, 1999a ). However, a wide range of relative shade tolerance exists between turfgrass species ( Barrios et al., 1986 ; McBee and Holt, 1966 ; Morton et al., 1991 ; Qian and Engelke, 1999a , 1999c ; Qian et al., 1998 ; Tegg and Lane, 2004 ; Winstead
Bradley S. Sladek, Gerald M. Henry and Dick L. Auld
Jeffrey C. Dunne, W. Casey Reynolds, Grady L. Miller, Consuelo Arellano, Rick L. Brandenburg, A. Schoeman, Fred H. Yelverton and Susana R. Milla-Lewis
trees and/or other structural objects ( Beard, 1973 ) and of the warm-season turfgrasses typically used in the south, bermudagrass exhibits the poorest shade tolerance ( Dudeck and Peacock, 1992 ). The effects of shade can elicit profound physiological
Laurie E. Trenholm and Russell T. Nagata
The objectives of this research were to rank the relative shade tolerance of some new st. augustinegrass (Stenotaphrum secundatum) cultivars and to determine what levels of shade the various cultivars can tolerate. Two consecutive studies were conducted in a glasshouse at the University of Florida Turfgrass Research Envirotron. Cultivars tested were `Bitter Blue', `Floratam', `Palmetto', `Seville', and `1997-6'. Grasses were grown in full sun or under shade structures that provided 30%, 50%, or 70% shade. In trial 1, `Seville' and `1997-6' generally provided best performance under increasing shade, with worst responses seen in `Floratam'. `Seville' and `1997-6' were predicted to maintain an acceptable quality rating of 6 at all shade levels. In trial 2, `Floratam' again had lowest visual quality scores. At 30% shade, `Seville', `Palmetto', and `Bitter Blue' ranked in the highest category, while only `Seville' and `Bitter Blue' had highest rankings at 50% shade. Reduced density was a major factor in turf decline as shade increased. Most of the cultivars performed best under some degree of shade. With the exception of `Floratam', acceptable visual scores were maintained at shade levels exceeding 60% in trial 1 and up to 61% in trial 2.
Laurie E. Trenholm, Lawrence E. Datnoff and Russell T. Nagata
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 (CaSiO3) was pre-incorporated into pots with commercial potting soil at the rate of 3.36 kg·ha-1 (0.069 lb/1000 ft2). `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.
Tara E. Paranick and N. Suzanne Lang
Shaded environments present major obstacles for establishing high quality, persistent, and resistant turfs. Exogenous fructose applications are being examined as a potential method to counteract the effects of shade on turf. This work examines the effectiveness of fructose applications under different light levels on two fine leaf fescue cultivars: chewings fescue (Festucarubra var. commutata) `SR5100' and creeping red fescue (Festucarubra var. rubra) `Dawson'. The experiment was conducted at Michigan State University, East Lansing, inside a simulated dome environment. The experiment was a randomized complete-block design that began 21 Oct. 2004 with two main factors: light and fructose. There were three light treatments: ambient light (shaded); supplemental high light; and supplemental low light. Fructose (0% or 1.25% weight/volume), dissolved in water with an organosilicone adjuvant, was applied once per week. Quality and color ratings, clippings, core samples, density, and leaf reflectance were recorded. In addition, light response curves (LRC) were taken inside an Econoair®
growth chamber using a LI-COR-6400® on the fine fescues, kentucky bluegrass (Poa pratensis) `Cynthia', and bermudagrass (Cyondon dactylon) `Princess'. Preliminary results show that fructose had no significant effect in each light treatment for turf quality and color. However, fructose had a significant impact on clipping weights and density. The LRC specified the required and potential carbon needs as well as indicated the threshold levels, respectively, by species. The impact of fructose alone and in combination with supplemental light on photosynthesis efficiency will be presented.
Ben Wherley, Ambika Chandra, Anthony Genovesi, Mason Kearns, Tim Pepper and Jim Thomas
, 1973 ; Stier and Gardner, 2008 ); however, there is limited published information pertaining to comparative shade tolerance of st. augustinegrass. Trenholm and Nagata (2005) compared performance of five st. augustinegrass cultivars in mild to
Xiaoya Cai, Laurie E. Trenholm, Jason Kruse and Jerry B. Sartain
tolerance than many other warm-season grasses ( Busey, 2003 ). There are many commonly produced cultivars of st. augustinegrass, which show different physiological and morphological responses to shade. Peacock and Dudeck (1981) reported that ‘Bitter Blue
Meghyn Meeks, Ambika Chandra and Ben G. Wherley
Shade tolerance is an important factor for selecting turfgrasses for home lawns and recreational facilities. Beard (1973) estimated that 20% to 25% of established turfgrass stands are impacted by some type of light restriction. Cool-season (C 3
Kenton W. Peterson, Jack D. Fry and Dale J. Bremer
throughout the transition zone. The lower input requirements of zoysiagrass compared with other available turfgrasses make it a desirable choice for use as a turfgrass in this region ( Fry and Huang, 2004 ). Zoysiagrasses vary in shade tolerance. In general
James P. Syvertsen, Juan C. Melgar and Francisco García-Sánchez
type, elevated CO 2 , and shade to modify growth and water use of salinized citrus and to link high WUE with low Cl − accumulation and salinity tolerance. Although higher salinities over longer durations may have elicited different responses, it is