Influence of temperature and salinity stress on seed germination and seedling growth of soybean (Glycine max L.)

The high salt level of a germinating environment can lead to reduced, delayed, and even complete inhibition of germination and seeding growth due to osmotic action and/or ion toxicity. Based on this viewpoint, the aim of this study was to investigate germination temperature and salinity effects on germination and early seedling growth of soybean, which can be sown as first and second crops.

Soybean seeds were subjected to NaCl induced saline germinating media prepared in petri dishes under two different germination temperatures (20±2 and 25±2oC). Thirty sterilized seeds per petri dish were sown in ten salt treatments (0, 100, 150, 250, 750, 1000, 2250, 5000, 7500 and 10000 ppm NaCl L¹). The study was carried out according to the completely randomized design with four replications.

Lower temperature promoted seed germination, while the high temperature significantly inhibited the seed germination at all NaCl doses tested. As a result, 25oC temperatures, which can only be measured at the time of the second sowing, have been found to negatively affect germination and also increase the negative effects of salt. Due to the moderate tolerance of soybeans to salt stress, the germination rate was positively affected up to 750 ppm NaCl L⁻¹ dose and resulted in severe reductions in subsequent doses. Also, the tolerance of soybean was negatively influenced by the interaction of temperature and NaCl concentration.