SAWFLY RESISTANCE IN WHEAT: IV. SOME EFFECTS OF LIGHT INTENSITY ON RESISTANCE

Abstract
The degree of resistance to the wheat stem sawfly (Cephus cinctus Nort.) of seven varieties of wheat grown under shaded conditions was shown to be lower than that of plants grown under unshaded conditions. The breakdown of resistance of Rescue wheat grown in the greenhouse in the winter was prevented by a high-intensity light supplement of 4000 foot-candles but not by a supplement of 1500 foot-candles. The low resistance of Rescue wheat grown in the greenhouse results from low light intensities in the greenhouse in both summer and winter. It was concluded that high light intensities are required for the maximum expression of stem-solidness and sawfly resistance in Rescue wheat.