Seed germination and early growth of physic nut seedlings under salinity stress

Abstract

Soil salinity is one of the major abiotic stresses that limit seed germination and plant growth, causing yield loss in crop species. The phytotoxic effects of salt stress on seed germination and early growth of physic nut (Jatropha curcas L.) seedlings were investigated in the present study. Physic nut seeds were subjected to five levels of salinity [0 (control); 25; 50; 75 and 100 mmol L^-1 of NaCl], using the solution-paper method, with five replications. The experimental unit consisted in a germitest paper roll with 25 physic nut seeds. Salt treatments were evaluated based on the following tests: first count of germination test (7 days), total germination (12 days) and early growth of physic nut seedlings (12 days). Results showed that the addition of 100 mmol L^-1 of NaCl reduced the first count of germination test (45%), total germination (50%), shoot length (42%), root length (59%), shoot dry matter (34%) and root dry matter (44%) of physic nut seedlings compared to the NaCl-free control. The exposure to high salt concentrations severely restricted the seed germination and early growth of physic nut seedlings. These data suggest that physic nut crop is a moderately sensitive species to high salinity levels during the stage of seed germination and early seedling growth.