Characterization of salt tolerance in tomato plant in terms of photosynthesis and water relations

Three commercial tomato cultivars (UC-97, Momotaro, and Edkawi) were subjec ted to a gradual increase of NaCl concentrations and the effect on biomass production and its parameters was compared, The data indicated that salinit y reduced plant growth and the reduction was more pronounced in UC-97 and l ess in Edkawi. The apparent photosynthetic rate (P-0) was also depressed by the salt treatment and the depression was more remarkable in UC-97 and les s in Edkawi, Edkawi shoot showed a much higher concentration of sodium ion and proline compared with the other cultivars, which may result in the main tenance of a higher turgor potential. In all the cultivars examined the ste m diameter decreased after the beginning of exposure to light and recovered after the light was turned off. The decrease in the stem diameter during d ay light was enhanced and the recovery at night decreased after Id of salt treatment and the changes in the stem diameter were less conspicuous in Edk awi than in the other cultivars, These results suggest that Edkawi is more tolerant to salinity than the other cultivars due to a higher ability of ma intaining the root function for the uptake and supply of water to shoot und er salinity conditions but not due to the adjustment of transpiration from stomata.