Changes in some plant-water relation parameters of some oil producing plants over a range of salinity stresses

Abstract

When cultivated in culture solutions salinized with different concentrations (0 to 100 meq I-1), of either NaCl or Na2SO4, the oil producing castor bean, flax and sunflower plants exhibited significant changes in their water relationship parameters (stomatal frequency, rate of transpiration and water content). Although the trend of these changes was nearly the same, their magnitudes depended on the plant treated as well as on the type and level of the salinizing agent. In this respect the values of the stomatal frequency and the rates of transpiration increased significantly with the rise of salinization up to the level 40 meq I-1. Above this the values of these parameters were generally reduced with the rise of salinization up to the highest level used. In addition a considerable number of stomata in either the lower or upper epidermis was found to be closed at the levels ranging from 60–100 meq l-1. The water content of leaves of either castor bean or sunflower subjected to low or moderate salinization levels, remained more or less constant, but with a general tendency to decrease at high levels. However, in the case of flax the leaf water content was generally elevated at nearly all salinization levels.