Evaluation of Resistance to Stem Borers (Sesamia spp.) in some Sugarcane Cultivars at Tillering Stage

Stem borers (Sesamia cretica and S. nonagrioides) cause dead heart at tillering stage on sugarcane. In year 2001, 148 sugarcane cultivars were compared based on dead heart criterion. Screening for resistance was carried out under natural infestation in the field condition at two prominent Agro-Industries located in Khuzestan. Percentage of dead heart was deretmined on each cultivar at both stations. In order to unify the findings of two stations, a Dead Heart Index (DHI) was developed. Since the distribution of the data was in a normal pattern, an Interval of Standard Deviation from the Mean (ISDM) was developed to classify the cultivars. Following the classification, Canonical Discriminant Analysis (CDA) was used to assess the contribution of variables for separation, and also investigation of the effectiveness of the classification procedure. The results of CDA confirmed the accuracy of the classification procedure used, showing that 95.9% of the original data was correctly classified in the predicted group membership. Cultivars of sugarcane showed a wide spectrum of resistance to stem borers, therefore potential long-term breeding program should address this resistance problem. According to the results of this investigation, cultivars with less than 4.71% dead heart were resistant such as CP57-614 and more than 12.24 were susceptible such as NCO310.