Effects Of Density On Growth And Development Of Summer Maize (Zea Maize L.) And Evaluation On Maize Hybrids With Density-tolerant Property

In this field experiment,the effects of four plant densities (45000,60000,75000 and 90000plants/ha)on growth and development, morphological and photosynthetic characters, dry matter accumulation and partitioning, yield and grain-quality at mature and the relationship between these indexes and density were studied on six maize hybrids (DY39, ND108, ZD958, JD28, JK308 and DH3719) The subordination degree was introduced as a comprehensive evaluation way to study the method and indexes of density-tolerant property. These results could be used as consultation of evaluation of density-tolerant property and suitable paint density. The results were as follows:The morphology indexes of maize plant had big change with density increasing:The plant height and ear height showed increasing trend, the stem diameter of the basal internode and the vascular bundles of the third internode were decreased. And the change . of every index is significant in different density except ear height. So these indexes could be as index-evaluation of density-tolerant property. The plant-type of plat was more sensitive than plant-type erect.The density has big influence on morphological and photosynthetic characters .The leaf area of the single plant and the relative chlorophyll content were decreasing with plant density increasing and had significant difference at silking to 15-days-after-silking.The leaf area index and the the leaf area duration were in creasing within increase of the plant density and had the significant difference at 7-leaf stage.It was found that density was the main content of influencing maize yield. The yield of plant-type erectophile was increasing from 45000～90000plants/ha with density increasing, plant-type of plat had the highest yield at 75000plants/ha. In the yield components, the percentage of plant without kernel and effectual kernels increase and the amount of seeds per ear and the 100-grain weight decrease with density improvement and the difference was obviously expect 100-grain weight . So making out of suitable density according to plant-type in the farm produce was very important.The effects of density on dry matter accumulation and distribution was as follow : With the density increased ,and the dry matter accumulation of single plant dropped and the community dry matter accumulation increased .And there was obvious difference between density. The canopy distribution of dry matter was influenced obviously by density .And the percentage of the first and second floor of the whole plant decrease instead of the third increase, and the change of third floor was reached significant difference between densities.The effect of density on quality of sees was not obvious. The content of crude protein and crude fat and sugar decrease instead of grain unit weight of seeds increase, with density increasing .But the range of change was not significant.The text introduced Subordination degree to evaluate density-tolerant property of maize on the basis of analysis of the effect of density on growth and development of maize. The results showed that the density-tolerant property of plant-type maize of plat was better than the plant-type maize erectophile. The plant height, the stem diameter of the basal internode, the leaf area index, the effectual kernels per ha, the length of kernel and economy index could be used as evaluation indexes of density-tolerant property of maize.