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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.
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.
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
, nondestructive procedures (e.g., chlorophyll measurements and remote sensing) for determining crop N status ( Ziadi et al., 2008a ). Quick tests Sap tests. The measurement of NO 3 concentration in plant tissue sap extracts has been documented for a long time
achieve this objective are 1) the collection of spatial data from pre-existing conditions in the field (e.g., remote sensing, canopy size, or yield measurement), 2) the application of precise fertilizer amounts to the crop when and where needed, and 3) the
concept of optical (remote) sensing as a method to improve and automate phytotoxicity assessments of ornamental crops. Assessment of phytotoxicity in ornamental plants is typically based on visual inspection of leaves, shoots, or flowers at different
vegetation index (EVI) remote sensing method with a detailed soil water balance (SWB) analysis for 1 year in a heterogeneous landscape consisting of several plant species, planting densities, and microclimates found the EVI method to closely parallel the SWB
New technologies such as differential global positioning systems (DGPS) and geographical information systems (GIS) are making it possible to manage variability in soil properties and the microenvironment within a field. By providing information about where variability occurs and the patterns that exist in crop and soil properties, DGPS and GIS technologies have the potential of improving crop management practices. Yield monitoring systems linked to DGPS receivers are available for several types of horticultural crops and can be used in variety selection and/or improving crop management. Precision soil sampling and remote sensing technologies can be used to scout for infestations of insects, diseases, or weeds, to determine the distribution of soil nutrients, and to monitor produce quality by measuring crop vigor. Combined with variable rate application systems, precision soil sampling and remote sensing can help direct fertilizer, herbicide, pesticide, and/or fungicide applications to only those regions of the field that require soil amendments or are above threshold levels. This could result in less chemical use and improved crop performance. As with any information driven system, the data must be accurate, inexpensive to collect, and, most importantly, must become part of a decision process that results in improvements in crop yield, productivity, and/or environmental stewardship.
Major citrus blackfly (Aleurocanthus woglumi) outbreaks occur periodically in the Lower Rio Grande Valley (LRGV) of Texas, causing a reduction in citrus (Citrus sp.) tree yields. This research reports on the integration of airborne color-infrared (ACIR) imagery and geographic information system (GIS) technology for mapping citrus blackfly outbreaks appearing in this area in separate years. For this study, the 1993 and 2002 citrus blackfly infestations were mapped and compared. Outbreaks did not appear at the same sites for 1993 and 2002. In 1993, infestations occurred in the southern part of Hidalgo and Cameron counties compared with outbreaks primarily appearing in the western portion of Hidalgo County in 2002. For both years, Hidalgo County was affected more than the other citrus producing counties in the LRGV. This study demonstrated airborne remote sensing imagery integrated with GIS technology could be used to develop maps for comparing citrus blackfly infestations appearing in separate years.
Research suggests that blackleaf (a leaf disorder in grape, Vitis labrusca L.) is induced by high levels of ultra violet (UV) radiation and overall light intensity, resulting in color changes (purple-brown-black) for sun-exposed leaves of the outer canopy, and a corresponding >50% reduction in photosynthesis. Metabolic indicators (photosynthesis and leaf water potential), percent blackleaf expression, and full spectrum leaf reflectance were mapped within vineyards using global positioning system (GPS) and digital remotely-sensed images. Each image and data record was stored as an attribute associated with a specific vine location within a geographical information system (GIS). Spatial maps were created from the GIS coverages to graphically present the progression of blackleaf across vineyards throughout the season. Analysis included summary statistics such as minimum, maximum, and variation of green reflectance, within a vineyard by image capture date. Additionally, geostatistics were used to model the degree of similarity between blackleaf values as a function of their spatial location. Remote-image analysis indicated a decrease in percent greenness of about 45% between July and August, which was related to a decrease in photosynthesis and an increase in blackleaf symptom expression within the canopy. Examination of full spectral leaf reflectance indicated differences at specific wavelengths for grape leaves exposed to UV or water-deficit stress. This work suggests that remote-image and leaf spectral reflectance analysis may be a strong tool for monitoring changes in metabolism associated with plant stress.