PRUNING SYSTEM EFFECT ON GREENHOUSE GRAFTED TOMATO YIELD AND QUALITY

Summary

This study aimed to evaluate the effects on tomato yield and quality of three pruning systems (2, 3 and 4 stems) of grafted plants (cv. Vinicio and Multifort) used to prevent the incidence of soil diseases. It was also investigated if the two stems from nodes of the cotyledon leaves improved crop performance compared to the two stems from the first true leaves nodes. The experiment was conducted in the spring/summer season, under greenhouse conditions at NW Portugal, with a randomized block design with 3 blocks and the four pruning crop treatments.
Total yield was significantly increased for the double-stem tomato crop, without significant differences between both stem nodes position (26.5 kg m-2), compared to plants with 3 and 4 stems (19.5 kg m-2). The fruit grade between 57-102 mm represented 96.3% of total yield and this was similar for all plant treatments. Fruit quality was not influenced by the pruning systems and mean characteristics were: fruit firmness (1.0 kg), content of soluble solids (5.1°Brix), acidity (1.0 g 100 g-1), pH (4.4), dry mater content (4.9%), and unblemished fruits (90.9%). Higher yield and fruit quality from double-stem tomato plants offset the increased planting labour and higher plant cost, compared to the 3 and 4 stems grafted plants. The similar results obtained with double-stem plants from cotyledon leaves nodes and from the first true leaves suggest that the former plants should not be recommended due to the higher nursery pruning care they need.