Implications of calcium nutrition on the response of Caesalpinia crista (Fabaceae) to soil salinity

Greenhouse experiments were conducted to assess the effects of supplemental calcium in salinised soil on the response of germination and seedling growth of Caesalpinia crista, L. (Fabaceae). NaCl and CaSO4·2H2O were added to the soil and 0:0, !:0, 1:0.25, 1:0.50, 1:0.75, 1:1, 1:1.25, and 1:1.50 Na/Ca ratios were maintained. Salinity significantly retarded the seed germination and seedling growth, but the injurious effects of NaCl on seed germination were ameliorated and seedling growth was restored with calcium supply at the critical level (1:0.50 Na/Ca ratio) to salinised soil. Calcium supply above the critical level further retarded the seed germination and seedling growth due to the increased soil salinity. Salt stress reduced N, P, K and Ca content in plant tissues, but these nutrients were restored by addition of calcium at the critical level to saline soil. The opposite was true for Na+. The results are discussed in terms of the beneficial effects of calcium supply on the seedling growth of C. crista grown under saline conditions.