Differential Early Stage Water Relations, Gaseous Exchange and Photosynthetic Responses of Tomato (Solanum lycopersicum L.) to Water and Salt Stress

Abstract

Aims: Distinguish the effect of water stress and salt stress on early stage water relations, gaseous exchange and photosynthetic parameters on tomato seedling (Cv.GT-2). Study Design: The research was conducted with three replicates in a completely randomised experimental design with one tomato genotype. Place and Duration of Study: The experiments were conducted under nethouse condition in October-2015 at ASPEE College of Horticulture and Forestry, Navsari Agricultural University, Navsari-Gujarat, India. Methodology: Seeds were germinated in five levels of iso-osmotic concentrations of sodium chloride (NaCl) and polyethylene glycol. Seeds were sown in -0.2,-0.4,-0.6,-0.8 and -1.0MPa of osmotic concentrations of sodium chloride (NaCl) and polyethylene glycol (PEG-8000). The water stress effects, due to treatments of different iso-osmotic concentrations of NaCl and PEG, were compared with control (distilled water). The photosynthetic parameters viz. photosynthetic rate, quantum efficiency of PS-II, chlorophyll content and gaseous exchange parameters viz. transpiration rate, stomatal conductance were recorded at 14th and 21stdays after sowing (DAS). Results: Significant reduction was recorded in photosynthetic parameters, gaseous exchange parameters and water potential at -0.2Mpa of NaCl and PEG at 14 and 21 DAS. At -1.0MPa, the lowest values/readings for physiological parameters were observed in both PEG-8000 and NaCl solutions. Conclusion: On the basis of the results obtained, it was revealed that isosmotic concentration of NaCl had more inhibitory effect on the physiological parameters. Thus at early stage of growth, ion toxicity seems to be more inhibitory than water limitation.