Selection for Seed Set in a Wheat Population Treated with a Chemical Hybridizing Agent
Production of hybrid seed is an important component of hybrid wheat (Triticum aestivum L.) utilization. A recurrent selection program was initiated using gridded mass selection to select for increased seed set on individual plants that had been treated with a chemical hybridizing agent (CHA). Four cycles of selection with recombination were completed using the spring wheat random-mating population NDPI. To determine the effectiveness of this selection procedure, 32 random half-sib selfed families from both the CO and the C4 cycles of selection, 32 random inbreds from the original NDP1 population, and 32 inbred lines from several wheat breeding programs were compared for both fertile seed yield (no CHA) and hybrid seed yield (0.6 kg ha−1 CHA) in replicated tests at two locations in 1986. Differences were found among entries for all traits when averaged across treatments. A significant rate ✕ entry interaction was found only among the inbred lines for grain yield, test weight, grain protein concentration, kernel weight, and kernels per spike. The families from the mass-selected population had a 20% greater seed set than the families from the original population and a 73% greater seed set than the inbred lines when treated with the CHA. Inbreds developed from the population had a 45% greater seed set than the conventional inbreds when treated. The increased hybrid seed production was associated with longer spikes and an increase in the number of spikelets per spike. When not treated with the CHA, the mass-selected group also had grain yield greater than the original population. The results indicate that outcrossing ability can be improved in wheat either directly through selection or indirectly through the use of random-mating populations.
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