Relation of temperature to the expression of resistance in wheats to hessian fly

Cartwright, W.B.; Caldwell, R.M.; Compton, L.E.

Relation of temperature to the expression of resistance in wheats to hessian fly

1946

Cartwright, W.B. | Caldwell, R.M. | Compton, L.E.

The percentage of plants infested and the intensity of infestation by the hessian fly, Phytophaga destructor Say, were studied in seedlings of four resistant and two susceptible varieties of wheat grown in the greenhouse at the two temperature ranges of 60 degrees to 65 degrees and 75 degrees to 80 degrees F. At the higher temperatures the percentages and the intensities of infestation were significantly greater on the resistant spring wheat W38 and its resistant winter-type progeny B36162A13-12. The effects of temperature were similar with the susceptible varieties B42, a spring type, and Wabash, a winter type, but in each case the relative magnitude of the effect was much smaller than for the resistant varieties. From the experiments conducted it was not possible to determine whether the effects of temperature on infestation were due to the response of the host plant alone or to a combined response of both the host plant and the insect. The near immunity of the durum P.I. 94587 was found not to be reduced at the higher temperature. The resistance of a common wheat (42-chromosome) derivative of this durum, however, was greatly affected by temperature. The immutability of the resistance of the durum P.I. 94587 at different temperatures is believed to indicate a fundamentally different resistance in that strain, as contrasted with the resistance of the common-wheat varieties studied.

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