Effects of Recurrent Selection in Corn Populations
Recurrent selection methods were conducted in corn (Zea mays L.) populations to increase the frequency of favorable alleles for grain yield. Populations under recurrent selection were evaluated to estimate response to selection and to compare the relative effectiveness of the different methods of recurrent selection for grain yield improvement. Ten populations, their improved strains, and the S1 generation of the original and improved strains were evaluated in four field environments. This study was conducted to estimate the direct and indirect responses to selection of the 10 populations and their respective S1 generations for different methods of selection. Positive response to selection for greater grain yield was realized for each selection method except for one population (BSCB1) undergoing reciprocal recurrent selection. Average response (0.249 Mg ha−1 cycle−1) for the intrapopulation selection methods was greater than the average response (0.033 Mg ha−1 cycle−1) for the interpopulation selection methods. Response in the S1 generations was similar to the response of the noninbred populations. Reduction in inbreeding depression averaged 12%. The S1 generations of two selected populations [BS13(S)C4 and BS12(HI)C7] had significantly greater yields than the nonselected, noninbred populations from which the selected populations were derived. Positive response to selection was accomplished without selection for taller, later-maturity genotypes. No consistent trends were detected for changes in root and stalk lodging with selection for grain yield.
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