Evaluation For Grain Dehydration And Grain Filling Rate And Correlation Research In Maize Inbred Lines

The grain moisture content at harvest period is an important index to determine whether it can be harvested and stored successfully and safely.The purpose of this study was to screen maize inbred lines with low moisture content and fast dehydration rate and to provide reference for breeding new maize varieties which suitable for mechanization harvest of grain.In order to solve the problem of high moisture content of grain at harvest period and accelerate the development of mechanical harvesting of maize grain.44 maize inbred lines were chosen as experimental materials in this experiment.The design of single factor random block were used under field conditions during 2016 and 2017.Measuring the moisture content of grain,husk and cob by using oven-drying method and calculating the dehydration rate,grain filing rate then fitting grain filling characteristic parameters by using Logistics equation.The characteristics of grain,ear and agronomic of each inbred line were measured after physiological maturity.Then studied the relationship between the moisture content,dehydration rate,filling rate and various characters.The main results are as follows:1.The measured results of grain weight,moisture content,dehydration rate and filling rate in 44 maize inbred lines shows that the 100-grain fresh weight continued increasing after being pollinated 15 days and has a slight decrease after physiological maturity.And 100-grain dry weight increase continuously till the end of sampling.The grain moisture content isn't attain a minimum until the sampling ends.Both grain dehydration rate and filling rate show a fluctuating downward trend.2.The analysis results of grain weight,moisture content,dehydration rate and filling characteristic parameters of maize inbred lines in different groups shows Huanggai group's grain fresh weight and moisture content is significantly higher than Reid and Lancaster group.What's more Reid and Lancaster group's grain dehydration rate are faster than Huanggai group's so that their moisture content being lower at harvest stage.As for grain filling duration,Reid and Lancaster group's which have higher Gmax and R₀ are shorter than Huanggai's.The characteristics of whole filling process are high-strength and short time.3.According to the length of growing period to divide 44 maize inbred lines into four types of maturity which including medium-maturing,medium late-maturing,late-maturing and extremely late-maturing.Through comparing grain moisture content,dehydration rate and filling characteristic parameters of different maturing find that the inbred lines which have lower grain moisture content at physiological maturity stage always have higher moisture content at harvest stage.By using cluster analysis 44 maize inbred lines was divided into 3types that including fast,medium and slow dehydration rate.Different types of dehydration include different maturing inbred lines.The more early maturity of maize inbred lines,the stronger filling initiation potential,higher Gmax and shorter grain filling duration they have.The correlation analysis between the 100-grain weight,moisture content,dehydration rate and filling rate shows that filling rate was highly significant positive correlated with the100-grain weight and significant positive correlated with moisture content of grain.The dehydration rate is highly significant negative correlated with the grain filling rate,100-grain weight and moisture content of grains.4.Study on the characteristic of grain has found that there are significant differences between pericarp thickness and grain size from different genotypes.The pericarp thickness is positively correlated with the grain moisture content.There is highly significant positive correlation between grain thickness and moisture content in harvesting.The grain length is significantly negatively correlated with the moisture content in harvesting,and is positively correlated with the grain dehydration rate.Study on ear traits has found that moisture content of sheets and cob significantly influenced the grain moisture content and dehydration rate during physiological maturation.What's more the dehydration rate of sheets was negatively correlated with the grain moisture content during physiological maturation.The results of studies on plant traits show that low moisture content of inbred lines should have low plant height,high ear position,slender ear and suitable growing period.The study on grain quality find that starch content was positively correlated with the grain dehydration rate and protein content was significantly negatively correlated with grain dehydration rate also has a significant effect on the filling characteristic parameters.5.There are 9 inbred lines which have good traits and fit breeding targets were obtained by comparison analysis and screening.Including PH4CV,ShenNongH7648,HM12111,ShenNongH563,ShenNongH564,ShenNong52104,Shen Nong7654,ShenNongH7008 and ShenNongH7059.