Spectral characterization acreage and production estimation through remote sensing and management of pod borer Helicoverpea annigera through polycroping in pigeonpea

Abstract

Investigations were carried out on spectral characterization, acreage and production newlineestimation through remote sensing and management of pod borer (Helicoverpa armigera) newlinethrough polycropping in pigeonpea during 2005-06 to 2007-08 in Gulbarga district, newlineKarnataka. The spectral reflectance values of crop measured through ground truth radiometer newlineat different ground truth sites located in the study area (Chitapur taluk) were the lowest in blue newlineand highest in near infrared (NIR) regions with moderate and low in green and red regions newlinerespectively while, satellite derived reflectance was moderate in green, low in red, peak in newlineNIR and a further decline in SWIR regions. The satellite derived NDVI ranged from 0.21 to newline0.23, 0.43 to 0.53 and 0.25 to 0.29 at vegetative, flowering and at maturity stages newlinerespectively. The acreage estimates deviated merely by 7.84 and 4.58 per cent from DES newlineestimates during 2006-07 and 2007-08, respectively. However, the production estimates newlinederived through satellite mean NDVI and LAI model at flowering stage during the newlinecorresponding periods deviated to an extent of 47.60 and 15.55 per cent respectively. newlineFurther, the study on polycropping at Agricultural Research Station, Gulbarga newlinerevealed reduced Helicoverpa damage and higher pigeonpea equivalent yield (1472 kg ha-1) newlinewith pigeonpea + sunflower (6:1 row proportions) system as compared to sole pigeonpea newline(1310 kg ha-1) or other intercropping systems except pigeonpea + mesta (1448 kg ha-1). newlinePopulation dynamics of insects was found to be greatly influenced under sunflower newlineintercropping due to creation of favourable microclimate (temperature and relative humidity) newlinein the system for predator and parasitoid insect s proliferation. Besides, standing sunflower newlinestalks retained in the field after harvest of heads acted as animate perch for alighting newlinepredatory bird black drongo. Consequent to these benefits the system registered higher newlinemonetary advantages (Rs. 29,445, 20,643 and 3.43 of gross return, net return and B:C ratio newlinerespectively). newline