播期和密度对玉米干物质积累动态的影响及其模型的建立

Effect of Sowing-Date and Planting Density on Dry Matter Accumulation Dynamic and Establishment of Its Simulated Model in Maize

在大田条件下,以益农103、先玉335和登海661为材料,设置3个播种期(5月3日、5月28日和6月22日)和4个密度处理(4.5、6.0、7.5和9.0万株hm-2),测定其干物质积累动态和产量,分析播期、密度和玉米群体干物质积累动态特征的关系及其积温关模型。结果表明:(1)将3个播期玉米不同处理的最大群体干物质积累和出苗至成熟的积温分别定为1,建立了相对群体干物质积累和相对积温关系的Richards模拟,方程为y=a/(1+eb-cx)1/d。(2)方程参数a值(终极生长量参数)基本为1;b值(初值生长量参数)和c值(生长速率参数)在播期、品种间变异较大,密度间变异较小;d值(形状参数)在播期、品种和密度间变异较小,可见播期主要通过调节参数b、c值来实现对整个方程的调控。应用2008年本试验和另一试验的数据对模型进行验证,模拟准确度(以k表示)均在1.0486**以上;精确度(以R2表示)均在0.9534**以上。(3)拔节期至蜡熟期是玉米群体干物质积累变化速率对密度的敏感反应期;晚播玉米所需积温在群体干物质积累变化速率的缓慢增加和下降阶段逐渐减少,在快速增加阶段逐渐增加。全生育期的群体干物质积累平均速率表现为先玉335>登海661>益农103;且早播>中播>晚播;密度越高群体干物质积累平均速率越大,达到显著水平。

The research and application of crop growth model is a foundation of agricultural production information and digital technology,the quantitative research of leaf area index（LAI） model in different sowing dates can provide a theoretical basis for the highing-yield in maize,and further study the relationship of dry matter accumulation with sowing date and densities.Three maize cultivars（Yinong 103,Xianyu 335,and Denghai 661） with four density treatments in 45 000,60 000,75 000,and 90 000 plants ha^-1 in three sowing date（May 3rd,May 28th,and June 22nd） were used in field experiments,dynamic dry matter accumulation and grain yield were measured.A Richard curve equation,y = a/（1＋e^b-cx）^1/d,was developed with relative DMA and relative accumulated temperature.The basic parameter of ultimate growth（a） was 1,initial growth parameter（b） and growth rate parameter（c） changed dramatically,shape parameter（d） changed small.The accuracy and precision of relative model were tested with the data in 2008 and 2007 in Huadian,Jilin province,the dynamic model could make a good estimation for DMA dynamics with the accuracies of above 1.0486^＊＊,and the precision（R2） of above 0.9534^＊＊.According to accumulated temperature and the largest dry matter accumulation,the model can better predict the dynamic dry matter accumulation of the growth period.Sowing-date and density had a regulated role in the change rate of dry matter accumulation.The sixth leaf and waxy stage was the sensitive reaction period of dry matter accumulation rate with density.In the slow increase and decrease stage of the dry matter accumulation rate,the accumulated temperature for maize increased gradually;in the rapid increase stage,the accumulated temperature for maize decreased gradually;in the growing period,the average rate of dry matter accumulation of different cultivars showed as Xianyu 335〉 Denghai 661 〉Yinong 103.The average rate of dry matter accumulation of treatments with different sowing dates showed as early sowing 〉 middle sowing〉late sowing,and increased with the density increasing.