Plant density and optimum fertilization are two important agronomic practices to enhance productivity of cotton (Gossypium hirsutum L.) varieties. The objective of this study was to investigate the effect of high density planting (HDPS) and fertilization rate, especially their interactions, on yield, yield components of cotton varieties in sub-tropical India. Split-split plot design was adopted and replicated thrice. The main plots were assigned to low, medium and high plant densities (16.7, 13.3 and 11.1 plants/m 2 ). Pre released cotton varieties TCH-1705 and LH-2298 were tested in low, moderate and high rates of fertilizers recommended for the region (100, 125 and 150 %) in sub-sub plots. Significantly higher seed cotton yield (1148 kg/ha) was achieved in narrow inter row spaced at 60 cm over normal plant row spacing of 90 cm (1025 kg/ha). Compact genotype TCH-1705 was out yielded (1146 kg/ha) over LH 2298(1044 kg/ha). Application of fertilizers at higher rate improved seed cotton yield (1232 kg/ha) Leaf area index (3.8) and light interception (0.98) over blanket recommendation. The results of the study inferred that seed cotton yield improvement was possible under HDPS production system with compact varieties grown at narrow spacing and higher fertilizer dose.

To evaluate the efficacy of new insecticides against brinjal shoot and fruit borer (BSFB), L. orbonalis, field experiment was carried out in a randomized block design with seven treatments (six insecticides and one control) and three replications during kharif 2017 at Main Agricultural Research Station (MARS), Raichur. Among the treatments the lowest mean per cent shoot damage was recorded in the treatment with emamectin benzoate 5 SG (5.41) followed by chlorantraniliprole 18.5 SC (5.83) and flubendiamide 39.5 SC (5.93) and were superior than the untreated control (14.66) after first and second spray. After third spray the lowest mean per cent fruit damage was recorded in the treatment with chlorantraniliprole 18.5 SC (14.32) followed by flubendiamide 39.5 SC (15.78) and emamectin benzoate 5 SG (16.30) and were superior than the other treatments. The highest yield was observed in the treatment with emamectin benzoate 5 SG (25.9 t.ha -1 ) followed by flubendiamide 39.5 SC (23.7 t.ha -1 ) and chlorantraniliprole 18.5 SC (21.8 t.ha -1 ) compared to the untreated control (10.4 t.ha -1 ) and recorded maximum benefit cost ratio in the field treated with emamectin benzoate 5 SG (1: 3.17) followed by flubendiamide 39.5 SC (1: 2.96) and chlorantraniliprole 18.5 SC (1: 2.63).

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Abstract:Field experiment was conducted at the Main Agricultural Research Station, University of Agricultural Sciences, Raichur during 2012-13 to identify and evaluate the suitable refuge strategy systems for pink bollworm resistance management in Bt cotton (Gossypium hirsutum L.) cultivation. The experiment was laid out in randomized complete block design with nine refuge systems : 0 % N-Bt (BIR), 5 % N-Bt (BIR), 10 % N-Bt (BIR), 15 % N-Bt (BIR), 20% N-Bt perimeter refuge, 100% Non Bt, 50% Non Bt, 10% structured refuge and 20% structured refuge as treatments with three replications in replacement series. Significantly lowest incidence (3.55 larvae/plant) and number of bolls with exit holes (11.22) due to pink bollworm was recorded in 0% BIR (41.25 q/ha) followed by 5 % N -Bt (BIR) with yield of 38.74 q/ha and this was on par with 10 % N-Bt (BIR) with yield of 37.79 is next best refuge systems with Bt cotton for higher production and greater economic benefits.

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