Thursday, November 16, 2006 - 10:15 AM

Auxin-Boosted Biosolids Impact on Drought Resistance in Kentucky Bluegrass.

Xunzhong Zhang, CSES (0404), Virginia Tech, 429 Smyth Hall, Blacksburg, VA 24061, Erik Ervin, Virginia Tech, CSES Dept.Virginia Tech Univ., 335 Smyth Hall, Blacksburg, VA 24061, Gregory Evanylo, 426 Smyth Hall, CSES (0403), Virginia Tech, Blacksburg, VA 24061-0403, and K. Haering, Crop and Soil Environmental Sci., Virginia Tech, Blacksburg, VA 24061.

This study was conducted to examine impacts of auxin-boosted biosolids on drought resistance of 'Midnight’ Kentucky bluegrass under greenhouse conditions.  Anaerobically-digested biosolids were dosed with tryptophan and incubated at pH 7 for two months prior to soil amending. Auxin-boosted (containing 6.3 µg/g IAA) and regular biosolids (containing 0.8 µg/g IAA) at 2250 kg/ha were applied to rooting tubes filled with calcined clay during Kentucky bluegrass establishment. Two months after establishment, Kentucky bluegrass was subjected to drought stress (soil water potential maintained at -0.5 MPa) or well watered (-0.01 MPa) for three months. The auxin-boosted biosolids treatment delayed leaf wilting under drought stress relative to the non-biosolids control.  Auxin-boosted biosolids also resulted in increased leaf contents of proline, cytokinin, and superoxide dismutase activity under drought stress when compared to the control. The data suggest that auxin-boosted biosolids may improve metabolic adaptation of Kentucky bluegrass to drought stress conditions.