Repositori Obert UdL

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Spatially variable pesticide application in olive groves: Evaluation of potential pesticide-savings through stochastic spatial simulation algorithms
(Elsevier, 2021-03-02) Rodríguez-Lizana , Antonio; Pereira , M. J.; Castro Ribeiro , M.; Soares , A.; Azevedo, L.; Miranda-Fuentes, Antonio; Llorens Calveras, Jordi
Site-specific management using spatial crown volume characterization can greatly reduce the amount of pesticides applied in agricultural treatments performed with air-assisted sprayers, while helping farmers achieve the European legislation on safe use of pesticides. Nevertheless, variable rate treatments in olive groves have received little attention. Thus, field research was conducted in a 20.6-ha traditional olive grove. Two attributes of the trees - tree crown volume (V) and tree projected area - were determined, using 67 samples for V and all trees of the field (1433) for tree projected area. Spatial continuity of both attributes was modelled with exponential variograms. To gain a measure of local uncertainty, stochastic simulation algorithms were applied. One hundred simulated images were obtained for tree projected area using direct sequential simulation. Tree projected area simulations were used to improve spatial prediction of V, more difficult and more expensive to obtain, taking advantage of the high linear correlation between both variables (rxy = 0.72,p < 0.001). Thus, direct sequential cosimulation was employed to predict the spatial distribution of V, obtaining 100 geostatistical realizations of V. In order to estimate the potential reduction of pesticide use in the farm with variable rate treatments, two cut-off values of V were considered (50 and 100 m3crown volume). Local uncertainty, understood as the probability of each tree belonging to a given crown volume interval was determined. Probability maps were further transformed to morphological maps and finally to variable prescription maps. Two scenarios with 2 and 3 management zones (MZs) were obtained. In comparison with a conventional phytosanitary application, the variable rate treatments could reduce the pesticide amounts by 21.3% with 2 MZs, and by 38% with 3 MZs. The joint use of V and tree projected area in stochastic sequential simulation algorithms has shown to be useful to determine MZs in olive groves.
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Open Access
Diapause and biological cycle of Cydalima perspectalis (Walker) in the eastern Pyrenees
(Wiley, 2019-10-09) López Alonso, Carmen; Eizaguirre Altuna, Matilde
Boxwood is a very important component of the natural forests of the eastern Pyrenees. In the low altitudes of these forests, the invasive species Cydalima perspectalis (Walker) causes considerable damage, and there is concern that it will migrate towards the natural forests at higher altitudes. To determine the biological parameters of the local pest population, a semiartificial diet with lyophilized powdered Buxus sempervirens L. leaves was developed. The results obtained indicate that the studied population of C. perspectalis is very similar to the native Japanese population in terms of the number of larval instars to complete development, the development rate and the critical photoperiod for the induction of diapause. It has also been demonstrated that long photoperiods can shorten the duration of larval development. The diapause induction response was classified as type I, and diapause termination was classified as type III. At the two studied temperatures, 25º and 15ºC, the larvae seemed to require a similar number of days in diapause, approximately 3 months, to spontaneously resume development; temperatures can also prompt larvae to resume development. The critical photoperiod in the study area occurs during the second half of August, varying somewhat according to temperature. The greatest defoliation is caused by the offspring of the first generation, while the majority of the larval offspring of the second generation will enter diapause. The survival of natural boxwood in this area will depend on its ability to regrow one or two years after extensive defoliation and on the adaptation of several indigenous natural enemies in the region to feed on C. Perspectalis.
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Open Access
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Differential proteomics analysis reveals that Azospirillium brasilense (Sp7) promotes virus tolerance in maize and tomato seedlings
(Springer, 2019-10-21) Lade, Sarah Boyd; Román, Carla; Cueto-Ginzo, Ana Isabel; Serrano Endolz, Luis; Sin Casas, Esther; Achón Samá, Mª Ángeles; Medina Piles, Vicente
Plant growth-promoting rhizobacteria such as Azospirillum brasilense Sp7 can protect plants against viruses but the molecular basis of this phenomenon is unclear. We therefore used differential proteomics to study two pathosystems in the presence and absence of Sp7 during early vegetative growth: tomato (Solanum lycopersicum L. cv. Boludo)/Potato virus X (PVX, KJ631111)/Sp7, and maize (Zea mays cv. B73)/Maize dwarf mosaic virus (MDMV, AM110558)/Sp7). In the maize/MDMV system, PDQuest revealed significant variations in the levels of 19 proteins compared to uninfected controls, including the upregulation of NADP-dependent malic enzyme as a form of host-specific viral anticipation, causing a simultaneous increase in the abundance of proteins related to photosynthesis and plastid functions. However, 42 proteins varied significantly in the maize/MDMV/Sp7 system, including the upregulation of radical-scavenging enzymes and proteins related to methionine metabolism, the glutathione-ascorbate cycle and photosynthesis, increasing the photosynthetic rate. In the tomato/PVX system, we observed significant variations in the levels of 58 proteins reflecting the disruption of the Calvin-Benson cycle, responses to oxidative stress and the inhibition of photosystem II (PSII) activity. We identified 26 proteins that varied in the tomato/PVX/Sp7 system; PSII and plastid proteins transiently declined but partially recovered over time as the Calvin-Benson cycle was induced to compensate. Sp7 therefore triggers induced systemic resistance in both pathosystems without affecting the virus titer, although it does delay the appearance of MDMV. The role of ribulose-1.5-bisphosphate carboxylase/oxygenase small subunit as a host target for viruses is discussed in both pathosystems.
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Understanding the spread of agriculture in the Western Mediterranean (6th-3rd millennia BC) with Machine Learning tools
(Springer Nature, 2025-01-15) Castiello, Maria Elena; Russo, Emmanuele; Martínez-Grau, Héctor; Jesus, Ana; Prats Ferrando, Georgina; Antolín i Tutusaus, Ferran
The first Neolithic farmers arrived in the Western Mediterranean area from the East. They established settlements in coastal areas and over time migrated to new environments, adapting to changing ecological and climatic conditions. While farming practices and settlements in the Western Mediterranean differ greatly from those known in the Eastern Mediterranean and central Europe, the extent to which these differences are connected to the local environment and climate is unclear. Here, we tackle this question by compiling data and proxies at a superregional and multi-scale level, including archaeobotanical information, radiocarbon dates and paleoclimatic models, then applying a machine learning approach to investigate the impact of ecological and climatic constraints on the first Neolithic humans and crops. This approach facilitates calculating the pace of spread of farming in the Western Mediterranean area, modelling and estimating the potential areas suitable for settlement location, and discriminating distinct types of crop cultivation under changing climatic conditions that characterized the period 5900 – 2300 cal. BC. The results of this study shed light onto the past climate variability and its influence on human distribution in the Western Mediterranean area, but also discriminate sensitive parameters for successful agricultural practices.