Abstract

Studies were carried out on detection and estimation of infestation caused by sucking pests of brinjal using hyperspectral radiometry in potted plants grown in green house during 2013 - 14 at Department of Remote Sensing and GIS, Tamil Nadu Agricultural University (TNAU), Coimbatore. The results revealed that the spectral reflectance curve of brinjal plants infested by redspider mites, mealybugs and aphids were different from that of the healthy plants. The Red Edge Position (REP) of mites infested plants with medium (25 - 50%), high (>50 %) level of damage (10 - 25 %) and plants with high infestation of mealybug, shifted from 720.26 to 707.64 nm, 701.33 nm and 718.68 nm, respectively. Whereas, REP of aphid infested plants were same as that of healthy plants (720.26 nm). There was a significant negative correlation between damages caused by sucking pests and vegetation indices (VIs) namely, normalized difference vegetation index (NDVI), simple ratio (SR), green red vegetation index (GRVI) and soil adjusted vegetation index (SAVI) values. Linear regression equations were developed for estimating pest damages based on NDVI, SR and GRVI values. SR, NDVI and SAVI were more sensitive to sucking pest infestation in brinjal. The respective per cent sensitivity of SR, NDVI, GRVI and SAVI were - 60.1, -35.4, -5.3 and -38.6, for mite infestation; – 48.6, -39.2, -8.8 and -24.1, for mealybug infestation and - 43.3, -31.7, -8.9 and -12.3, for aphid infestation indicating the usefulness of SR and NDVI, which were the highest in magnitude irrespective of the sign. Thus, it was found that detection, estimation and discrimination of infestation caused by sucking pests of brinjal could be done using hyperspectral radiometry.

Keywords: Hyperspectral radiometry, Brinjal, Mites, Mealy bug, Vegetation index, Red edge position