| Drought is becoming one of the most important abiotic factors limiting maize production. Exploration of germplasm resources, improvement of drought tolerance of maize, cultivation and extension of drought toleranced maize were effcient pathes to reduce the harm of drought. Evaluation on drouhgt resistance of maize germplasm was important and operation significance to breed hybrids with drought resistance in China. In order to investigate the genetic basis of drought tolerance and find useful information for genetic improvement to drought tolerance further,196 maize inbred lines and 6 advanced backcrossing introgression lines with genetic background of Chang7-2 were identified and analyzed for drought tolerance and improving effect under two water regimes(normal control and water stressed) in this study. The major results are as follows.1. The main agronomical traits(days to seeding, days to anthesis, days to spining, ASI(Anthesis-silking Interval), plant height, ear height, tassel length, ear length,ear diameter, bared tip, seeds per row, rows per ear, yield per ear and yield per plant) of 196 maize inbred lines were evaluated and analysised under water stressed with alpha-lattice field design by three replicate experiments. The results showed that the effect sequence of the all agricultural traits factors contributed to yield per plant were:ear-traits>plnat-type traits > growth-traits.2. Plant height, ear height, Tassel length, ear length, ear diameter, seeds per row, rows per ear, yield per ear and yield per plant were identified to evaluate drought tolerance of 196 maize inbred lines in three replicate experiments. The results of showed that the drought tolerance of yield per ear, seeds per row and ear diameter are significant positive correlation with drought tolerance of yield per plant, and 196 maize inbred lines were divided into three classes according to drought tolerance of plant:the strongest, the middle and the weakest. The 35 maize inbred lines with the strongest drought tolerance, such as 888-9, H152, Ye52106, Ji4112,1029, B(?)P44, Si387, K14, Moqunl7, Zhongmiao28 and Zao49, could be used in different breeding aims.3. The linear regression analysis showed that the defferences of ASI under two water regimes with drought tolerance of inbred lines were significant negative correlation in three replicate experiments. the linear equations were Y=0.97286-0.04374X(R2=0.8365, F=951.40**), Y=0.82975-0.03272X (R2=0.6435, F=348.36**) and Y=0.90369-0.04033X(R2=0.8596, F=1144.89**), of which X means the defferences of ASI and Y means drought tolerance of inbred lines.4. 70 SSR markers were used to reveal 244 alleles in 35 strongest and 27 weakest drought tolerance inbred lines. The average number of alleles per SSR locus was 3.49 and polymorphism information content (PIC) for the SSR locus was 0.58. Using UPGMA analysis, principal coordinate analysis (PCoA) and the STRUCTRUE clustering grouped the 62 inbred lines into 6 clusters which were consistent with their pedigree information, and each cluster has the strongest and weakest drought tolerance inbred lines, which will have very important for improving germplasm, creativing and selection inbred lines.5. The study on advanced backcrossed introgression lines indicated that the drought-tolerance of the susceptible genetic background was improved largely by advanced backcrossed introgression, and the efficiency was dependent upon the specific combinations. The efficiency for each trait was decided by the donor. The Drought resistance of combinations of 515×Chang7-2, Shuang105×Chang7-2 and 502×Chang7-2 were better than the others among the BC2F3 populations and could be used in germplasm enhancement and breeding. |
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