Effects of Ca(NO₃)₂ stress on contents of different forms of polyamines in leaves of grafted tomato plants

Using ‘Kagemusya’ (Lycopersicon esculentum Mill.), a salt tolerant cultivar, as rootstock and ‘Baoda 903’ as scion, grafting was made to compare the differences in plant growth and leaf contents of different forms (free, conjugated and bound) of polyamines between grafted and own-root tomato plants under 80 mmol/L Ca(NO3)2 stress for 10 days. The results showed that the biomass production in grafted plants was significantly higher than that of own-root plants. The contents of three forms of putrescine (Put), spermidine (Spd) and spermine (Spm) in leaves of grafted plants increased significantly during the course of stress. The contents of three forms of Put in leaves of own-root plants decreased significantly, the contents of free and conjugated forms of Spd and Spm increased significantly, but the contents of bound forms of Spd decreased significantly. However, no significant difference was observed in bound forms of Spm after treatment. These results indicated that three forms of Put and bound forms of Spd and Spm played important roles in the leaves of grafted tomato plants for salt tolerance.