Study On Grain Filling And Dehydration Characteristics Of Selected Maize Inbred Lines From Shaan A Group And Shaan B Group And Analysis Of Its Influencing Factors

The field grain filling and dehydration characteristics of maize grain have a significant impact on the yield,quality and production and processing of maize in China.Previous studies showed that the grain filling and dehydration rates of different maize materials were significantly different,and there was a positive correlation with parents inbred lines.At present,most of the existing studies at home and abroad mainly focus on hybrids,but few on inbred lines.Therefore,the study of grain filling and dehydration rate of maize inbred lines is of great significance for improving maize yield and quality,as well as for the identification theory and technology of inbred lines with fast dehydration rate and high yield potential,especially for further breeding of maize mechanical grain harvesting materials.In this study,10 inbred lines bred from Shaan A group and Shaan B group were used as materials,and Chang 7-2 and Zheng 58 were used as controls.The grain filling and dehydration characteristics from pollination to harvest were analyzed.The effects of climatic and environmental factors on grain filling characteristics and the relationship between maize self-traits and grain dehydration characteristics were also studied.The main results are as follows:1.During grain development,grain weight showed a "S" type growth,grain filling rate showed a single peak curve trend,and the maximum value generally appeared around 21-23 days after pollination.Grain weight and grain filling rate were significantly different in different inbred lines,inbred lines × year,and grain weight was also very significant in inter-annual.The greater the final grain weight of maize inbred lines,the later the maximum grain filling rate appeared.The higher the average grain filling rate of inbred lines during the whole filling period,the higher the maximum grain filling rate.Rapid increase period is the key period of grain weight formation.The contribution of average grain filling rate to grain weight in rapid increase period is greater than the duration of rapid increase period.2.Effective accumulated temperature during grain filling period has a more obvious promoting effect on the grain filling characteristics of gradual increase period.Total rainfall during grain filling period could significantly increase the duration of rapid and slow increase period of inbred lines,thus prolonging the whole grain filling duration.The average sunshine time during the filling stage had a positive effect on the filling rate of the inbred lines at the gradual increase period,and then increased the grain weight increment at the gradual increase stage.High temperature(? 33 ?)days during the filling period can promote the filling rate and duration of the gradual increase period,but significantly shorten the duration of the rapid increase period and the slow increase period,resulting in shortening the whole filling process and ultimately reducing the grain weight.3.The grain moisture content of the inbred lines showed a monotonous trend of decreasing rapidly at first and slowing down gradually with the accumulated temperature after pollination.Using the grain moisture content and accumulated temperature of each inbred line and fitting Weibull model to construct regression model,the relationship between grain moisture content of different inbred lines and accumulated temperature after pollination can be well displayed,and the grain moisture content at physiological maturity can be well predicted.4.The fitting results of 12 inbred lines in two years showed that the grain moisture content of existing inbred lines decreased from pollination to 23%,the accumulated temperature after pollination was 1349.6-1468.1 ?·d,the accumulated temperature after pollination was 1556.0-1736.2 ?·d to 18%,and the accumulated temperature after pollination was 1755.6-2069.2 ?·d to 14%.Among them,KB043,KB206,KB262 and KB593 have the lowest accumulated temperature required to reduce the moisture content of grain to 23% or 18%,which is suitable for mechanical grain harvesting in areas with short frost-free or tense agricultural periods.5.There were significant differences in grain moisture content among different maize inbred lines at harvest stage.The grain moisture content of the tested inbred lines at harvest stage was 20.03%-25.03%.There were significant differences in the average grain dehydration rate among different maize inbred lines.The average grain dehydration rate of the tested inbred lines was 1.13%-1.25%/d.6.The less the number of bracts,the smaller the area of bracts,the faster the dehydration rate of bracts and the lower the average water content of bracts in filling stage,the faster the dehydration of grains and the lower the moisture content in harvest stage.At the same time,the smaller the mean leaf area of maize inbred lines at grain filling stage and the lower the chlorophyll content at grain filling stage,that is,the faster the leaves senescence in later stage and the faster the grain dehydration.