Effect of post-inoculation temperature and light intensity on expression of resistance to stripe rust in some Australian wheat cultivars

Abstract

Temperature sensitive resistance to stripe rust in selected Australian wheat cultivars was found to be most strongly expressed at a constant post-inoculation temperature of l9¦C and at high light intensities. At 25¦C the infection type on the susceptible host was reduced, indicating incompatability, while at the lower temperature of 13¦C all cultivars were susceptible to the rust. At low light intensities there was a movement towards low infection types in cultivars possessing this resistance even at low temperatures. This made it essential to use high light intensities to differentiate this resistance to stripe rust. The host-pathogen interaction leading to the low infection types became irreversible after 6 to 7 days' exposure to the higher temperatures. As well as affecting disease progress towards the end of the growing season in the warmer areas of the wheat belt, this resistance could have a marked effect on the ability of Puccinia striiformis fsp. tritici to oversummer in the Australian wheat growing areas.