Bio-efficacy and phytotoxicity assessment of SVK DRIP bio-stimulant on okra (Abelmoschus esculentus L. Moench)

Abstract

Aims: To evaluate the bio-efficacy, phytotoxic potential and yield impact of SVK DRIP bio-stimulant on okra hybrid Arka Nikita cultivated in southern transitional agro-climatic zones. Methodology: A randomized complete block design (RCBD) field experiment with seven treatments replicated thrice was conducted from December 2023 to May 2024 at Zonal Agricultural and Horticultural Research Station (ZAHRS), KSNUAHS, Shivamogga, Karnataka (13°58′N, 75°34′E, 650 m altitude). Treatments included SVK DRIP at 0.50, 1.00, 1.50 and 2.00 L acre-1 applied as soil drench at 25 and 45 days after sowing (DAS), compared against untreated control and recommended fertilizer dose (RDF). Morphological parameters (plant height, leaf area, LAI) were recorded at 35, 55 and 75 DAS. Chlorophyll content was measured via DMSO extraction at corresponding intervals. Yield components were quantified over 26 harvests. Phytotoxicity was assessed on a 0-100 scale at 1, 3, 5-and 10-days post-application. Soil properties were analysed pre-and post-harvest. Data were subjected to ANOVA at P = 0.05. Results: SVK DRIP at 2.00 L acre-1 (T5) significantly enhanced plant height (82.0 cm), leaf area (4232 cm2 plant-1), LAI (1.176) and total chlorophyll (2.385 mg g-1 leaf fresh weight) at 75 DAS, representing 16.0%, 15.4%, 15.4% and 17.5% increases over control, respectively. Yield per hectare reached 12.78 t ha-1 at T5 versus 10.84 t ha-1 in control (17.9% gain). Fruit number increased by 16.3% (50 fruits plant-1 vs. 43 in control). No phytotoxic symptoms (0 rating on 0-100 scale) were observed across all treatments and observation intervals. Post-harvest soil analysis revealed efficient nutrient uptake (N: 15.7%, P: 20%, K: 5.0% reduction) without toxicity or micronutrient accumulation. Conclusion: SVK DRIP bio-stimulant at optimized dose (2.00 L acre-1) offers a safe, effective alternative for enhancing okra productivity through improved morphophysiological attributes and nutrient utilization, without phytotoxic or edaphic risks, aligning with sustainable agriculture paradigms in tropical and subtropical horticulture.