EVALUATION OF PHYTOTOXICITY OF BLACK SOLDIER FLY LARVAE (Hermetiaillucens L.) MEDIATED COMPOST ON CHINESE CABBAGE (Brassica rapa) USINGTHE SEED GERMINATION BIOASSAY

Abstract

A lab experiment was conducted at Department of Entomology, Professor Jayashankar Telangana State Agricultural University, Rajendranagar, Hyderabad during September to December 2021. The phytotoxicity of six dif ferent entocomposts obtained from rearing black soldier fly larvae on different feed substrate was tested on Chinese cabbage by seed germination bioassay. For each compost type, the effect of four concentrations of water extracts of compost on seed germination and root
growth of Chinese cabbage were investigated. Composts were also analyzed for C/N ratio, pH and electrical conductivity. The C/N ratio, pH and EC ranged from 12 to 43.10, 6.87 to 8.81 and 5.70 to 11.30 dSm-1 respectively. Highest relative seed germination (88.44 %) was recorded in frass from Gainesville diet (12.5 %), highest relative root growth (91.23 %) was recorded in frass from fruit waste (12.5 %), and sheep droppings (12.5 %), and highest germination index (73.41) was recorded in the frass from sheep droppings (12.5 %) aqueous extract. Since all the examined BSFL composts extracts were not mature as reflected by germination index of less than 80 resulting in different levels of phytotoxicity, hence suitable neutralizing additives may be added before application in crop.