TY - EJOU AU - Peláez, AU - Mayor, MD AU - Elia, OR AU - Martínez, SA TI - Effect of post-fire defoliation on growth of two native grasses in the Caldenal, Argentina T2 - Phyton-International Journal of Experimental Botany PY - 2009 VL - 78 IS - all SN - 1851-5657 AB - Plant growth in semiarid rangelands may be affected by time grazing is excluded during the post-fire regeneration period. The objective of this field work was to study the effect of post-fire defoliation at different phenological stages [vegetative (early-season defoliation) and internode elongation (late-season defoliation)] on growth of Piptochaetium napostaense and Poa ligularis, two very important perennial native grasses in the temperate semi-arid region of central Argentina (Caldenal). In general, the post-fire defoliation treatments did not affect the number of green leaves on tillers of P. napostaense. Early-season post-fire defoliation generally reduced the number of green leaves on tillers of P. ligularis in comparison to those in control plants. Late-season defoliation, however, usually increased the number of green leaves on tillers of P. ligularis. Nevertheless, very few significant (p<0.05) differences were detected within either one or the other phenological stage. Height and total green length (leaves + stem + sheaths) of tillers on plants of P. napostaense and P. ligularis exposed to defoliation were lower (p<0.05) or similar (p>0.05) than values on non-defoliated plants, respectively. Immediately after early- and late-season defoliation treatments, relative growth rates for tiller height and total green length were reduced (p<0.05) on plants of both species with respect to control plants. Our results suggest that a one-year-period without severe defoliations after fire would be at least necessary for not risking the persistence of these perennial grasses in the Caldenal community. KW - Piptochaetium napostaense KW - Poa ligularis KW - Caldenal KW - grass growth KW - post-fire resting DO - 10.32604/phyton.2009.78.017