Feasibility of irrigating pickleweed (Salicornia bigelovii. Torr) with hyper-saline drainage water

Reuse of drainage water (DW) for irrigation reduces the volume of DW requiring treatment or disposal. We conducted a greenhouse study to evaluate the performance of the halophyte Salicornia bigelovii Torr. when irrigated with hyper-saline DW and seawater (SW) treatments, ranging from 1/3 strength to full strength (18-49 dS m(-1)), in a sand-culture system. Results indicate that Salicornia grows well over the entire range of iso-osmotic SW and DW salinity treatments. Moreover, when boron (B) was added to SW treatments to concentrations equivalent to that of corresponding 1/3- and 2/3-strength DW treatments (i.e., 9 and 17 mg L(-1)), growth was not affected, and tissue B concentrations were <150 mg kg(-1) dry wt. However, when plants were irrigated with synthetic DW where B was reduced to solution culture levels (0.5-1.0 mg L(-1)), plants generally performed worse than when irrigated with actual DW high in B at the same salinity level. Evapotranspiration (ET) rates exceeded that lost from an evaporation pan from 1.5 to 2.5 times. Using a method accounting for changes in the isotopic signature of water in the reservoir due to evaporation, we estimated that high ET rates were due primarily to high transpiration rates (>78% of ET). The salt content in the tissue was very high (ash content 43-52%), but ionic composition in the shoot tissue reflected that of the treatment water used to irrigate the plants. These data indicate that hyper-saline DW, characteristic of California's San Joaquin Valley, can be used to irrigate Salicornia and substantially reduce drainage volumes.