Selection for tillering rate in annual ryegrass and its influence on potential forage production under irrigated conditions

Abstract

No information exists regarding the productivity of annual ryegrass and the influence of morphological yield components on yield under Libyan conditions. Therefore, the performance of two contrasting populations of annual ryegrass, and the correlated responses to selection for high (HTR) and low (LTR) tillering rate, and original population (Co) were evaluated over a period of two years. Micro swards of the populations were grown in the field under supplemental irrigation. Two harvests were taken from the plants during each growing season. In general, populations selected for differing tillering density under space planting had corresponding tiller density when grown in replicated plots, but an inverse yield/ tiller. Total dry yield was 8.16, 8.01 and 7.84 tons/ ha for the HTR, LTR and Co population, respectively. Difference in forage yield from the first harvest between populations was probably related to the greater light interception in early growth stages by the HTR population. In the first harvest, a close relationship existed between forage yield and tiller density. However, in the second harvest, yield/tiller was the most critical yield determinant. Selection of annual ryegrass for high tillering may be beneficial for grazing management system. Annual ryegrass can be used in conjunction with some other crops to substitute for the deficiency in the availability of forage during the winter and early spring.