Natural Outcrossing on Genetic Male Sterile Barley 1

In 1960, we grew 11 male sterile barley, Hordeum vulgare L., lines at five dryland and three irrigated locations in Montana. Significant differences in mean seed set on male sterile plants were found with different locations (0.7 to 6.2% outcrossing), lines (0.6 to 9.2% outcrossing) and varieties (outcrossing on msms in three different varieties ranged from 1.2 to 6.7%). In 1960 to 1965 natural outcrossing on male sterile plants differed between years at Bozeman in nine male sterile lines. In 1960, we studied natural outcrossing on single male sterile plants and spikes of 16 male sterile barley lines at Bozeman. We found: ( 1 ) the single plant standard error for average seed set per spike was 0.96 seed per spike; ( 2 ) the percent seed set on individual spikes which set seed ranged from 2 to 70% and had a standard error of about 11%; and ( 3 ) the average number of seed set on primary secondary, and second crop tillers was 3.18, 0.26, and 0, respectively. Natural outcrossing on male sterile plants was too low in all experiments to allow practical production of hybrid barley in Montana without additional manipulation of pollen shower, female receptivity, and “nicking” time.