ANALYSIS OF ADAPTATION OF BARLEY, TRITICALE, DURUM AND BREAD WHEAT UNDER MEDITERRANEAN CONDITIONS

Yield data obtained from a comparative small grain cereals trial, grown for five consecutive growing seasons at a total of 23 environments in Cyprus, were subjected to regression analysis. Within each environment, yield trials consisted of a standard set of three cultivars or elite lines of barley, triticale, durum and bread wheat. The regression coefficient (b) of crop mean on the environmental index (1) and the mean square deviation from regression (sd2) were calculated for each crop. Each crop tended to have its own characteristic value of sd2 and its magnitude was an excellent indicator of specific crop-environment interaction. The causes of large sd2, for two of the four crops, were the susceptibility of barley to lodging, when favourable conditions were encountered at high yielding environments, and triticale dependence on late season precipitation. Durum wheat and triticale had an average response to different yielding environments (b = 1.19) and both were significantly different from those of bread wheat (1.08) and barley (0.54). Hence, barley, bread and durum wheat are specifically adapted to low, average and high yielding Mediterranean environments, respectively. The cultivation of triticale at the expence of durum wheat is not feasible. Furthermore, interactions between crops and environments demonstrated by the regression parameters, should constitute the basis for decision making, regarding crop adaptation in a region. The average yield in all environments should not be considered as a proper criterion for adaptation. In this study, triticale had a similar mean grain yield (3,842 kg/ha) to that of bread wheat, but was significantly higher yielding than barley or durum wheat (5 and 7%, respectively).