Assessment of Narrow-band Canopy Spectral Reflectance and Turfgrass Performance under Drought Stress

Abstract

<jats:p>Canopy reflectance has the potential to determine turfgrass shoot status under drought stress conditions. The objective of this study was to describe the relationship of turf quality and leaf firing versus narrow-band canopy spectral reflectance within 400 to 1100 nm for different turfgrass species and cultivars under drought stress. Sods of four bermudagrasses (<jats:italic>Cynodon dactylon</jats:italic> L. × <jats:italic>C. transvaalensis)</jats:italic>, three seashore paspalums (<jats:italic>Paspalum vaginatum</jats:italic> Swartz), zoysiagrass (<jats:italic>Zoysia japonica</jats:italic>), and st. augustinegrass (<jats:italic>Stenotaphrum secundatum</jats:italic>), and three seeded tall fescues (<jats:italic>Festuca arundinacea</jats:italic>) were used. Turf quality decreased 12% to 27% and leaf firing increased 12% to 55% in 12 grasses in response to drought stress imposed over three dry-down cycles. The peak correlations occurred at 673 to 693 nm and 667 to 687 nm for turf quality and leaf firing in bermudagrasses, respectively. All three tall fescues had the strongest correlation at 671 nm for both turf quality and leaf firing. The highest correlations in the near-infrared at 750, 775, or 870 nm were found in three seashore paspalums, while at 687 to 693 nm in Zoysiagrass and st. augustinegrass. Although all grasses exhibited some correlations between canopy reflectance and turf quality or leaf firing, significant correlation coefficients (<jats:italic>r</jats:italic>) were only observed in five grasses. Multiple linear regression models based on selected wavelengths for turf quality and leaf firing were observed for 7 (turf quality) and 9 (leaf firing) grasses. Wavelengths in the photosynthetic region at 658 to 700 nm or/and near-infrared from 700 to 800 nm predominated in models of most grasses. Turf quality and leaf firing could be well predicted in tall fescue by using models, evidenced by a coefficient of determination (<jats:italic>R</jats:italic><jats:sup>2</jats:sup>) above 0.50. The results indicated that correlations of canopy reflectance versus turf quality and leaf firing varied with turfgrass species and cultivars, and the photosynthetic regions specifically from 664 to 687 nm were relatively important in determining turf quality and leaf firing in selected bermudagrass, tall fescue, zoysiagrass and st. augustinegrass under drought stress.</jats:p>

Evaluation of Remote Sensing to Measure Plant Stress in Creeping Bentgrass (Agrostis stolonifera L.) Fairways

“…The 0800 h measurements were taken before mowing to minimize the effect of mowing on the ratings. Dew was removed from the leaf surface using a dew whip, because research has shown that dew causes lower R NIR /R Red ratios and a 40 to 60% increase in visible wavelength reflectance (Pinter and Jackson, 1981; Jackson and Pinter, 1986). Measurements were collected when the shelter was over the plots.…”

“…Kuntze], and tall fescue under drought stress and in annual ryegrass, Kentucky bluegrass (Poa pratensis L.), tall fescue, and hybrid bluegrass (Poa arachnifera Torr. × P. pratensis L.) under defi cit irrigation (Jiang and Carrow, 2005;Lee and Bremer, 2006;Baghzouz et al, 2006). Refl ectance has also been correlated to visual quality in creeping bentgrass and annual ryegrass under nitrogen treatments (Kruse et al, 2006;Baghzouz et al, 2006).…”

Plant Colorants Interfere with Reflectance‐Based Vegetation Indices

“…Bremer et al (2011a) showed that models relating visual quality and NDVI were generally different for each species, cultivar, and growing season. Similarly, Jiang and Carrow (2005) reported that, although canopy reflectance can be used to evaluate drought stress, each cultivar and species they evaluated had a different predictive model. Lee et al (2011) found that these relationships also varied depending on mowing height, and they concluded that comparisons using NDVI should be limited to plots with the same species maintained at the same mowing height.…”

“…Bremer et al (2011a) showed that models relating visual quality and NDVI were generally different for each species, cultivar, and growing season. Similarly, Jiang and Carrow (2005) reported that, although canopy reflectance can be ABSTRACT Reflectance-based vegetation indices are commonly used to quantify turfgrass color, estimate chlorophyll content, and make inferences about plant health. These methods…”

Using hyperspectral radiometry to predict the green leaf area index of turfgrass

“…In turfgrass, spectral vegetation indices have been developed to evaluate visual quality, chlorophyll content, injury, and environmental stress in turfgrass (Trenholm, Carrow, and Duncan 1999;Bell et al 2002;Duncan 2003, 2004;Jiang and Carrow 2005;Bremer et al 2011aBremer et al , 2011b. In some turfgrass studies, spectral indices have been used to estimate LAI (Trenholm, Carrow, and Duncan 1999;Duncan 2003, 2004;Jiang and Carrow 2007;DaCosta and Huang 2006;Merewitz et al 2010).…”