Study On Combining Ability And Heterosis Of 13 Waxy Maize Inbred Lines

In this test, There were 13 waxy maize inbred lines designed and tested according to the incomplete double row cross design of NC II, and obtained 42 waxy maize hybrid combinations. It used morphological marker and SSR molecular marker to analyze the combining ability and genetic distance of 13 waxy maize inbred lines and 42 hybrid combinations, and the cluster analysis of waxy maize inbred lines was conducted. It used the test data from the inbred lines and hybrid combinations to analyze the average dominance and heterobeltiosis of 15 characters. Comparative analysis the results of genetic distance and heterosis. Study the relationship of waxy maize genetic distance and heterosis. The main results are as follows:1. The analysis of combining ability of waxy maize inbred lines and hybrid combinationsThe general combining ability of inbred lines was G3, G4, G5, Y3, Y4, and the hybrid combinations with good special combining ability was Y1 * G3, Y3 * G3, Y3 * G4, Y6* G5,Y3* G6,Y5* G6, Y2 * G7.2. Genetic distance and cluster analysis of SSR molecular markers in waxy maize inbred lines20 pairs of SSR primers in 13 waxy maize inbred lines detected 105 polymorphic alleles,and each pair of primers amplification effect is good, with an average of 5.22, each locus detected the change range of 2-9.The genetic distance of 13 waxy maize inbred lines ranged from 0.1433 to 0.9221, the average value was 0.7112.G4 and Y3 was the largest, which was 0.9221; the G4 and Y1 genetic distance was the smallest, only 0.1433. With the genetic distance of 0.7400 as the standard, the 13 waxy maize inbred lines were divided into five categories. The first kind has G2 and Y3 two waxy maize inbred lines; the second type has G6 and Y2 two waxy maize inbred lines; the third category divided into two subsets included three waxy maize inbred lines, subgroup 1 included Y6, subgroup 2 including G4, Y1; the fourth category points two subsets included three waxy maize inbred lines, subgroup 1 included Y5, subgroup 2 including G3, G7; the fifth divided into two subsets including three waxy corn inbred lines, subgroup 1including Y4, subgroup 2 including G1, G5.3. The analysis results of waxy maize inbred lines and hybrid heterosis.The 15 characters of 13 waxy maize hybrid combinations showed that plant height, ear height, single ear weight traits variation and Heterosis index larger, while the stem diameter,ear diameter, axis diameter, rea ear length traits changes in amplitude and heterosis index was smaller. There was a big difference between the waxy maize inbred lines and the hybrid combinations. The mean values of the traits of the hybrid combinations were superior to those of the inbred lines.The single ear weight mean value and change range of hybrid combinations was significantly greater than those of the parents, and 97.62% of the hybrid combinations was larger than those of the parent.The average dominance and heterobeltiosis of 15 traits of 42 hybrid combinations were more positive than negative heterosis, and cross combination Y2 * G1, Y4 * G3, Y2* G4, Y5* G4, Y6 * G5, Y3 * G6, Y3 * G7 had strong heterosis. Heterosis index average ranking:single ear weight > ear height > row grains > axle weight > plant height > ear length >amylose content of starch > ear diameter > axis diameter > stem diameter > ear row number >skin residuce rate > crude starch content > rea ear length > amylopectin content of starch.4. Analysis results of the relationship between genetic distance and heterosisThere reached extremely significant level in the traits of hybrid combinations of waxy maize, and there was a real and genetic differences.Waxy maize hybrids parents were derived from different groups the heterosis index of single ear weight was higher than that of amylopectin content of starch, and vice less. From different groups and large genetic distance of parental breeding heterosis combinations strong; and from the same group and lower genetic distance of parental breeding of heterosis combinations was weak and waxy maize inbred lines between genetic distance is not a simple linear relationship.