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Inheritance of Tolerance to Septoria Leaf Blotch of Wheat. O. Ziv, Former graduate research assistant, Division of Mycology and Plant Pathology, Department of Botany, Tel Aviv University, Tel Aviv, Israel, Present address of senior author: Division of Field Crops, Agricultural Research Organization, Volcani Center, Bet Dagan, Israel; J. M. Sacks(2), and Z. Eyal(3). (2)geneticist, Division of Statistics and Experimental Design, Agricultural Research Organization, Volcani Center, Bet Dagan, Israel; (3)Associate professor, Division of Mycology and Plant Pathology, Department of Botany, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel. Phytopathology 71:119-123. Accepted for publication 17 May 1980. Copyright 1981 The American Phytopathological Society. DOI: 10.1094/Phyto-71-119.

The effect of Septoria leaf blotch on yield components and plant height was investigated in parents, segregating populations, and selected lines of crosses between tolerant and nontolerant (Miriam Bet Dagan 233) and tolerant and moderately resistant (Miriam Yafit) cultivars. The unselected F3 and F4 bulks were susceptible and suffered moderate losses in yield components. Selection in segregating F3 and F4 populations produced susceptible semidwarf lines that were as tolerant and high yielding as Miriam under severe Septoria epidemics. Selection for low kernel weight produced dwarf lines with low kernel weight and kernel number that phenotypically resembled the vulnerable dwarf cultivar Bet Dagan 233. Tolerance derived from Miriam seemed to be incompatible with dwarf plant stature. The rapid achievement of tolerance by selection implied a trait controlled by a small number of additive loci. In contrast, the resistance of Yafit appeared to be controlled by the joint action of several loci. Plants of cultivar Miriam and the selected lines from crosses with Miriam maintained high 1,000-kernel weight and yield under dry conditions. Tolerance may represent a compensatory response mechanism to physiological stresses that affect the grain-filling process. Breeding for tolerance appears to be possible if the selection goals are high kernel weight and semidwarf or taller plant stature. Selection for high kernel number per head should be done among promising tolerant lines.

Additional keywords: Septoria tritici, Triticum aestivum.