BIOPHYSICAL AND BIOCHEMICAL EVALUATION OF COWPEA GERMPLASM AGAINST MAJOR INSECT PESTS
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Date
2016
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Indira Gandhi Krishi Vishwavidyalaya, Raipur
Abstract
Investigation on “Biophysical and biochemical evaluation of cowpea germplasm against major insect pests” was conducted at Horticulture experimental field, department of Entomology and laboratory works were conducted in department of Crop Physiology, Agricultural Biochemistry and Herbal Science of Indira Gandhi Krishi Vishwavidyalaya, Raipur (C.G.) in Kharif, 2015.
The study revealed that the major insect pest viz., spotted pod borer, flower thrips, pod sucking bug and green stink bug were attacking in cowpea germplasm. The incidence of pod sucking bug, green stink bug and flower thrips started from third week after transplanting, further increased and recorded the peak activity of 9.0 bugs per plant and 12.3 bugs per plant during second week of November, whereas the peak activity of 4.3 thrips per plant was observed during first week of October. The cowpea spotted pod borer infestation was first appeared during fifth week of September, increased gradually with peak pod infestation of 19.7 per cent during third week of October.
The population of lady bird beetle and spider coincided with the appearance of host insects throughout the crop season with peak population of 1.5 beetles per plant during fourth week of November and 1.6 spiders per plant during fifth week of October.
The results of screening the cowpea germplasm against tested insect pest showed that among the thirteen germplasm, 2015/COPBVAR-2, 2015/COPBVAR-6, 2014/COPBVAR-1, 2014/COPBVAR-2, 2014/COPBVAR-4, 2014/COPBVAR-5, 2014/COPBVAR-6, KASHI KANCHAN, Lola and Arka Garima were least preferred by insect pest while 2015/ COPBVAR-5 found moderately resistance for the insect pest.
The population of flower thrips and pod sucking bug was positively and non significant correlated with maximum and minimum temperature while negatively correlated with maximum and minimum relative humidity, rainfall and sunshine hours. The cowpea spotted pod borer infestation showed positive and non significant correlation with maximum and minimum temperature, rainfall and sunshine hours, maximum and minimum relative humidity.
The per cent pod borer infestation showed positive correlations with plant height at 70 DAT. The positive correlation was found between per cent pod borer infestation and pod length (r = 0.849) and pod weight (r = 0.628), whereas, negative correlation was found with number of pods per plant (r = – 0.715) and pod width (r = – 0.153). A strong negative correlation between the cowpea spotted pod borer infestation and total phenol content (r = – 0.794), while strong positive correlation with total sugar content (r = 0.851) was noticed on cowpea germplasm
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105 p.