Characterization of a Promising Buffel Grass Hybrid Based on its Behaviour under NaCl-induced Salt Stress

GRIFFA, S.; RIBOTTA, A.; LÓPEZ COLOMBA, E.; CARLONI, E.; TOMASSINO, E.; ANDRÉS, A.; BIDERBOST, E.; GRUNBERG, K.

Campo Grande , Matto Grossso Do Sul. Brasil

Simposio; II Simpósio Internacional sobre Melhoramento de Forrageiras.; 2009

Embrapa Gado de Corte

Genetic improvement of Buffel grass, a forage grass species, is limited by its obligate apomictic reproductive behaviour. An introduced sexual line available in Argentina was used to initiate an improvement program for the species with the aim of obtaining an enhanced germplasm for the arid, semiarid and salt stress conditions prevailing in the north west of Argentina (NOA). Controlled crosses between the sexual line and introduced obligate apomictic cultivars yielded numerous possible F1 plants; some plants phenotypically different from their parentals were selected. The latter were analyzed using the AFLP molecular technique adjusted to Buffel grass, and hybrid plants were recognized (Griffa et al., 2006). One of them, named 3/1, was morphologically characterized by comparing it with its parentals, the introduced sexual line and the cv Biloela, the latter being widely distributed in the NOA, and showed, by contrast, an overdominant behaviour in some morphological characters (Griffa et al., 2005), suggesting that obtaining a promising genetic combination by hybridization largely depends on the occurrence of heterotic expression. This observation is also supported by the phenotypic similarity exhibited by several F1 plants obtained with the introduced sexual parental, which does not carry characters of interest for biomass production.   Incorporating the promising hybrid into the forage chain of the NOA would be very important. Buffel grass drought tolerance is known worldwide, although it varies with the cultivar. The cv Texas-4464 is the most tolerant to drought and Biloela is the most tolerant to salt stress, according to the scarce literature on Buffel grass tolerance to environmental stress factors. Drought tolerance was confirmed in the 3/1 hybrid in a field assay (AAPA, 2008); tolerance or susceptibility to salinity, however, still remains to be confirmed. It has been reported that salinity tolerance may vary with ontogenic stage and that it might be regulated by different independent genes