371 research outputs found
Comparing the interactive effects of water and nitrogen on durum wheat and barley grown in a Mediterranean environment
No full textThe 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
Remarks on some of the Smarandache's problem. Part 2
No full textIn 1999, the second author of this remarks published a book over 30 of Smarandache's problems in area of elementary number theory (see [1, 2]). After this, we worked over new 20 problems that we collected in our book [28]. These books contain Smarandache's problems, described in [10, 16]. The present paper contains some of the results from [28]
Mladen Pavičić (SZERK.): Szlovén irodalmi antológia III: Budapest: Balassi Kiadó. 2009. 232 pp.
No full textThe author presents a book edited by Mladen Pavičić, Szlovén irodalmi antológia III.Avtor predstavlja knjigo, katere urednik je Mladen Pavičić, Szlovén irodalmi antológia III
Impacts of climate change on olive crop evapotranspiration and irrigation requirements in the Mediterranean region
No full textThe Mediterranean basin is the largest world area having specific climatic conditions suitable for olive cultivation, which has a great socio-economic importance in the region. However, the Mediterranean might be particularly affected by climate change, which could have extensive impacts on ecosystems and agricultural production. This work focussed on the climate change impact on olive growing in the Mediterranean region considering the possible alterations of cultivable areas, phenological dates, crop evapotranspiration and irrigation requirements. Monthly climate data, with a spatial resolution of 0.25°×0.25° (latitude by longitude), have been derived from Regional Climate Models driven by ECHAM5 for the A1B scenario of the Special Report on Emissions Scenarios (SRES). The data used in the analysis represented two time periods: (i) present, called year 2000 (average values for the period 1991-2010), and (ii) future, called year 2050 (average values for the period 2036-2065). The areas suitable for olive cultivation were determined using the temperature requirements approach known as the Agro Ecological Zoning method. Crop evapotranspiration and irrigation requirements were estimated following the standard procedure described in the FAO Irrigation and Drainage Paper 56. Results showed that the potentially cultivable areas for olive growing are expected to extend northward and at higher altitudes and to increase by 25% in 50 years. The olive flowering is likely to be anticipated by 11±3 days and crop evapotranspiration is expected to increase on average by 8% (51±17mmseason-1). Net irrigation requirements are predicted to increase by 18.5% (70±28mmseason-1), up to 140mm in Southern Spain and some areas of Algeria and Morocco. Differently, effective evapotranspiration of rainfed olives could decrease in most areas due to expected reduction of precipitation and increase of evapotranspirative demand, thus making it not possible to keep rainfed olives' production as it is at presen
Climate change and Mediterranean agriculture: Impacts on winter wheat and tomato crop evapotranspiration, irrigation requirements and yield
No full textReclaimedwater for vineyard irrigation in a mediterranean context: Life cycle environmental impacts, life cycle costs, and eco-efficiency
No full textThe agricultural sector in the Mediterranean region, is increasingly using reclaimed water as an additional source for irrigation. However, there is a limited number of case studies about productbased life cycle analysis to ensure that the overall benefits of reclaimed water do indeed outweigh the impacts. The Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) methods are used in this study to investigate the environmental impacts and costs of vineyard cropping systems when tertiary reclaimed water is used as a supplementary source of irrigation water (integrated system). The conventional production system utilizing 100% groundwater was used as a reference system. As a proxy for sustainability, eco-efficiency, which combines economic and environmental performance, was assessed. The LCA revealed that the integrated system could reduce the net environmental impact by 23.8% due to lower consumption of irrigation water (−50%), electricity (−27.7%), and chemical fertilizers (−22.6%). Nevertheless, trade-offs between economics and the environment occurred as an integrated system is associated with higher life cycle costs and lower economic returns due to lower crop yield (−9.1%). The combined eco-efficiency assessment (ratio of economic value added to total environmental impact) revealed that the integrated system outperformed in terms of eco-efficiency by 12.6% due to lower environmental impacts. These results confirmed that reclaimed water could help to ensure an economically profitable yield with net environmental benefits. Our results provided an up-to-date and consistent life cycle analysis contributing to the creation of a valuable knowledge base for the associated costs and benefits of vineyard cultivation with treated wastewater
SHOULD WE BE READING MLADEN BARBARIĆ’S MANUSCRIPTS?
No full textMladen Barbarić (1873-1936), born in Ilok, belonged to the Franciscan order and acted in accordance with his priestly duties as the abbot of Ilok’s Franciscan monastery, and was highly active in Ilok’s social life. Namely, at the begining of the 20th century, Barbarić founded a private, jolly society called »Tikvara«, which gathered reputable citizens of various trades from Ilok. This society was nominally based around fishing, but this wasn’t the case at all; its purpose was to allow its members to socialize. Their leisurely gatherings were further enriched with their own form of literary entertainment called Udica (fishhook); a magazine under the editorial purview of the abbot of Ilok’s Franciscan monastery, i.e. Mladen Barbarić himself. All of this is known from Barbarić’s autobiography, Tikvarija, which contains his memoirs as a manuscript, issues of Udica, and Barbarić’s handwritten poetry, dedicated to the so-called fisherman of Tikvara. The focus of this work is precisely those preserved manuscripts, which reveal a new side of Mladen Barbarić, who spent his leisurely afternoons having fun in good company, as well as his anacreontic handwritten poetry, which naturally alters our established views on the literary accomplishments of author from Srijem
Salinity Properties Retrieval from Sentinel‐2 Satellite Data and Machine Learning Algorithms
No full textThe accurate monitoring of soil salinization plays a key role in the ecological security and sustainable agricultural development of semiarid regions. The objective of this study was to achieve the best estimation of electrical conductivity variables from salt-affected soils in a south Mediterranean region using Sentinel-2 multispectral imagery. In order to realize this goal, a test was carried out using electrical conductivity (EC) data collected in central Tunisia. Soil electrical conductivity and leaf electrical conductivity were measured in an olive orchard over two growing seasons and under three irrigation treatments. Firstly, selected spectral salinity, chlorophyll, water, and vegetation indices were tested over the experimental area to estimate both soil and leaf EC using Sentinel-2 imagery on the Google Earth Engine platform. Subsequently, estimation models of soiland leaf EC were calibrated by employing machine learning (ML) techniques using 12 spectralbands of Sentinel-2 images. The prediction accuracy of the EC estimation was assessed by using k-fold cross-validation andcomputingstatistical metrics. The results of the study revealed that machine learning algorithms, together with multispectral data, coulda dvance the mapping and monitoring of soil and leaf electrical conductivity
Effect of Water Regime, Nitrogen Level, and Biostimulant Application on the Water and Nitrogen Use Efficiency of Wild Rocket [Diplotaxis tenuifolia (L.) DC]
No full textThe use of biostimulants in agriculture is an emerging technique that can contribute to improved production and resource use efficiency. This research was carried out in southern Italy to evaluate the biostimulating effects of seaweed extract (SW) and azoxystrobin (AZ) on wild rocket subjected to two water regimes (WRs) and three nitrogen levels (NLs), and grown in pots under unheated greenhouse conditions. The following treatments were compared: (i) two WRs: restoration of 100% (WR100) and 50% (WR50) of crop evapotranspiration; (ii) three NLs: 0 (N0), 75 (N75), or 150 (N150) kg ha−1 of N; and (iii) three biostimulants (BSs): an untreated control (C), and the application of AZ or SW. This paper reports the effects on N uptake (Nup), N use efficiency (NUE), and water use efficiency (WUE). The following indicators of NUE were assessed: apparent recovery efficiency (RE), internal utilization efficiency (IE), partial productivity factor (PFPn) of N supplied, agronomic efficiency (AE), and physiological efficiency (PE). The following indicators of WUE were assessed: photosynthetic WUE (p_WUE), yield WUE (Y_WUE), biomass WUE (B_WUE), and irrigation yield WUE (IY_WUE). The indicators of NUE were affected differently by treatments. RE was 20% higher with SW. IE was higher with AZ. PFPn increased by 10.4 and 8.1% with AZ and SW, respectively. AE increased by 10.9 and 19.9% after applying AZ and SW, respectively. PE rose by 6.7 and 9.3% after applying AZ and SW. AZ and SW improved p_WUE, mainly under water deficit (interaction of WR × BS). With AZ application, Y_WUE, B_WUE, and IY_WUE were higher by 17.8, 13.8, and 19.3%, respectively, while the application of SW resulted in a smaller increase (9.5–7.7 and 9.9%). SW and AZ were shown to be effective through the moderate improvement of wild rocket’s nitrogen and water use efficiency. The two biostimulants were more effective at improving p_WUE in water deficit conditions, proving to be particularly useful for farmers operating with water scarcity. Therefore, they can provide valuable support to farmers by improving the sustainability of resource use
Comparative Performance of Aerial RGB vs. Ground Hyperspectral Indices for Evaluating Water and Nitrogen Status in Sweet Maize
No full textThis study analyzed the capability of aerial RGB (red-green-blue) and hyperspectral-derived vegetation indices to assess the response of sweet maize (Zea mays var. saccharata L.) to different water and nitrogen inputs. A field experiment was carried out during 2020 by using both remote RGB images and ground hyperspectral sensor data. Physiological parameters (i.e., leaf area index, relative water content, leaf chlorophyll content index, and gas exchange parameters) were measured. Correlation and multivariate data analysis (principal component analysis and stepwise linear regression) were performed to assess the strength of the relationships between eco-physiological measured variables and both RGB indices and hyperspectral data. The results revealed that the red-edge indices including CIred-edge, NDRE and DD were the best predictors of the maize physiological traits. In addition, stepwise linear regression highlighted the importance of both WI and WI:NDVI for prediction of relative water content and crop temperature. Among the RGB indices, the green-area index showed a significant contribution in the prediction of leaf area index, stomatal conductance, leaf transpiration and relative water content. Moreover, the coefficients of correlation between studied crop variables and GGA, NDLuv and NDLab were higher than with the hyperspectral indices measured at the ground level. The findings confirmed the capacity of selected RGB and hyperspectral indices to evaluate the water and nitrogen status of sweet maize and provided opportunity to expand experimentation on other crops, diverse pedo-climatic conditions and management practices. Hence, the aerially collected RGB vegetation indices might represent a cost-effective solution for crop status assessment
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