduce grain moisture, Shaanxi spring maize dense planting and high-yield mechanical grain harvest production was realized.

国家重点研发计划项目(2017YFD0300304)和陕西省重点研发计划项目(2017ZDCXL-NY-02)