Research On The Screening Of High And STab. Yielding Spring Maize Hybrids And Corresponding Cultivation Techniques

Maize is one of the most important and the most widely distributed food crops. With the current economic crises and high incidence of extreme weather, maintaining high and sTab. yields of maize in JiLin province, the most important production base of corn, became a great concern of agricultural scientists. In this study, large area of field experiments and field demonstrations were conducted in different ecological zones, in order to illustrate the route of cultivation techniques achieving high and sTab. yield of maize year after year in Jilin province from 2005 to 2009. The main conclusions obtained were as follows:1.The result of experiment suggested that middle maturity and density tolerant varieties had higher yiedls potency. Density tolerant varieties overyielded of 21.1% compared with sparse maize, density tolerant species of maize with middle-maturity overyielded of 1.8% compared with middle- or late-maturity varieties, middle-maturity varieties overyielded of 6.4% compared with middle- or late-maturity varieties, middle-maturity varieties overyielded of 4.7% compared with late-maturity varieties, and effects of overyielding were significant. Number of kernels per ear significantly was increased in grain yield components for (ultra) high- density tolerant maize varieties and bareen ear tip length was significantly decreased, which was the key on high yield for compact corn especially in high-density conditions. Type of varieties for maize should be focused on moderate- or late-maturity and density tolerance in order to achieve high yield in Jilin province.Density tolerance varieties of maize with relatively large leaf area and leaf area index, was small in leaf angle and spaceing of leaf, and was large in leaf orientation.Their spatial distribution of leaves was more reasonable to make compact plant type, and forming like " pyramid "- type structure.In addition, density tolerant variety was good at stay-green degree, extending the photosynthetic time, laid the foundation for the yield. Density tolerant varieties compared with sparse-type varieties, its plant height, ear height and ear coefficient was relatively lower coefficient of large diameter, reducing the risk of occurrence off crops lodging especially in high-density conditions.Root pulling resistance and stem bust strength were relatively better for ultra-high density tolerant varieties at maturity than sparse varieties. Higher yield varieties of compact maize maintained the quality advantage of its roots.Number of endosperm cell showed a significant positive correlation with content of grain starch, rate of grain filling stage and kernels weight for (ultra) high-yield varieties. Invertase and starch phosphorylase activity was very significant or significant related to starch accumulation rate and enzyme activity, and also showed a significant positive correlation. Density tolerant species of Xianyu 335 and Zhendan958 were better than normal sparse-type varieties of Nongda364 and Changcheng799.2.The density of different varieties resistant than conventional fertilization were increased in varying degrees in high fertility conditions. Appropriate plant density was 80 000 plants/ha for Xianyu335 and 65 000 plants/ha for Jundan8. Density also affected on yield components, which affected bareen ear tip length, followed by ear length, kernels per era and 100-kernel weight.When spacing of rows in 70 cm and 50 cm, their chlorophyll content, Hill reaction activity and PEPCase activity were higher than the spacing of rows in 65 cm and 60 cm in the late growth stages for Xianyu335 and Jundan8. Two treatments showed higher photosynthetic rate in the primary reaction in photosynthesis light reaction and dark reaction at all growth stages. Late higher photosynthetic capacity in late growth stage to ensure the grain accumulation of assimilation, was effective to reduce the bareen ear tip length and improve yield.3.Results of single factor experiment on fertilizer demonstrated that the highest yield reached 10 648 kg/hm2 when rate of N applied was 248 kg (R2 = 0.9813*), the highest yield reached 11 078 kg/ hm2 when rate of P2O5 applied was 58.73 kg (R2 = 0.8909*), and the highest yield reached 10 115 kg/ hm2 when rate of K2O applied was 64.75 kg (R2 = 0.968*) in the density of 60 000 plants/ hm2 for Xianyu335. The highest yield reached 11 259 kg/ hm2 when rate of N applied was 202.38 kg (R2 = 0.9863*), the highest yield reached 10 637 kg/ hm2 when rate of P2O5 applied was 64.76 kg (R2 = 0.9634*), and it achieved 10 793 kg/ hm2 when rate of K2O applied was 83.26 kg (R2 = 0.965*) in the density of 60000 plants/ hm2 for Jundan8.The number of kernels per ear increased with increasing application of N (range of 175 to 250 kg/ hm2) and K (range of 30 to 60 kg/ hm2) in certain plant density and 100-kernel weight increased with increasing rate of P2O5 (range of 46 to 92 kg/ hm2) for Xianyu335. The number of kernels per ear increased with increasing application of N (range of 175 to 200 kg/ hm2), P2O5 (range of 46 to 92) and K2O (range of 60 to 90 kg/ hm2) in certain plant density and 100-kernel weight increased with increasing rate of N (range of 175 to 200 kg/ hm2) and P2O5 (range of 46 to 92 kg/ hm2) for Jundan8.