2017 ASHS Annual Conference

Tomato is a major vegetable crop produced in high tunnels world-wide. This study compared two fertilizer sources, an integrated fertilizer treatment program (composted poultry manure plus urea) with commercial chemical fertilizer applications and the use of grafted plants on fruit yield and quality of tomato grown in high tunnels in northwest Washington in 2015 and 2016. 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^-1were 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. Fruit were harvested once a week when at least 75% ripe. At each harvest, weight and number of both total and marketable fruit were recorded, and the quality of marketable fruit evaluated for juice content, total soluble solids (TSS) and pH. In 2015 and 2016, number and weight of total and marketable fruit did not differ due to fertilizer source. In 2015, there was no difference due to grafting in total fruit weight, nor in weight or number of marketable fruit; however, the number of total fruit was greater for non-grafted plants. In 2016, the number of total and marketable tomato fruit did not differ due to grafting, but the weight of total and marketable fruit was greater for grafted plants as compared to non-grafted plants. There was no effect due to fertilizer source on juice content (%) either year. In contrast, fruit from grafted plants had higher juice content than non-grafted plants in 2015, but not in 2016. In 2015, total soluble solids (TSS, ^oBrix) was not different due to the fertilizer or grafting treatments. In 2016, TSS was higher for tomato fruit grown with the integrated fertilizer program and for grafted plants. No differences in pH were found due to fertilizer source or grafting either year.