Biomass accumulation and partitioning into different plant parts is a dynamic process during the plant growing period, which is influenced by crop management and climate factors. Adequate knowledge of biomass partitioning is important to manage the crops to gain maximum partitioning of assimilates into plant parts of economic significance, i.e. tubers in potato. This study was conducted using two potato cultivars grown in a sandy soil with center pivot irrigation under full irrigation (FI; irrigation to replenish 100% of water loss by evapotranspiration [ET]) and deficit irrigation (DI; replenish only 80% ET) and two nitrogen(N) rates (pre-plant + in-seasonN rates of 56+112 or 168+336 kg/ha). Plant samples were taken on 22, 44, 66, and 98 days after seedling emergence (DAE). With high N rate, tuber biomass of 'Umatilla Russet' cultivar in relation to total plant biomass varied from 23%-88% and 25%-86% over 22 to 98 DAE for the FIand DI treatments, respectively. The corresponding partitioning ranges were 30%-93% and 38%-93% at the low N rate. With respect to the'Ranger Russet' cultivar, biomass partitioning to tubers ranged from 36%-82% and 23%-84% for the FIand DI, respectively, at the high N rate, and 29%-87% and 39%-95% at the low N rate. Overall, this study demonstrated that within the range of N rate and irrigation treatments the biomass portioning into tubers was largely similar in both cultivars.
