Wednesday, November 15, 2006 - 4:00 PM

Impact on Water Conservation and Turf Performance from Systematic Use of Surfactants in Soils with only Slight Evidence of Water Repellency.

Sowmya Mitra, Paitawee Suphantharita, Magdy Fam, and Russell Plumb. Cal Poly-Pomona, Dept/Hort&Plnt Sci, 3801 West Temple Avenue, 3801 West Temple Avenue, Pomona, CA 91768, United States of America

The objective of this research project was to evaluate water conservation strategies by systematically injecting wetting agents in the irrigation lines when irrigating a GN-1 hybrid bermudagrass maintained under golf course fairway conditions on a clay loam soil.  Twenty-four plots (3m by 3m) were laid out in a split-plot design, with three replicates.  During the experiment, twelve plots were irrigated with potable drinking water and twelve with recycled water. Irrigation-water quality (potable or recycled) was the primary factor and the use of wetting agents (Dispatch at 877 ml/ha) was the secondary factor. The experiments were conducted during the summer of 2003, 2004 and 2005. In the month of May the plots were irrigated at 100% of the reference evapotranspiration (ETo) for that month. In June, the amount of water was reduced to 70%ETo followed by a further reduction to 30%ETo in July. Finally in August, the plots were irrigated at 10%ETo to induce moisture stress. Overall the wetting agent treatment helped in retaining more moisture compared to the untreated plots under the moisture stress (30-10%ETo) irrigation regime.  The chlorophyll-a, b, carotenoid and total chlorophyll synthesis in bermudagrass was significantly higher with the wetting agent treatment compared to the untreated plots when irrigated with potable water.  The effect was not significantly different under recycled water irrigation and the difference could be due to the dissolved ions mainly higher levels of nitrogen in recycled water compared to potable water.  Arginine and proline amino acid synthesis was upregulated under moisture stress.  The proline content in the leaf tissues was higher in the Dispatch treated plots compared to the untreated plots in both the water sources.  Hence the wetting agent was helping the plant in maintaining turgor pressure by increasing proline synthesis under moisture stress.