The effect of grafting on nitrogen use in determinate field-grown tomatoes

ABSTRACTGrafting tomato (Solanum lycopersicum L.) onto disease resistant rootstocks has grown in use in North America over the past two decades. Rootstocks have traditionally been bred and used for their resistance packages to numerous soil-borne diseases but some rootstocks appear to improve scion yield and vigour in comparison to non-grafted plants in conditions lacking disease challenge. In this study, the tomato rootstocks ‘Maxifort’ or ‘RST-106’ were used to determine if vigour improved ‘Tribute’ scion traits, especially yield, and if marketable yield could be maintained in grafted plants at reduced nitrogen fertiliser inputs. Plants were grown in an open-field plasticulture production system at five rates of nitrogen from 0 kg ha−1 to 224 kg ha−1 applied via drip irrigation. Marketable yield was significantly affected by nitrogen rate and rootstock in both years. ‘Tribute’ grafted onto ‘Maxifort’ rootstock had the greatest, most consistent impact and increased marketable yield 15% and 30% in 2013 an...