2017 ASHS Annual Conference

This study was carried out in northwest Washington in 2015 and 2016, and compared an integrated fertilizer treatment program (composted poultry manure plus urea) with commercial chemical fertilizer applications and the use of grafted plants for high tunnel tomato production. Composted poultry manure was applied at 2.4 t^.ha^-1 (15N-60P-35K and 320 Ca kg^.ha^-1) during both growing seasons. Urea fertilizer (90 kg^.ha^-1 N) additions at 112N-68P-45K and 322 Ca kg^.ha^-1 were adjusted each year for comparable N application rates. Tomato cv. Panzer was grafted on rootstocks ‘Estamino’, ‘Maxifort’, ‘DRO138TX’, and compared with non-grafted ‘Panzer’ (control). The experiment used a randomized complete block split plot design with four replications; the main plot was fertilizer and the subplot was grafting. At 21 and 42 days after transplanting (DAT) in 2015 and at 44 DAT in 2016, the number of leaves was greater with commercial fertilizer than with the integrated fertilizer treatment. There was no effect on number of leaves due to grafting either year. At 21 and 42 DAT in the 2015 and on all sampling dates but 107 DAT in 2016, plants grown with commercial fertilizer were taller than those grown with the integrated fertilizer treatment. There was no effect on plant height due to grafting in 2015; but in 2016, grafted plants were significantly taller than non-grafted plants on all sampling dates except 107 DAT. In 2015, pruning biomass was greater at 35 and 42 DAT due to commercial fertilizer, and due to rootstocks at 82, 101 and 124 DAT. In 2016, plants grown with commercial fertilizer also had higher pruning biomass on almost half the sampling dates, and due to grafting on all but 74 DAT. There was no effect of nitrate-N in plant tissue and fresh petiole sap due to fertilizer sources either year. And while there was no effect on nitrate-N in plant tissue due to grafting in 2015, grafted plants had higher nitrate-N in plant tissue at 46 and 61 DAT in 2016. A significant increase in nitrate-N of fresh petiole sap was observed as a result of grafting with ‘Estamino’ at 31 DAT in 2015, and with the three rootstocks on all sampling dates but 35 DAT in 2016.