Salt stress effects in the physiological quality of Cajanus cajan (L.) millspaugh seeds at different temperatures

Cajanus cajan (L.) Millspaugh, known as pigeon pea, is considered a rustic legume, high-temperature tolerant, well adapted to environments with low water availability, saline, and low fertility soils. This study aimed to evaluate the germination and vigor of Cajanus cajan seeds under conditions of salt stress and different temperatures. A completely randomized experimental design was used, with treatments distributed in a 6 x 3 factorial scheme (salinity levels and temperatures), with four replications of 50 seeds. After determining the seed water content, the seeds were placed on germitest paper moistened with sodium chloride (NaCl) solutions in concentrations of 0.0 (control); 2.0; 4.0; 6.0; 8.0 and 10.0 dS m-1; Seeds were incubated in a B.O.D, at constant temperatures of 25 and 30 °C and alternating 20-30 ºC. The germination and vigor tests (first germination count, germination speed index, length and dry mass of roots and shots) were evaluated. An interaction between the salt concentration and temperature for all variables analyzed was observed, with a negative effect on the germination and vigor of Cajanus cajan seeds as the salinity levels increased. Salt stress simulated with NaCl reduced the germination and vigor of Cajanus cajan seeds, mainly when submitted to the temperature of 25 °C. However, the increase in NaCl concentration, up to the potential 10.0 dS m-1, was not high enough to impair seed germination.