Effect of Physical Characteristics and Phenolic contents on Jassid and Pod Borer of Cowpea

Abstract

Host-plant resistance to insect pest damage is the most economically and environmentally sound method of pest management in cowpea. The present study was taken up with seventeen cowpea genotypes to investigate the influence of physical characteristics and phenolic contents conferring pest resistance. Different biophysical parameters, viz. vine length, number of pods/plant, pod length, individual pod weight, yield/plant, days to flowering, days to first harvest and the biochemical parameter like total phenol content of green leaves were studied in relation to the expression of reaction towards jassid (Empoasca kerri Pruthi) and spotted pod borer (Maruca vitrata Fab.). Pest infestation varied significantly amongst different cowpea genotypes. The mean jassid infestation was the minimum in Lafa Sohini 7 (0.54 jassid/leaf) as against the maximum in the variety Kashi Kanchan (3.00 jassid/leaf). Two varieties namely Pusa Fulguni Gold and UV-5 (0.00 larva/plant) were found completely free from spotted pod borer infestation as against the maximum infestation in the variety Ankur Gomoti (1.19 larva/plant) flowed by Bidhan Barboti 1 (1.18 larva/plant). The cowpea genotypes varied significantly in different biophysical characteristics and phenolic contents. Correlation studies of these parameters with jassid and pod borer infestation revealed that the number of pods per plant was found to be positively and significantly correlated (r = 0.495) with the jassid population as well as pod borer per plant (r = 0.486). The pod borer infestation was found to register significant negative correlation with the days to flowering (r = -0.556) and days to first harvest (r = -0.553). The jassid as well as the pod borer infestation was found to have negative association with the phenol content (mg/g of fresh leaf) but the association was not statistically significant.