渐密种植条件下玉米植株形态特征及其相关性分析

在大田条件下，以郑单958、先玉335、登海661和益农103为试验材料，采用行距固定(80 cm×40 cm大小行)、株距从1 m开始由大至小的“渐密”种植方式，形成1.67~16.67株 m^-2共13个种植密度，在拔节期、大喇叭口期和生理成熟期分别测定株高、茎粗、穗位高、产量等指标，研究密度对玉米植株形态特征的影响及其相互作用效应。结果表明，随着密度的增加，株高呈先增加后降低的抛物线变化，穗位高和穗株比不断增高，当穗株比大于0.4时植株易倒伏，降低穗位高可明显减少植株倒伏率；穗下各节间呈伸长趋势，而穗上各节间呈缩短趋势，整株自下而上各节间粗均呈减小趋势，而各节间宽窄比无显著变化。植株株高、穗位高、茎粗等形态指标间对密度协调反应，共同对密度变化作出响应。茎部的伸长主要表现在穗位以下各节间，穗位高、穗株比与各时期的茎粗均成极显著负相关(r = –0.7701^**以上)。

Characteristics of Plant Morphological Parameters and Its Correlation Analysis in Maize under Planting with Gradually Increased Density

The object of this study was to analyze the dynamic characteristics of plant stalks morphological parameters and its effect using four maize cultivars(Zhengdan 958,Xianyu 335,Denghai 661,Yinong 103) with 13 treatments of gradually increased density from 1.67 to 16.67 plants m-2 under planting with gradually increased density in field experiments.Final yield and physical plant height,stem diameter at jointing stage,huge bellbottom stage and physiological maturity stage were measured.The results showed that with density increase progressively,the plant height rose at jointing stage and then declined after huge bellbottom stage,the ear height and height ratio of ear to plant climbed up.Lodging easily occurred when height ratio of ear to plant was greater than 0.4.Therefore lodging rate could be decreased if the ear height lowered.Internodes had the trends of elongation below the ear and contraction above the ear,and shortened from top to bottom in the whole stem.The ratio of broadside to narrowside of stem diameter had no significant changes.Plant height,ear height and stem diameter all reflected to densities harmonically.Stem elongation mainly displayed by internodes below the ear,ear height and height ratio of ear to plant had very significant negative correlation with stem in different stages,and the correlation coefficient was above-0.7701.