Applied Study On The Method Of Measuring Synthetic Heterosis Of Multi-Character

The application of synthetic heterosis of multi-character was investigated in maize.The materials consisted of 9 inbred lines and their 20 single crosses in incomplete diallel cross design.The results are as follows:1. Five crosses:RP15x005 ,8110x1584,ST6xl584,ST10x9523-llll,ST10x 005 are selected through considering of synthetic heterosis and "yield factor" principal heterosis,and yield expression of them are better than that of other crosses.The selection effect is better than that by yield heterosis.Synthetic heterosis of multi-character can be considered as a reliable parameter to assess expression of crosses.2. The multi-correlation coefficient between synthetic heterosis of multi-character and henetic distance/comprehensive index of hybrid is higher than that between yield heterosis and them. Synthetic heterosis of multi-character can be considered as a reasonable parameter to study the relationship between heterosis and genetic divergence.3. Provide the relative significant weight of grain yield 0.5. Decide the relative significant weight of other characters based upon the decisive coefficient between them and grain yield,the summation of their relative significant weight is O.S.This method avoids inconvenience when there are so many characters than it is difficult to decide the relative i significant weight of other characters based upon experience.4. Several factors affecting synthetic heterosis are analyzed,they are Genetic divergence,heritability,combining ability and genetic basement. They can be considered as theoretical direct for using synthetic heterosis in breeding practice.5. The method of measuring synthetic heterosis of multi-character based upon the principle of principal component analysis has merits as follows:Effict of environments is eliminated because of principal component analysis based on heredity correlative matrix.Correlation among characters is eliminated because of independence among principal components.The relative importance of each character is under consideration.