Genetic Diversity and Heterosis in Tropical Maize under P Stress in Acid Soils
In this study, we characterized the genetic diversity among tropical maize inbred lines from the CIMMYT South America maize breeding program Using simple sequence repeat (SSR) markers, we estimated the correlation of genetic distance (GD) among inbred lines with F1 yield performance (F1) and midparent heterosis (MPH), and determined how the environment can affect these relationships. The level of genetic diversity among the 36 inbred lines was moderate (H=0.423+0.037), with an average of 3.14 alleles/locus and polymorphism information content (PIC) ranging from 0 (phi108411 and phi213984) to 0.73 (phi109188 and phi064). Cluster analysis grouped the lines into six clusters that were generally consistent with their pedigrees. A diallel study, consisting of six P-efficient and six P-inefficient lines, was done under stress (low P, 4ppm) and non stress (high P, 15ppm) soil conditions at two sites in the Colombian savannahs. Positive and moderate correlation between GD and F1 (r=0.52) and MPH (r= 0.43) was found among all crosses under high soil P conditions. However, these correlations became insignificant under low P. Higher correlations in both GD and F1 (r=0.80) and GD and MPH (r=0.77) were seen in crosses between lines within a cluster (ave GD=0.45) than in crosses between lines from different clusters (ave GD=0.62) under high P. No correlations were found in crosses between lines above a! GD threshold of >0.66. The correlations between GD and F1 and between GD and MPH were moderate for crosses between P-inefficient lines (r= 0.65 and r=0.58, respectively) and slightly higher between P-efficient lines (r=0.73 and r=0.70, respectively). However, only the correlations in crosses between the P-inefficient lines were stable under P stress.
M. L. C George F. Salazar E. Regalado L. Narro
CIMMYT Philippines
国际会议
第九届亚洲玉米大会(the Ninth Asian Regional Maize Workshop)
北京
英文
228-232
2005-09-05（万方平台首次上网日期，不代表论文的发表时间）