Divergent Selection for Stalk Quality and Grain Yield in an Adapted ✕ Exotic Maize Population Cross

The choice of breeding materials, evaluation techniques, and breeding methodologies crucial in improving lodging resistance of maize (Zea mays L.). The present study was conducted to evaluate progress from selection for different stalk quality traits and for grain yield in the F₂ of Illinois Stiff Stalk Synthetic Composite (RSSSC) ✕ South African Photoperiod Insensitive Composite II (PIC2), population that has good potential for stalk quality and yield improvement. One cycle of divergent S¹ family selection was practiced for the following traits:(i) grainy ield, (ii) lodging resistance (iii) rind puncture resistance using penetrometer measurement (iv), stalk crushing strength, and (v) a desired gain selection index based the first three traits. In addition, one cycle of divergent mass selection for rind puncture resistance was completed. Evaluation of progress from selection was based on Cycle S1 populations, testcrosses to FRMo17 an d Oh43,a ndo n random Cycle 1 $1 families grown in 1984 and/or 1985. When valuated as C₁ populations, response to S₁ selection was significant for all five traits. Selection for higher grain yield resulted in a deterioration of stalk quality. Index selection was effective in increasing rain yield while maintaining acceptable lodging resistance. For improving stalk lodging resistance, selection for lodging resistance, per se, was most effective, followed by selection for high rind puncture resistance and high stalk crushing strength. In testcrosses, the selections for high rind puncture resistance showed greatest gains in stalk lodging resistance. Based on Cycle 1 S₁ families, the direct response to positives election for grain yield, index, and rind puncture resistance were 1.2, 0.9, and 1.1 phenotypic standard deviations respectively. Significant genetic variance was present, indicating further progress from selection is possible. Mass selection for rind puncture resistance was as effective as S₁ selection and resulted in fewer undesirable correlated changes for simultaneous talk quality andg rain yield improvement, S₁, index selection, including rind puncture resistance and yield, appears promising.