Response of sunflower genotypes to varying plant geometries and integrated nutrient management practices on growth and yield of sunflower

Field investigations were conducted at the experimental farm of Annamalai University during February-May and June-September 2024 to examine the combined effects of genotype, plant geometry and integrated nutrient management (INM) on sunflower growth, yield attributes and productivity in the North-Eastern zone of Tamil Nadu. The trial was laid out in a Factorial Randomised Block Design (FRBD) with 20 treatment combinations and three replications. Treatments comprised two factors: Factor-A (genotype and spacing): A1- COSFH 4 at 60 × 30 cm, A2- COSFH 4 at 60 × 45 cm, A3- KBSH 44 at 60 × 30 cm and A4- KBSH 44 at 60 × 45 cm; and Factor-B (INM levels): B1- Control, B2- 100 % RDF + 45 kg S ha-1, B3- 75 % RDN + 100 % PK + 25 % N through vermicompost + 45 kg S ha-1, B4- 75 % RDN + 100 % PK + 25 % N through poultry manure + 45 kg S ha-1 and B5- 75 % RDN + 100 % PK + 12.5 % N through vermicompost + 12.5 % N through poultry manure + 45 kg S ha-1. Results demonstrated that genotype selection, spacing and INM significantly affected morphological, physiological and yield parameters. COSFH 4 at 60 × 30 cm (A1) recorded superior performance. Among INM strategies, B5 proved most effective in enhancing yield. Interaction effects were notable, with A1B5 achieving the highest seed yield (2441.74 kg ha-1), while A4B1 was the lowest. The study underscores the pivotal role of genotype choice, optimum spacing and balanced INM in maximizing sunflower productivity in this region.