Evaluation of four soilless substrate systems for greenhouse strawberry production

Growing demand for locally produced strawberries (Fragaria × ananassa) with high flavor quality has led to an increase in US soilless strawberry production under controlled environment in recent years. Soilless substrate-based production systems need to be optimized for plant productivity, plant health, and ultimately grower profit. This study investigated effects of four different substrate systems, which included two commercial substrate mixes, on ‘Albion’ plant vigor, fruit yield, and fruit quality. The first commercial mixture (Com1) was used with a plastic trough (container) and contained peat moss, perlite, coco coir chips, supplemental arbuscular mycorrhizal fungi (Glomus intraradices, strain PTB297 syn. Rhizophagus irregularis DAOM 197198) (AMF), and biofungicide bacteria (Bacillus pumilus, strain PTB180) (BP) while the second commercial mixture (Com2) was composed of peat moss, composted pine bark, coco coir fiber, AMF, and BP, packaged in a plastic bag. Our standard lab substrate mixture (StMix-S) for strawberry production consisted of perlite, fine particle coco coir, and peat moss. Additionally, this same mix was used in the same plastic trough but supplemented with AMF (StMix-M). Forty-eight ‘Albion’ plants were grown in each of the four systems from October 2017 to May 2018 in a north-south oriented glass greenhouse (Columbus, OH, USA). Com1 and Com2 had 26-31% greater cumulative fruit yield per plant (619.9±35.6 to 652.5±34.1 g) than StMix-S (476.3±41.0 g) but did not have significantly different yields than StMix-M (575.6±32.7 g). AMF colonization was confirmed in StMix-M but not in Com1 nor Com2. BP was confirmed in Com1 and Com2. These findings suggest that physical, chemical, and biological properties must be integrated in order to maximize soilless strawberry yield.