Effects of optimized fertilizer and water management on nutrient uptake and distribution in open-field peppers in Southwest China

Objectives In southwest China, excessive fertilizer application and the mismatch between nutrient and water supply and crop demand in open-field pepper production have led to prominent issues, such as poor coordination between fertilizer and water and low utilization efficiencies. This study aimed to investigate the absorption, allocation, and translocation patterns of nitrogen, phosphorus, potassium, and secondary and micronutrients in different pepper organs at various growth stages, and to compare the effects of optimized integrated water-fertilizer management with conventional farmer practices and optimized fertilization treatments.

Methods A field experiment was conducted in Lüfeng Town, Tongliang District, Chongqing, using pepper cultivar ‘Jingxi No. 8’. Three treatments were established: Farmers’ practices (T1), optimized fertilizer (T2), and optimized integrated fertilizer and water treatment (T3). Dry matter accumulation and the uptake of nitrogen, phosphorus, potassium, and secondary/micronutrients in whole plants and different organs were measured at the flowering-fruiting, mid-fruiting, peak-fruiting, and late-fruiting stages.

Results Nutrient accumulation in pepper exhibited an S-shaped growth curve throughout the growing season, with 53.4%−74.9% of total accumulation occurring during the mid- and peak-fruiting stages. During this period, the nutrient accumulation rate peaked, with N, P, K rates reaching 1.30−2.03, 0.384−0.565, 2.08−3.10 kg/(hm²·d), respectively. During the entire growth cycle, the overall N, P, K uptake ratio was 1.00:0.33:1.48, while the accumulation of secondary and trace elements followed the order: Ca>Mg>Fe>Na>Mn>Zn>Cu>B. Compared to T1, T2 treatment increased total NPK accumulation by 6.67%−11.0%, and T3 enhanced this accumulation by 9.76%−14.9% relative to T2. No significant difference in nutrient accumulation was observed among treatments at the flowering-fruiting stage, mid-fruiting stage, or final-fruiting stage. However, at the peak-fruiting stage, T3 increased total NPK accumulation by 15.9%−29.1% and 4.50%−8.70% compared to T1 and T2, respectively.

Conclusions Compared with conventional farmer practices, the optimized water-fertilizer management strategy integrating root-zone regulation with drip fertigation significantly enhanced the uptake and utilization of macro-, secondary, and micronutrients in pepper plants, particularly during the peak-fruiting stage. These findings provide a scientific foundation for achieving synergistic improvement in water-fertilizer efficiency and high-yield sustainable pepper production in southwest China.