Abstract:
Four sunflower hybrids viz., NK012, Cargill-204, SF-IOO and Hysun-30 were tested for disease resistance against 26 isolates of Macmßlomina phaseolina collected from sunflower growing areas in Pakistan. Stem inoculations were made using a tooth-pick and spread of charcoal rot was measured from the point of inoculation. Disease reaction was scored on a O to 5 scale; where no rot and 52 plant death. Resistance was characterized using analysis of variance. A highly significant main effect for both varieties and isolates was detected. "Ihis indicated a highly significant difference in horizontal resistance betwéen varieties and in aggressiveness between the isolates. However, the interaction varieties x isolates was nosignificant, indicatng no evidence of vertical resistance.
