Phosphorus use Efficiency of Safflower (Carthamus tinctorius L.) and Sunflower (Helianthus annuus L.)

Abstract

This study comparatively evaluates phosphorus (P) use efficiency of safflower and sunflower in view of identifying low input oil crops. Sunflower accumulated more P than safflower at all equivalent P supplies. Sunflower was more efficient at their best P supplies to utilize absorbed P than safflower in terms of efficiency ratio and utilization index. Yield response curves interpreting the functional relationship between nutrient supply and yield using Michaelis-Menten equation indicate that sunflower is less sensitive to inadequate P supply and thus more P-efficient than safflower with respect to yield, as the term ‘Km’ is lower for sunflower. The minimal P amount per pot required to trigger yield formation (term ‘Cmin’) was lower in sunflower than safflower. Harvest Index in sunflower out-yielded that of safflower at all P supplies. Critical deficiency contents of sunflower were lower than that for safflower. It can be concluded that safflower cannot be considered as low-input crop.

Keywords:

• phosphorous
• nutrient utilization efficiency
• yield response curve
• Carthamus tinctorius
• Helianthus annuus

ACKNOWLEDGMENT

The authors wish to express their gratitude and Miss Tanja Edler for help with the P determination at the Institute for Plant Nutrition at the University of Hanover, Germany.

FUNDING

The authors wish to express their gratitude to the German Academic Exchange Service (DAAD) for financial support.