ABSTRACT

This research was carried out to determine the seed yield and yield components of two-orobance (Orobanche cumana L.) resistant dwarf hybrids compared with one standard height sunflower hybrid (Helianthus annuus L.) at different nitrogen rates and planting densities under natural rain fed conditions. The research was conducted at the Thrace Agricultural Research Institute in Edirne-Turkey, between 1999 and 2001. The experiments were established in split-split plots in randomized Complete Block Design with three replications. Main plot treatments were three different sunflower hybrids, TR-DW-1, TR-DW-2, and Trakya-80. The sub plots were three levels of nitrogen, 0, 60, and 120 kg N/ha. The sub-sub plots were three planting densities, 10X70(142.850 plant/ha), 15X70(95.230 plant/ha), and 20x70cm(71.430 plant/ha). Observations were made for seed yield, oil content, oil yield, 1000 seed weight, test weight, plant height, head diameter, time to flowering, and time to physiological maturity.

The seed yield of three hybrids was significantly affected by the rates of nitrogen fertilizer in natural rain fed conditions. Based on marginal economical analyses, optimum economical seed yield from per ha was obtained at 50 kg N/ha for TR-DW-1, 80 kg N/ha for TR-DW-2 and Trakya-80 hybrids. The highest seed yield was obtained on 15x70 cm (95.230 plant/ha) plant population for both dwarf hybrids.

Key words: Sunflower, dwarf, density, fertilizer, and nitrogen.