COMPARATIVE SALINITY TOLERANCE OF 2 LEGUMES, VIGNA-LUTEOLA AND VIGNA-VEXILLATA, FROM THE COAST OF TRINIDAD

The germination and growth responses of two legumes, Vigna luteola and Vigna vexillata, to different salinity levels were compared in labora tory experiments. Vigna luteola seeds tolerated a higher level of sali nity and germinated significantly better at high salinities than corre sponding results for V. vexillata. Seedlings of V. luteola exhibited a significant increase in dry weight at 10% seawater followed by a sign ificant decrease at 30% seawater and above. Vigna vexillata seedlings showed a gradual decrease in dry weight with increased salinity. Excep t at 0% seawater, dry weights of V. luteola seedlings were significant ly higher than those of V. vexillata at all salinities tested. The pro portion of root weight to total plant dry weight increased with increa sed salinity in V. luteola; the reverse was the case in V. vexillata. In both species, increased salinity resulted in increased sodium conte nt but decreased potassium and calcium contents. While the sodium cont ent of the shoot of V. vexillata was higher than that of V. luteola, t he amount in the roots of V. luteola was higher. The potassium and cal cium contents were higher in V. luteola than in V. vexillata and the s odium to potassium ratio values were lower in V. luteola than in V. ve xillata. The results are compared with those of other legumes and disc ussed in relation to the habitats of the species, the characteristics of halophytes, and the uses which these legumes may have in salt-enric hed lands.