种植密度对紧凑型玉米鲁单818根系生长动态及产量的影响

Influence of Planting Density on the Root Dynamic Growth and Yield in Erectophile Type Maize LD818

大田条件下研究3种种植密度对紧凑型高产玉米品种鲁单818(LD818)根系生长动态及产量的影响。结果表明,LD818在9万株/hm2的群体产量分别比3万、6万株/hm2提高96.10%和10.96%,具有较高的增产潜力。不同种植密度下,LD818单株根系体积、根系体积密度、单株根系活跃吸收面积和根系吸收面积指数(RAI)均随生育进程的推进呈先增加后减小的变化趋势;单株根系体积和吸收面积随种植密度的递增呈递减趋势,根系体积密度和RAI呈升高趋势。种植密度递增,LD818个体根系水平方向高密度区(0～6 cm)根系干重比例不断递增,中密度区(7～12 cm)和低密度区(13～18 cm)不断递减;垂直方向上层高密度区(0～20 cm)、中密度区(21～40 cm)根系干重比例不断递减,下层(41～60 cm)低密度区和稀密度区(61～80 cm)递增。LD818单株根系呈"横向紧缩,纵向延伸"的特点,较适应随种植密度递增导致水平方向空间受限制的"拥挤",可适当减小株距密植。

A field experiment was conducted to compare the influence of planting density on the root dynamic growth and yield of LD818. The results indicated that LD818 was a maize type resistant to close planting, comparing with those at the planting densities 30 000 and 60 000 plant/ha, the grain yield of LD818 at the planting density 90 000 plant/ha was increased by 96.10% and 10.96% respectively. The root volume per plant, root volume density, actively surface area per plant, and root actively surface area index（RAI） of LD818 increased at first and then de- creased with the advance of growing stages. And the root volume and actively surface area per plant decreased with the increase of planting density, then root volume density and RAI of LD818 decreased. With increasing planting density, the horizontal distribution percent of root dry weight increased in higher density zone increased, and decreased in mid, lowerdensity zone, the vertical-distribution percent of root dry weight decreased in higher, mid density layer, and in- creased in lower, and thin density layer. The root distributing of LD818 shows the characteristic of ＂vertical extension and horizontal contraction＂, and it is adaptive to horizontal restriction owing to higher density, so it is suitable to culti- vate under higher density condition.