Comparison of different methods used in calculating the effect of stripe rust on wheat grain yields

Abstract

One of the most important diseases of wheat in Turkey is yellow rust. The severe epidemic in the 1997–1998 growing season, which caused significant yield reductions, and the absence of infection at the Hamidiye Substation of the Anatolian Agricultural Research Institute made it possible to calculate the yield losses due to stripe rust. This calculation was based on yield differences between genotypes at infected and disease-free locations using various methods.Using the method suggested by Campbell et al. (1975) the calculated yield loss due to stripe rust varied among genotypes and locations with an overall range of 12.7 to 87.0%.By the second method, entries were divided into five groups according to their Average Coefficients of Infection (ACI) and the yield losses in each group were calculated. Yield reductions when ACI was over 70 reached up to 57.5 % in Regional Yield Trials.In the third method, regression analysis was applied to estimate the effect of ACI on grain yields. A highly significant linear relationship was found between the ACI values of the entries and their grain yields, with an estimate of 21.4 kg/ha yield reduction per unit increase in ACI.