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Chloris gayana cultivars: RAPD polymorphism and field performance under salinity

Perez, H., Bravo, S., Ongaro, V., Castagnaro, A., Garcia Seffino, L., Taleisnik, E.
Grass and forage science 1999 v.54 no.4 pp. 289-296
Chloris gayana, cultivars, genetic polymorphism, salinity, field experimentation, germplasm, genetic distance, electrical conductivity, seedling emergence, crop yield, dry matter accumulation, yield components, stolons, leaves, salt tolerance, random amplified polymorphic DNA technique, biological resistance, Argentina
Variability in the response to salinity within Chloris gayana (Rhodes grass) germplasm was evaluated under field conditions, and random amplified polymorphic DNA (RAPD) markers were used to assess genetic relatedness among cultivars/accessions. RAPD analysis showed a clustering of cultivars of known relatedness: cv. Pioneer and accessions Local and Trancas (derived from an old Pioneer pasture established in saline soil) belonged to the same cluster, Katambora to another and tetraploid Boma and Callide could be further separated, Boma belonging to a fourth, distant cluster. Field experiments were laid out in two types of plots: control [with electrical conductivity of the saturation extract (EC) = 3.64 dS m-1] and saline (EC = 13.l0 dS m-1) and two experiments were carried out: one to evaluate the effects of salinity on emergence and establishment, and the other, with a uniform number of plants per plot, to evaluate yield under saline conditions. All cultivars/accessions had salinity-associated decreases in dry-matter (DM) production during the establishment phase. After this stage, 1-year DM yield was similar in all cultivars within each salinity level and production in the saline plots was significantly lower than in controls only in cv. Callide and accession Trancas. Second-year production in the non-saline plots increased by 30% on average over the previous year, whereas an average 40% reduction was observed in the saline plots. Thus, salinity had a negative effect on Rhodes grass establishment and persistence. The cultivars could not be ranked unequivocally by production under saline conditions, but tetraploids Boma and Callide may be said to be less tolerant than the rest on the basis of an increased proportion of dead leaves and decreased number of stolons observed in the saline plot.