An examination of selection criteria for salt tolerance in wheat, barley and triticale genotypes

Abstract

This study of 20 genotypes of barley, wheat, durum wheat and triticale had three aims: (1) To determine whether simple measurements on plants grown in salinity tanks in a glasshouse would reflect the documented reputations for salinity tolerance of the genotypes; (2) to test whether rapid development, commonly associated with barleys, is linked with salinity tolerance; (3) to assess several types of measurements as screening tools for salinity tolerance. Measurements of whole-plant leaf area expansion rates were well correlated with biomass production and ranked the genotypes largely in accord with their documented reputations. There was no evidence, either from experimental manipulation of rate of development, or from regression analysis amongst genotypes, that rapid development was linked with salinity tolerance. The origins of tolerance were twofold, deriving from (1) a physiological tolerance - this was defined as a small relative reduction in growth due to salinity, and (2) an absolute tolerance - this was shown as an intrinsic high growth rate of the genotype, i.e. apparent both in and out of salinity. A good indicator of high absolute tolerance, and of potential for screening purposes, was large area of seedling leaves. Regression analysis indicated that absolute tolerance contributed more to productivity in saline conditions than physiological tolerance. Indeed, in one study the latter failed to correlate significantly with productivity. Cl- concentration also was a poor general indicator of productivity in salinity, as was extension rate of single leaves during 10 days after NaCl was applied. It is proposed that screening for intrinsic high growth rate and physiological tolerance should go hand in hand, with more emphasis on the former. This is the reverse of the usual situation.