Establishment of Italian ryegrass (Lolium multiflorum Lam.) by self-seeding as affected by cutting date and degree of herbage removal in spring in pastures of the southern Great Plains of the United States

摘要

Annually sown cool-season small-grain cereal species can provide a valuable source of cool-season herbage for livestock in the southern Great Plains of the USA but limited access to field equipment for cultivation and sowing is an obstacle to their use. Italian ryegrass (Lolium multiflorum Lam.) (IRG) can persist through self-seeding and may offer an alternative source of cool-season herbage. The effects of cutting dates in mid-April, early May or mid- to late May following sowing in the previous September, and of removing 0p"57, 0p"73 or 1p"00 of the herbage mass at this time, on subsequent seed deposition, seedling re-establishment and herbage production of IRG were measured. Later cutting dates reduced seed production, seed deposition, 1000-seed weight and eventual re-establishment of IRG seedlings. Removing different proportions of the herbage mass did not compensate for reduced seed deposition arising from later cutting dates. Numbers of seed heads and seed required to achieve a self-seeded target population of 500 established seedlings mpo ranged from 885 to 5650 seed heads mpo and 3360 to 5850 deposited viable seeds mpo. Re-establishment of IRG through self-seeding showed a failure rate of 0p"43 indicating that self-seeded IRG will need periodic resowing. Any economic benefit derived from self-seeded IRG will depend heavily on the success of its rate of re-establishment.