Effect of leaf rust infection on yield of certain varieties of wheat
1931
Johnston, C.O.
Experiments conducted for three years in the greenhouse and for two years in the field at Manhattan, Kansas, proved that heavy infections of leaf rust greatly reduced the yield of wheat. In the greenhouse, the yield of Malakof CI 4898, a susceptible variety, was reduced 55.71%, while a reduction of 22.30%, was noted for Fulhard CI 8257, a resistant variety. In the susceptible variety, the loss in yield was due principally to a reduction in the number of kernels produced, although there also was a slight reduction in the number of heads per plant and in the size of the individual kernels. The loss in yield in a resistant variety, such as Fulhard, probably is due to the killing of many of the green leaf cells. This is visibly expressed in the form of flecking. In these experiments the loss in yield in the resistant variety was about one-third of that in the susceptible variety. No shriveling of the grain resulted from heavy leaf rust infection in the greenhouse. The seed from inoculated plants frequently contained many small kernels. These, however, were plump and well formed. Experiments conducted in the field with Prelude spring wheat and Turkey winter wheat substantiated the results of the greenhouse experiments. Partial control of rust in field plats by sulfur dusting at two-day intervals during the late spring resulted in an increase of 1.7 bushels per acre for Prelude and 2.3 bushels per acre for Turkey. Field experiments also indicated that at least part of the reduction in yield due to leaf rust was caused by the smaller size of individual kernels of the infected plants.
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