Field experiments were conducted at Sakha Agric. Res. Station in the two successive seasons 2006 and 2007, to study the effect of different furrow- spacing and furrow wetting depths on yield and some water relations of sunflower. Three furrow spacing (i) Wide-spaced furrow (90cm apart) WSF, ii) alternate wide-spaced furrow with every-furrow (60cm apart) WSF/EF and iii) every-furrow EF, in the main plots, in the used split plot design. The sub main plots were irrigation to a wetting depths 30, 45 and 60cm.
The result showed that there were highly significant differences in the seed yield, seed weight/head, head numbers/m2 and head diameter with various furrow spacing and wetting depths, in both seasons. Sunflower seed yield under WSF and WSF/EF were higher than EF by 35.09 and 14.92 % in the first season and 32.39 and 13.69 % in the second season. Also, the mean values of seed yield were 1037.3, 908.2 and 697.4 Kg/fed. in the first season and 1151.1, 1007.08 and 781.4 Kg/fed. in the second season, for 30, 45 and 60 cm wetting depths, respectively. The highest seeds yield was produced from interaction between wide spaced furrow and irrigation at a wetting depth of 30cm.
Wide spaced furrows and application of water to a wetting depth of 30cm received the lowest amount of irrigation water. The highest values of field and crop water use efficiencies were achieved from interaction between wide spaced furrows and irrigation at a wetting depth of 30cm, while the lowest values were recorded from combination between every furrows and irrigation to a wetting depth of 60cm in both seasons. The highest value of water application efficiency was found with wide spaced furrows. At the same time the water application efficiency was decreased with increasing the wetting depth.Wide-spaced furrows and wide-spaced furrows alternate with every-furrows saved irrigation water by 4.40 and 1.19% in the first season and 8.33 and 5.99% in the second season, respectively compared to every-furrows. Irrigation to a wetting depth of 30 cm saved irrigation water by 15.24 and 14.66 % compared to a wetting depth of 60 cm in the first and second seasons, respectively. Also, 45cm wetting depth saved 13.55 and 7.50 % compared to 60 cm wetting depth in the first and second seasons, respectively.