Salt stress-induced changes in leaf antioxidant activity, proline and protein content in ‘Shah Anjir’ and ‘Anjir Sabz’ fig seedlings

A major portion of the Iranian fig (Ficus carica) industry is located in high-salinity regions, and salinity is an important limiting factor in the production of this fruit. The present study was conducted to investigate the changes of leaf antioxidant-enzyme activity, proline and total protein content in two fig cultivars with two leaf shapes: ‘Anjir Sabz’ with lobate and palmate leaves, and ‘Shah Anjir’ with lobate and palmate leaves, under salt stress condition. The seedlings were exposed to different NaCl concentrations so that six different electrical conductivity levels of 0.6, 3, 6, 9, 12 and 15 dSm-1 were achieved in pots. This experiment was performed as factorial based 6×2(2) in a completely randomized design with four replications and two seedlings in each replicate. The results showed that as the soil salinity increased, the proline and protein contents of both cultivars were increased. However, palmate leaves of both cultivars accumulated more proline and protein than those of their lobate leaves. The activities of antioxidant enzymes increased in seedlings of both cultivars; however, superoxide desmutase and catalase showed more activity in palmate leaves than lobate leaves. There were no significant differences between the two leaf shapes in relation to peroxidase. The results seem to suggest that seedlings with palmate leaves are more salt tolerant than seedlings with lobate leaves.