Effect of Salinity on Seed Germination Characteristics of Five Arid Zone Tree Species

Abstract

This study was carried out to investigate the effect of salinity on seed germination characteristics of five arid zone tree species under ambient laboratory conditions. The species used were Acacia cyanophylla, A. seyal, A. tortilis, A. tumida and Parkinsonia aculeata. Seeds were sown on filter papers in petri dishes and watered with different salinity levels of 0, 1, 2, 5, 10 and 20 dSm -1 . A split plot design was used. Effects of salinity on the commencement of germination, germination speed and germination percentage of the five species were evaluated. The results showed considerable interspecific variation in the response of seed germination to salinity among the studied species. No germination took place in all the species in salt concentration of 20 dSm -1 . The salinity levels of 5 dSm -1 and 10 dSm -1 significantly (P>0.05) delayed the initiation of seed germination of all the species except A. cyanophylla, which appeared less sensitive to salinity stress than the other species. The high salinity level (10dSm -1 ) induced significant (P>0.05) reduction in the germination speed of seeds of A. seyal and A. tumida, while it had no significant effect on the germination speeds of the other species. The germination percentage of A. seyal was significantly (P>0.05) retarded by salinity level as low as 2 dSm -1 ; however, the germination percentage of the five species was significantly reduced at moderate (5 dSm -1 ) and high (10dSm -1 ) salinity levels. The results were discussed in context of selection of species with seed characteristics acceptable for plantation establishment in salt-affected areas.