Pruning system effect on greenhouse grafted tomato yield and quality

Resumo

Vegetable grafting used to prevent biotic and abiotic stresses is an important crop management strategy. For tomato crop the number of stems per each grafted plant which determine the planting density for the same stem density and sunlight exposure of the crop, should be investigated to improve growers’ decisions. This study evaluates the effects on fruit yield and quality of grafted tomato plants (cv. Vinicio and Multifort rootstock) pruned with 2, 3 and 4 stems developed from the first true leaves nodes and pruned with 2 stems developed from the cotyledon leaves nodes. The experiment was run in the spring/summer season, under greenhouse conditions, with a randomized block design with three blocks. Total yield was significantly increased for the double-stemmed tomato plants, without significant differences between the position of both stem nodes (average yield 26.5 kg m^-2), compared to the 3 and 4 stemmed plants (average yield 19.5 kg m^-2). These results could be related to stronger competition between stems within the plant for water and nutrients, as well as root system limitations of the 3 and 4 stemmed plants to couple with increased water and nutrient plant demand. The fruit grade between 57-102 mm represented 96% of overall tomato yield without significant differences between treatments and fruit quality was not influenced by the pruning systems (average firmness 1.0 kg, soluble solids 5.1°Brix, acidity 1.0 g 100 g^-1, pH 4.4 and dry mater 4.9%). Higher yield from double-stem tomato plants offset the increased planting and seedlings costs.