VIEW ARTICLE

Resistance

Effect of Puccinia coronata on Straw Yield and Harvest Index of Oats. M. D. Simons, Plant pathologist, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, Department of Plant Pathology, Iowa State University, Ames 50011; Phytopathology 70:604-607. Accepted for publication 20 November 1979. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1980. DOI: 10.1094/Phyto-70-604.

The effect of Puccinia coronata infection on straw yield and harvest index (ratio of grain yield to grain-plus-straw yield) was determined for 110 strains of oats (Avena sativa). Rust was artifically initiated, and controls were maintained rust-free with a fungicide. Because of inherent differences among the strains, the data were expressed as ratios obtained by dividing the value for a rusted plot by the corresponding value for the rust-free plot. The 110 strains differed significantly in yield of both grain and straw and in harvest index in the rust-free plots. Ratio values for straw yield (which showed statistically significant effects of P. coronata) ranged from 0.539 to 1.039 in 1976 and from 0.477 to 1.225 in 1977. The ratios of rusted to rust-free harvest-index values ranged in 1976 from 0.667 to 1.260 and in 1977 from 0.497 to 1.359, showing that harvest indexes of the 110 strains were affected differentially by crown rust. There was no correlation between inherent grain yield and the effect of crown rust on either grain or straw yields. Heritability values calculated from components of variance derived from appropriate analyses of variance were 50 and 64% for straw-yield ratio in 1976 and 1977, respectively, and 83 and 61% for harvest-index ratio in 1976 and 1977, respectively.