Phosphorous Use Efficiency of Safflower and Sunflower Grown in Different Soils

Abstract

The use of nutrient efficient alternative crops is a possible strategy of sustainable land use. Plant species vary in their phosphorous (P) use efficiency under suboptimal P supplies in different soils by using different strategies. Cultivating P efficient species to improve yields may be possible if P efficiency mechanisms are elucidated. Therefore P use efficiency of the alternative oil crops safflower and sunflower was studied under semicontrolled conditions in sandy and loamy soils using three P supplies. Both species responded strongly to increasing P supplies in both soils and performed better in loamy soil. In both soils, both species contained similar P concentrations in shoots at low P supplies, but safflower accumulated less P amounts in shoots than sunflower at all P levels. Sunflower had less external P requirements than safflower in both soils. Safflower had higher efficiency ratio than sunflower at low P supply in sandy soil, and less values in loamy soils. Safflower had lower utilization index than sunflower in both soils at all P levels. Safflower recovered less external P (added P, extractable-P, soil solution-P) than sunflower in both soils. The P use efficiency of crops is based on different competitive components. Neither safflower nor sunflower showed a combination of high values of all P use efficiency components in both soils at all P levels, but safflower was inferior to sunflower in most studied traits. Therefore safflower cannot be considered a low input species as compared to sunflower in terms of P uptake and utilization efficiency.

Mechanisms of Phosphorous Uptake Efficiency of Safflower and Sunflower Grown in Different Soils

“…The recovery of fertilizer P is very low [9], often below 15% in the first year of application and hardly reaches 50% after 30 years [10]. Although, in view of limited P resources [5] and serious environmental and economic consequences [11], a considerate use of P is mandatory to correct nutrient deficiencies [12,13]. P application has been shown to be particularly effective with respect to yield formation in safflower and sunflower [14,15,16], but in organic farming, where application of inorganic P fertilizers is not permitted [17,18], the P availability is not easily increased [19].…”

“…Although, in view of limited P resources [5] and serious environmental and economic consequences [11], a considerate use of P is mandatory to correct nutrient deficiencies [12,13]. P application has been shown to be particularly effective with respect to yield formation in safflower and sunflower [14,15,16], but in organic farming, where application of inorganic P fertilizers is not permitted [17,18], the P availability is not easily increased [19]. Plant species and even cultivars differ in their ability to grow or yield well at suboptimal P supply with remarkable ability to acquire sparingly available soil P, and to utilize internal P efficiently, that could be explored for future use in crops selection [5,12,13,15,16].…”

“…P application has been shown to be particularly effective with respect to yield formation in safflower and sunflower [14,15,16], but in organic farming, where application of inorganic P fertilizers is not permitted [17,18], the P availability is not easily increased [19]. Plant species and even cultivars differ in their ability to grow or yield well at suboptimal P supply with remarkable ability to acquire sparingly available soil P, and to utilize internal P efficiently, that could be explored for future use in crops selection [5,12,13,15,16]. In developing countries, where the proportion of less fertile soils is particularly high, it may be difficult to fulfil the nutritional requirements of high-yielding crops [20].…”

“…It is thus desirable to aim for efficient use of P, both in view of resource limitations and environmental constrains for increasing the production potential on marginal land [21][22][23][24][25][26][27]. The use of alternative oil crops that differ in their response to P nutrition is a possibility to meet the increasing global demand for vegetable oil, and may be possible if phosphorus efficiency mechanisms are illustrated [12,13]. NUE involves various soil and plant mechanisms that contribute to the variability in uptake and utilization of nutrients by different plants in different soils [13,28,29].…”

“…NUE involves various soil and plant mechanisms that contribute to the variability in uptake and utilization of nutrients by different plants in different soils [13,28,29]. Definitions of nutrient efficiency vary greatly [14,21], and in some cases may be even misleading in the quest for identification of mechanisms for enhanced nutrient acquisition and utilization [12,13,30,31,32].…”