Examinando por Autor "Ruiz-Valenzuela, Luis"
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Ítem A new aerobiological indicator to optimize the prediction of the olive crop yield in intensive farming areas of southern Spain(Elsevier, 2019-06) Aguilera-Padilla, Fátima; Ruiz-Valenzuela, LuisIn the present study, bio-meteorological regression models for forecasting the fruit produced by the olive trees in Jaen (southern Spain), the province with the largest extension of olive groves in the world, were revised and improved. The new forecasting models were constructed using partial least-squares regression, taking the annual olive yield as the dependent variable and several aerobiological and meteorological parameters as the independent variables. The models were validated following a full cross-validation method. A 23-year period (1994–2016) was used. The number of days with pollen concentrations ≥400 pollen grains m−3 was revealed as a newfangled predictive variable to accurately predict the olive harvest in this area, being included in the forecasting model with the highest determination coefficient value (R2 = 0.89). Weather-related variables such as the cumulative precipitation from October to December of the previous year or the mean maximum temperature from January to March were also factors of particular importance on crop production. The new model proposed provides early and effective olive crop forecasting by using independent variables which can be easily obtained towards the middle of June, also incorporating to the model the phenological variability associated with changes in the local weather. The approach shown in this study readily could be applied to any potential new situation and to be extensible to other similar olive growing areas across the Mediterranean region.Ítem Airborne-pollen maps for olive-growing areas throughout the Mediterranean region: spatio-temporal interpretation(Springer, 2015) Aguilera-Padilla, Fátima; Ben-Dhiab, Alí; Msallem, Monji; Orlandi, Fabio; Bonofiglio, Tommaso; Ruiz-Valenzuela, Luis; Galán-Soldevilla, Carmen; Díaz-de-la-Guardia, Consuelo; Giannelli, Angelo; Trigo, María Mar; García-Mozo, Herminia; Perez-Badia, Rosa; Fornaciari, MarcoThe aim of this study was the elaboration and the spatio-temporal interpretation of Olea europaea L. airborne-pollen maps across the main olive cultivation areas within the Mediterranean basin (i.e. Tunisia, Spain, Italy). The study was performed using aerobiological databases recorded from 27 georeferenced study sites. Maps were elaborated for different 10-day period through spring and summer: 1, 10, 20, 30 April; 10, 20, 30 May; 9, 19, 30 June; and 10 July. Average pollen counts in each study site were considered for the 13-year period from 1999 to 2011. Both these 10-day period of pollen emission data and the geographical coordinates were used as variables in the elaboration of the 10-day period maps. The ‘Natural Neighbour’ interpolation method was used. The statistical relationship between spatial location and maximum pollen emission was studied using linear regression and cluster analyses. The airborne-pollen maps show a spatio-temporal pattern in the pollen season. The maximum pollen emission is progressively delayed with northward changes in latitude, and the classification of the Olea maximum pollen emission date into four latitudinal categories is defined. The maximum Olea pollen concentrations were mainly recorded around 20 May. Early flowering in Tunisia coastal zones can indicate the onset of the olive pollen release season in the occidental Mediterranean region, while the central olive-growing areas in Italy can indicate the end of the olive pollen release season. These maps give information of the major risk days to the people who are allergic to olive pollen.Ítem Analysis and interpretation of long temporal trends in cumulative temperatures and olive reproductive features using a seasonal trend decomposition procedure(Elsevier, 2015-04) Aguilera-Padilla, Fátima; Orlandi, Fabio; Ruiz-Valenzuela, Luis; Msallem, Monji; Fornaciari, MarcoThe aim of the present study was to analyse long temporal trends in cumulative temperatures and olive (Olea europaea L.) reproductive features, including full flowering dates and daily pollen concentrations, in three Mediterranean areas. The study used a 19-year database (1993–2011) of pollen and temperature records from the sites of Perugia (Italy), Jaen (Spain) and Zarzis (Tunisia). The analysis of long-term trends in both temperatures and olive reproductive cycles was performed using two approaches. The first is a seasonal trend decomposition procedure based on locally weighted regression (Loess) smoothing (STL), which is a filtering procedure for decomposing seasonal time series into three components: trend, seasonal, and remainder. The second approach analyses the trend components using Mann–Kendall tests. Loess smoothing provides a good approach to study long-term meteorological and phenological trends. Removing both the seasonal and the remainder components, the real rising trends over time can be interpreted. In general, a significant and clear increasing trend in the spring cumulative temperature was revealed, with decreasing trends in the full flowering dates of the olive trees located in Perugia and Zarzis. Moreover, olive pollen emissions are decreasing, which is more evident for the highest and lowest latitudinal study sites. These data indicate that increasing temperatures result in both anticipation of olive tree flowering and lower airborne pollen emission. As a consequence, the lower atmospheric pollen levels will reduce human exposure to olive pollen in the Mediterranean area. These patterns are evident for the highest and lowest latitudes, but not clear in the intermediate latitudes of Jaen, where further analysis is needed.Ítem Better prediction of Mediterranean olive production using pollen-based models(Springer France, 2014) Oteros-Moreno, José Antonio; Orlandi, Fabio; García-Mozo, Herminia; Aguilera-Padilla, Fátima; Ben-Dhiab, Alí; Bonofiglio, Tommaso; Abichou, Mounir; Ruiz-Valenzuela, Luis; Trigo, María Mar; Díaz-de-la-Guardia, Consuelo; Domínguez-Vilches, Eugenio; Msallem, Monji; Fornaciari, Marco; Galán-Soldevilla, CarmenOlive oil is a major economic resource of the Mediterranean region. Olive crop management can be improved by models that forecast the variable reproductive biology of olive tree. However, the processes controlling olive harvest are complex on large scales. Here, we study the parameters that influence olive fruit production for developing accurate forecasting models. Seventeen aerobiological sampling points have monitored olive pollen grains in Spain, Italy and Tunisia from 1993 to 2012. Six crop models have been developed at two provinces and country scales. The modelling has been done in two steps: (1) typification and (2) modelling by partial least square regression. Results show that higher pollen indexes and water availability during spring are related to an increase of final fruit production in all the studied area. Higher pollen indexes are also positively correlated with air temperature during early spring and autumn. Furthermore, a decrease of fruit production is related with increasing air temperature during winter and summer. To conclude, we have designed accurate models that allow accurate predictions of olive production.Ítem Forecasting olive crop yields based on long-term aerobiological data series and bioclimatic conditions for the southern Iberian Peninsula(Consejo Superior de Investigaciones Científicas-CSIC, 2014-02) Aguilera-Padilla, Fátima; Ruiz-Valenzuela, LuisIn the present study, bio-meteorological models for predicting olive-crop production in the southern Iberian Peninsula were developed. These covered a 16-year period: 1994-2009. The forecasting models were constructed using the partial least-squares regression method, taking the annual olive yield as the dependent variable, and both aerobiological and meteorological parameters as the independent variables. Two regression models were built for the prediction of crop production prior to the final harvest at two different times of the year: July and November. The percentage variance explained by the models was between 83% and 93%. Through these forecasting models, the main factors that influence olive-crop yield were identified. Pollen index and accumulated precipitation, especially as rain recorded during the pre-flowering months, were the most important parameters for providing an explanation of fluctuations in fruit production. The temperature recorded during the two months preceding budburst was another important variable, which showed positive effects on the final yield. The July model that provides accurate predictions of fruit production eight months prior to the final harvest is proposed as an optimal model to forecast fruit produced by olive trees in western Mediterranean areas.Ítem Heat accumulation period in the Mediterranean region: phenological response of the olive in different climate areas (Spain, Italy and Tunisia)(Springer, 2014) Aguilera-Padilla, Fátima; Ruiz-Valenzuela, Luis; Fornaciari, Marco; Romano, Bruno; Galán-Soldevilla, Carmen; Oteros-Moreno, José. A; Msallem, Monji; Orlandi, FabioThe main characteristics of the heat accumulation period and the possible existence of different types of biological response to the environment in different populations of olive through the Mediterranean region have been evaluated. Chilling curves to determine the start date of the heat accumulation period were constructed and evaluated. The results allow us to conclude that the northern olive populations have the greatest heat requirements for the development of their floral buds, and they need a period of time longer than olives in others areas to completely satisfy their biothermic requirements. The olive trees located in the warmest winter areas have a faster transition from endogenous to exogenous inhibition once the peak of chilling is met, and they show more rapid floral development. The lower heat requirements are due to better adaptation to warmer regions. Both the threshold temperature and the peak of flowering date are closely related to latitude. Different types of biological responses of olives to the environment were found. The adaptive capacity shown by the olive tree should be considered as a useful tool with which to study the effects of global climatic change on agro-ecosystems.Ítem Time trend in the viability of pollen grains in the ‘Picual’ olive (Olea europaea L.) cultivar(Taylor & Francis, 2013) Aguilera-Padilla, Fátima; Ruiz-Valenzuela, LuisThe aim of this study was to evaluate the viability and longevity of the pollen grains of the olive cultivar ‘Picual’, the most extensive and important olive cultivar in the Iberian Peninsula. Over a 3-year period (2007–2009), viability of the pollen grains of 15 ‘Picual’ cultivar trees was measured using the Fluorochromatic Reaction (FCR). These olive trees were distributed along different altitudinal areas of the province of Jaen (southeast Iberian Peninsula). The percentages of viability did not show any geographical variability. In general, the percentage of viability did not vary from one year to another. With an average value of 49%, the viability of the pollen in the cultivar ‘Picual’ could be classified as medium-range. ‘Picual’ pollen grains have the highest viability after 24 hours of anther dehiscence. Viability declines rapidly with time. The longevity of the pollen grains was about seven days. The first three days after anthesis are the most important for fertilisation. A rapid decline in pollen viability may considerably reduce effective fertilisation and could negatively influence fruit production. For this reason, these findings should be considered for the improvement of olive fruit yields.Ítem Trends in airborne pollen and pollen-season-related features of anemophilous species in Jaen (south Spain): A 23-year perspective(Cambridge Univ Press, 2018-03) Ruiz-Valenzuela, Luis; Aguilera-Padilla, FátimaOver the last few decades, global warming is prompting phenological changes in numerous plant species across Europe, and a trend towards rising airborne pollen concentrations has been detected. This study, focused on the most frequent pollen types from arboreal and herbaceous species in the airborne spectrum of Jaen (southern Spain), revealed significant changes in airborne pollen intensity and duration of the pollen season over the 23-year study period. Here Cupressaceae, Olea, Pinus, Platanus, Quercus as arboreal taxa and Plantago as herbaceous taxa were the most important with notable changes of at least three pollen season characteristics. Airborne pollen trends from arboreal taxa with high to very high allergenic potential are rising in line with the local temperature increasing trend, and their pollen seasons tend to end later and last longer. However, both the pollen concentrations and the duration of the pollen season of some herbaceous taxa are declining. The climate conditions projected for south Europe under different greenhouse emissions scenarios could continue to prompt greater pollen release and longer pollen season in tree species, especially those that flowering in winter and early spring, but these warming trends might be adverse for the local development of some herbaceous species and favorable for others sharing the same ecological niche. If similar warming trends accompany long-term climate change, greater exposure times to seasonal allergens may occur with subsequent effects on health.