Biophysical and Biochemical Evaluation of Pigeonpea, Cajanus cajan (L.) Millsp.in Relation to Pod-borer, Helicoverpa armigera (Hubner) Infestation

Abstract

An experiment was conducted to study the biophysical and biochemical attributes of Pigeonpea, Cajanus cajan (L.) Millsp. genotypes in relation to their susceptibility to the pod borer, Helicoverpa armigera. Among10 different genotypes evaluated, ICP 7803-1 recorded significantly highest pod damage (47.50%) followed by ICP 1535-1 (42.50%) and ICP 9577-1 (41.3 %). No pod damage was recorded in ICP 16674-1 and ICP 60-1 whereas lowest pod damage was recorded in ICP 939-1, ICP 11281-1, IPA-203 and Asha, being 0.50%, 0.50%, 15.50% and, 17.50%, respectively. In context to the biophysical parameters, the trichome density and length (leaves and pods) and pod wall thickness exhibited significantly negative correlation (r = -0.969**, -0.985**, -0.984**, -0.935**and -0.948**) with percent pod damage whereas, pod length and width showed strong positive correlation (r = 0.925 and 0.940).Among the biochemical characteristics, the protein and sugar levels in seeds demonstrated a notable positive correlation, while the total phenolics, tannins, and total flavonoids indicated a significant negative correlation with the percentage of pod damage caused by the pod borer, H. armigera. Consequently, the genotypes exhibiting the thickest pod walls, longer densely packed trichomes, and elevated levels of phenols, tannins, and flavonoids demonstrated greater resistance to the pod borer, H. armigera.