Determination of Morphological and Biochemical Basis of Resistance Against Top Borer, Scirpophaga excerptalis Walker in Sugarcane

Utilization of plant defence mechanism against insect pests is considered to be a viable and environmentally safe strategy. In the present study, attempt was made to decipher the morphological and biochemical factors contributing towards resistance/susceptibility of sugarcane genotypes against top borer, Scirpophaga excerptalis Walker, a major insect pest in subtropical region of India. The experiment was conducted at the experimental farm of ICAR-Indian Institute of Sugarcane Research, Lucknow, India. Nine sugarcane varieties, viz. CoS 94257, CoSe 92423, CoPant 97222, CoS 96268, CoS 767, Co 0238, CoLk 94184, CoJ 64 and CoLk 8102 were selected from a diverse group in terms of growth period, degree of pest infestation and other morphological characters. Observations taken on various morphological characters of different sugarcane varieties showed a significant difference on pest incidence. Out of these morphological parameters studied, the thickness of leaf midrib (r = − 0.56) and plant height (r = − 0.44) recorded significant and negative linear correlation with incidence of top borer. However, leaf breadth showed significant and positive correlation (r = 0.52) with incidence of top borer. Amongst the biochemical parameters, such as reducing sugar, total phenol, poly phenol oxidase-specific activity, proteinase inhibitory activity, total soluble protein, nitrogen, phosphorus, potassium contents, correlation study revealed that the reducing sugar was significantly positively correlated (r = 0.77) while proteinase inhibitor activity (r = − 0.82) showed significantly negative correlation. It is noteworthy that the total phenol and polyphenol oxidase activity were significantly positively correlated to proteinase inhibitory activity. The study holds promise for future varietal development programme.