Water Content and Fruit Yield Under Different Levels of Irrigation From a Raised-Bed Substrate Trough System for Strawberries.

Strawberry fruit production in California is facing urgent challenges in controlling soilborne diseases and pathogens, a practice that has traditionally relied on soil fumigation with methyl bromide. With the phase-out of methyl bromide and rising human and environmental concerns with alternative chemicals, non-chemically based disease management strategies are more plausible. The objective of this study was to evaluate irrigation rates on strawberry growth using a raise-bed substrate trough system as a potential alternative to chemical soil fumigation.  A two-year field study (2009 and 2010) was conducted, on a commercial strawberry farm, to measure substrate water content and strawberry fruit yield under three irrigation levels: 100%, 150%, and 200% replacement of evapotranspiration (ET).  Five substrate media were used in 2009, three in 2010.  A time domain reflectometry (TDR) system was used for water content measurement during the two strawberry growing seasons. In each substrate trough, three replicated TDR probes were used and average water content was computed for each irrigation and substrate treatment.  Both marketable and non-marketable fruit yields were measured from each treatment using a commercial harvest crew.  As expected, experimental results showed significant differences in substrate water content, e.g. higher water content in the 150% or 200% ET than that in the 100% ET treatment.  However, there was no significant yield difference between the different levels of irrigation.  Most of the substrate media produced a fruit yield comparable to the grower standard soil beds.  Overall, the study showed that the raise-bed substrate trough system could be a potential alternative to chemical soil fumigation for strawberry fruit production.