Yield and Growth Response of Strawberry (Fragaria X ananassa) to Deficit Irrigation

A field experiment was conducted at the University of Maryland Wye Research and Education Center during 2014-15 to study the effect of deficit irrigation (DI) on strawberry (Fragaria X ananassa) growth, yield and yield parameters, and water use efficiency. The randomized complete block design experiment had four replications, 0.8 m wide by 6.1 m long plots, and 1.5 m spacing between the raised bed centers. Plugs of strawberry cv. Chandler were planted in two staggered rows with 0.3 m spacing between and within rows. Irrigation treatments were based on soil matric potential (SMP) values established for a control (-30 kPa) and three DI treatments (-40 kPa, -50 kPa and -60 kPa). Corresponding volumetric water content (VWC) values were obtained from soil water retention curves developed for the study site using a Hyprop apparatus (UMS, Germany). The VWC values were used as threshold/set-points to trigger irrigation events when the average VWC from two 10HS soil moisture sensors (Decagon Devices, Inc., Pullman, WA) placed in the root-zone of plants in each plot was lower. Treatments were implemented via a wireless sensor network consisting of nR5-DC control nodes (Decagon Devices, Inc.). In-situ field SMP data for each plot were obtained using MPS-6 matric potential sensors (Decagon Devices, Inc.) and irrigation volumes for each plot were also measured using flow meters (Badger Meters, Milwaukee, WI). Deficit irrigation treatments significantly reduced water applications. Significant yield reductions were observed for deficit irrigation treatments due to reduced number of fruits per plant. There were no differences in average fruit weight and irrigation water use efficiency between treatments. The results indicated the sensitivity of strawberry plants to changes in plant available water within the relatively narrow SMP range imposed in the study. The study is being repeated during 2015-16, using T8 field tensiometers (UMS) to further validate SMP levels imposed in the treatments and to accurately quantify plant available water in the control and DI treatments. Understanding responses of strawberry plants to changes in soil water status is essential to identify DI strategies to improve irrigation water use-efficiency and reduce potential nutrient leaching from strawberry production.