Physiological Responses of Tomato to Inoculation with Piriformospora indica under Osmotic Stress and Chloride Toxicity

International Journal of Agriculture and Forestry 5(4): 226-239

2015

Khalid Al-Absi, Nofal Al-Ameiri

A greenhouse to study the response of 'Hildares' tomato (Solanum lycopersicum Mill.) to Piriformospora indica inoculation under osmotic and specific chloride toxicity conditions was conducted in a controlled glasshouse, during the summer season of 2013. The osmotic stress was introduced by irrigation with multicomponent saline water of different electrolyte concentrations (0, 50 and 100 molc/m3) and two ionic compositions, i.e., Cl:SO4 ratio (1:1 or 3:1) at a fixed SAR of 5. The plants were harvested at three times. Irrigation with high osmotic potential solutions (100 molc/m3) significantly reduced fresh and dry weights of both shoots and roots, height of the plants, photosynthesis (Pn) and transpiration (T) rates and leaf water potential (Ψw). Increasing Cl:SO4 ratio of the irrigation water from 1:1 to 3:1 significantly increased the former reductions in the plant parameters. Considerable insignificant variations in growth, leaf water potential and gas exchange of P. indica non-inoculated and inoculated plants were observed. The results have shown insignificant increases in growth of P. indica inoculated plants grown under severe salinity stress, corresponded a significant increase in CO2 assimilation rate in the final harvest and leaf water potential and transpiration rate in the first harvest. The P. indica inoculated plants irrigated with 50 and 100 molc/m3 of Cl:SO4 ratio of 3:1 had significantly higher proline contents than those non-stressed and non-inoculated plants. In conclusion, the study suggests that tomato response to inoculation with P. indica is affected by the single effect of electrolyte concentration an ionic composition of the irrigation water rather than the interaction between the osmotic stress and specific chloride toxicity. For successful irrigation with saline water, attention, as a consequence, should be directed to use saline water that is characterized by high electrolyte concentrations and predominance of chloride ion.