Early stage water and ion stress responses of salinity in tomato

Salinity is one of the most serious factor limiting the productivity of agricultural crops, with adverse effects on germination, plant vigour and crop yield. However, the way in which salinity exerts its influence on these vital processes, whether it is through an osmotic effect or specific ion toxicity, is still not resolved.Our experimental results indicated that germination parameters viz., germination percentage, germination rate, root and shoot length, root and shoot dry weight and relative water content were significantly reduced due to effect of ion stress induced by NaCl and water stress induced by PEG-8000. The -1.0MPa water potential was found to be a completely inhibitory for seed germination. Ionic stress was found more inhibitory than water stress. The photosynthetic parameters viz. photosynthesis rate, transpiration rate, stomatal conductance, and quantum efficiency of PS-II also found to decreased significantly with increase stress induced by PEG-8000 and NaCl. Based on the results of the experiment, it seems that for tomato cv.GT-2 the ionic effect of salinity is more detrimental then osmotic