Fertilizer improves seed and oil yield of safflower under tropical conditions

Safflower (Carthamus tinctorius L.) has gained importance as an oilseed crop due to its hardiness and oil, which can be used in the production of biofuels. Studying proper crop management methods is highly important for the development of safflower in Brazil, since applying fertilizers correctly and using the appropriate time are efficient ways to achieve higher yield. Thus, the objective of this study was to evaluate safflower yield components, seed yield and oil content in two growing seasons. Two experiments under dryland conditions were conducted in 2014 in Cascavel, PR, Brazil. A randomised complete block design with three replications was used. Five rates of NPK fertilizer were used (0, 200, 400, 600 and 800 kg ha−1 of N-P2O5-K2O formula 4-14-8) in two growing seasons (autumn and winter). Even in a Rhodic Acrudox with high concentrations of P and K, the application of NPK fertilizer in the furrow improved seed yield and oil yield in the autumnal growing season. Safflower seed yield averaged 2068 and 3820 kg ha−1 in autumn and winter, respectively. The application of NPK fertilizer to safflower in the autumnal growing season significantly increased oil content (23.9%). The linear plateau model predicted increased yield with NPK rates <652 kg and <610 NPK ha−1, resulting in seed yield and oil yield of approximately 4374 kg ha−1 and 1048 kg ha−1, respectively. Safflower seems promising as an alternative oilseed crop for Southern Brazil when seeded in autumn with basic fertilization.