RESISTANCE TO FUSARIUM WILT DISEASE IN SOME EXPERIMENTAL GENOTYPES AND COMMERCIAL CULTIVARS OF COTTON

This study aimed to evaluate some cotton germplasm as a part of the Screening Program of Fusarium Wilt Resistance. This program has been conducted annually in the greenhouses of Cotton and Fiber Crops Diseases Research Section, Plant Pathology Research Institute. The present study included 200 families of ten experimental genotypes and 933 families of seven commercial cultivars. Healthy survival rate of families was used as a criterion to evaluate the reactions of the tested germplasm to Fusarium wilt. The experimental genotypes showed a very narrow range of reactions to Fusarium wilt with healthy survival rate of families this narrow range, ranging from 94.73 to 99.48%. Thus, all the tested genotypes were classified as very highly resistant (VHR).However, within significant differences were observed among some of the tested  genotypes. Most of the families of the tested commercial cultivars were also classified as VHR.The percentages of families in this reaction class ranged from 57.82 (families of Giza 87) to 100% ( families of Giza 88).The commercial cultivars were classified into three distinct groups based on the dissimilarity distances(DDs)generated from cluster analysis of the profiles of their reaction classes. Within each group, the cultivars were almost identical in the patterns of their reaction classes.