Abstract: Based on the strategic needs of sustainable agricultural development and focusing on the efficient use of fertilizers, we investigated the effects of optimal application of phosphorus fertilizer on photosynthetic efficiency, population structure, and dynamic dry matter accumulation pattern of potatoes. The experiment was carried out in 2018-2019 in Haiyuan County, Ningxia, with ‘Qingyan Potato No. 9’ as the test material, using a randomized block group design. We analyzed leaf fluorescence characteristics, population growth, dynamic accumulation of dry matter, and yield of potatoes under five phosphorus application levels of 0 kg·hm^-2 (P0), 60 kg·hm^-2 (P1), 120 kg·hm^-2 (P2), 180 kg·hm^-2 (P3), and 240 kg·hm^-2 (P4). The results showed that at 60 days after seedling emergence, compared with P0, the 2-year average increases of F_v/F_m (PSII maximum photochemical efficiency), F_v/F_o (PS potential maximum photosynthetic capacity), PI (photosynthetic institutional performance parameter), and ABS/RC (PSⅡ light energy capture efficiency) in leaves under the P1, P2, P3, and P4 treatments ranged from 0.6% to 2.0%, 3.4% to 10.06%, 3.5% to 14.3%, and 8.4% to 18.8%, respectively. The P2 treatment significantly increased potato leaf area index (LAI), photosynthetic potential (LAD), population growth rate (GCR),  net assimilation rate (NAR), and biomass at the point of achieving peak accumulation rate (W_max), along with the highest dry matter accumulation rate (V_max). Compared with P0, the two-year average increases in LAI, LAD, CGR, NAR, W_max, and V_max across P1, P2, P3, and P4 treatments were 1.9%-35.7%, 2.0%-40.7%, 9.5%-29.5%, 13.1%-29.4%, 3.3%-56.8%, and 16.4%-72.2%, respectively. Meanwhile, the 2-year average increase in potato yield of P1, P2, P3, and P4 treatments ranged from 6.1% to 32.9% compared with P0. Among the five phosphorus application levels, potato yield reached the maximum in the P2 treatment. The quadratic function was fitted to yield and phosphorus application level to obtain the optimal economic phosphorus application level of 124 kg·hm^-2 in 2018 and 118 kg·hm^-2 in 2019. W_max and V_max were significantly positively correlated with F_v/F_m, F_v/F_o, PI, ABS/RC, LAI, and LAD, while potato yield was significantly positively correlated with F_v/F_m, F_v/F_o, PI, ABS/RC, LAI, and LAD. The principal component analysis indicated that the composite score of each treatment in the two years was in order of P2>P1>P3>P4>P0. Therefore, phosphorus application level of 120 kg·hm^-2 was the appropriate amount for green and efficient production of potatoes in the semi-arid region of Northwest China.

Key words: potato, phosphate fertilizer dosage, fluorescence characteristics, dry matter accumulation characteristics, yield formation