Effects of exogenous putrescine and calcium on growth and ions assimilation of strawberry seedlings under NaCl stress.

摘要

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 Ca2+ to Na+ ratios in leaf and root cells. Removing Ca2+ from the culture solution showed least biomass, maximal membrane damage and chloride (Cl-) concentration, minimum K+/Na+ and Ca2+/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 Ca2+ to Na+, while the membrane permeability was lower. Putrescine application treatment also alleviated the harmful effects of NaCl to seedlings. In the absence of Ca2+, an increased K+ to Na+ ratio and Ca2+ to Na+ ratio was also observed with exogenous 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 Ca2+. These results suggested that Ca2+ 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.