Diallel analysis of plant and ear heights in tropical maize (Zea mays L.)

Plant breeders and geneticists often use diallel mating designs to obtain genetic information about a trait of interest from a fixed or randomly chosen set of parental lines. Diallel designs and analyses have been developed for parents that range from inbred lines to genetically broad-based varieties. The object of this study was to determine the combining ability for the plant and ear height by both Griffing Method and Gardner & Eberhart Method, and compare the results obtained by two methods. Hybrids and parents averaged over hybrids differed significantly for plant and ear height. Relative ear position over plant height (REPH) was also calculated from plant and ear heights. By Griffing Method, general combining ability (GCA) was significant in plant height. Specific combining method (SCA) was highly significant in all three measurements. Average heterosis for the plant and ear heights were 33.3% and 61.9%, respectively. However, REPH showed 21.6% heterosis effect. The traits with low heterosis showed higher ratios of GCA/ SCA, while these ratios were smaller in traits with high heterosis. REPH could be used as one of valuable selection criteria over plant and ear heights in the breeding program for low ear height. Above mentioned two statistical methods produced some different results.