Author(s): SUDHAVANI V., VIJI C. P., LAVANYA A. AND SYAMSUNDAR REDDY P.

Abstract: Isothiocyanate is a crucifer specific volatile which plays an important role in plant defence as attractants and deterrents. Field Experiment was conducted at Horticultural College and Research Institute, Venkataramannagudem, West Godavari (Dist.) during the period from October, 2010 to January, 2011 to study the effect of sowing dates (1st October, 15th October, 1st November and 15th November) and spacings (45 x 10 cm, 45 x 20 cm and 45 x 30 cm) on the level of isothiocyanate content, its influence on the pest population and root yield of radish cv. Pusa Chetki. The study revealed that population of Lipaphis erysimi appeared in 3rd or 4th week after sowing (WAS) and increased with crop maturity. Highest aphid population was recorded in 8 WAS (16.2 aphids leaf-1) in closely planted late sown crop. Isothiocyanate concentration increased with delay in sowing and decreased with increase in spacing. Highest isothiocyanate concentration was recorded in closely spaced late sown crop (20.00 mg–100g). Highest yield was recorded in D S (closely spaced crop and 1st October sowing) (13.88 t ha-1) which had high isothiocyanate content (12.50 mg 1 1 g-100) and harboured more aphids. Even though aphid population is more in closer spacing, root yield of radish was high since more number of plants was recorded per unit area.

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