Defoliation of wall barley under sub-humid Mediterranean conditions

Abstract

Wall barley (Hordeum murinum) is a winter annual, native to Europe and the southern Mediterranean region. It can be used to establish permanent pasture in semi-arid rangeland. The crude protein content and response of wall barley to time of defoliation were investigated during 2 growing seasons in the northern mountains of Jordan. Field trials were conducted in the 1999–2000 and 2000–2001 growing seasons in Samta (32°23′N, 35°50′E) at an elevation of 1043 m. The highest crude protein content (P < 0.05) of 24.8% was recorded on 28 February and it thereafter declined gradually to reach the lowest values (4%) at maturity. The fiber content gradually increased and peaked (56.0%) when the plants reached maturity.

Clipping plants on 28 February and 15 March produced shorter plants but encouraged tillering. Oven-dry shoot weights of individual plants and the population showed similar responses to time of defoliation during both years. Clipping the individuals on 28 February (8.1 and 4.7 g/plant, in respective years) and 15 March (8.2 and 4.6 g/plant, respectively) did not reduce the plant shoot weight. Forage amounts produced when plants were clipped on 28 February and 15 March were similar to the amounts of forage produced from unclipped plants (1816 and 959 kg/ha, respective years). Clipping plants on 30 March and 15 April inhibited seed production. Defoliation during the early vegetative stage optimised seed yield and forage quantity and quality.