The research reported in this paper was conducted in the humid, temperate area of Patzcuaro in the state of Michoacan, in Mexico, where there is a high natural incidence of Septoria/Stagonospora spp. Nine wheat genotypes that had previously been selected for resistance to Septoria/Stagonospora spp. were included in the study. They were compared to two check varieties, one tolerant and one susceptible. The materials were tested with and without chemical protection. Three years’ data were analyzed and relative yield losses of 10-32% were found. Two different responses were observed among the outstanding genotypes. On the one hand, several lines expressed little reduction in yield when challenged by the septoria pathogens. Depending on their yield potential, final yield could be moderate to quite good. These could be classified as resistant or tolerant to Septoria/Stagonospora spp. Some of these same materials did show a considerable level of severity; their response would thus be better classified as tolerance rather than resistance. On the other hand, certain materials with high yield potential did lose yield following the attack by the septoria foliar blights, but retained sufficient expression of yield potential to compete well with the local check variety. These should not be classified as resistant nor tolerant, but may well be desirable from a production standpoint. The line that best combined these traits is IAS20/ H567.71/5*IAS 20. It is being considered for release under the name Patzcuaro. Severity of foliar disease on the flag leaf proved to be well correlated with yield loss.

English

9910|AGRIS 0001|R99-00CIMPU

Jose Juan Caballero

CIMMYT Publications Collection