Identification of Donors with Favorable Alleles for Grain Yield to Improve lebreds in a Philippine Maize Breeding Program

摘要

Selecting donor inbreds to improve elite single crosses is fundamental in line recycling in a maize hybrid breeding program. Elite donor inbreds from different sources were identified to improve the grain yield of Pi17 X Pi23 (known as IPB 911, the first publicly released yellow single cross hybrid in the Philippines) and the different published estimators of favorable alleles were compared. The alleies were evaluated based on estimators such as modified mu G*, probability of net gain (PNG), minimumupper bound (UBND), net improvement (Nl), predicted three-way cross (PTC) and general combining ability (GCA). Biplot analysis was used to combine the results of different estimators and to describe the estimator x genotype interactions. Top donors wereidentified with favorable alleles lacking in IPB 911 hybrid based on biplot of different estimators. The donors are CIVIL 172, CML 432, CML 487, CIVIL 451, Ki32, Nei 9008, CA14520, CIMMYT TL8 and ARMP 36. Comparison showed that mu G* was very highly correlated with Nl (0.95) but only moderately highly correlated (0.61-0.88) with the other estimators. Based on genetic relationship values, the top donors belong to the Pi23 heterotic group. Inbred line development from BC1 or F2 populations between recipient and donor was recommended to recover favorable aileles that could be transferred to the recipient parent. This study has shown how the different estimators could be used in identifying donors to realize the short-term and long-term objectives of linerecycling in corn hybrid breeding.