Biomass allocation to root, culm, leaf, and grain of 20 upland rice cultivars was assessed in pots set up in an open field experiment. The cultivars consisted of 18 upland NERICA rice (N 1 to N 18) and Funaabor 1 and 2. The rice cultivars were grown under rainfed condition on 5 kg soils collected along a toposequence designated as Upper Crest (UC), Middle Slope (MS), and Valley Bottom (VB) soils. Plants were harvested at maturity for biomass allocation pattern into various organs. Toposequence soils and cultivar significantly (p<0.01) influenced all the fractions of biomass and standing biomass to different organs except root dry weight (RDW) and root mass fraction (RMF) for the latter. The lowest standing and fraction of biomass to root (3.64g and 0.08 respectively), culm (17.92g and 0.42 respectively), and leaf (3.59g and 0.08 respectively) of the rice cultivars were observed on VB soils. Principal Component (PC) biplot accounted for 95.67% and 97.38% of the total variation in standing biomass and fractions of biomass to organs respectively. Higher grain weight per plant was observed in NERICA 2 and 15 and was closely associated with standing biomass to root than to culm and leaf. Upland rice grown on UC soil accumulated more biomass to vegetative parts with concomitant decrease in fraction of biomass allocated to reproductive structures unlike rice cultivars grown on VB soils. Hence, growing upland rice on VB of a toposequence promotes increase of biomass allocation to grains. JTAS-1106-2017