Some Effects of Yellow Rust (Puccinia striiformis) on the Growth and Yield of a Spring Wheat

Abstract

Yellow Rust had a considerable effect on the yield of the spring wheat Jufy I, that of severely infected plants being reduced by as much as 64.5 per cent. This was due to a reduction in the number of florets per ear, the number of grains per ear, and in some cases the weight of individual grains. There was also a marked effect on the general growth and vigour of the plant, the growth of leaves being retarded and the final length and breadth greatly reduced. The roots were more seriously affected than any other part of the plant with reductions in dry weight of as much as 78 per cent in fully infected plants. The relatively direct effect of a late rust infection greatly reduced the yield, while the effects of an early infection, although indirect, still caused large reductions. The varied effects of rust on the several factors contributing to the yield, and the relative importance of the effects on these factors are discussed.