Yield gap analysis for sustainable potato production.

Potato is a major cash crops in the Netherlands. Therefore, there is a commercial interest in optimizing yield. One approach to aid in optimizing yield is through using crop models to understand the causes of current yield gaps. Crop models are capable of simulating potential yield (Yp), water limited (Yw) and water-and-nutrient limited yield (Yn). In this PhD, three crop models will be used. These are WOFOST, LINTUL-POTATO-DSS and Tipstar. These models differ in their photosynthesis, biomass allocation, and inclusion of tuber quality aspects. The model WOFOST will be used to simulate yield and yield quality (dry matter content, tuber size and tubers affected by secondary growth). To this aim WOFOST will be improved and applied. The other two models will be used to improve WOFOST. Model improvement will focus on yield and on quality, photosynthesis, biomass partitioning, dry matter content of the tubers and tuber size. Effects relevant to the Netherlands will be considered. The improvements consist of updating parameters, incorporating relevant aspects of LINTUL-POTATO-DSS and Tipstar, and, if needed, model expansion to better capture relevant processes. We also propose to do three model applications. First is exploring the spatial differences in Yp, Yn and Yw among commercial potato regions within the Netherlands. Second, the effects of nematodes on yield will be explored by combining WOFOST to a nematode model. Third, the improved model will be used for 2050 KNMI climate scenarios with a focus on heat effects on yield and yield quality across the Netherlands.