Improve the yield and quality of strawberries by manipulation of the ‘source/sink’ ratio

MSc-thesis abstract (submitted 30 March 2017): Source/sink balance can influence fruit yield and quality in horticultural crops.
The aim of the present study was to determine the effect of a reduction in sink strength relative to the source strength on the yield and quality of greenhouse grown strawberries (Fragaria × ananassa) cv. Sonata produced in the winter.
The experiment was conducted in a greenhouse located in the South of the Netherlands. Supplementary lighting was applied to reach every day an inside radiation of 1000
In order to reduce sink strength young leaves and old leaves were removed. Besides, two different fruit pruning regimes were applied: 30 fruits per plant and 35 per plant. ‘Young leaves’, ‘old leaves’ and ‘control’ treatments contain 40 fruits per plant.
A complete randomized block design with 4 blocks was used, with 26 replicate plants per plot.

Removing young leaves resulted in a significant higher production (kg.m-2).The ‘30Fruits’ treatment had the highest average individual fruit size (g per fruit), but total yield per plant for the fruit pruning treatments was significantly lower.

The ’30Fruits’ treatment had significantly the highest average Total Soluble Solids (TSS) value.
For all treatments the TSS values increased over time. In practise, young leaves removal will not be applied because extra costs were larger than the increase in revenues. The same holds for fruit pruning, where the expectation is that the loss in yield will not be compensated by an increase in revenues due to higher fruit quality.

Keywords: source/sink ratio - young leaves – old leaves - fruit pruning - fruit yield - total soluble solids - strawberries (Fragaria × ananassa)