EFFECTS OF EXOGENOUS PUTRESCINE AND CALCIUM ON GROWTH AND IONS ASSIMILATION OF STRAWBERRY SEEDLINGS UNDER NACL STRESS

Abstract

Effects of exogenous putrescine and calcium on growth, membrane permeability and ion assimilation of strawberry seedlings under 150 mmol L -1 NaCl stress were studied. The growth was inhibited, and shoot fresh weight, dry weight and root fresh weight, dry weight were all decreased under NaCl stress. The salt damage index was 40%. The increased membrane was also observed in leaf cell of strawberry seedlings under salt stress, in the meanwhile the assimilation of natrium and chlorine increased, which resulted in low K + to Na + ratios and low Ca 2+ to Na + ratios in leaf and root cells. Removing Ca 2+ from the culture solution showed least biomass, maximal membrane damage and chloride (Cl - ) concentration, minimum K + /Na + and Ca 2+ /Na + . Calcium application treatment alleviated the harmful effects of NaCl to seedlings, as manifested by the higher levels of fresh weights and dry weights, the ratio of K + to Na + and that of Ca 2+ to Na + , while the membrane permeability was lower. Putrescine application treatment also alleviated the harmful effects of NaCl to seedlings. In the absence of Ca 2+ , an increased K + to Na + ratio and Ca 2+ to Na + ratio was also observed with exgenous putrescine treatment, but no differences were observed in fresh weight, dry weight and membrane between treated with putrescine and those treated of distilled water in the absence of Ca 2+ These results suggested that Ca 2+ could influence the ability of salt tolerance of strawberry seedlings, the role of putrescine in improving growth and suppressing the assimilation and transport of sodium was promoted by calcium, whereas, it was weakened overall or partly by calcium-deficiency.