Influence of Silicon on Drought and Shade Tolerance of St. Augustinegrass

The objectives of these studies were to evaluate the effects of silicon on drought and shade tolerance of st. augustinegrass ( Stenotaphrum secundatum ). Studies were conducted during 2001 in a glasshouse at the University of Florida Turfgrass Research Envirotron in Gainesville. For both drought and shade evaluations, calcium silicate slag (CaSiO 3 ) was pre-incorporated into pots with commercial potting soil at the rate of 3.36 kg·ha -1 (0.069 lb/1000 ft 2 ). `FX-10' and `FHSA-115' st. augustinegrass were planted into 15.2-cm-diameter × 30.5-cm-deep (6 × 12 inches) plastic pots for the drought study and subjected to minimal irrigation. Under severe drought stress, silicon-amended plants had better responses than non-amended plants. Little improvement was seen under moderate drought stress. `Floratam' and genotype 1997-6 were placed under full sunlight or 50% to 70% shade. There was no benefit from use of silicon under shaded conditions. These findings suggest that silicon might provide improved tolerance to st. augustinegrass under severe drought stress.