1,721,062 research outputs found
Water resources use optimisation in the mediterranean basin. In: Rana G., Mastrorilli M., Albrizio R. (Ed.), “WEMED Workshop: How to advance the knowledge on water use efficiency in the Mediterranean region?”
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Comparing the interactive effects of water and nitrogen on durum wheat and barley grown in a Mediterranean environment
Full text linkThe understanding of the interactive effect of water and N availability, associated with the ability of crops to efficiently use these resources, is a crucial issue for stabilizing cereal production in Mediterranean areas. A 3-year side by side experiment on durum wheat and barley, under different water regimes and nitrogen levels, was carried out in a typical Mediterranean environment of Southern Italy, to identify the outstanding features of these species that contribute to enhanced grain yield and improved water and nitrogen use efficiency. Wheat and barley response was assessed under three water supply regimes (I100, I50, I0: full irrigation, 50% of full irrigation and rainfed) coupled with two N fertilizer levels (high N: 120 kg ha-1 and low N: not fertilized). In order to evaluate barley yield response under lower N rates, 60 kg ha-1 were applied in 2006. The occurrence of abundant rainfall during the experimental period determined only mild water stress during most of the growing season, especially in 2006 and 2007. Under these conditions, nitrogen fertilization was the main factor affecting crop response, and different crop traits in response to irrigation were primarily evident on tissue N concentrations. Grain number per unit land area explained a high proportion of grain yield and it was mainly influenced by N fertilization. Water availability enhanced N absorption: the response of both crops to N fertilization, in terms of N uptaken and grain N concentration, was higher in the year characterized by greater water availability during the most sensitive stages to drought stress. Under unfertilized conditions, the two crops showed similar response in terms of number of grains per unit land area; under N fertilization, barley exhibited a higher increase in number of grains per unit land area, but wheat achieved similar yields as consequence of the higher grain weight. In years characterized by similar average productivity of wheat, barley did not show further increase in number of seeds, even doubling the rate of N supplied. By increasing irrigation water supply, the two crops showed a similar yield response, but a different N partition, as confirmed by the lower nitrogen harvest index values for barley over 2007-2008. At similar total availability of N, barley reached higher N utilization efficiency than wheat, mainly because of a lower N concentration in the grain rather than a higher efficiency in using the available N. © 2009 Elsevier B.V. All rights reserved
Impiego del Potenziale Idrico del Fusto e della Conduttanza Stomatica come Indicatori Fisiologici per l'Ottimizzazione della Gestione Irrigua in Uva da Tavola
No full textEffectiveness of pre- and post-veraison calcium applications to control decay and maintain table grape fruit quality during storage
No full textA two year research was carried out on a table grape vineyard, cv. Italia, to evaluate the effectiveness of pre- and post-veraison calcium applications for controlling postharvest table grape rots and maintaining high fruit quality during cold storage. Two calcium application timings (from fruit set to veraison and from veraison to harvest) were compared to an untreated control. Clusters were sprayed with calcium chloride as Ca EDTA 44%. After each calcium application, bunch samples were collected and Ca 2+ concentration was measured in berry compartments (skin, flesh and seeds). The main mechanical and chemical characteristics were measured on bunch samples at harvesting and during storage. In addition, the incidence of Botrytis cinerea rots, computed as McKinney index, was evaluated in field on natural inoculum and after harvesting on bunches artificially inoculated and maintained at room temperature. The highest Ca 2+ concentrations were detected in skin tissues and after pre-veraison applications. Calcium accumulation in skin and flesh tissues stopped after veraison, whereas it continued up to ripening in seeds since the axial flow, differently from the peripheral, remains functional. In both years, calcium applications to bunches were effective both in maintaining postharvest fruit quality, as shown by flesh firmness and berry breaking force, and in reducing B. cinerea rots during storage. The applications were particularly efficacious if carried out between fruit set and veraison when stomata are functional and the re-translocation of calcium not directly absorbed by the bunches may occur via xylem transport. © 2012 Elsevier B.V
Spatial variability of soil physical and hydraulic properties in a durum wheat field: An assessment by the BEST-procedure
Full text linkSpatial variability of soil properties at the field scale can determine the extent of agricultural yields and specific research in this area is needed. The general objective of this study was to investigate the relationships between soil physical and hydraulic properties and wheat yield at the field scale and test the BEST-procedure for the spatialization of soil hydraulic properties. A simplified version of the BEST-procedure, to estimate some capacitive indicators from the soil water retention curve (air capacity, ACe, relative field capacity, RFCe, plant available water capacity, PAWCe), was applied and coupled to estimates of structure stability index (SSI), determinations of soil texture and measurements of bulk density (BD), soil organic carbon (TOC) and saturated hydraulic conductivity (Ks). Variables under study were spatialized to investigate correlations with observed medium-high levels of wheat yields. Soil physical quality assessment and correlations analysis highlighted some inconsistencies (i.e., a negative correlation between PAWCe and crop yield), and only five variables (i.e., clay + silt fraction, BD, TOC, SSI and PAWCe) were spatially structured. Therefore, for the soil–crop system studied, application of the simplified BEST-procedure did not return completely reliable results. Results highlighted that (i) BD was the only variable selected by stepwise analysis as a function of crop yield, (ii) BD showed a spatial distribution in agreement with that detected for crop yield, and (iii) the cross-correlation analysis showed a significant positive relationship between BD and wheat yield up to a distance of approximately 25 m. Such results have implications for Mediterranean agro-environments management. In any case, the reliability of simplified measurement methods for estimating soil hydraulic properties needs to be further verified by adopting denser measurements grids in order to better capture the soil spatial variability. In addition, the temporal stability of observed spatial relationships, i.e., between BD or soil texture and crop yields, needs to be investigated along a larger time interval in order to properly use this information for improving agronomic managemen
Contribution of EMI and GPR proximal sensing data in soil water content assessment by using linear mixed effects models and geostatistical approaches
No full textThe estimation of topsoil water content is of primary interest in the framework of precision farming, but, in general, such assessment is costly and complicated by several interfering factors which do not allow an accurate prediction. Proximal sensing can provide suitable technological facilities to support researchers and technicians in this task. GPR and EMI sensors are valuable instruments as they can provide very informative covariates to be used for improving soil water content estimation. In the present work, it was explored the single (EMI or GPR) and the combined (EMI + GPR) contribution of these proximal data sources. Furthermore, geostatistical (Ordinary Kriging and Kriging with external drift) and linear mixed effects models were applied to compare their respective predictive capabilities. As a result, GPR demonstrated to be more effective in estimating topsoil water content with respect to EMI but, combining both the information, an improvement in the prediction accuracy was observed. Moreover, adding more covariates in the models (GPR outcomes or GPR + EMI outcomes) allowed filtering out the structured spatial component of soil water content. Finally, the statistical approaches proved to behave very similarly, with a slight better performance of Kriging with external drift
N concentration and plant mass accumulation in processing tomato under different N and water regimes
No full textOptimization of sampling design for soil total organic carbon assessment in the precision agriculture framework: Impact of different variogram models and potentiality of ground penetrating radar (GPR) covariate information
Full text linkAssessing soil organic carbon (SOC) at the field scale is crucial for efficient environmental and agronomic management, especially within the precision agriculture framework. This enables the implementation of crop and soil management strategies to enhance soil quality, increase carbon sequestration, and improve crop yields. However, the process of sampling and assessing SOC is resource-intensive, demanding both in time and labour. This aspect is particularly relevant in agronomic research, where the need to assess the spatial correlation structure of the investigated variables requires the collection of large datasets with georeferenced data and often measurements need to be repeated over time as in the case long-term field experiments - LTE. Methods for minimizing information loss while reducing the sampling scheme, such as spatial simulated annealing (SSA), are particularly valuable in the scope of SOC assessment, especially when faced with budget and time/labour constraints. Within the structure of the SSA method, two critical components can be identified: i) the inclusion of highly informative covariates for the primary variable (SOC); ii) the selection of the most appropriate variogram model for spatial variability assessment. Covariates strongly correlated with SOC, such as those obtained from ground penetrating radar (GPR) that can be collected at a higher spatial density compared to SOC data, along with a well-performing model, can significantly enhance the efficiency of the sampling scheme reduction process. We conducted a study using data from an agronomic field experiment, which included 71 georeferenced sampling locations and, through an iterative downsizing process utilizing SSA, we progressively reduced the number of sampling points by removing 10, 15, and 20 observations. The sampling scheme was refined according to two distinct variogram models: the spherical and Gaussian-Matern models, both for the primary variable (SOC) and the covariate GPR variable. This process allowed us to identify the optimal variogram model, which has a key role in maximizing the reduction of redundant points while preserving those with valuable information, and to assess the role of the covariate variable both in improving the optimization of the sampling scheme for SOC and in replacing the primary variable to optimize the sampling scheme. Finally, to assess the impact of sampling scheme reduction, a validation process was performed by estimating the dropped points by means of the remaining points using ordinary kriging and regression kriging and analysing the accuracy of such estimation. Our analysis demonstrated that it was possible to reduce the original sampling scheme by approximately 20%, equivalent to eliminating 15 sampling points out of 71, without compromising its predictive capability
Soil mineral N content and dynamic after three years of conventional, low input and organic farming in a Mediterranean environment
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