a1 Department of Agriculture, University of Aberdeen, Aberdeen, AB9 1UD
Damage to barley grain cv. Golden Promise was induced in the laboratory by putting seed at 8·7, 14, 18, 22, 26 and 35% moisture content (MC) through a mechanical laboratory thresher for 10, 20 or 45 sec. The extent of visible external damage was greatest at 8·7 and 14% MC with reduced and similar levels of damage after handling at 18–35% MC. At moisture contents up to and including 26%, seeds could tolerate extensive mechanical damage with little effect on seed quality. Seed germination and seedling vigour were, however, reduced after handling at 35% MC despite similar levels of external damage to those seeds handled at 18, 22 and 26% MC. Samples of grain of cv. Triumph produced by whole-crop harvesting included mainly slightly damaged seeds with little effect of harvest moisture content, which ranged from 22·5 to 44%, on the incidence of damage. Seed germination and seedling vigour increased when seeds were harvested at progressively lower moisture contents, with the largest increase between 36% MC (56% germination, 6·1 vigour rating) and 29·5% MC (94% germination, 7·8 vigour rating). The seed quality of whole-crop harvested seed at 29% MC was similar to that of combined seed harvested at the same moisture content. It is suggested that 30 % is the maximum harvest moisture content at which commercially acceptable seed may be produced by the whole-crop harvesting method.
(Received February 10 1986)
p1 Present address: West of Scotland Agricultural College, Auchincruive, Ayr, KA6 5HW.