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Rangelands from central Argentina characterize by insufficient warm-season, palatable perennial grasses to domestic livestock. Two palatable and water-stress tolerant cultivars ("Magnar" and "Trailhead") of Leymus cinereus were introduced into Argentina with the purpose of increasing the warm-season forage offer. Some mechanisms involved in determining defoliation tolerance and competitive ability, and subsequent dry matter production, were investigated in the study genotypes. Studies were conducted within an exclosure to domestic livestock. Two severe defoliation treatments were applied in 2006/07 and 2007/08. Only Pappophorum vaginatum, the native genotype, produced and dispersed seeds. Natural water stress during the second study year advanced phenology of all three genotypes. This advancement, together with the high production of total, reproductive and daughter tillers in P. vaginatum, even under defoliation, might contribute to explain its greater abundance than the other native, warm-season perennial grasses in rangelands of central, arid Argentina. Although plant survival and forage production were lower (p0.05), but not lower, in the introduced than in the native genotype. Future research is needed to substantially improve plant establishment of L. cinereus, genotype which can be seeded by conventional drilling. Fil: Torres, Yanina Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Universidad Nacional del Sur. Departamento de Agronomía. Laboratorio de Ecología; Argentina Fil: Busso, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Universidad Nacional del Sur. Departamento de Agronomía. Laboratorio de Ecología; Argentina Fil: Montenegro, Oscar Alberto. Provincia de Buenos Aires. Ministerio de Asuntos Agrarios. Chacra Experimental de Patagones; Argentina Fil: Giorgetti, Hugo Dosindo. Provincia de Buenos Aires. Ministerio de Asuntos Agrarios. Chacra Experimental de Patagones; Argentina Fil: Rodriguez, Gustavo Dionisio. Provincia de Buenos Aires. Ministerio de Asuntos Agrarios. Chacra Experimental de Patagones; Argentina Fil: Ithurrart, Leticia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; Argentina |
