Water-use efficiency in rice (Oryza sativa L.) in relation to resistance to salinity

Abstract The effects of sodium chloride on water-use efficiency of a number of varieties of rice have been investigated. Sensitivity to salinity in rice arises in large part from excessive rates of sodium ion transport to the shoot consequent upon high rates of transpirational water loss. Varietal differences in water-use efficiency were found: these were greater when measured for whole shoots over a period of one week, than when made as instantaneous measurements on individual leaves. Salinity had rather little effect on water use efficiency but overall resistance of seedlings to salt was, in general, greater the greater the water-use efficiency. The reasons for the differences between varieties are discussed in terms of differences in growth pattern: among the seven varieties investigated, water-use efficiency and salt-resistance were lower in dwarfed as opposed to non-dwarfed varieties.