Potassium Use Efficiency of Safflower and Sunflower Grown in Different Soils

Using alternative crops that use supplied nutrients efficiently is a possible approach in land use sustainability. Plant species vary in their potassium (K) use efficiency in soils of low K availability by using different strategies. Growing K efficient species to improve yield may be desirable if K efficiency mechanisms are illustrated. Therefore K use efficiency of the alternative oil crops safflower and sunflower was investigated under semi-controlled conditions in sandy and loamy soils using four K supplies. Both species reacted strongly to increasing K supplies in both soils and performed better in loamy soil, although they contained less K concentration in loamy soil. Under suboptimal K supply in both soils, safflower was superior over sunflower by having higher agronomic efficiency (greater relative yield), higher internal K concentration, better relative K accumulation in dry matter. Both species had similar K efficiency ratio (KER) in sandy soil, but sunflower was more efficient in loamy soil. Sunflower was superior over safflower in terms of utilization index (UI) in both soils. Sunflower had less external K requirement and recovered more K than safflower in both soil types. The K use efficiency of crops is based on different competitive components. Thus using different measures of utilization efficiency parameters to differentiate plant species and genotypes to superior and inferior could be in some cases misleading. Neither safflower nor sunflower showed a combination of high values of all K uptake and utilization efficiency components in both soils at studied K levels.Financial support for this study was provided by the German Academic Exchange Service (DAAD), through a Re-invitation Programme for Former Scholarship Holders (A/12/08202 and 50068612), the Palestinian funding program for research and training “ZAMALAH”, and the Dutch EP-NUFFIC through NICHE-PAA 233 project. Technical support by Mrs. Suzanne Koch in department of plant nutrition and yield physiology, George-August University, Goettingen, Germany is gratefully acknowledged for her generous assistance in samples analyses