Effect of pasture competition on barley grass seed production

摘要

Barley grass seeds were sown into pasture which was either untreated or sprayed with paraquat at the time of sowing. In some experiment seed was sown at dIfferent rates, and the effect of grazing subsequent to sowin was examined in others.The survival of seedlings and the reproductive capacity of the grass were recorded.Initial establishment was not consistently affected by the presence of pasture but the decline in seedling numbers tended to be greater in untreated pasture.Seed head production was heavily reduced by pasture competition, and in some cases grazing also reduced seed head numbers.Increasing the barley grass sowing rate led to higher seed head numbers,but the numbers of heads produced per sown seed tended to decline.In the pastures studied,the number of seeds produced would not have been adequate to maintain plant populations in the presence of pasture competition,but where this competition was removed at the time of sowing more than enough seeds were formed to maintain and even increase the population.