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Libertad Mascarini, Gabriel A. Lorenzo, and Fernando Vilella

In roses (Rosa ×hybrida L.), the bending of branches is a technique that modifies the canopy of the plant and could affect such parameters as the leaf area index (LAI), the quality of reflected light, and the water index (WI) of the plant. The measurement of spectral reflectance with remote sensors is a nondestructive, quick, and simple method to study these parameters. The aim of this paper is to quantify the modification of reflected radiation quality, the LAI and the water index of the plant with different canopies, and its impact on flowering and the number and quality of flowers produced. In R. ×hybrida `Terracotta', using the spectral crop reflectance, the red: far red ratio [red (R) = 680 nm; far red (FR) = 730 nm], percentage of blue light of reflected radiation, and vegetation indices [normalized difference vegetation index (NDVI), simple ratio index (SRI), water index (WI)] were calculated in two architectural managements: traditional (upright hedge) and bent shoot. NDVI had a greater correlation with LAI than SRI (r2 = 0.98 and 0.85, respectively), but SRI was more reliable for LAI values of 1 to 3.5. The bent shoot system compared to the traditional one decreased the R:FR ratio of reflected radiation and increased LAI and plant water content. These changes were related to a higher commercial quality of the flowers (longer flowering shoots with a larger stem diameter and fresh weight), although there was no significant difference in the number of flowers harvested. The period that showed the largest difference in the quality of the flower using the bent shoot system had a LAI of 2.8 vs. 1.8 with traditional management and a marked reduction in the R:FR of the light reflected by bent plants. The bent shoot system advanced the peak production by 1 month at the end of winter and improved the flowers at a time when sun radiation is limiting factor for production.

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Yiwei Jiang, Huifen Liu, and Van Cline

needed. As a result of the potential variations in drought response of turfgrass in the field, the use of multiple remote sensors to detect changes in canopy temperature and reflectance patterns may allow turfgrass performance under water deficit

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Francisca López-Granados, M. Teresa Gómez-Casero, José M. Peña-Barragán, Montserrat Jurado-Expósito, and Luis García-Torres

, and it can be measured by on-ground or remote sensors. In fact, plant species have been discriminated by exploiting reflectance differences based on their canopy structure ( Brown et al., 1994 ; Jurado-Expósito et al., 2003 ) or distinctive

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Joan Lordan, Miquel Pascual, Francisco Fonseca, Víctor Montilla, Josep Papió, Josep Rufat, and Josep M. Villar

. However, as an indirect method to estimate the LAI, it requires several measurements to characterize the crop canopy. Over the last 25 years, precision agriculture has been introduced in many areas of the world along with the arrival of remote sensors