Georgios K. Ntinas

• PhD
• Researcher at Hellenic Agricultural Organization - DIMITRA (ELGO-DIMITRA)

A research project was conducted during winter period, to investigate the effect of a hybrid solar energy saving system (HSESS) on yield and quality of hydroponically cultivated tomatoes in a heated green-house. Water filled transparent cylindrical polyethylene sleeves along with peripheral perforated air-filled tubes consisted the solar energy sto...

The intensive greenhouse energy requirements are a major operational and economical problem for producers around the world. Energy conservation techniques and innovative applications of solar energy for heating are being employed in greenhouse operation to reduce heating costs during cold periods. The present study investigated the development of a...

Introduction: Aquaponics provide multiple benefits due to the simultaneous yield of vegetables and fish, however they are characterized by increased greenhouse gas emissions owing to intensive production system. The most appropriate method for quantifying the environmental effects of these systems is Life Cycle Assessment with which the identificat...

Plant factories with artificial lighting (PFALs) are indoor crop production systems aiming at the growth of high-value products in terms of yield and quality, while maximizing resource use efficiency. The emergence of PFALs opened a new world for crop production and offered an option to tackle problems related to climate change, land availability,...

Introduction: Aquaponics is an integrated food production system that links recirculating aquaculture with hydroponics, leading to higher water use efficiency than conventional food production systems while also saving on fertilizers. In the present study, baby lettuce and baby rocket plants cultivated hydroponically in a deep water culture system...

Intensive recirculating systems are a fast-developing sector of aquaculture. While several warm-water fish have been reared in aquaponics, almost no data are available for cold-water species. The determination of nitrate toxicity thresholds in recirculating aquaculture is crucial. Different pollutants are typically more toxic at elevated temperatur...

Sustainable greenhouse production has been brought to the forefront as one of the pillars in achieving the objectives set by the Green Deal strategy in 2020, for drastically decreasing net emissions from agriculture. The scope of this review was to capture the current situation regarding the sustainability of greenhouse production in the European U...

Dairy farming is accountable for increased greenhouse gas emissions. Life cycle analysis constitutes a valuable tool determining the primary factors that increase carbon footprint and other important environmental indicators, under the prism of developing methods to reduce the environmental impact of the farms. The purpose of this study was to meas...

Wild rocket is a leafy vegetable with economic interest as a consequence of baby leaf ready-to-eat salads. The climate crisis is expected to influence wild rocket production, but these effects could be confronted with cultivation in greenhouses and plant factories with artificial lighting (PFALs). Climate responses are related to growing seasons. O...

Soilless systems, such as hydroponics and aquaponics, are gaining popularity as a sustainable alternative to traditional soil-based agriculture, aiming at maximizing plant productivity while minimizing resource use. Nonetheless, the absence of a soil matrix poses challenges that require precise management of nutrients, effective control of salinity...

By applying three different LED light treatments designated as Blue (B), Red(R)/Blue(B), Red(R) and White (W) light as well as the control, the effect on Diplotaxis tenuifolia phenotype (yield and quality), physiological, biochemical, molecular status as well as growing systems’ resources use efficiency, was examined. We observed that basic leaf ch...

As the greenhouse cultivation industry considers new ways to reduce energy demand and increase sustainable production, the global energy crisis constitutes a major issue. In this paper, two different energy sources for heating and cooling the root zone area of baby leafy vegetables grown in hydroponic tanks by resistors and chillers, respectively,...

More info: www.aquaponicsystem.gr RAINBOW TROUT PERFOMANCE IN AN INTELLIGENT AQUAPONIC SYSTEM 1. Study scope The performance of rainbow trout (O. mykiss) in aquaponic system utilizing intelligent monitoring of the system. 2. Aquaponics Aquaponics, combining the technology of recirculation aquaculture systems (RAS) and hydroponics in a closed-loop n...

Simple Summary Climate change and overexploitation of natural resources drive the need for innovative food production within a sustainability corridor. Aquaponics, combining the technology of recirculation aquaculture systems (RAS) and hydroponics in a closed-loop network, could contribute to addressing these problems. Aquaponic systems have lower...

Vine leaves are considered a delicacy food however they are only produced as a byproduct for a short harvest period due to grape cultivation practices and numerous chemical applications. In this work, vine plants were cultivated hydroponically in a greenhouse, to extend the cultivation period and along with high plant density, maximize fresh leaves...

Greenhouse production of baby leaf vegetables grown in hydroponic floating trays has become extremely popular in recent years. Rocket (Eruca sativa Mill.) can grow in temperatures varying between 10 and 20 °C; nevertheless, a root-zone temperature (RZT) range of 18–23 °C is considered optimal for high productivity, photosynthesis, and production of...

Sustainable agriculture relies on replacing fossil-based mineral fertilizers, which are highly cost-energetic to produce, and demand extensive use of scarce natural resources. Today, agronomic practices within the concept of circular economy are emerging and, as such, the exploitation of digestate as a biofertilizer and soil amender is extensively...

BACKGROUND A floating system is a suitable low‐cost hydroponic method for growing baby leaf vegetables. Among other, an important characteristic of the system is the use of large volume of nutrient solution which is characterized by high heat capacity. The aim of this study was to evaluate the effect of different root‐zone temperatures on baby leav...

Consumer and trade organisations demand year-round healthy diets including fresh, high quality vegetables from local producers. However, greenhouse gas emissions (GHG) of heating high-tech greenhouses in northern countries are higher than transporting vegetables produced in southern Europe in unheated tunnels. The aim of this work was to assess GHG...

In this study, we evaluated crop productivity and physiology during the hydroponic cultivation of medium-sized and cherry tomato crops, using two experimental greenhouses. Of the greenhouses, one used dye-sensitized solar cell (DSSC) technology for covering material, whilst the other, a conventional one (CONV), was covered using diffusion glass as...

Detailed airflow information around a building can be crucial for the design of naturally ventilated systems and for exhaust air dispersion practices in agricultural buildings like greenhouses and livestock buildings. Full-scale measurements are cost-intensive and difficult to achieve due to varied wind conditions. A common method to gain insight o...

The presence of two or more mounted ribs in air duct or wind tunnel causes strong turbulence, affecting basic flow properties in mechanical or agricultural applications. The purpose of this work was the detailed analysis and visualization of turbulent flow around two successive ribs on the floor of a wind tunnel, with dynamic approximation. The sta...

The present work studied, numerically, the airflow inside and outside an agricultural structure with openings. The governing Navier-Stokes and continuity equations were solved with finite element method. The numerical experiment was designed so that it simulates the airflow inside and outside of an agricultural structure model placed in a wind tunn...

The horticultural industry consumes increasing amounts of energy and water contributing to greenhouse gas emissions and global warming. The aim of this study was to investigate the energy flow and the environmental impact of different tomato cultivation systems when renewable energy sources are implemented in the production chain. Seven scenarios i...

The inside and outside velocity distribution was highly related with contaminant transport of naturally ventilated buildings. The building sidewall openings have a large impact on the velocity distribution at wind-driven conditions, but were not comprehensively investigated in previous studies. To achieve knowledge on that, a laboratory experiment...

A lot of efforts have been noticed nowadays trying to replace the conventional fuels with alternative ones for two reasons: a. the continuously increasing prices of the fossil fuels and b. the environmental distress due to the polluting gases emitted by them. Renewable energy sources appear to be a reliable solution for covering the heating needs o...

The wind flow over a greenhouse structure is a complex and complicated phenomenon which mainly depends on the wind characteristics (speed, direction etc.), the geometry of the structure and the type of the greenhouse. One of the main stress factors of the bearing structure of the greenhouse is the wind. For the calculation of the wind load, the ext...

Greenhouses are usually constructed in high density and are located mainly in rural areas. The high density of greenhouses affects the local wind characteristics and subsequently the pressure coefficient distribution on the greenhouse frame, which is usually constructed by steel. The external pressure coefficient (cpe) is used for the design and co...

A mathematical model (developed by Ntinas et al., 2014) is describing the thermal performance of a hybrid solar energy saving system in a heated greenhouse. According to this model, a large amount of the heat released from the solar system by thermal radiation was either transferred to the greenhouse cover and lost to the outer space, or it was tra...

Instantaneous velocities were measured both upstream and downstream of a rib, in order to study the attributes of turbulent flow in a low speed wind tunnel (AU). The flow over the rib was simulated by solving the Reynolds-Averaged Navier-Stokes equations (HAU) and also by solving the full transient Navier-Stokes equations (AUTh). The statistical ap...

In this paper, flow patterns and vortex shedding phenomena produced by successive rectan-gular ribs which were placed on the smooth inner flat surface of a solar air heater, were stud-ied numerically followed by performing a wind tunnel experiment. Turbulent flow over rough surfaces can be encountered in a wide range of agricultural engineering app...

Wind and snow are the most important key stress factors for greenhouse structures. The maximum values of these two factors are directly affecting both safety and cost of the struc-ture. The air flow over a greenhouse structure is a complex and complicated phenomenon which mainly depends on the wind characteristics (speed, direction etc.), the geome...

The implementation of variable artificial roughness patterns on a surface is an effective technique to enhance the rate of heat transfer to fluid flow in the ducts of solar air heaters. Different geometries of roughness elements investigated have demonstrated the pivotal role that vortices and associated turbulence have on the heat transfer charact...

6 video clips demonstrating streamline patterns evolution, streamwise and transverse instantaneous velocity evolution for two different rib aspect ratios and Reynolds number 1000.

Livestock production buildings are a source of ammonia and greenhouse gas emissions. The transport mechanism of gas dispersions depends on a better understanding of airflow patterns surrounding agricultural buildings. With rapid development of technology of computational fluid dynamics (CFD), it becomes more and more popular to study the wind field...

The CO2 enrichment of greenhouses is a method to increase plant growth and productivity and it is applied successfully in many regions all over the world. However, in places where high temperatures occur during the main cultivation period, special application of the CO2 enrichment is needed due to the fact of high ventilation needs which reduce the...

Airflow characteristics such as air velocity and pressure are unsteady and undergo random high and low frequency fluctuations, when the flow is turbulent. Turbulent flow is resulted, even in small air velocities, if a structure is present because it impedes the air flow. This complex flow affects the external and the internal environment of agricul...

The use of solar energy saving systems contributes to the reduction of greenhouse heating cost for the off-season crop production. Moreover, the improvement of the microclimate conditions can result in higher yields and product quality. At the northern latitudes of the Mediterranean region, the greenhouse cultivation period is mainly starting at ea...

The present study investigates the possibility of energy saving during the spring period in a conventionally heated greenhouse, using an innovating hybrid solar energy saving system.The greenhouse was divided in two equal parts (experimental and control), where tomato plants were cultivated hydroponically. The control part of the greenhouse covered...

This paper shows the airflow over two successive, single span tunnel greenhouses into a wind tunnel. The governing Navier-Stokes and continuity equations are solved numerically, using the Galerkin finite element method. The Reynolds number is calculated according to the height of the structures and the inlet free streamvelocity and its values are v...