. By accounting for actual field conditions, this remote sensing method can provide better water requirement estimates than conventional, time-based crop coefficients ( Bausch, 1995 ; Hunsaker et al., 2005 ). Ongoing data collection programs will
Thomas J. Trout, Lee F. Johnson, and Jim Gartung
Lee Johnson and Thibaut Scholasch
Airborne multispectral image data were compared with intercepted photosynthetic photon flux (PPF) in commercial winegrape (Vitis vinifera) vineyards of Napa Valley, Calif. An empirically based calibration was applied to transform raw image pixel values to surface reflectance. Reflectance data from the red and near-infrared spectral regions were combined into a normalized difference vegetation index. Strong linear response was observed between the vegetation index and PPF interception ranging from 0.15 to 0.50. Study results suggest the possibility of using optical remote sensing to monitor and map vineyard shaded area, thus providing spatially explicit input to water budget models that invoke evapotranspiration crop coefficient based calculations.
Jason Singhurst, D. L. Creech, and J. Williams
In Texas, 5,500 native species are distributed over an area comprised of ten regional habitat types. In the Piney Woods region of east Texas, 2,300 plant species occupy 15 million acres. In east Texas, the USFWS has identified 4 species that are federally endangered and 15 that are candidates for that listing. Interest in protecting rare plant habitats and reintroducing those species into similar and appropriate ecosystem types has led to new tools in research and development. Remote sensing is one; this technology is used to derive information about the earth's land and water areas from images acquired at a distance Multispectral and spatial techniques are applied to process and interpret remote sensing imagery for the purpose of producing conventional maps, thematic maps, reource surveys, etc., in the fields of agriculture, botany, archeology, forestry, geography, geology. and others. Remote sensing is used to classify vegetation, interpret forest photogrammetry, estimate timber production, and identify crops, individual plants and leaf structure. This specific project was initiated to determine the potential of remote sensing as a tool to locate known and new rare plant communities in east Texas. To develop benchmark data, a Daedalus scanner image of a previously surveyed and AutoCAD® mapped area, the Vista forest on the SFASU campus, was utilized to develop correlations between imagery, vegetation types and species. By inserting various scan images under the Vista forest AutoCAD® map, known tree species were analyzed through their specific spectral emission characteristics across nine bands. This pilot project has indicated that it is simple to separate pines from hardwoods and illustrate major land use features. However, separation at the species level or groups of species has not been achieved. This paper will trace the history of this project, describe problems and obstacles encountered, and make recommendations for future strategies.
James A. Poss, Catherine M. Grieve, Walter B. Russell, and Stacy A. Bonos
Six cultivars or selections of Kentucky bluegrass (Poa pratensis L.) exposed to salinity stress were evaluated with ground-based remote sensing plant reflectance (R) measurements at wavelengths ranging from 350 nm to 2500 nm. Cultivars Baron, Brilliant, Cabernet, Eagleton, Midnight, and the selection A01-856, a Texas × Kentucky bluegrass hybrid (Poa arachnifera × P. pratensis), were grown outdoors from vegetative clones in a gravelly-sand medium from Apr. to Sept. 2005, in Riverside, Calif., at soil water salinities ranging from 2 to 22 dSm-1. Two Normalized Difference Vegetation Indicies (NDVI) were developed based on: 1) canopy reflectance in the visible domain at 695 and 670 nm and 2) an average of eight wavelengths in mid-infrared [Ravg = (R:1500, R:1680, R:1740, R:1940, R:2050, R:2170, R:2290, and R:2470 nm/8)] and the reference wavelength (670 nm). Both NDVIs were significantly sensitive to salinity-induced changes in grass canopies and were able to discriminate significantly between the salt-tolerant cultivars (`Baron', `Brilliant', and `Eagleton') and salt-sensitive cultivars (`Cabernet', `Midnight', and A01-856). Another remotely sensed index, based on the derivative of the absorbance (1/R) in the red-edge region between 600 and 800 nm, also generated a similar ranking to the NDVIs and biomass for the six cultivars. These findings indicate that remote sensing of canopy reflectance may represent an additional tool to evaluate and explain the biophysical or physiological differences among Kentucky bluegrass cultivars related to salt tolerance.
The initial surge of interest in precision agriculture technologies exhibited by innovators and early adopters involved in crop production appears to have crossed over an important threshold. As valuable field experience increases and learning by doing advances, successful applications of management practices are being identified even though few are adequately documented with economic benefits. Access to accurate information pertaining to applications of site-specific management would be expected to motivate more producers to incorporate technology uses with crop production. This next group of producers has been watching technology developments as they preferred to avoid risk and wait for identifiable benefits. Waiting for detailed case studies involving high value fruits and vegetables may be the wrong approach to take. Fierce competition and strict confidentiality are expected in the fresh market industry. Thus, personal experience with technology becomes more relevant to innovative producers than published literature. This is especially true in California where 350 different crops are produced. High resolution imagery from digital aerial and satellite sensors has been used in crop production in California to identify plant stress, direct plant tissue and soil sampling efforts, and provide information for analysis and interpretation of crop growth. Examples of remote sensing imagery that have provided valuable in-season progress reports will be identified. The focus will be on practice, not theory, as seen from an industry perspective.
Noboru Muramatsu, Naoki Sakurai, Naoki Wada, Ryoichi Yamamoto, Keiichi Tanaka, Toshikazu Asakura, Yuko Ishikawa-Takano, and Donald J. Nevins
Developmental changes in fruit texture during ripening were determined based on remote sensing of surface vibrations. The technique was evaluated with fruit having a range of firmness and textural characteristics including kiwifruit [Actinidia deliciosa (A. Chev.) Liang et Ferguson, `Hayward'] treated with ethylene, apple (Malus ×domestica Borkh. `Ourei') stored at 10 or 20 °C and persimmon (Diospyros kaki L. `Fuyu') stored at 10 °C. In each case fruit were placed on a stage capable of imparting sine wave vibrations with frequencies ranging from 5 to 2,000 Hz. The vibration transmitted through the fruit to the top surface was precisely measured without any direct contact with the Doppler laser vibrometer. The perceived fruit surface signal was corrected by subtraction of the stage vibration based on an accelerometer signal, hence the true vibrational signal of the fruit mass was determined. The phase shift at selected frequencies was based on the difference between the input and output vibration. The phase shift significantly increased in the range of 1,200 to 1,600 Hz in all three kinds of fruit analyzed as a function of maturation. The resonance frequency, peak height, and peak width of second resonance peak were also determined. The resonance frequency decreased in all fruit as a function of maturation. In apple, the peak height decreased as a function of storage duration, but in kiwifruit and persimmon the peak height fluctuated and a consistent pattern in this particular parameter was not observed. The amplitude of vibration decreased as a function of maturation when the imposed vibration exceeded 1,200 Hz. Data clearly showed that the Doppler laser vibrometer is capable of detecting the phase shift and vibration amplitude of fruit, and can be used as a versatile remote sensory tool for determining fruit firmness and for evaluations of maturity.
Eileen M. Perry, Ian Goodwin, and David Cornwall
( Fitzgerald et al., 2010 ; Perry et al., 2012 ) shows that using remote sensing to estimate N in wheat canopies is effective, and calculation of the Canopy Chlorophyll Content Index (CCCI) from canopy spectral reflectance of wheat showed good correlation with
Jean-Pierre Goffart, Marguerite Olivier, and Marc Frankinet
potato CNS. At the canopy scale, most of the usable methods for crop monitoring are noninvasive, relying on measurements of light transmitted below the canopy or reflected above it. They belong to the remote sensing methodology (based on spectral canopy
Derald A. Harp and Edward L. McWilliams
As the World Wide Web (WWW) expands, information is rapidly becoming more accessible. Using satellite data previously required high-end computers running complex imaging software, sophisticated downloading equipment, and high monetary support. Satellite data is now available on the internet for little or no cost and can be handled on standard desktop computers using common software programs. The purpose of our project was to determine the availability and cost of different types of data and how this data may benefit horticultural instruction. Satellite data currently is archived at NASA, NOAA, the Department of Defense, the US Geological Survey, and various meteorological departments throughout the world. Satellite data such as large-scale thermal imagery can be used to determine microclimate effects within urban areas, including the cooling effects of urban plants. Natural Density Vegetation Index (NDVI) imagery can indicate changes in vegetational cover or give general indications of plant health in large areas. NASA photographic imagery can show the effects of erosion on a large scale. Higher resolution imagery can give indications of plant stresses in large plantings such as orchards or vegetable plots.
Tara H. Hayes and Caula A. Beyl
Flowering dogwoods. (Cornus florida L.) have been attacked by dogwood anthracnose. In vivo leaf reflectance values of infected leaves from Summer 1993, Fall 1993, and Fall 1994 were obtained using a spectroreflectometer at wavelengths from 300 to 2500 nm to determine what wavelengths could best detect differences between dead and healthy leaves. At -those wavelengths, a mathematical expression was devised and used to calculate the predicted reflectance value for that percent disease severity (Rexp50%). The predicted reflectance values were compared with actual mean reflectance values (Rmean) obtained from leaves with up to 50% disease severity achieving correlations of 0.95, 0.66, and 0.84, for the Summer and Fall 1993, and Fall 1994, respectively. For Fall 1994, actual disease severity values were obtained by scanning and image analysis to compute an expected reflectance for these actual percentages (Rreal%) for a correlation value of 0.98.