Physiological factors affecting intrinsic water use efficiency of potato clones within a dihaploid mapping population under well-watered and drought-stressed conditions

• 23 clones of a dihaploid potato mapping population were grown in a glasshouse.
• Intrinsic water use efficiency (WUEi) was investigated under two water conditions.
• Clonal difference in WUEi was found under both well-watered and drought stress.
• WUEi was positively correlated with photosynthetic rate and leaf nitrogen content.
• Chlorophyll content index could be an easy screening method for high WUEi in potato.

Optimizing crops water use is essential for ensuring food production under future climate scenarios. Therefore, new cultivars that are capable of maintaining production under limited water resource are needed. This study screened for clonal differences in intrinsic water use efficiency (WUEi) within a dihaploid potato (Solanum tuberosum L.) mapping population under well-watered (WW) and drought-stress (DS) conditions. The factorial dependency of WUEi on several plant bio-physiological traits was analyzed, and clonal difference of WUEi was compared. Significant differences in WUEi were found among the clones within the population. Under WW the two clones showing the highest WUEi were significantly different from the two lowest WUEi performing clones. This could only be seen as a trend under DS. Under WW, WUEi differences were closely associated to net photosynthetic rate (An) and nitrogen isotope composition (δ15N) in the leaf biomass, but did not relate to stomatal conductance (gs) and carbon isotope composition (δ13C) in the leaf biomass. An was found to correlate significantly with leaf nitrogen concentration ([N]leaf) and chlorophyll content index (CCI) under WW. Leaf abscisic acid concentration did not correspond to the changes in gs, indicating that other factors might have been involved in controlling gs among the different clones. Collectively, the clonal differences in WUEi were attributed mainly to the variation in An, which in turn was influenced by plant N metabolism. Clones with high WUEi could be potentially used as material in future breeding programs. Furthermore CCI seemed to be a reliable tool in estimating the clonal An and thereby WUEi.