Effect of yellow rust on yield components of winter wheat in China

Experiments were done in 1983,1984 and 1985 in Beijing and Zhengzhou, People's Republic of China, to determine the relationship of yield components of wheat to the severity of yellow rust ( Puccinia striiformis f.sp. tritici ). Epidemics were manipulated by timing inoculation and fungicide applications. Disease, plant yield, number of ears per plant, number of grains per ear and 1000-grain weight were measured. Analysis indicated that there were interactions among the yield components. However, path coefficient analysis did not detect any statistically significant compensation and showed that there was a positive correlation among yield components. The correlation coefficients between AUDPC (area under disease progress curve, accumulated to each growth stage) and each yield component increased gradually with growth stage, thus providing no evidence of a critical stage at which a yield component was most affected by disease.