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Weed Technology
Studies were conducted from 1993 through 1995 to determine broomrape control from imazethapyr app... more Studies were conducted from 1993 through 1995 to determine broomrape control from imazethapyr applied to pea seeds. Soaking seeds for 1 to 10 min in 0.0001% to 1% imazethapyr (Pursuit-10) solutions or coating seeds with imazethapyr at 0.025 to 0.30 mg/g (herbicide/seed, equivalent to 5 to 60 g/ha for a seeding rate of 200 kg/ha) did not affect seed germination or crop emergence and growth. Broomrape control with imazethapyr applied by coating seed at 0.1 to 0.2 mg/g (herbicide/seed, 20 to 40 g/ha) or by soaking seeds for 5 min in 0.1% to 1% imazethapyr solution was from 75 to 80% and 50 to 70%, respectively. Pea biomass and seed yield increased, compared to broomrape-infested nontreated control, when pea seeds were treated with imazethapyr and imazapyr at 5 g/ha was applied late postemergence, as a result of the excellent broomrape control.
Journal of the American Society for Horticultural Science
Hyperspectral reflectance curves of olive (Olea europaea L.) trees under different N or K treatme... more Hyperspectral reflectance curves of olive (Olea europaea L.) trees under different N or K treatments, and the best wavelengths or vegetation indices to discriminate between different N or K applications using discriminant analysis were investigated. Field hyperspectral studies were carried out in two olive orchards located at Cabra and Lucena (southern Spain) for N and K experiments, respectively, in 2004 and 2005. At Cabra, olive trees have been fertilized since 1993, and annual applications of N per tree consisted of 0 kg (N0), 0.5 kg [N1 (normal)], or 1 kg [N2 (high)]. At Lucena, olive trees were fertilized since 1997, with 0%, 2.5%, and 5% K2CO3. Hyperspectral measurements were collected for each N and K treatments using a handheld field spectroradiometer (spectral range, 400–900 nm) in July of both years. To determine the nutritional status, a leaf analysis was carried out in July 2004 and 2005 at both locations. At Cabra, leaf N concentrations under N0 treatment were below the...
Journal of the American Society for Horticultural Science
In Spain, water for agricultural use represents about 85% of the total water demand, and irrigate... more In Spain, water for agricultural use represents about 85% of the total water demand, and irrigated crop production constitutes a major contribution to the country's economy. Field studies were conducted to evaluate the potential of multispectral reflectance and seven vegetation indices in the visible and near-infrared spectral range for discriminating and classifying bare soil and several horticultural irrigated crops at different dates. This is the first step of a broader project with the overall goal of using satellite imagery with high spatial and multispectral resolutions for mapping irrigated crops to improve agricultural water use. On-ground reflectance data of bare soil and annual herbaceous crops [garlic (Allium sativum), onion (Allium cepa), sunflower (Helianthus annuus), bean (Vicia faba), maize (Zea mays), potato (Solanum tuberosum), winter wheat (Triticum aestivum), melon (Cucumis melo), watermelon (Citrillus lanatus), and cotton (Gossypium hirsutum)], perennial herb...
Weed Technology
Field studies were conducted from 1991 through 1994 in several locations of Southern Spain to det... more Field studies were conducted from 1991 through 1994 in several locations of Southern Spain to determine the efficacy of imazapyr as late postemergence application in sunflower for broomrape control and the crop response to this herbicide under weed-free conditions. Single applications of imazapyr at 10 to 15 g/ha on sunflower plants at about the V12 (12 leaves) to V19 (19 leaves) growth stages, infected with broomrape plants at the predominant growth stages “c” (small nodule with shoot bud visible) and “d” (shoot bud and roots well developed), resulted in effective control without damaging the crop. Double applications of imazapyr at 10 + 10 g/ha at about the same crop growth stages V12 to V19, at a time interval of 12 to 14 d between single applications, were also efficacious and well tolerated by the crop. The same herbicide treatments applied to weed-free sunflower did not adversely affect the biomass, head diameter or yield of the crop as compared with the nontreated check. As a...
Weed Science, 2006
Field research was conducted to determine the potential of hyperspectral and multispectral imager... more Field research was conducted to determine the potential of hyperspectral and multispectral imagery for late-season discrimination and mapping of grass weed infestations in wheat. Differences in reflectance between weed-free wheat and wild oat, canarygrass, and ryegrass were statistically significant in most 25-nm-wide wavebands in the 400- and 900-nm spectrum, mainly due to their differential maturation. Visible (blue, B; green, G; red, R) and near infrared (NIR) wavebands and five vegetation indices: Normalized Difference Vegetation Index (NDVI), Ratio Vegetation Index (RVI), R/B, NIR-R and (R − G)/(R + G), showed potential for discriminating grass weeds and wheat. The efficiency of these wavebands and indices were studied by using color and color-infrared aerial images taken over three naturally infested fields. In StaCruz, areas infested with wild oat and canarygrass patches were discriminated using the indices R, NIR, and NDVI with overall accuracies (OA) of 0.85 to 0.90. In Flo...
European Journal of Agronomy
RESUMEN La clasificación de los diferentes cultivos de regadío según su desarrollo fenológico con... more RESUMEN La clasificación de los diferentes cultivos de regadío según su desarrollo fenológico con técnicas de Teledetección es importante para estimar el área que ocupan, sus requerimientos hídricos, y realizar un seguimiento exhaustivo de las prácticas de regadío en grandes superficies de terrero. En el Valle del Guadalquivir, dichos cultivos presentan gran diversidad y suelen sembrarse en parcelas < 1 ha. Para su discriminación utilizamos 3 imágenes multiespectrales de satélite QuickBird tomadas en Posadas (Córdoba) en primavera, principios y finales de verano 2007 (bandas: Azul, Verde, Roja e Infrarrojo-cercano; 84 km 2 cada una). Los principales usos de suelo presentes en las tres fechas fueron: suelo desnudo, rastrojo, cultivos herbáceos (dependiendo de la época del año: ajos, alfalfa, algodón, espárragos, girasol, habas, maíz, cucurbitáceas, trigo y patatas), leñosos (cítricos), suelo urbano, carreteras, agua (río). Se tomaron datos con DGPS para muestreos "verdad-terr...
The software SARI® has been developed to implement precision agriculture strategies through remot... more The software SARI® has been developed to implement precision agriculture strategies through remote sensing imagery. It is written in IDL® and works as an add-on of ENVI®. It has been designed to divide remotely sensed imagery into "micro-images", each corresponding to a small area ("micro-plot"), and to determine the quantitative agronomic and/or environmental biotic (i.e. weeds, pathogens) and/or non-biotic (i.e. nutrient levels) indicator/s of each micro-plot. Spatial patches aggregation of biotic/ non-biotic factors and their corresponding pesticide/ fertilizer variable rates application prescription maps can be achieved through SARI® from remote images and complementary ground-taken data. An example of SARI® implementation in the remote image of a pea's field infested by the parasitic weed/ pathogen Orobanche crenata Forsk. at Montalban (Cordoba, Spain) is described. Infestation pressure between micro-plots greatly varies from virtually parasitic weed fre...
Satellite and airborne remote sensed images cover large areas, which normally include dozens of a... more Satellite and airborne remote sensed images cover large areas, which normally include dozens of agricultural plots. Agricultural operations such as sowing, fertilization, and pesticide applications are designed for the whole plot area, i.e. 10 to 30 ha, or through precision agriculture. This takes into account the spatial variability of biotic and of abiotic factors and uses diverse technologies to apply inputs at variable rates, fitted to the needs of each small defined area, i.e. 25 to 200 m 2 ("microplots"). Therefore, using remote sensing for precision agriculture the first step is to isolate the image of the field in which to implement the desired action, and subsequently sectioned it into "microimages" each corresponding to a microplots, and then interpreting the adequate agri-environmental indicator for the desired operation for each microplot. Once isolated a selected agricultural plot where site-specific operations are to be implemented, the following pr...
Weed Technology
Studies were conducted from 1993 through 1995 to determine broomrape control from imazethapyr app... more Studies were conducted from 1993 through 1995 to determine broomrape control from imazethapyr applied to pea seeds. Soaking seeds for 1 to 10 min in 0.0001% to 1% imazethapyr (Pursuit-10) solutions or coating seeds with imazethapyr at 0.025 to 0.30 mg/g (herbicide/seed, equivalent to 5 to 60 g/ha for a seeding rate of 200 kg/ha) did not affect seed germination or crop emergence and growth. Broomrape control with imazethapyr applied by coating seed at 0.1 to 0.2 mg/g (herbicide/seed, 20 to 40 g/ha) or by soaking seeds for 5 min in 0.1% to 1% imazethapyr solution was from 75 to 80% and 50 to 70%, respectively. Pea biomass and seed yield increased, compared to broomrape-infested nontreated control, when pea seeds were treated with imazethapyr and imazapyr at 5 g/ha was applied late postemergence, as a result of the excellent broomrape control.
Journal of the American Society for Horticultural Science
Hyperspectral reflectance curves of olive (Olea europaea L.) trees under different N or K treatme... more Hyperspectral reflectance curves of olive (Olea europaea L.) trees under different N or K treatments, and the best wavelengths or vegetation indices to discriminate between different N or K applications using discriminant analysis were investigated. Field hyperspectral studies were carried out in two olive orchards located at Cabra and Lucena (southern Spain) for N and K experiments, respectively, in 2004 and 2005. At Cabra, olive trees have been fertilized since 1993, and annual applications of N per tree consisted of 0 kg (N0), 0.5 kg [N1 (normal)], or 1 kg [N2 (high)]. At Lucena, olive trees were fertilized since 1997, with 0%, 2.5%, and 5% K2CO3. Hyperspectral measurements were collected for each N and K treatments using a handheld field spectroradiometer (spectral range, 400–900 nm) in July of both years. To determine the nutritional status, a leaf analysis was carried out in July 2004 and 2005 at both locations. At Cabra, leaf N concentrations under N0 treatment were below the...
Journal of the American Society for Horticultural Science
In Spain, water for agricultural use represents about 85% of the total water demand, and irrigate... more In Spain, water for agricultural use represents about 85% of the total water demand, and irrigated crop production constitutes a major contribution to the country's economy. Field studies were conducted to evaluate the potential of multispectral reflectance and seven vegetation indices in the visible and near-infrared spectral range for discriminating and classifying bare soil and several horticultural irrigated crops at different dates. This is the first step of a broader project with the overall goal of using satellite imagery with high spatial and multispectral resolutions for mapping irrigated crops to improve agricultural water use. On-ground reflectance data of bare soil and annual herbaceous crops [garlic (Allium sativum), onion (Allium cepa), sunflower (Helianthus annuus), bean (Vicia faba), maize (Zea mays), potato (Solanum tuberosum), winter wheat (Triticum aestivum), melon (Cucumis melo), watermelon (Citrillus lanatus), and cotton (Gossypium hirsutum)], perennial herb...
Weed Technology
Field studies were conducted from 1991 through 1994 in several locations of Southern Spain to det... more Field studies were conducted from 1991 through 1994 in several locations of Southern Spain to determine the efficacy of imazapyr as late postemergence application in sunflower for broomrape control and the crop response to this herbicide under weed-free conditions. Single applications of imazapyr at 10 to 15 g/ha on sunflower plants at about the V12 (12 leaves) to V19 (19 leaves) growth stages, infected with broomrape plants at the predominant growth stages “c” (small nodule with shoot bud visible) and “d” (shoot bud and roots well developed), resulted in effective control without damaging the crop. Double applications of imazapyr at 10 + 10 g/ha at about the same crop growth stages V12 to V19, at a time interval of 12 to 14 d between single applications, were also efficacious and well tolerated by the crop. The same herbicide treatments applied to weed-free sunflower did not adversely affect the biomass, head diameter or yield of the crop as compared with the nontreated check. As a...
Weed Science, 2006
Field research was conducted to determine the potential of hyperspectral and multispectral imager... more Field research was conducted to determine the potential of hyperspectral and multispectral imagery for late-season discrimination and mapping of grass weed infestations in wheat. Differences in reflectance between weed-free wheat and wild oat, canarygrass, and ryegrass were statistically significant in most 25-nm-wide wavebands in the 400- and 900-nm spectrum, mainly due to their differential maturation. Visible (blue, B; green, G; red, R) and near infrared (NIR) wavebands and five vegetation indices: Normalized Difference Vegetation Index (NDVI), Ratio Vegetation Index (RVI), R/B, NIR-R and (R − G)/(R + G), showed potential for discriminating grass weeds and wheat. The efficiency of these wavebands and indices were studied by using color and color-infrared aerial images taken over three naturally infested fields. In StaCruz, areas infested with wild oat and canarygrass patches were discriminated using the indices R, NIR, and NDVI with overall accuracies (OA) of 0.85 to 0.90. In Flo...
European Journal of Agronomy
RESUMEN La clasificación de los diferentes cultivos de regadío según su desarrollo fenológico con... more RESUMEN La clasificación de los diferentes cultivos de regadío según su desarrollo fenológico con técnicas de Teledetección es importante para estimar el área que ocupan, sus requerimientos hídricos, y realizar un seguimiento exhaustivo de las prácticas de regadío en grandes superficies de terrero. En el Valle del Guadalquivir, dichos cultivos presentan gran diversidad y suelen sembrarse en parcelas < 1 ha. Para su discriminación utilizamos 3 imágenes multiespectrales de satélite QuickBird tomadas en Posadas (Córdoba) en primavera, principios y finales de verano 2007 (bandas: Azul, Verde, Roja e Infrarrojo-cercano; 84 km 2 cada una). Los principales usos de suelo presentes en las tres fechas fueron: suelo desnudo, rastrojo, cultivos herbáceos (dependiendo de la época del año: ajos, alfalfa, algodón, espárragos, girasol, habas, maíz, cucurbitáceas, trigo y patatas), leñosos (cítricos), suelo urbano, carreteras, agua (río). Se tomaron datos con DGPS para muestreos "verdad-terr...
The software SARI® has been developed to implement precision agriculture strategies through remot... more The software SARI® has been developed to implement precision agriculture strategies through remote sensing imagery. It is written in IDL® and works as an add-on of ENVI®. It has been designed to divide remotely sensed imagery into "micro-images", each corresponding to a small area ("micro-plot"), and to determine the quantitative agronomic and/or environmental biotic (i.e. weeds, pathogens) and/or non-biotic (i.e. nutrient levels) indicator/s of each micro-plot. Spatial patches aggregation of biotic/ non-biotic factors and their corresponding pesticide/ fertilizer variable rates application prescription maps can be achieved through SARI® from remote images and complementary ground-taken data. An example of SARI® implementation in the remote image of a pea's field infested by the parasitic weed/ pathogen Orobanche crenata Forsk. at Montalban (Cordoba, Spain) is described. Infestation pressure between micro-plots greatly varies from virtually parasitic weed fre...
Satellite and airborne remote sensed images cover large areas, which normally include dozens of a... more Satellite and airborne remote sensed images cover large areas, which normally include dozens of agricultural plots. Agricultural operations such as sowing, fertilization, and pesticide applications are designed for the whole plot area, i.e. 10 to 30 ha, or through precision agriculture. This takes into account the spatial variability of biotic and of abiotic factors and uses diverse technologies to apply inputs at variable rates, fitted to the needs of each small defined area, i.e. 25 to 200 m 2 ("microplots"). Therefore, using remote sensing for precision agriculture the first step is to isolate the image of the field in which to implement the desired action, and subsequently sectioned it into "microimages" each corresponding to a microplots, and then interpreting the adequate agri-environmental indicator for the desired operation for each microplot. Once isolated a selected agricultural plot where site-specific operations are to be implemented, the following pr...