The effect of pruning systems on yield and fruit quality of grafted tomato

Efeito do sistema de condução na produtividade e qualidade dos frutos de tomateiro enxertado

Abstract

Vegetable grafting is an increasingly used crop management strategy that aims to prevent soilborne biotic and abiotic stresses. For tomato crops, the number of stems per grafted plant determines planting density and crop exposure to sunlight. The effects of pruning grafted plants on yield and fruit quality have not been established, and this information is crucial to support decision-making by growers. A greenhouse experiment was run in the spring/summer season in the NW Portugal to assess the yield and quality parameters for grafted tomato plants (cv. Vinicio grafted onto Multifort rootstock) pruned to 2, 3 and 4 stems developed from the plant first nodes, or pruned to 2 stems developed from cotyledonary nodes, according to common practice. Total yield was significantly increased for the double-stemmed tomato plants, irrespectively of node origin (average yield 26.5 kg/m²), as compared to the 3- and 4-stemmed plants (average yield 19.5 kg/m²). These results can be explained by root system limitations to uptake water and nutrients coupled with the stronger competition between stems for the 3- and 4-stemmed plants. Fruit quality assessed through firmness (1.0 kg/cm²), soluble solids (5.1°Brix), acidity (1.0 g/100 g fresh weight), pH (4.4) and dry mater content (4.9%) was not affected by pruning systems. The greater yield obtained from double-stemmed plants offsets the increased planting and seedlings costs of using grafted tomato plants, particularly so for double-stemmed plants grown from first nodes, as they do not require intensive nursery care and are therefore less costly than those grown from cotyledonary nodes.

Keywords:
Solanum lycopersicum; cotyledonary and plant nodes; Multifort rootstock; stem number; vegetable grafting.