Effects of combining phosphorus (P) and zinc (Zn) fertilization on P-Zn distribution and yield in safflower

The interaction of P and Zn is a crucial factor affecting plant growth and yield. The aim of this study was to investigate the combined effects of P and Zn on P-Zn distribution in safflower tissues and seed yield. A two-year study was conducted in farmer fields in northeastern Turkey during 2014 and 2015 years. P applications consisted of four levels (0, 3, 6 and 9 kg P2O5 da−1) that were allotted to the main plots. Sub-plots were composed of three Zn levels (0, 0.5 and 1 kg Zn da−1). The results showed that P and Zn applications had a significant effect on the P and Zn concentration of straw, head, seed, and yield. P concentration in straw, head, and seed increased significantly with increasing P and Zn levels. Zn concentration decreased with high P levels compared to the control, while it increased with increasing Zn levels regardless of P application. At low P levels, yield did not respond to Zn treatments; however, at high P doses, Zn application resulted in a dramatic increase in yield compared to the control. In order to increase seed yield, instead of P and Zn sole application, their combined application was very effective, and doses of 9 kg P2O5 da−1 and 0.5 kg Zn da−1 showed the optimum performance. In conclusion, this study revealed that in P- and Zn-deficient soil, P treatments increased seed yield remarkably, but the combined application of P and Zn resulted in even higher yield increases.