Synergistic regulation of the growth and fruit quality of cherry tomato by remaining fruit spikes and number of interspike leaves after pruning

In this study, we aimed to understand the synergistic effects of the number of fruit spikes and leaves between the fruit spikes on fruit quality in cherry tomatoes. We conducted a 2-factorial experiment combining three fruit remaining spike rate treatments, i.e., 4, 6, and 8 remaining fruit spike per branch (F4, F6, and F8, respectively) with three interspike leaf number treatments (1, 2, and 3 interspike leaves abbreviated as L1, L2, L3); thus, in total, nine different treatments (3 × 3) were performed (L1F4, L1F6, L1F8, L2F4, L2F6, L2F8, L3F4, L3F6, and L3F8). The results revealed that the number of fruit spikes and interspike leaves exhibited a significant effect on the relative growth rate of leaf area (RGH-LA) and leaf area index. RGH-LA increased with the increase of the remaining fruit spike number. The leaf area index was higher in L3F6 and L3F8 than in other treatments. Water use efficiency (WUE) was reduced with the increase of leaf number at the same fruit spike retention in 4 and 8 fruit spikes; however, 6 fruit spikes exhibited an opposite trend. The WUE was higher in L3F6 and L1F8 than in other treatments. Both soluble sugars and soluble proteins contents in leaves (LSP) were the lowest in L3F6. However, the contents of vitamin C, soluble solids, soluble proteins and starch, and the activities ofsucrose and sucrose synthase were the highest in L3F6. In addition, the fruit yield, single fruit fresh weight, and fruit firmness were the highest in L3F6. Correlation analysis revealed that the remaining fruit spike and number of leaves between the spikes regulated the photosynthetic characteristics, in particular carbon and nitrogen metabolism in the leaves, and fruit quality. Collectively, L3F6 exhibited the highest potential to improve photosynthetic characteristics, WUE, fruit quality (particularly sugar accumulation), and yield of cherry tomatoes.