Comparison of phosphorus efficiency among spring oilseed rape cultivars in response to phosphorus deficiency

Crops that acquire phosphorus more efficiently could reduce some of the environmental problems of fertilizers. We conducted two experiments to evaluate seven spring oilseed rape cultivars for their relative efficiency to use or acquire P under conditions of deficiency (4.6 mg Olsen P kg(-1)) and P application (80 mg P kg(-1)). Based on biomass, P content, P acquisition and use efficiency, cultivars were categorized as efficient responsive, non-efficient responsive, efficient non-responsive and non-efficient non-responsive. We also measured and compared root diameter, root surface area and total root length in two selected cultivars, and found that the Dalgan cultivar, which was efficient in P acquisition, was also an efficient accumulator of biomass under the P deficiency, and that P acquisition was related to higher Ca uptake. The responsible mechanism for P efficiency was suggested to be higher P uptake, which prompts the formation of larger root systems and improves plant access to soil P.