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

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+eb-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 sowinglate sowing,and increased with the density increasing.