Defoliation time and intensity of wall barley in the Mediterranean rangeland

Wall barley (Hordeum murinum L.) is the dominant species in northeastern ra ngeland of Jordan that decreases under grazing. We investigated the respons es of wall barley to clipping time and height during 2 growing seasons in t he semiarid rangeland of Jordan. A natural stand was utilized to conduct th e experiments that were arranged in a randomized complete block design duri ng 1994/95 and 1995/1996 growing seasons. Treatments were combinations of c lipping heights (5 or 10 cm above soil surface) and plant growth stages (ti llering, jointing, or booting), in addition to unclipped check. Results sho wed that clipping to 5 and 10 cm stubble height at tillering produced 1,167 and 1,349 kg ha(-1) dry matter, respectively, compared to 1,122 kg ha(-1) for unclipped check. Clipping to 5 and 10 cm stubble height reduced shoot w eight by 28 and 21% at jointing stage and 52 and 38% at booting stage. Defo liation during tillering stage did not impact plant height of regrowth nor seed yield. Weed biomass were higher when plant defoliation was delayed to the jointing and booting stages. Therefore, it is recommended to defoliate wall barley early at tillering stage but before plants reach jointing or re productive stages.