The 2012 ASHS Annual Conference

Tatsoi, Brassica rapa (Narinosa group), also called rosette bok choy, is an Asian leafy vegetable, and is currently gaining popularity in organic production. Tatsoi can be grown at low temperatures, but performs best in the raised temperatures of a protected growing environment like a high tunnel during winter and early spring months. The incorporation of organic amendments, such as poultry compost, into soil may pose food safety risks if pathogenic microorganisms are present. A high tunnel study was conducted in early Spring 2011 on the Eastern Shore of Maryland to determine the effect of two commercially available products: arbuscular mycorrhizal fungi (AMF) and poultry compost, on the development and microbial food safety of tatsoi. The experimental design was a randomized complete block (RCB, n = 4) for each of the following treatments: Pelletized organic chicken compost, AMF, Poultry compost, and AMF + Poultry compost. Treatments were applied to tatsoi seeds at planting, and baby leaves were sampled over three harvests. Treatment rates were 12.4 g/m² for poultry compost and 16.0 g/m² for AMF. When used separately, AMF or poultry compost increased baby tatsoi leaf fresh weight, dry weight, length and width in comparison to the control plants.  However, when these treatments were combined they significantly decreased fresh weight, but did not influence leaf area.  All leaf samples were negative for E. coli O157:H7 and Salmonella, while one sample was positive for generic E. coli. This study indicates that AMF + compost may not have a synergistic effect on tatsoi growth and development, and that these soil amendments, at the levels used, may not pose a food safety risk factor to baby tatsoi grown in the protection of a high tunnel.