GERMINATION OF PROSOPIS-ARGENTINA AND PROSOPIS-ALPATACO SEEDS UNDER SALINE CONDITIONS

Prosopis argentina and P. alpataco are shrubs occupying areas with dif ferent soil characteristics within the temperate arid zone of Argentin a: P. alpataco occurs in periodically flooded, clayish and saline area s; P. argentina occurs in non-saline sand dunes. The former may have d eveloped adaptive tolerance to salt stress while the latter did not. T he objective of this work was to determine the effects of salinity, an d its interaction with temperature, on the germination of these specie s. Increasing concentrations of NaCl solutions (0, 0.2, 0.3, 0.4 and 0 .6 molkg(-1) NaCl) at 25 degrees C and 35 degrees C were tested. Daily and final germination percentages, as well as germination rate, were recorded under controlled conditions. Results show that increasing sal inity caused a decrease in both rate of germination and final percenta ges for both species, P. alpataco being more salt-tolerant than P. arg entina. The greatest differences appeared between 0.3 and 0.4 molkg(-1 ) NaCl. Germination was more affected by salinity at 35 degrees C than at 25 degrees C for both species. (C) 1997 Academic Press Limited.