Investigations of the mechanisms of cross pollination in wheat and combining ability as indicated by forage production in hybrids of male sterile stocks and commercial varieties

Abstract

Average seed set in lateral florets of male sterile plants with T. timopheevi, Ae. caudata and Ae. ovata cytoplasms, cross pollinated by 45 wheat strains, ranged from 11.1 to 61.2, 4.3 to 57.5 and 1.6 to 35.9%, respectively. The pollinators included hard red winter, soft red winter, durum and club varieties; and derivatives of species crosses involving Agropyron and several species of Aegilops. The percentage seed set (lateral plus central florets) ranged from near 0.0 to 25.5% for plants with Ae. ovata cytoplasm, 3.0 to 45.0% for Ae. caudata type steriles and 7.0 to 49.0% for T. timopheevi type steriles. Considerable variability in seed set on male sterile plants was evident among plants in the row regardless of the pollinator used. Seed set in lateral florets of fertile wheat spikes of the pollinators ranged from 70.4 to 94.6%. The seed set in central florets ranged from 0.0 to 69.6% and the total ranged from 46.9 to 81.6%. There was no significant difference in seed set of awned and awnless spikes obtained from World Wheat Collection, fertile wheat. The male sterile plants of all cytoplasms, especially Ae. ovata cytoplasm plants, tended to be later in maturity than pollinators, fertile wheat and was undoubtedly a factor contributing to the low seed set. Seed set in hybrids used in a forage study was about the same as for the pollinator study. The soft red winter variety Knox set 16.4% seed in central florets and 10.5% in the Knox sterile plants, whereas the hard red winter wheat varieties and steriles set very little seed in the central florets. ...