Effects of Phosphorus Application Rates on Yield and Fatty Acid Composition of Safflower (Carthamus tinctorius L.) Cultivars under Southeastern Anatolia Conditions

This study investigated the effects of different phosphorus application rates on the yield and fatty acid composition of safflower (Carthamus tinctorius L.) cultivars. Dinçer and Remzibey, were used as plant material. Phosphorus fertilizer was applied at five levels (0, 80, 120, 160, and 200 kg ha⁻¹). The experiment was conducted at Dicle University during the 2020–2021 growing season, following a randomized complete block split-plot design with three replications. The study evaluated plant height, number of branches and heads, head diameter, number of grains per head, 1000-seed weight, grain yield, leaf chlorophyll content, protein content, oil content, and fatty acid composition. Significant differences were observed among the cultivars and phosphorus treatments. Phosphorus applications significantly influenced plant height (109.29–127.21 cm), number of branches (8.80–12.56 per plant), number of heads (12.20–17.49 per plant), head diameter (4.04–4.92 cm), number of grains per head (24.43–36.60), 1000-seed weight (37.13–42.20 g), seed yield (2466.0–3872.4 kg ha⁻¹), protein content (12.27–15.42%), chlorophyll content (258.53–394.42 SPAD units), and oil content (28.01–33.13%). Phosphorus levels and cultivar differences also significantly affected fatty acid composition, including oleic acid (13.08–25.85%), arachidic acid (0.41–0.50%), eicosenoic acid (0.13–0.18%), stearic acid (2.82–3.16%), palmitic acid (6.88–7.64%), myristic acid (0.11–0.14%), linoleic acid (62.47–74.84%), and linolenic acid (0.78–0.98%). Overall, phosphorus application had a significant impact on both yield and quality characteristics of safflower, emphasizing its importance in safflower production.