2017 ASHS Annual Conference

We have been conducting field experiments to study the effect of soil moisture regimes on the growth, yield and quality of strawberry (Fragaria X ananassa) cv. ‘Chandler’. In order to implement incremental drought stress, four irrigation treatments were selected based on soil matric potential (SMP) threshold values: control (Cont. = -30 kPa) and three deficit irrigation treatments (DI1 = -40 kPa, DI2 = -50 kPa and DI3 = -60 kPa). Corresponding volumetric water content (VWC) values for the SMP levels were obtained from soil moisture release curves developed using Hyprop apparatus (UMS, Germany). Irrigation events occurred when the average VWC from two 10HS soil moisture sensors (METER Group Inc., Pullman, WA) placed in the root-zone of plants in each plot was lower than the corresponding VWC, utilizing a wireless sensor network composed of nR5-DC control nodes (METER Group, Inc.) and Sensorweb^TM software (Mayim LLC., Pittsburgh, PA). MPS-6 sensors (METER Group, Inc.) and T8 field tensiometers (UMS) were used to validate field SMP levels in order to accurately quantify plant available water in all treatments. Significant yield differences were observed between Cont. and the DI2 and DI3 treatments during the 2014/15 season. The Cont. treatment applied significantly more water and resulted in 10.5%, 22.8% and 31.7% greater yield than the DI1, DI2 and DI3 treatments, respectively. Significant differences in the number of fruits per plant contributed to yield differences as opposed to average fruit mass, which was similar between treatments. Differences in the fruit quality parameters pH, titrable acidity and total soluble solids (^o Brix) were not significantly different between treatments for all harvest dates. During the 2015/16 season, yield and fruit quality differences observed between treatments were not significant although the DI3 treatment applied significantly less water compared to the rest. There were no significant differences for all plant growth parameters measured, except for root dry mass that was significantly lower for the DI3 treatment. Real-time SMP measurements (MPS-6 sensors and T8 tensiometers) are being utilized to control irrigation in the experiment during the 2016/17 growing season. 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.