Nitrogen Use Efficiency of Safflower as Compared to Sunflower

ABSTRACT

This study compares the nitrogen (N) use efficiency of safflower and sunflower in pot experiments, as the putatively high nitrogen use efficiency of the former is not sustained. Safflower out-yielded sunflower at low N supply, while at ample supply the opposite was observed. Both species accumulated similar amounts of N per pot at equivalent N supplies, but safflower was a better N accumulator due to lower dry matter production. Safflower utilizes absorbed N more efficiently than sunflower to produce seed yield at suboptimal N supply in terms of efficiency ratio and utilization index, but the opposite holds true at optimal and high supply. Functional analysis of utilization efficiency for dry matter and seed production substantiated the higher efficiency of safflower. It is concluded that in terms of N utilization safflower represents a low input crop and outperforms sunflower with respect to seed yield on soils low in available N.

Keywords:

• Carthamus tinctorius L.
• Helianthus annuus L.
• nitrogen
• NUE
• safflower
• sunflower
• uptake efficiency
• utilization efficiency

ACKNOWLEDGMENTS

The authors wish to express their gratitude to the German Academic Exchange Service (DAAD) for financial support through a PhD scholarship (A/03/33909). Technical support for N determination by B. Biegler is gratefully acknowledged. This paper is dedicated to the late Professor Dr. Burkhard Sattelmacher.