Comparative effects of kaolin and calcium carbonate on apple fruit surface temperature and leaf net CO2 assimilation

The use of reflective particles on apple fruits has been suggested as a tool to diminish its thermal charge and thus mitigate stress effects caused by high temperature. The products effectiveness is often expressed in terms of damaged fruit, however it is influenced by the sensitivity of the variety, growing conditions and application method. Therefore, it is necessary to quantify the temperature of the fruits surface (FST) achieved according to the residue deposited to determine the degree of thermal protection for each product. Moreover, the residue deposited in the canopy enhances the albedo on the leaves reduces the availability of incidental light. The goal of this work was to evaluate the efficiency of reflective particles in the reduction of superficial temperature of the fruits and its effect on net CO2 assimilation rate (ACO2 ) in apple trees (Malus domestica, Borkh). The fruits were treated with: one, two and four (1X; 2X and 4X) applications of kaolin (treatment K) or calcium carbonate (treatment C) at 2.5% P/V and untreated fruit as control. The residue effect on ACO2 was evaluated in individual leaves at 2X concentration. Both products showed a thermic protective effect as compared with control. The protection degree depended upon the concentration. The highest temperature of the control was 49.8 ºC and in these conditions kaolin was significantly more effective than carbonate, the thermic reduction was 1.9 ºC vs. 1.3 ºC at 2X and 2.5 ºC vs 2.1 ºC at 4X for kaolin and carbonate, respectively. At 1X there were no statistical differences between products. In turn ACO2 is only negatively affected under low intensities of light (< 700 mmoles m2 s-1 of PAR). Higher radiation levels compensate the shading effect over leaves and also the maximun ACO2 (Amax) was not affected.Fil: Alvarez, H. L.. Universidad Nacional del Comahue; ArgentinaFil: Di Bella, Carlos Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Clima y Agua; ArgentinaFil: Colavita, Graciela María. Universidad Nacional del Comahue; ArgentinaFil: Oricchio, P.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Clima y Agua; ArgentinaFil: Straschnoy, J.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Clima y Agua; Argentin

SPOT-VEGETATION GEOV1 biophysical parameters in semi-arid agro-ecosystems

The VEGETATION system, which has been delivering global observations of the surface on a daily basis since 1998, provides key information for regional to global climate, environmental and natural resource management applications. Just recently, VEGETATION-derived GEOV1 biophysical products (LAI, FAPAR, and FCOVER) became available for the scientific community and were evaluated in this study for semi-arid forests in the Dry Chaco ecoregion, Argentina. Indirect validation with the MODIS-derived biophysical products (MOD15A2) shows a very good temporal consistency between both products for the period 2000-2011, with a remarkably smooth behaviour of the GEOV1 products. A good relationship between both products was found in the regression analysis with an R2 of 0.826 and 0.724 for LAI and FAPAR, respectively. Using direct validation with digital hemispherical photography (DHP) and ceptometer ground measurements, a relatively small RMSE (RMSELAI ≈ 0.31 and RMSEFAPAR ≈ 0.11) was found. The novel PASTIS-57 technique, which can derive continuous plant area index (PAI) estimates from light transmittance measurements, shows a similar temporal profile to the GEOV1 LAI product with a relatively high but constant offset for the dry forest study sites and a nearly identical profile for the deforested site (R2 = 0.86). Overall, PASTIS-57, in combination with satellite-based observations, shows potentials in LAI/PAI research and ecosystem carbon studies in general, but more ground measurements taken over multiple growing seasons and vegetation types are required to confirm these findings.Fil: Raymaekers, D.. Institut National de la Recherche Agronomique; Francia. Vlaamse Instelling Voor Technologisch Onderzoek; BélgicaFil: Garcia, A.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Di Bella, Carlos Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires; ArgentinaFil: Beget, María Eugenia. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires; ArgentinaFil: Llavallol, C.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires; ArgentinaFil: Oricchio, P.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires; ArgentinaFil: Straschnoy, J.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires; ArgentinaFil: Weiss, M.. Institut National de la Recherche Agronomique; FranciaFil: Baret, F.. Institut National de la Recherche Agronomique; Franci