Mass Selection and Mating Systems in Cereals1

Abstract

Responses to two cycles of mass selection under two mating systems were compared in the F2 and F3 generations of one cross each of spring wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.). The number of green tillers prior to head emergence was used as the critical character. Additional characters, time from sowing to flowering and fertility number at maturity, were measured also in the evaluation of selection response for green tillers. The mean response for increased tillring, evaluated at two sites against unselected control generations, was higher in the wheat at 10.3%cycle than in the barley at 6.3%/cycle. Broad sense hentability estimates for tillering were between 10 and 25% for each cross.In both species the selection responses were greater in the hybrid than in the selfed selection series. The hybrid series was obtained by random mating among the selections in each cycle. The respective responses in barley realized over two selection cycles, were 17.1% with outbreeding and 8.7% with inbreeding at site 1, and 13.9% with outbreeding and 10.3% with inbreeding at site 2. In wheat at site 1, the responses were 22.6% with outbreeding and 18.5% with inbreeding. (Site 2 of the wheat had poor establishment.) Since the same F2 selection generated the hybrid and selfed series, the differences in response were attributed to the second cycle only. Asso. ciated selection responses for time to flowering and tiller number at maturity were detected only in the wheat.The results showed that mass selection with concurrent random mating could be a useful breeding stratcgy in self‐pollinated crops.