The objective of this study was to evaluate the mitigating role of exogenous spermidine on the seed germination, seed vigor and seedling growth of alfalfa forage cultivars, pigeon pea and lablab subjected to salt stress. The seeds were sown in plastic gerboxes lined with filter paper moistened with saline solutions at concentrations of 0, 20, 40, 60, 80 and 120 mM NaCl containing 0 or 0.5 mM spermidine. The experimental design was a completely randomized factorial 3 x 6 x 2 (forage x salinity x spermidine) with five replicates of 25 seeds. Germination was evaluated on the fourth and tenth days, along with the germination speed index, measured until the ninth day after sowing. The salt concentration had reduced germination and the dry weight of shoot and root by 50% on the tenth day after sowing. The application of exogenous spermidine resulted in a greater dry root weight of lablab cv. Rongai, 50% germination of pigeon pea seeds cv. Caqui at the salt concentration of 72.09 mM NaCl, and a higher GSI for alfalfa cv. Crioula and lablab cv. Rongai seeds.
salt stress; Medicago sativa L.; Cajanus cajan (L.) Millsp; Dolichos lablab (L.); germination speed index
