Objective  Effects of N-reducing fertilization combined with vine pruning on the growth, yield, and fruit quality of passion fruit plants were studied.

  Method  A field test was conducted in two consecutive years on Tainong No. 1 passion fruit with the single-fruiting vine cultivation method under different N-reducing fertilizations in combination with varied pruning methods. Effects of regular N application at 240 kg·hm⁻² without pruning as control (T1) and 9 treatments using varied N-reducing fertilizations and vine pruning on the plant growth and fruit formation, yield, and quality were determined.

  Result   From 2021 to 2022, the stem diameter and the numbers of effective leaves, floral buds, flowers, and successfully formed fruits were increased by the treatments. The use of 80% of the normally applied N fertilizer with pruning, T6 significantly improved those indices to the highest level among all treatments and control and shortened the average internode between fruits by 19.04%. The treatments significantly changed the average fruit yield per plant over control (P＜0.05) with the greatest increase of 71.74% delivered by T6. T6 also produced the highest number of fruits per vine, average individual fruit weight, and proportion of medium and large fruits with the increases of 48.90%, 15.29%, and 1.65%, respectively. And the fruits the vines bore were 25.89% higher on total sugars, 75.24% higher on sugar-acid ratio, and 28.18% lower on acid than they were under T1.

  Conclusion  The 20% reduction on the use of N fertilizer (i.e., at the application rate of 192 kg·hm⁻²) along with severe branch pruning on a passion fruit vine could significantly improve the plant growth, flowering, and fruiting as well as the fruit yield and quality.