Evaluation Of Breeding Potential Of Ten Domestic And Exotic SS Group Maize Inbred Lines To Improve Maize Hybrid DN98×Q4

The narrowly genetic basis of maize germplasm has always been the most essential factor restricting the continuous growth of maize breeding in China,some domestic research institutions and seed companies have improved their local main extending varieties with elite maize inbred lines,which is one of the most important methods of enriching domestic genetic basis for maize germplasm and breeding excellent maize varieties.With the advantages of high yield,strong resistance and wide adaptability,maize hybrid DN98×Q4 has had the rudiment of an excellent maize variety,but there exist some shortcomings such as poorer grain dehydration,later silking period,later all growth period,higher plant height,higher ear height when planted in mountainous areas of southwest China.However,the domestic and exotic elite SS group maize inbred lines were used to improve the female parent DN98 of maize hybrid DN98×Q4,this is expected to breed a new maize variety with good comprehensive traits.In this study,10 domestic and exotic elite SS maize inbred lines,3 tester included by elite inbred line DN98,Q4 and FN120 were crossed through the partial diallel mating design,40 three-way cross hybrids were evaluated at Shi Cao Xi,Long Chi,Li chuan and Fang county in Hubei Province in a nested test design.According to the estimate of the genetic parameters of Dudley and other researchers,the breeding potential of 10 SS elite lines as donors of favorable alleles for improving maize hybrid DN98×Q4.The results of this research were summarized as follows:（1）Ten SS inbred lines were not ideal when directly improving DN98×Q4,Still,the single cross hybrid Z10×Q4 had higher yield than DN98×Q4,and inbred line Z10（628411）had the potential improvement in the yield,water content at harvest,percentage of erect plant of DN98×Q4 with the F₁generation continuous self-crossing line that crosses Z10 and DN98.（2）The single cross combination of 10 SS lines were crossed with elite inbred lines had better effect to improve DN98×Q4.According to the PTC value of donor combinations yield and the heterosis of three-way cross combinations yield,it was evaluated that single cross donor combinations A4（HF12202×DN98）,A5（B73×DN98）,A6（PHG39×DN98）and A10（628411×DN98）had better breeding potential on the improvement of the yield of DN98×Q4,based on comprehensive analysis of agronomic traits,and their potential for improvement in a descending order was A10,A5,A6 and A4.（3）The yield of three-way cross hybrid A10×Q4（8.34 kg）was higher than that of DN98×Q4（8.13 kg）,which increased the yield by 2.63%.It is considered that A10was the best donor and had a greatest breeding potential in improving the yield,all growth period and percentage of erect plant of DN98×Q4,at the same time,A10 had a breeding potential in improving harvest water content,plant height,ear height,tasselling period and silking period.And,the donor A10 is used by direct self-crossing or induction of haploids and artificial double breeding elite inbred lines.（4）The yield of three-way cross hybrid A5×Q4（8.30kg）was higher than that of DN98×Q4（8.13kg）,and the yield was increased by 2.10%,the yield of the three-way cross hybrids A6×Q4（7.99kg）was not significantly lower than that of DN98×Q4（8.13kg）,a reduction of 1.78%.A5 was the best donor and had a greatest breeding potential in the improvement of harvest water content,all growth period,tasselling period,silking period and percentage of erect plant of DN98×Q4,and it also had better potential to improve yield,plant height and ear height,its improved method was A5 directly self-crossing selected lines;While A6 was the best donor in the improving of gray leaf spot,harvest moisture content,tasselling,silking and plant height of DN98×Q4,and it also had better breeding potential in terms of improved yield,all growing period,ear height and percentage of erect plant using A6 and recurrent parent DN98 backcrossed for 1-2 generations and then continuous selfing selected lines.（5）Z10（628411）was the best donor inbred line and had a greatest breeding potential in the improvement when directly improving maize hybrid DN98×Q4,and the single cross hybrid donor combination A10 was also the best donor combination when improving DN98×Q4,Therefore,Taking Z10 as a source of favourable alleles to improve DN98×Q4,It is likely that new maize variety with better comprehensive traits than DN98×Q4 will be breeding in southwest China.（6）A new heterotic pattern（pioneer hybrid improved line×Reid）×Suwan was obtained in the improvement of breeding potential of the maize hybrid DN98×Q4,and this had a higher potentia in the southwestern mountainous area,but needs further verification;the American SS maize germplasm has the advantages of higher yield potential,better grain dehydration,lower plant height,stronger lodging resistance,etc.,and has great breeding potential to improve inbred lines of the Reid maize population,which indicates that the America SS germplasm has great potential for improving a elite maize hybrid in Southwest China,so as to broaden the genetic basis of the maize female parent group in southwest mountainous regions.