FERTILITY INDICES IN CROSS-POLLINATED GRASSES

Abstract

Floret fertility indices of 0.62, 0.65, 0.46, and 0.57, respectively, were shown by northern commercial bromegrass, diploid Fairway crested wheatgrass, tetraploid Summit crested wheatgrass, and Ree intermediate wheatgrass. Southern strains of bromegrass were lower in fertility than northern bromegrass and this was reflected in lower seed yields. The Summit variety of crested wheatgrass was lower in fertility than the Nordan variety. Years and replications influenced the fertility indices of grasses but less so than strains. Good uniformity in fertility was observed for central sections of spikes in the wheatgrasses. Upper florets within spikelets were less fertile than lower florets in all grasses. Somewhat lower fertility indices were found for border plants in space-planted nurseries than in the centers of nurseries.