Investigation on the effect of salinity stress in Prosopis juliflora, P. cineraria and P. koelziana in two life cycles (germination and seedling)

In this study, responses of three prosopis species to salinity stress in two life cycles (germination and seedling). In order to investigate the effects of salinity stress to germination, the experiment carried out based on the completely randomized design with 3 replicates and different salinity levels (0, 2.5, 8.5, 14 and 20 ds/m). Germination rate, germination percentage, roots and shoot length and weight in seeds and the amount of proline, sugar and chlorophyll in seedlings stage were measured. In the habitat of the species, seasonal changes of Na and K content of leaves were measured. Results showed that the germination rate, germination percentage, roots and shoot length and weight decreased in all species with increasing salinity stress. The highest and lowest germination characteristic accured in control and 14 ds/m treatments, respectivly. No germination occurred in salinity of 20 ds/m.  P. juliflora and  P. koelziana showed the highest germination rate in all treatments. P. juliflora showed the highest germination percentage and root length (except in 14 ds/m) of salinity. Results also showed that the salinity caused the accumulation of proline in all species. P. juliflora and then P. koelziana showed the highest accumulation of proline and sugar.  The amount of sugar decreased in P. cineraria by increasing salinity. Chlorophyll decreased in all plant by increasing salinity stress and P. juliflora did better compare to two the others plants. Compared to P. cineraria and P. koelziana,   P. juliflora accumulated highest Na and K. In summer, the accumulation of these ions in P. juliflora were higher than the other seasons. It can be concluded that although P. juliflora is a suitable plant for plantation in arid lands, great care should be taken for places that endemic plants are able to regenerate or plantation of them is easy.