Differential Comparison of Root Morphology and Matter Accumulation of Spring Maize under Different Plant Densities in Northeast China

With the aid of field experiment site of Gongzhuling city,Jilin Province,the study of maize(Zhengdan958 in 2009 and Xianyu335 in 2010) close plant was carried out in 2009-2010.The main root morphological index and root dry matter accumulation in 0-60 cm depth soil profile in the key growth period were measured under the densities of 45 000,67 500,90 000 plant/ha.The results showed that the root biomass on the basis of individual plant in 0-60 cm depth soil decreased with the increasing density,but the community root dry weight kept an increasing trend.Under all three densities,root morphology index of Zhengdan958,including root length,root surface area,root volume and root length density,showed a change of single-peak curve from jointing stage to milk stage with growth development and reached the maximum at tasseling-silking stage.However,all root morphology index of Xianyu335 showed a declined trend from jointing stage to milk stage,and reached the maximum at jointing stage.Root length,root surface area and root volume index of individual plant of two maize varieties substantially decreased with increasing density at tasseling-silking stage and milk stage;on the contrary,root length,root surface area,root volume and root length per volume of maize population increased with the increasing density.