We investigated the effects of different inorganic nitrogen forms (NO₃ ⁻–N and NH₄ ⁺–N) on the morphology, physiology, and carbohydrate accumulation of male and female Populus deltoides. Results showed that both NO₃ ⁻–N and NH₄ ⁺–N supply forms significantly increased plant growth, C and N contents of all plant organs, chlorophyll pigment contents, net photosynthesis rates (P _n), and instantaneous photosynthetic N-use efficiencies (PNUE) in the leaves of both male and female P. deltoides. Females exhibited high total plant dry mass accumulation, P _n, PNUE, and N contents in leaves but lower non-structure carbohydrate accumulation than males under nitrate treatment. However, males showed significantly higher P _n, PNUE, and ¹⁵NH₄ ⁺ in the leaves, free amino acid content, and nitrate reductase (NR) activities than females under each nitrogen form supply treatment. These results suggested that male and female P. deltoides used different adaptive strategies in dry mass accumulation, allocation, and exhibited different interactions between nitrogen and carbon metabolism. Males exhibited higher nitrogen assimilation ability and N-use efficiency than females under nitrogen fertilizations, whereas females showed more sensitivity to inorganic nitrogen forms of treatments and distinct preference for NO₃ ⁻–N. Male P. deltoides showed no obvious bias to the two different N forms. Therefore, the different preferences of male and female P. deltoides of N supplied forms can serve as an important strategy for minimizing intraspecific competition between the two genders.