Remove it to improve it? The impact of young-leaf pruning on high-wire cucumber production

In high-wire tomato, pruning young leaves at the top of the canopy is common practice to increase yield. While pruning young leaves increases dry matter partitioning to the fruits, it also leads to decreased leaf area index (LAI), which could counteract this benefit. This research investigated the impact of young-leaf pruning on the yield of a high-wire cucumber crop. Moderate pruning was hypothesized to slightly increase yield over the non-pruned canopy due to increased dry matter partitioning to the fruits. In contrast, heavy pruning was expected to decrease yield attributed to a reduction in LAI. In a greenhouse experiment, 0%, 33%, and 50% of leaves were removed at an early leaf development stage and a yield component analysis was conducted. Young-leaf pruning led to a lower cumulative fruit yield. Unexpectedly, the 33% and 50% pruning treatments had similar yields. Dry matter partitioning to the fruits did not increase with pruning. An assimilate partitioning model, based on organ sink strengths, illustrated that the observed increase in fruit abortion and fruit growth duration reduced the impact of young-leaf pruning on dry matter partitioning mainly for the 33% treatment. LAI reduced from 3.1 to 2.3 to 1.9 for the 0%, 33%, and 50% treatments, respectively. Reductions in LAI and light interception due to young-leaf pruning resulted in reduced yield. Therefore, young-leaf pruning in a high-wire cucumber greenhouse, using similar cultivation parameters, is not recommended for the purpose of increasing yield.