Characteristics Of Filling And Photosynthetic In Three Ear-leaves During Grain Filling Stage Of High-yield Maize Under Different Densities

Grain filling is an important process of the formation of maize,which is particularly important for the accumulation of grain in the community by the complex physiological activities of the organs in the population.In this paper,ZD958(Zhengdan 958)and XY335(Xianyu 335)which are the high yield hybrid maizes are regard as materials.The photosynthetic parameters and photosynthetic pigment content in superior leaf,ear leaf and inferior leaf,grain filling rate,dry matter accumulation of single plant,relative expression of photosynthesis key enzyme gene PEPC and PsbA in ear leaf were investigated under three densities of 45000 plants/hm2,60000 plants/hm2 and 75000 plants/hm2,in order to analysis the grain filling characteristics,photosynthetic characteristics and relative expression of key enzymes gene of different cultivar maizes under different densities during grain filling stage.It is expected to provide the theoretical basis for the breeding of high-yield maize in terms of photosynthetic characteristics and molecular aspects,and provide reference for the screening of maize resistant cultivars.The main results are as follows:(1)Effects of plant density on high-yield maize yield.The response of different varieties of maize yield to density was different.With the increase of plant density,the yield per plant decreased significantly,but the population yield increased with the increase of plant density.ZD958 production reached 9708 kg/hm2 under 60000 plants/hm2.XY335 reached 10117kg/hm2 at the same density treatment as ZD958.(2)Effects of plant density on 100-grain weight in high-yield maize.100-grain weight increased rapidly at early grain filling stage(20?40 d).100-grain weight increased steadily at late grain filling stage(40?60 d).Increase the plant density will reduce the grain filling rate during the early grain filling stage.The increase rate of 100-grain weight of ZD958 and XY335 decreased with the increase of density.The grain filling rate greast drop under 75000 plants/hm2.(3)Effects of plant density on dry matter accumulation and distribution in high yield maize during grain filling stage.With the increased plant density,the population yield and dry matter accumulation raised significantly,and the yield per plant and dry matter accumulation were the opposite.During the process of grain filling,the dry matter accumulation rate in ZD958 and XY335 was a single peak curve.At the early grain filling stage,the dry matter accumulation was based stem-sheath.At the later grain tilling stage,the dry matter accumulation was grain.(4)Effects of plant density on fluorescence parameters in three ear-leaves of high yield maize during grain filing stage.Compared with 45000 plants/hm2,under 60000 plants/hm2 and 75000 plants/hm2,the activity of PSII in three ear-leaves of ZD958 and XY335 showed down trend.The number of active response centers(RC)in superior leaf,ear leaf and inferior leaf was 75000 plants/hm2<60000 plants/hm2<45000 plants/hm2,the degree of damage of the oxygenated complex(Wk)was 75000 plants/hm2>60000 plants/hm2>45000 plants/hm2.In three ear-leaves,the inferior leaf decline was the largest.(5)Effects of plant density on photosynthetic pigment content of three ear-leaves in high-yield maize during grain filling stage.With the increase of plant density the contents of chlorophyll a,chlorophyll b,carotenoids and lutein in superior leaf,ear leaf and inferior leaf of ZD958 and XY335 were decreased.The photosynthetic pigment content between superior leaf and ear leaf during early grain filling stage were no significant differences,and more than inferior leaf.Photosynthetic pigment of three ear-leaves was the lowest during late grain filling stage,the difference was significant(P<0.05).(6)Effects of plant density on relative expression of PEPC and PsbA in ear leaf of high yield maize during grain filling stage.With the increase of plant density,the relative expression of PEPC decreased during grain filling stage.But the decrease range of relative expression under different density was 75000 plants/hm2>60000 plants/hm2>45000 plants/hm2.Under different densities,the relative expression of PsbA showed a fluctuat trend during the whole grain filling stage,which was the highest at 0 d and 20 d after pollination.There was no significant difference between the three densities,which was possible related to stress resistance.The results showed that significantly increase the yield by increase the plant density suitablly.Under 60000 plants/hm2 density,it was more suitable for the grains weight of dry matter accumulation in ZD958 and XY335.Except bald long,the size of other ear characters were significantly reduced,production per plant is reduced.This was related to the photosynthetic ability and the expression of key enzymes of photosynthesis in the leaves during grain filling stage.With the increase of the density,the fluorescence parameters and photosynthetic pigment content of superior leaf,ear leaf and inferior leaf were decreased.Increased plant density increased population yield,reveal that the key factor of increase production was the appropriate increase plant density.