Comparative tolerance of tropical grain legumes to salinity

Abstract

The tolerances of a range of tropical grain legumes to salinity were compared during early vegetative growth of plants grown in pots with NaCl added to a sandy loam soil to achieve electrical conductivities (sat. extract, ECe) over the range, 1.3-13.8 dS m-1. Tolerance, based on the ECe at 50% of maximum growth (in parenthesis) was of the order: Sesbania cannabina (13.2 dS m-1) > guar cv. CP 177 (10.1 dS m-1) > guar cv. Brooks (9.8 dS m-1) > cowpea cv. Caloona (9.0 dS m-1) > soybean CPI 26671 (6.7 dS m-1) > pigeon pea cv. Hunt (5.4 dS m-1) > black gram cv. Regur (5.0 dS m-1) > pigeon pea cv. Royes (4.9 dS m-1) > green gram cv. Celera (3.5 dS m-1). Genotypes exhibited differences in Na+ accumulation, with black gram, green gram and pigeon pea accumulating large quantities in shoot tissues, compared with effective exclusion of Na+ by Sesbania, guar and soybean. Smaller relative differences existed between species in terms of Cl- uptake, and the relative yield reduction was closely related to the amount of cl- in shoots. These results are discussed in terms of current understanding of the nature of salt tolerance in nonhalophytes.