2018 ASHS Annual Conference

We are investigating the effect of sustained substrate moisture levels on the growth, yield and fruit quality of the strawberry (Fragaria X ananassa) cv. ‘Chandler’ and ‘Sweet Charlie’. The experiment was setup in a randomized complete block design with four replications in the Research Greenhouse at the University of Maryland, College Park. Plugs of the cultivars were transplanted to 3.8 L pots filled with a commercial substrate (Sunshine LC1 Mix, Sungro Horticulture, Agawam, MA) composed of 75-85% peat moss and 15-25% perlite on volume basis. The moisture release curve for the substrate mix was developed using Hyprop device (METER Group Inc., Pullman, WA) in order to correlate volumetric water contents with corresponding matric potential and four soil volumetric content levels were selected as treatment set-points. These VWC set-points were 40%, 30%, 20% and 15% and represented 67.7%, 50%, 33.3% and 25% of container capacity for the substrate mix, respectively. Corresponding matric potential values for the VWC set-points were -4.3, -13.8, -36.7 and -63 kPa. GS-1 Soil moisture sensors (METER Group Inc.,) were inserted in three plants per experimental unit and readings were recorded on a 5-minute basis using Em50R data loggers (METER Group Inc.,). Data was transmitted to Sensorweb^TM software (Mayim LLC., Pittsburgh, PA) and averaged on a 15-minute basis. Irrigation happened whenever averaged values were less than corresponding set-point for each treatment. In addition to VWC, substrate matric potential (MPS-6), electrical conductivity and temperature (GS-3), and irrigation volumes (Model 25, Badger Meter, Milwaukee, WI) were also recorded on a 5-min basis using the Em50R data loggers. For four weeks after transplant, all treatments were irrigated fully to allow establishment. Destructive harvest was done at the end of December in order to quantify growth effects. There were significant differences in branch crown number, leaf area, leaf fresh mass, stem fresh mass, leaf dry mass, stem dry mass and root dry mass for ‘Sweet Charlie’. None of these parameters were significantly different for Chandler. While both cultivars are short day (June bearing), Sweet Charlie is an earlier cultivar compared to Chandler and is likely to have more rapid growth compared to Chandler. Additional destructive harvest will be done at the end of vegetative growth in the spring and after fruits harvest. Our understanding of how plant growth, yield and quality respond to varying soil moisture regimes is important to devise efficient irrigation practices for strawberry production in various soils as well as soilless substrates.