DIALLEL EVALUATION OF CORN BELT X EXOTIC POPULATIONS
Abstract
There is lack of information on the efficiency of the various selection methods but the performance of the resulting populations can be compared. This study was therefore undertaken to compare the performance of seven Corn Belt x Exotic populations and their diallel crosses with one another and with two standard hybrid checks over a period of two years. The diallel entries were grown in a randomized complete block design of three replicates at three locations in 1978 and six replicates at two locations in 1979. The materials were compared for the characters percent plant stand, percent lodging, percent moisture in grain, disease rating, prolific tendency, ear height, plant height and yield of grain. Only the character percent lodging had appreciable interaction with the environment. The diallel entries were not significantly different for prolific tendencies, ear height, plant height and disease ratings. A genetic analysis indicated that most of the variations among the genotypes for percent plant stand, percent lodging and percent moisture could be described adequately by the V(,j) effects alone. For grain yield however, both the V(,j) effects and average heterosis effects (h) accounted for the variation among the populations and their crosses. Average heterosis values of 10.1% and 2.2% were obtained from the crosses over the mid parents and higher parents respectively. The highest yield among the crosses was about 70% of the mean of the two standard hybrid checks. The ranking of the populations on the basis of average heterosis was: Antigua 2D x (B10 x B14), Exotic II, Colus 71, Westigua, Eto x CBC, Thick Rind and Composite with values of 16.6%, 12.1%, 12.0%, 9.4%, 9.1%, 8.2% and 3.4% over the mid parents and 9.3%, 3.5%, 5.1%, 0.5%, 1.3%, 4.7% and -8.6% over the higher parents respectively. This study has shown that Antigua 2D x (B10 x B14), Colus 71 and Exotic II could produce promising inbred lines to work with. The performance of the Composite population and its crosses have shown that great genetic diversity alone was of little value.
Degree
Ph.D.
Subject Area
Agronomy
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