Single-cross hybrid development in maize by reciprocal half-sib selection

Maize (Zea mays L.) inbred lines were developed from two diverse populations, Across-8045 and GROP-272, by a reciprocal half-sib selection scheme for developing single-cross hybrids. Selection, which was based on half-sib progenies, was carried out both among and within lines during the S 0 × S 0 through S 5 × S 5 generations. Genetic gain was measured by comparing progeny yields to the mean of six adapted check hybrids each year. After six generations of inbreeding and selection, gain was 4.0% per generation for Across-8045 and 6.5% per generation for GROP-272. The mean yield of the S 0 × S 0 topcrosses was 11.8% less than that of the checks for Across-8045 and 30% less than that of the checks for GROP-272. The mean yield of the best S 5 × S 5 topcrosses was 11.8% greater than the mean of the checks for Across-8045 and 15.8% greater than the mean of the checks for GROP-272. The advantages of the breeding scheme are that it provides abundant half-sib seed for testing while coupling the development of inbreds and hybrids throughout the process