Resumo

RUIZ, MA; GOLBERG, AD  e  MARTINEZ, O. Water stress and forage production in Tetrachne dregei Nees, Panicum coloratum L. and Eragrostis curvula (Schrad) Nees. Phyton (B. Aires) [online]. 2008, vol.77, pp.7-20. ISSN 1851-5657.

Tetrachne dregei, Panicum coloratum and Eragrostis curvula are perennial forage C₄ grasses, introduced from South Africa to the pampean semiarid region. This work was carried out to compare water stress tolerance; forage production and quality of T. dregei, P. coloratum and E. curvula. Studies were conducted under greenhouse and field conditions. In the greenhouse, watering was stopped after eighty one days of plant emergency in the water stress treatment. Water potential (ψ), stomatal resistance (SR) and shoot and root weights were evaluated. Under water stress, ψ diminished earlier and SR increases were higher in P. coloratum than in T. dregei and E. curvula. Plant survival in T. dregei and E. curvula was higher than that of P. coloratum. Under field conditions (INTA, Agricultural Experimental Station Anguil, La Pampa, Argentina), biomass production of T. dregei was lower than that of the other species (p<0.05) during the first year, but forage production was higher (p<0.05) in E. curvula, followed by T. dregei, than in P. coloratum in the following years. In spring, P. coloratum showed a greater forage digestibility (p<0.05) than E. curvula and T. dregei; P. coloratum and T. dregei had more protein percent than E. curvula. In summer, protein percent of T. dregei was higher (p<0.05) than that in the other species; however, there were no significant differences in forage digestibility among species. This study provided strong evidence that T. dregei could be a suitable species for semiarid environments. Panicum coloratum showed very good forage quality characteristics, although its high biomass production was limited to the first year.

Palavras-chave : Tetrachne dregei; Panicum coloratum; Eragrostis curvula; Water stress; Forage production; Forage quality.

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