The Gene Effect Analysis And Breeding Potential Research Of Two Tropic Maize Populations

By the trial, we studied the gene effect combining ability and clustering analysis of 2 tropic maize populations from CIMMYT. we utilized the maize inbreds (Dan340,Ye478 and HuangC,178) and their F₁ hybrids(Nongdal08,Yedanl3) as testers by TTC mating design. These combinations were mated Yuanjiang county of Yunnan province and then planted them in pengjiang farm of school.The main results were summarized as following:1. The general presentation in field of 2 populations indicated that the 2 populations had adapted to the southwest ecological environment, the yield of population was high ,At the same time , they had the good ability of resisting diseases. So they were valuable germplasm and could be used to enlarge the genetic foundation of existing maize germplasm. But we need to strengthen the genetic improvement of plant height and ear height.2. The results were summarized as following through the gene effect analysis of all traits of 2 populations: In pob25, the additive effect had decisive function of all traits except sterile length, the dominant effect had important function in plant yield, ear height, rows per ear, ear weight and sterile length, the epistatic effect had important function in ear height, sterile length, axis diameter and axis weight. In pool 26, the additive effect had decisive function of all traits except ear height, the dgminant effect had important function in axis diameter, rows per ear, kernels per row, plant yield, plant height and ear height, the remarkable epistatic effect existed in ear length, ear weight, axis weight, shelling percentage, plant height and ear height, which indicated that epistatic effect had very important function in 2 populations. so, it was not apt for us to ignore the epistatic effect before we did not prove the epistatic effect to be not exist or relative function was little when we made out breeding project or improved traits.3. Both the average GD and variance extend through 2 different ways were large, which indicated that there was abundance of genetic diversity in the middle of 2 populations. At the same time, the average GD between populations was bigger than the GD between individuals .But the phenomenon that the GD of between individuals larger than the average GD of between populations often appeared. So, the GD of betweenindividuals was not always littler than the average GD of between populations, which proved that the 2 populations had abundance genetic diversity and offered possibility for us to select, on the other hand.4. We carried through clustering analysis to the individuals of 2 populations through SCA and SSR marker. As the whole, bgth of the 2 means had respective virtues and flaws. The results through SSR clustering analysis were more credible than the SCA clustering analysis. Although the SSR clustering analysis was affected by the sum of primer and the correlation degree between the marker and yield, it could quickly draw a conclusion to the genetic diversity and heterotic groups of populations, At the same time, it avoided the effect of environment. In a word, the SSR clustering analysis was more reasonable and reliant.5. The difference of GCA was large between the individuals of all traits in two populations, so, we should enlarge the selection scope and selected outstanding individuals as soon as possible. At the same time, we found 56 hybrids that SCA was positive through SCA analysis. In the middle of 56 hybrids, some hybrids SCA represented especially well, these hybrids were following : Ye478x6-44,Ye478x6-70,Dan340x6-8,Ye478><6-30, Dan340x6-40, Dan340x5-56, Dan340x5-9, Ye478x5-6, Dan340x5-16, Ye478x5-53.6. We evaluated these hybrids through the TCA effect of plant yield. The results indicated that TCA effect of plant yield the more large the plant yield the more high. So, the TCA effect of plant yield could correctly reflect the yield potential of hybrids.7. We found some hybrids that had the comparative superiority than the best comparison, these hybrids were following: Dan340*5-9, Dan340x5-16, Dan340W5-56, Ye478x5-6,Ye478x5-53,Yedanl3x6-39,Ye478x6-70,Ye478x6-44,Dan340x6-40,Yedanl3x 6-27, Yedanl3x6-40. We should carry through more identification to these hybrids and then selected the hybrids that maize yield needed. At the same time, we should quicken the purification of corresponding individuals and then selected eminent inbreds.