Inheritance of Resistance to Net Blotch in Barley in Morocco. A. Douiyssi, Plant Breeder, INRA, Settat, Morocco. D. C. Rasmusson, Professor, Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul 55108; and Roy D. Wilcoxson, Professor Emeritus, Department of Plant Pathology, University of Minnesota, St. Paul 55108. Plant Dis. 80:1269-1272. Accepted for publication 22 July 1996. Copy right 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-1269.

Barley cultivars currently grown in Morocco do not have satisfactory resistance to net blotch, caused by Pyrenophora teres. This study determined the inheritance of resistance in spring barley to net blotch in 11 F2:5 populations in the field in Morocco. Three populations were evaluated in both the field and glasshouse to compare inheritance of resistance of seedlings to single isolates in the glasshouse with natural inoculum occurring in the field. In the field, resistance in cvs. Heartland and Minn 7 was inherited in a monogenic manner in crosses involving moderately susceptible, susceptible, and highly susceptible cultivars. The degree of susceptibility of the susceptible parent appeared to have little effect on the resistance level in the progeny. AC-SAD 176 and Anoidium had single resistance genes and Manchurian had two independent genes that conditioned resistance. Crosses among resistant cvs. Heartland, Minn 7, and ACSAD 176 segregated 7: 8: I (homozygous resistant : segregating : homozygous susceptible) indicating different independent genes that condition resistance. Heartland appeared to possess a recessive gene that conditioned resistance to isolate I-12 in a cross involving Rabat 071 and a dominant gene to isolate I-1 in crosses involving Arig 8 and ACSAD 176. Since resistance to P. tens in five cultivars was simply inherited, incorporation of these genes into barley adapted to Morocco should be feasible.