Response of Some Sunflower Hybrids (Helianthus annuus l.) to Different Nitrogen Fertilizer Rates and Plant Densities

In order to improve sunflower productivity, this investigation aimed to study the performance of some genotypes to different doses of nitrogen and plant population density on seed yield and yield components. Two field Experiments carried out on the Experimental Farm of the Sakha Agriculture Research Station during 2015 and 2016 seasons. The objective of this study aimed to investigate the performance of some sunflower hybrids to different nitrogen fertilizer rates and plant population densities to growth, yield components, seed yield and its quality.The results indicated that tallest plants, highest leaves number/plant, number of achenes/head and highest values of head diameter were obtained from MS.sirena F1 genotype. Biest Brima genotype recorded the highest values of leaf area. The highest weight of 1000 seed and seed yield/ha were recorded from Nsovak genotype.The increases in nitrogen fertilizer rates to 168 Kg N/ha produced tallest plants,thick stems (cm), the highest leaves number/plant, leaf area (cm2), number of achenes/head, head diameter (cm), 1000 achene weight (gm) and achene yield (Kg/ha) in both seasons. It could observed that increasing nitrogen fertilizer from 72 to 168 Kg N/ha significantly increased seed yield by 12.0 and 11.6 % in the first and second seasons, respectively. Increasing hill spacing from 15, 20 and 25 cm produced thickness stem, highest number of leaves/plant, highest values of leaf area, maximum number of achenes/head, head diameter and weight of 1000 achene. The tallest plants and highest and achene yield were produced from 20cm hill spacing. It could concluded that increasing nitrogen fertilizer from 72 to 168 Kg N/ha and sown Nsovak genotype at dense hill spacing of 15 cm between plants maximized seed yield per unite area.