Phosphorus use efficiency, tuber yield and quality of potato processing varieties grown under different P levels in the Argentinian Pampas

To assess the effect of different P rates on Phosphorous Use Efficiency (PUE), tuber yield, quality, and economic return, a field trial under central pivot irrigation, with cultivars Daisy and Innovator, was carried in the southeast region (Balcarce, 37 degrees 45' SL; 58 degrees 18' WL, 130 masl) in a typical Argiudoll soil. In Daisy, increasing P rates increased dry matter accumulation in haulms and tubers, mainly in the period up to 90 days after planting (DAP). The higher P rates increased P level both in haulm and tubers up to 90 DAP, but decrease PUE at the higher P rate. In Innovator the response to P rates was much higher and this variety resulted more efficient in P use than Daisy. In Innovator, increasing P rates lead to a higher tuber yield and a higher net economic return. In these two varieties, a different fertilization approach must be followed to improve P use efficiency and crop return. Lower levels of P can be used in Daisy which will not impact on final tuber yield, while in Innovator higher levels of P are required to achieve higher yields and increase crop net return.