Study On Genetic Improvement Effect Of Important Foreign Germplasm Based On Maize DH Breeding Technology

Maize is an important food crop,and excellent varieties are the main techniques to improve maize yield per unit yield.The narrow germplasm is the main reason that affects the maize yield,and it is also the main reason that leads to the breeding process of our country,and the gap between the breeding level and the developed countries.Foreign germplasm is the basis of maize germplasm in China,so genetic improvement of foreign germplasm is of great significance.Maize DH breeding has strong stability,from basic material to get DH pure line only 2-3 generations,greatly shortened breeding years,for rapid,efficient,accurate industrial breeding to provide a feasible way.In this paper,according to the principle of "three heterosis group and their heterosis models",the basic materials are assembled,and the important germplasm abroad are improved by DH breeding technique,5 DH lines are selected,and 30 cross combinations are designed with 6 backbone lines according to NC?.The effects of genetic improvement are analyzed under three ecological conditions of Shenyang Yushu and Zhaodong.The stability and high yield of hybrid combinations of DH line are analyzed by setting the control variety Xianyu 335 at the same time.The findings are as follows:(1)The yield per plant and main agronomic characters have strong heterosis in different locations.The highest average heterosis per plant yield is 82.69%.The heterosis of grain number per row is 30.77%.The order of average heterosis of other characters is ear height,plant height,ear length,100-grain weight,ear diameter,bald tip length,stem diameter,row number of ear,axis diameter and seed yield.The average dominant average yield per plant in Zhaodong is 115.29 in the three sites.The yield per plant of hybrid combinations of DH1 and DH2 have strong heterosis under three ecological conditions.(2)Based on the super control variety(Xianyu 335),the super dominant value of 5% is determined to be a strong dominant combination.The results showed that the highest yield per plant of combination PH5 AD × DH1 is 16.68%.The next combination of PH4CV×DH2 is 12.78%,PH4CV×DH1 is 13.12%,and PH5AD×DH2 is 7.52%,they are considered a combination of strong strengths.Among the 4 strong dominant combinations,two combinations have DH1 parents,two combinations have DH2 parents,It shows that it has certain application potential.(3)General combining ability analysis shows that: The general coordination ability of different characters in different locations is significant.The general combining ability of DH1 and DH2 per plant is higher than that of DH1 per plant in each location,and the yield of GCA per plant is higher than that of DH2 in the same location,and higher than that of other DH lines in the same location.DH1 genetic basis(PH6WC × PH09B)is used as the Pioneer maternal line,DH2 genetic basis(PH6WC ×D1798Z)is used as the Pioneer maternal line and Monsanto maternal line.It is considered that the combining ability effect value of using the improvement in the group of Pioneer parent lines is higher than that of the between-group improvement.The yield characters of DH1,such as ear length,row number,and grain number per row,are higher in general combining ability.The general combining ability of plant height and stem diameter is higher and ear position general combining ability is low.It is useful for breeding high yield and lodging resistant varieties with DH1.(4)Special combining ability analysis shows that: There are 13 combinations with positive SCA effect and 17 negative values with a range of-24.05 ~ 29.19.The combination of the first five positive bits of the SCA effect value is PH5AD×DH1,PH4CV×DH2,PH6WC×DH3,D1798Z×DH4,PH6WC×DH5.The lowest combination of SCA effect values is PH6WC×DH1.(5)Analysis of stability and high yield shows that: There are 4 hybrid combinations with higher yield per plant than Xianyu 335,among which the coefficient of variation of PH4 CV × DH1 is the smallest,indicating that the combination has a high and stable yield.Hybrid combinations with a higher yield per plant than Xianyu 335 and lower coefficient of variation also have PH5AD×DH2,PH4CV×DH2,their coefficient of variation is 5.3%,7.67%.It is proved that the stability of these two combinations is also good.Comprehensive analysis of yield per plant under three different ecological conditions shows that: The yield per plant of the combination PH5 AD × DH1,PH4 CV × DH2,PH4 CV × DH1,PH 5AD × DH2 is higher than that of the control variety Xianyu 335,and the yield is better.(6)The results of path analysis showed that the direct effect of seed yield on yield per plant is the greatest in three different ecological conditions.