~ 335 ~ International Journal of Research in Agronomy 2024; 7(3): 335-343 E-ISSN: 2618-0618 P-ISSN: 2618-060X © Agronomy www.agronomyjournals.com 2024; 7(3): 335-343 Received: 12-01-2024 Accepted: 25-02-2024 Sneha MA Ph.D., Scholar, Department of Agronomy, UAS, GKVK, Bangalore, Karnataka, India BK Desai Director of Research and Professor, Department of Agronomy, UAS, Raichur, Karnataka, India MR Umesh Scientist, AICRP on Sunflower, UAS, Raichur, Karnataka, India Corresponding Author: Sneha MA Ph.D., Scholar, Department of Agronomy, UAS, GKVK, Bangalore, Karnataka, India Response of newly developed sunflower hybrids to planting geometry and fertilizer levels Sneha MA, BK Desai and MR Umesh DOI: https://doi.org/10.33545/2618060X.2024.v7.i3e.420 Abstract A field experiment was conducted to study the response of newly developed sunflower hybrids to planting geometry and fertilizer levels. The objective of the study was to find out optimum row spacing and fertilizer rate for new sunflower hybrids of UAS Raichur. Experiment was laid out in split-split plot design with three replications. The treatments consisted of sunflower hybrids RSFH-12-700, RSFH-12-705 and RSFH 1887 as main plots, row Spacings at 60 cm and 75 cm as sub plots and fertilizer rate at 100, 125 and 150% RDF as sub-sub plots. The results revealed that sunflower hybrid RSFH-12-700 has recorded 7.98 and 15.58 percent higher seed yield (2144 kg ha -1 ) compared to RSFH-12-705 and RSFH 1887, respectively. The growth, yield attributes viz., dry matter partitioning, total dry matter production, head diameter, seed volume, grain yield, stalk yield and harvest index (HI). Narrow row spacing at 60 cm had significant effect on growth attributes viz. dry matter partitioning, total dry matter production. Whereas, application of 150% RDF has produced significantly higher seed yield (2104 kg ha -1 ), growth and yield parameters but on par with 125% RDF and superior over 100 percent RDF. It was concluded that the new sunflower hybrid RSFH-12-700 showed greater growth and yield at optimum plant spacing of 60 cm and 150% recommended dose of fertilizers. Keywords: Fertilizer levels, sunflower, hybrids, seed yield, dry matter partitioning Introduction Oilseeds play an important role in agricultural economy of India. With the ever increasing demographic pressure the gap between domestic needs and production of agricultural produce in general and edible oil in particular is widening at an alarming rate. Coupled with the dwindling resources and their increasing cost, there is an urgent necessity to improve the productivity by improving production and resource use efficiency of oilseed crops for realizing higher yield potential. Sunflower (Helianthus annuus L.) is an important oilseed crop and is native to southern parts of USA and Mexico. Sunflower ranks fourth next to soybean, groundnut and rape seed in total production of oilseeds of the world. Seeds of sunflower contain high concentration of oil together with an appropriate proportion of unsaturated fatty acids with non-cholesterol and anti- cholesterol properties. It is cultivated for domestic and industrial purpose for its excellent quality and high oil content. The seeds contain 42-49% of oil and the cake contains 25-35% of protein. India is the largest producer of oilseeds in the world. In India, sunflower is grown over an area of about 0.27 m ha with a production of 0.25 m t and a productivity of 923 kg ha -1 . In India, Karnataka is the leading sunflower producing state in the country and contributes nearly 63 percent of total area and 54 percent of the total production in the country. The productivity of sunflower in India is low (923 kg ha -1 ) as compared to other sunflower growing nations and one of the major reason for low productivity is due to its cultivation mainly under rainfed conditions with sub optimal crop stand, imbalanced nutrition and lack of soil moisture conservation techniques, thus leading to poor seed set and high percent of chaffy seed, low oil content and yield. To achieve highest yield potential of a sunflower hybrid, providing ideal or optimum geometry is through best planting density. Planting geometry determines the distribution pattern of plants in a field.