The Ecophysiological Determinants of Tuber Yield in Response to Potato Genotype and Nitrogen Availability

The cultivar selection and nitrogen (N) fertilization are key management factors to improve potato yield. The aim of the present study was to evaluate the ecophysiological determinants of biomass and tuber yield in potato genotypes in response to N availability under field conditions. Experiments 1 and 2 were carried out in a volcanic soil of southern Chile during the 2021-2022 season. Treatments were applied in the factorial combination of (i) fifteen genotypes of potatoes and (ii) three N fertilization rates (0, 200 and 400 kg N ha(-1), 0 N, 200 N and 400 N, respectively). A wide range in total dry matter biomass (5.9-22.1 Mg DM ha(-1)) and tuber yield (5.1-18.3 Mg DM ha(-1)) was observed across the experiments. In both experiments, the total biomass and tuber yield were affected by the N rate (p < 0.05) and genotype (p < 0.01), but not by their interaction (p > 0.05). Tuber dry matter yield was strongly related (R-2 = 0.94, p < 0.01) to total biomass and weakly related to the harvest index (HI). In both experiments, the total biomass was explained by the radiation use efficiency (RUE) (R-2 = 0.69-0.75, p < 0.01). The principal components analysis showed that tuber yield, biomass and RUE were related. The Finlay and Wilkinson analysis revealed that different cultivars varied significantly (p < 0.001) in their sensitivity to N availability. Across environments (3 N rates x 2 experiments), the most responsive cultivars to N availability were Pukara, Rodeo, Asterix and Patagonia. This information will be useful for potato production systems aimed at improving tuber yield and N use efficiency.