Automated management of nutrient solutions based on target electrical conductivity,ph, and nutrient concentration ratios     

Dimitrios Savvas  Konstantinos Adamidis 《Journal of plant nutrition》2013,36(9):1415-1432

Abstract

An algorithm to automatically formulate the composition and prepare nutrient solutions for soilless cultures based on desired characteristics given as target values is proposed. To formulate the complete ionic composition of a nutrient solution, standard recommendations referring to the following solution characteristics should be available: (i) electrical conductivity (EC), (ii) pH, (iii) concentration ratios of macronutrients (meq basis), and (iv) micronutrient concentrations. Moreover, the mineral composition of the water used to prepare the nutrient solution should be taken into account. To develop the main steps of the algorithm, the total salt concentration (meq L‐¹) of the nutrient solution is related to the desired electrical conductivity. The target pH indicates the concentration of HCO₃ ^? in the nutrient solution, whereas the absolute concentration of each macronutrient is derived from the desired concentration ratios and the total salt concentration. The necessary calculations are standardized through the development of formulae. Furthermore, the differences in nutrient concentrations between desired levels in the solution and those found in the tap water represent the amounts of nutrients per volume nutrient solution (meq L^?1) which should be added through fertilizers. The above described steps of the algorithm have been tabulated to facilitate their implementation. Moreover, a numerical example concerning the composition of a nutrient solution for cucumbers is given. In the final steps of the algorithm, two standard formulae are used to calculate the quantities of individual macronutrient and micronutrients fertilizers needed to prepare particular volumes of stock solutions. Alternatively, when stock solutions of single fertilizers having known concentrations are used, the composition of the nutrient solution can be automatically adapted to new target values. This task can be performed without replacing the existing stock solutions by rearranging the formulae used in the last steps of the algorithm to calculate dilution ratios instead of fertilizer quantities.  相似文献   

Pulsed electromagnetic fields effect in oregano rooting and vegetative propagation: A potential new organic method     

Dimitrios Bilalis  Nikolaos Katsenios  Aspasia Efthimiadou  Panagiotis Efthimiadis  Anestis Karkanis 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(1):94-99

Abstract

Many types of magnetic fields have already been investigated in order to find new methods to enhance plant growth. This study reports the positive effect of pulsed electromagnetic field on the main root characteristics (fresh weight, dry weight, root surface and length) of unrooted oregano stem cuttings. For oregano, vegetative propagation is commonly used, with rooted or unrooted stem cuttings, because seed propagation is not suggested for commercial cultivation. Oregano seeds are very small and, thus, difficult to handle. Vegetative reproduction in organic cultivation faces the ethical problem of the use of hormones to induce the rooting process in propagation beds. The purpose of this study was to determine if magnetic field can replace hormones in plant propagation and what the results of the combination of both magnetic field and hormones would be. Two types of stem cuttings were used (apical and middle) and the experiment was established in two different seasons (spring and autumn). The findings showed that magnetic field alone stimulates the rooting process in plant material, with results similar to or even statistically significantly better than those obtained using hormones. However, the combination of magnetic field and hormones resulted in measurements statistically significantly lower than with magnetic field alone. Such methods can potentially be useful for plant materials growers, providing better oregano seedlings, especially in organic farming, where chemical compounds are forbidden.  相似文献   

Genetic structure of Curculio elephas Gyll. (Coleoptera, Curculionidae) in Greece: an important pest of sweet chestnut     

Dimitrios N. Avtzis  Anthony I. Cognato 《Journal of pest science》2013,86(3):491-497

The weevil, Curculio elephas (Coleoptera, Curculionidae), is one of the most abundant and widespread chestnut feeding pests in Greece. Together with the tortricid moths Cydia splendana and C. fagiglandana (Lepidoptera, Tortricidae), C. elephas greatly affect chestnut production. This weevil occurs in a continuous range throughout Greece; however, its population structure is unknown. Information concerning its population structure could help in the future control of this pest. A 790 bp portion of the mitochondrial Cytochrome Oxidase I gene was sequenced for 160 C. elephas larvae from ten populations. Compared to other Curculio species haplotype diversity with 31 haplotypes and nucleotide diversity with six nucleotide substitutions was low. The Bayesian inference of phylogeography in concert with nested clade analysis revealed a loose geographic distribution of genetic diversity that was likely the joint effect of isolation by distance and gene flow. In addition, population indices and Bayesian-based calculations showed that the populations of C. elephas in Greece are at the phase of expansion. Dating the phylogeny suggests about 300,000 years before present as the start of divergence among the populations of C. elephas in Greece.  相似文献   

Autologistic regression and multicriteria evaluation models for the prediction of forest expansion   总被引：1，自引：1，他引：0  

Dimitrios P. Triantakonstantis  Dionissios P. Kalivas  Vassiliki J. Kollias 《New Forests》2013,44(2):163-181

Land use changes are complex ecological processes driven by the interaction of biophysical and human related factors. The prediction of forest land use changes is important for sustainable forest management and biodiversity conservation. This study investigates the modelling process of the spatial dynamics of a forest ecosystem in north eastern Greece. For the prediction of forest expansion, based on land use data of the study area, a deterministic approach using logistic regression and heuristic methods of multi-criteria evaluation is adopted. The set of factors driving forest expansion are: the slope, the distance to roads, the distance to urban areas, the distance to forest, the soil depth, the soil erosion and the influence from the land uses of the neighbourhood. The spatial autocorrelation of driving factors is addressed using an autologistic regression model. The multicriteria evaluation approach is developed using weighted linear combination (WLC) and ordered weighted averaging (OWA) methods. In WLC method the relative importance of each factor was estimated using the analytical hierarchy process. In the OWA method, decision strategies are generated using a selection of relative linguistic quantifiers, which allow different Risk in decisions. The accuracy of the models produced was tested with real data for the year 2001 using the ROC validation method. All the methods produced satisfactory results. Autologistic regression showed slightly better performance than multicriteria evaluation methods due to higher degree of objectivity in defining the importance of driving factors for forest expansion.  相似文献   

Effect of different macronutrient cation ratios on macronutrient and water uptake by melon (Cucumis melo) grown in recirculating nutrient solution          下载免费PDF全文

Damianos Neocleous  Dimitrios Savvas 《植物养料与土壤学杂志》2015,178(2):320-332

The aim of the present study was to determine uptake ratios between macronutrients and water for melon (Cucumis melo L. cv. Dikti) grown in a closed soilless cropping system. The obtained data can be used to establish standard nutrient solution compositions for melon crops grown in closed hydroponic systems under Mediterranean climatic conditions. Nutrient and water uptake by plants in the closed hydroponic system was compensated for by supplying replenishment nutrient solutions (RNS) differing either in the concentrations of K⁺, Ca²⁺, and Mg²⁺ or in their mutual ratio. The RNS, used as control treatment, had an electrical conductivity (EC) of 1.74 dS m^?1 and contained 6.5 mM K⁺, 2.8 mM Ca²⁺, and 1.0 mM Mg²⁺ (K⁺ : Ca²⁺ : Mg²⁺ = 0.63 : 0.27 : 0.10). Control RNS was compared with two other RNS, both with a high Ca²⁺ level (4.2 mM). The K⁺ and Mg²⁺ levels in these two RNSs were: (1) not altered (corresponding to a ratio of K⁺ : Ca²⁺ : Mg²⁺ = 0.55 : 0.36 : 0.09; EC = 2.0 dS m^?1) or (2) increased to maintain the same K⁺ : Ca²⁺ : Mg²⁺ ratio as in the control RNS (EC = 2.45 dS m^?1). Nutrient to water uptake ratios, commonly termed uptake concentrations (UCs), were assessed by two alternative methods, i.e., (1) estimating the ratio between nutrient and water removal from the system or (2) estimating the ratio between the mass of the nutrient that was recovered from plant biomass and the water consumption. Over the two methods, mean UCs for N, P, K, Ca and Mg were 15.4, 1.31, 5.47, 3.78, and 1.02 mmol L^?1, respectively, and tissue analysis resulted in a K : Ca : Mg molar ratio of = 0.55 : 0.34 : 0.11 in the whole plant. Moreover, the UCs tended to decrease as the crop aged although, in absolute values, the mass of nutrients absorbed increased following dry‐weight accumulation. Based on the obtained results, adapting the composition of the nutrient solution at least three times during the cropping period of melon is recommended. Further, the results revealed that the damage caused by the increase of the EC when attempting to maintain a target K⁺ : Ca²⁺ : Mg²⁺ ratio in the replenishment NS is higher than the benefits from the optimal cation ratio. Increasing K⁺ and Mg²⁺ concentration in addition to that of Ca²⁺ to maintain a standard K⁺ : Ca²⁺ : Mg²⁺ ratio raises the EC in the root zone (4.62 dS m^?1), due to increased accumulation of nutrients, thereby reducing the mean fruit weight and concomitantly the total fruit yield (20% decrease). Leaf gas exchange, chlorophyll parameters and fruit taste quality were not influenced by the differences in macronutrient cation concentrations or ratios in the RNS, whereas phenolics and antioxidant capacity in melon fruit were enhanced by the increased root‐zone EC.  相似文献   

Climatology of Discomfort Index and Air Quality Index in a Large Urban Mediterranean Agglomeration   总被引：1，自引：0，他引：1  

Anastasia Poupkou  Panagiotis Nastos  Dimitrios Melas  Christos Zerefos 《Water, air, and soil pollution》2011,222(1-4):163-183

The paper studies the climatology of the Discomfort Index (DI) and the Common Air Quality Index (CAQI) in a large Mediterranean urban center (Greater Thessaloniki Area), examines the relations between the indices and the climatic conditions in the study area and investigates the linkage between the Urban Heat Island (UHI) effect and the enhanced discomfort and poor air quality in the city center. Discomfort conditions are more enhanced during July and August. Atmospheric conditions when the population suffers discomfort and feels severe stress are found mainly in the summer season hours with total frequency that can be up to about 4% in a month. Throughout the year, air quality conditions are unhealthier in the stations of urban characterization. Very high daily CAQI values are more frequent during the cold period (about 14%) than during the warm period (1?C2%) of the year in the urban stations. Daily DI???24°C could be more associated to increased temperature than relative humidity and is strongly related to high and very high CAQI values. During summer, when daily CAQI is ??76, the feeling of discomfort is the most probable. Consequently, a strong synergy between discomfort and bad air quality exists in summertime. High and very high CAQI values and the discomfort feeling by the majority of the population are related to stagnant atmospheric conditions. During summer season, the poor air quality and the unfavorable comfort conditions for the majority of the population in the city center are associated with the greater frequency of a more intense UHI effect. The above phenomenon is more pronounced during nighttime than daytime.  相似文献   

Effects of three commercial rootstocks on mineral nutrition,fruit yield,and quality of salinized tomato     

Dimitrios Savvas  Andreas Savva  Georgia Ntatsi  Andreas Ropokis  Ioannis Karapanos  Angelika Krumbein  Christos Olympios 《植物养料与土壤学杂志》2011,174(1):154-162

Tomato (Solanum lycopersicum Mill. cv. Belladona F₁) plants were either self‐rooted, self‐grafted, or grafted onto the commercial rootstocks “Beaufort”, “He‐Man”, and “Resistar” and grown in a recirculating hydroponic system. Three nutrient solutions differing in NaCl‐salinity level (2.5, 5.0, and 7.5 dS m^–1, corresponding to 0.3, 22, and 45 mM NaCl) were combined with the five grafting treatments in a two‐factorial (3 × 5) experimental design. At the control NaCl level (0.3 mM), fruit yield was not influenced by any of the grafting treatments. However, at low (22 mM NaCl) and moderate (45 mM NaCl) salinity levels, the nongrafted and the self‐grafted plants gave significantly lower yields than the plants grafted onto He‐Man. The plants grafted onto the other two rootstocks gave higher yields only in comparison with the nongrafted plants, and the differences were significant only at low (Beaufort) or moderate (Resistar) salinity. Yield differences between grafting treatments at low and moderate salinity arose from differences in fruit number per plant, while mean fruit weight was not influenced by grafting or the rootstock. NaCl salinity had no effect on the yield of plants grafted onto He‐Man but restricted the yield in all other grafting treatments due to reduction of the mean fruit weight. With respect to fruit quality, salinity enhanced the titratable acidity, the total soluble solids, and the ascorbic acid concentrations, while grafting and rootstocks had no effect on any quality characteristics. The leaf Na concentrations were significantly lower in plants grafted onto the three commercial rootstocks, while those of Cl were increased by grafting onto He‐Man but not altered by grafting onto Beaufort or Resistar in comparison with self‐grafted or nongrafted plants. Grafting onto the three tested commercial rootstocks significantly reduced the leaf Mg concentrations, resulting in clear Mg‐deficiency symptoms 19 weeks after planting.  相似文献   

Vibrational mode-specific reaction of methane on a nickel surface     

Beck RD  Maroni P  Papageorgopoulos DC  Dang TT  Schmid MP  Rizzo TR 《Science (New York, N.Y.)》2003,302(5642):98-100

  相似文献   

Reuse of drainage water in irrigation with the aid of 0-1 linear programming     

Dimitrios Gotsis  Mike Spiliotis  Spyros Giakoumakis 《Irrigation and Drainage Systems》2011,25(4):385-394

Water management for irrigation in areas with high water scarcity includes not only domestic wastewater treatment but also practices for the reuse of drainage water during the irrigation period. The main problem that concerns the reuse of drainage water for irrigation is the accumulation of salts due to the effluents existing in the soil. In this paper an optimization technique is proposed for the management of drainage water that uses, in combination, a soil-water-plant model (SWAP) and a mixed 0-1 linear programming method. The optimization routine was applied to the irrigation network of Alfeios River in Western Greece, an area that is characterized by high precipitation imbalances between winter and summer months.  相似文献   

Preliminary Evaluation of 3D Printed Chitosan/Pectin Constructs for Biomedical Applications     

Georgia Michailidou  Zoe Terzopoulou  Argyroula Kehagia  Anna Michopoulou  Dimitrios N. Bikiaris 《Marine drugs》2021,19(1)

In the present study, chitosan (CS) and pectin (PEC) were utilized for the preparation of 3D printable inks through pneumatic extrusion for biomedical applications. CS is a polysaccharide with beneficial properties; however, its printing behavior is not satisfying, rendering the addition of a thickening agent necessary, i.e., PEC. The influence of PEC in the prepared inks was assessed through rheological measurements, altering the viscosity of the inks to be suitable for 3D printing. 3D printing conditions were optimized and the effect of different drying procedures, along with the presence or absence of a gelating agent on the CS-PEC printed scaffolds were assessed. The mean pore size along with the average filament diameter were measured through SEM micrographs. Interactions among the characteristic groups of the two polymers were evident through FTIR spectra. Swelling and hydrolysis measurements confirmed the influence of gelation and drying procedure on the subsequent behavior of the scaffolds. Ascribed to the beneficial pore size and swelling behavior, fibroblasts were able to survive upon exposure to the ungelated scaffolds.  相似文献