Prediction of available water in creeping bentgrass and annual bluegrass using visible and near infrared spectroscopy.

摘要

Visible and near infrared spectroscopy (VIS/NIRS) was evaluated as a rapid and indirect analysis technique to determine water status of monostands of creeping bentgrass (Agrostis palustris Huds. cv. ‘Penncross’) and annual bluegrass (Poa annua var. reptans) grown in lysimeters containing either an Owosso sandy loam (fine-loamy, mixed, mesic Typic Hapludalfs) or a United States Golf Association (USGA) specification sand:peat (90:10, v/v). Every two days, volumetric soil moisture content (VSMC) and evapotranspiration (ET) were determined for each lysimeter by time domain reflectometry (TDR) and gravimetric analysis, respectively. At the same time, a field modified monochromator measured reflectance from the turfgrass canopy from 400 to 2500 nm at 2-nm increments. The explained variance (R2 ) for the relationship between reflectance and water status ranged from 0.59 to 0.92 for TDR and 0.39 to 0.97 for ET. Higher R 2 values were obtained under greenhouse compared to field conditions where experimental error was minimized. Wavelengths that contributed most to detection of water status occurred at 464 and 690 nm in the VIS region, and 1430 and 1900 nm in the NIR region which corresponds to absorption peaks for free water.