Effect of irrigation regimes and phosphorus rates on water and phosphorus use efficiencies in potato

• Potatoes were subjected to three irrigation regimes and two P fertilization rates.
• Plant growth, WUE and PUE were investigated.
• P enhanced plant growth; P uptake and WUE; whilst reduced root area to leaf area ratio and stomatal conductance.
• Compared to FI, PRD and DI reduced plant growth and P uptake.
• PRD enhanced root to shoot ratio and P partitioning into root, insignificantly increased PUE.

Water and phosphorus (P) are limited resources which constrain crop productivity worldwide. Therefore, there is urgent need to develop novel irrigation and fertilization practices to sustain crop yield, and simultaneously to improve water and P use efficiencies. In the present study, potato (Solanum tuberosum L.) plants were exposed to three irrigation regimes (full irrigation, FI; deficit irrigation, DI, and partial root-zone drying, PRD) and in combination with two P-fertilization rates (0 mg kg−1 soil, P0 and 60 mg kg−1 soil, P1); the effects of these treatments on plant growth, water use efficiency (WUE), and P uptake and utilization efficiency (PUE) were investigated. The results showed that P fertilization positively influenced the leaf, tuber and plant total dry mass (DM), leaf area (LA), total plant P uptake, and WUE; whilst negatively affected the root area (RA) to LA ratio, stomatal conductance, root P partitioning and PUE. Although PRD and DI performed similarly in affecting most of the variables and which were significantly lower than those observed for FI, there was a clear tendency that PRD irrigation could enhance the allocation of DM and P into the root, increase root to shoot ratio and insignificantly increase PUE. Therefore, the use of PRD irrigation may potentially improve both WUE and PUE for potato production in areas with limited freshwater resources.