Irrigation Management of Florida Potato.

Irrigation Management of Florida Potato Seth Byrd1, Diane Rowland1, Jerry Bennett1, Lincoln Zotarelli2, David Wright1, Ashok Alva3 1Agronomy Department University of Florida, Gainesville, FL. byrdsa@ufl.edu 2Horticulture Department University of Florida, Gainesville, FL. 3USDA ARS, Prosser, WA. Potato production in Florida occurs from January to June, typically a period of low precipitation in the state. Thus, irrigation is required for successful potato production, and several thousand cubic meters of water are used annually. Irrigation amount and frequency are typically maximal during tuber bulking. In an effort to investigate alternative irrigation management that had the potential to conserve water while avoiding detrimental decreases in yield, a regulated deficit irrigation (RDI) scheme was tested in a commercial potato field in Live Oak, FL in 2011 and 2012. Reduced irrigation in the RDI scheme was accomplished by incorporating periodic irrigation skips just after tuber initiation. Environmental and physiological responses were measured either continuously or during three time periods to determine the variation in plant stress between full and RDI treatments including: sap flow, soil moisture, and morning and afternoon stomatal conductance. The difference in water applied between full irrigation and the RDI scheme was 14.9 and 9.3cm in 2011 and 2012, respectively. In 2011, an initial decline in stomatal conductance during the first measurement period was observed in plants under the RDI regime (decline of 189 mmol m- 2s-1 and 198 mmol m-2s-1 in the morning and afternoon respectively); however, by the second and third measurements later in the season, plants in the RDI scheme appeared to acclimate to the RDI schedule. By the third measurement period, afternoon stomatal conductance in the RDI plots was slightly increased (31.65 mmol m-2s-1) over the full irrigation plots. The correlation of sap flow and soil moisture data indicated that RDI plants were probably utilizing deeper soil depths for water uptake, possibly compensating for reduced surface moisture. This project will provide information on the ability of the potato crop to acclimate to reduced irrigation and may result in RDI schemes that could provide improvements in the efficient use of environmental and economic resources.