Effects of temperature and light on non‐race‐specific resistance of potato leaflets to late blight

Abstract

Effects of temperature and illumination on colonization by Phytophthora infestans of detached leaflets of five potato cultivars differing in field resistance to blight were investigated using an ELISA system to qtiantify the pathogen. Leaflets of cvs Teena and Shelagh, and in one experiment cv. Brodick, were more resistant to colonization when infected leaflets were incubated at lO'C than at 2O'C, but temperature conditions before inoculation had little effect. Both photoperiod and light intensity during illumination of intact plants before inoculation interacted with genotype to determine subsequent colonization of infected leaflets incubated in darkness. Leaflets from plants of cv. Teena were more resistant to colonization after exposure to low, rather than to high, light intensities but photoperiod had no apparent effect. Leaflets of cv, Shelagh grown in a 20 h day were more resistant than those grown in a 10 h day but light intensity had no effect. Leaflets of cv. Brodick were more resistant after a 20 h day than a 10 b day and after exposure to low, rather than to high, light intensities. Leaflets of cv. Bintje were extensively colonized and those of cv. TorHdon remained relatively resistant to colonization, irrespective of temperature and lighting conditions. There was a high level of unexplained variation in all the experiments.

Aggressiveness of Phytophthora infestans on detached potato leaflets in four Nordic countries

“…Therefore, it is important to test all isolates in the same environmental conditions, and pay strict attention to inoculum and test‐plant production and preparation. Yet, even under a tightly controlled environment, experimental variation often remains high (Harrison et al ., 1994). In addition to controlling the test conditions, the experimental variation can also be controlled by selecting an appropriate experimental design with adequate blocking.…”