Southern Conservation Tillage

Improving tropical maize (Zea mays L.) tolerance for drought stress was initiated in 1991 in a fullsib recurrent selection program. This breeding program was initiated to compare two selection environments and to improve the yield stability of tropical maize under the north Florida drought-prone environments. Rainfed and irrigated plots were used to evaluate 140 fullsib families, along with four checks in a 12 X 12 partially balanced lattice design with four replications. Relative grain yield, plant and ear height leaf area, flower delay, canopy temperature, tassel weight, and drought index were used to select the fullsibs for the recombination phase. Yield reductions, ranging from 2 to 40% in the stress site, were mild due to appreciable rainfall. High variability existed among the fullsibs tested for grain yield. Irrigated grain yield ranged from 3987 to 8039 kg ha , and rainfed grain yield from 3066 to 7124 kg ha . A 15% selection pressureresulted in the advancement of 21 fullsibs from either site to the recombination process