Identification Of Main Characters And Analysis Of Combining Ability Of Maize Backbone Parents

The narrow genetic basis of maize germplasm has become an important limiting factor for the sustainable development of maize breeding and production.Characterization and evaluation the agronomic traits and genetic effect of germplasm resources from china and American,are the available ways to solve the inefficient corn germplasm resources and breeding fine varieties.In this study,we used zheng58,chang7-2,He344,k10 and Danhuang 02 as testers,while other 160 inbred lines crossed with them.Therefore,800 Hybrid combinations were made.The main agronomic traits of inbred lines and hybrid combinations were analyzed.The main results were as follows:1.The investigations of inbred lines agronomic characters:(1)The difference of plant height among the 165 inbred lines was significant which indicates extensive genetic diversity.The changed plant height analysis shows that maize plant gowned very fast during 15 th July to 30 th July.The add-value was aroud 6 cm per day.Plant height of heritability was over 70%,which belongs to high heritability traits.So,we can select in early generation of hybrid breeding.(2)The chlorophyll content of 165 inbred lines was between 30.64 ~ 66.88 SPAD,and the mean value is 52.19.The highest chlorophyll content for W668 inbred lines,the minimum value for PHT77 inbred lines.Chlorophyll content of general heritability was 31.6%,belong to medium heritability traits,can undertake high generation of choice.(3)In the condition of natural disease,most inbred lines showed a greater resistance performance.Among them,the head smut disease material is 14,accounted for 8.5% of all test materials.2.The investigation and analysis of main agronomic traits for hybrid combinations.(1)The growing stages of hybrid combinations were actually very differently.Some early-ripening and later-ripening maize cultivars were gained.(2)The plant height and ear height of hybrid combinations of have obvious diversity,which also affected by different years.We found that the plant height of a few hybrid combinations were more than 310 cm,which results in lodging more than 80%.(3)The yield of hybrid combinations showed significant differences.Nearly 20% of the hybrid combinations hundred-grain weight more than 35 g.The grain length,grain width,had significant differences among these combinations which could provide some materials for breeders.(4)The kernel moisture content of hybrid combinations were around the range of 17.8 ~ 35.9%.In the process of threshing,we found that grain breakage rate were above 60% when the kernel moisture content more than 30%.And water content below 25%,the damage rate is about 3%.(5)The SCA effect of hybrid combinations are significant.Maize ear traits were affected by additive effect.Five tests of general combining ability effect analysis results show that the yield of zheng 58 effect value is higher,the water content effect value of k10 is higher,chang 7-2 effect of hundred grain weight value is higher.On special combining ability effect analysis,we found that among all the hybrid combinations,there are 312 whose SCA yields were positive.Forever,higher yield performances were made when we used zheng 58,k10 as female parent,the combination of the inbred line as male parent.However,Danhuang 02 and He344,crossed with other lines,more than 90% hybrid combinations of the yield is low.At the same time,we also found the main agronomic characters of inbred lines of SCA effect were better than the domestic inbred lines.