Symptomatology incidence and resistance to phyllody disease in determinate sesame (Sesamum indicum L.) genotypes at lowland and highland conditions

As a result of difficulties in cultivation, decreasing sesame production is also effected by Phyllody disease which cause the yield losses seriously on sesame plant (Sesamum indicum L.). Up to the present, resistance is not reported againist phyllody disease on cultured sesame all around the world. The breeding of phyllody-resistant genotype is of great importance not only for our country but also for all the countries around the world which cultivate sesame. In this study, 20 determinate and 5 indeterminate genotypes were sown in lowland and highland locations of West Mediterranean Region of Turkey. After germination, the distance between and within the rows of traditional cultivation were decreased to half distance in order to increase plant number per unit area. Genotypes were observed in terms of disease symptoms, incidence, resistance level and also yield traits. The trials were set up in Antalya location for two years, lowland and Burdur for one year, representing the highland. Three replications were set up by according to Randomized Complete Blocks Design. Symptoms of phyllody disease were determined on determinate genotypes and were compared with indeterminate genotypes disease type symptoms. Incidence of the disease on determinate genotypes was compared with cultivatited and uncultivated locations. Also yield of determinate and indeterminate genotypes which show phyllody disease types were studied per plant. The presence of other genotype/mechanism in the same gene pool except for previously determinate genotype/mechanism non infected by phyllody was researched and yield characteristics were compared. Result of this study showed that, as a result of decreasing the distance between and within the rows of traditional cultivation in both locations, indeterminate genotypes which have less branches have less green part than determinate genotypes and contrary to expectation showed less phyllody. Despite this situation, the indeterminate genotypes were late in flowering and showed higher yield than determinate genotypes as expected. The types of phllody disease symptoms were observed and described for determinate sesame genotypes and compared with indeterminate phyllody disease symptoms in Antalya location which sesame is cultivated widely. Some plants showed more than one phyllody disease type symptoms. Phyllody disease observation proved that there are vector insects and host plants in highland which sesame is not cultivated. It is observed that yield loss on infected plants did not change according to phyllody disease type, it changed by infection severity and infection time. Phyllody disease observation on genotypes which thought to be resistant because of previous experiments showed that they had "escape" mechanism in connection with their earliness/vector insects behaviours.