Modélisation de la production de biomasse de la tomate sous l’effet des principaux paramètres climatiques de la serre Monochapelle

In modern horticulture, the use of plant growth models is very important. Due to the complexity of factors involved in crop production and their interactions, our level of analysis and decision-making gradually improves according to model quality and its calibration with local conditions. In Agadir region, producers rely on their experience to make decisions on crop management and generally the quality component of the environment remains the weak point of this approach. In our study, we used a classical model of plant biomass production and introduced other physical equations to improve the model to relatively reflect the field reality. The results showed that developed models correctly simulate the biomass accumulation in tomato under the Monospan greenhouse. However, their efficiency has been improved by the introduction of key climatic factors involved in improving the greenhouse environment. Thus, in adverse climatic periods for plant growth (summer and winter periods), greenhouse operators can rely on net radiation data to simulate biomass accumulation and estimate production losses and cost. Similarly, the use of models of prevention against greenhouse bio-aggressors is another way of feeding tested models in order to develop a more robust global model which integrates a maximum of data necessary to produce decision taking information for sustainable management of horticultural production. Keywords: Biomass model, greenhouse environment, sustainable production, cost, bio-aggressors, tomato.En horticulture moderne, l’utilisation des modèles de croissance des plantes est très importante. En raison de la complexité des facteurs et leurs interactions, notre niveau d’analyse et de prise de décision s’améliorent progressivement en fonction de la qualité du modèle et de son calibrage avec les conditions locales. Dans la région d’Agadir, les producteurs de tomate se basent sur leur expérience pour prendre les décisions sur l’exploitation et généralement la composante qualité de l’environnement reste le point noir de cette approche. Dans notre étude, nous avons essayé d’exploiter un modèle classique de la production de la biomasse des plantes et d’introduire d’autres équations physiques pour améliorer le rendement du modèle développé et traduire relativement la réalité du terrain. Les résultats ont montré que les modèles élaborés simulent correctement l’accumulation de biomasse chez la tomate conduite sous serre Monochapelle. Cependant, leur efficience a été améliorée par l’introduction de facteurs climatiques clés intervenant dans l’amélioration de l’environnement de la serre. Ainsi, en périodes climatiques défavorables pour la croissance de plantes (périodes estivale et hivernale), les serristes peuvent se baser sur les données du rayonnement net pour simuler l’accumulation de la biomasse et avoir une estimation des pertes de production et des dépenses y affectées. De même, l’exploitation des modèles de prévention contre les bio-agresseurs sous serre est un autre moyen d’alimenter les modèles testés afin de développer un modèle global plus robuste et qui intègre un maximum de données nécessaires pour produire des informations de prise de décision pour s’inscrire dans une logique de gestion d’une production horticole raisonnée et durable. Mots clés: Modèle de biomasse, environnement de la serre, production durable, dépenses, bio-agresseurs, tomate

Effect of active solar heating system on microclimate, development, yield and fruit quality in greenhouse tomato production

Heating greenhouses is essential to provide favorable climatic conditions for growing plants under cold periods. In this article, we have studied the performance of an Active Solar Heating System (ASHS) consisting of two solar water heaters equipped with flat solar collectors, two storage tanks and exchanger pipes. During the day, the water is heated in the thermosyphon solar collectors and stored in tanks before being placed into circulation in the exchanger pipes to distribute the heat to the aerial and root zones of plants. To assess the performance of the Active Solar Heating System, climatic and agronomic parameters were monitored in two identical canarian greenhouses, one equipped with ASHS heater and the second without. Experimental results show that the ASHS system improve the nocturnal climatic conditions under greenhouse. The thermal comfort created by the ASHS system in root zone, increases the absorption of nutrients, which improve the external quality (color, size, weight and firmness) and the internal quality (sugar content, acidity and taste) of tomato fruits. This improvement is also reflected by increasing total tomato yield by 55% in winter period. The results of economic analysis indicate that the ASHS system is a cost effective in terms of investment and energy saving

CFD Modeling of the Microclimate in a Greenhouse Using a Rock Bed Thermal Storage Heating System

The rock bed heating system is a more cost-effective concept for storing thermal energy use in greenhouses at night during the cold winter season. This system is considered an environmentally friendly solution compared to conventional heating systems that rely on fossil fuels. Despite the abundance of research on thermal energy-based heating systems, only limited work on climate modeling in greenhouses using rock bed heat storage systems has been reported. To fill this research gap, this study aims to simulate the microclimate in a greenhouse equipped with a rock bed heating system using computational fluid dynamics (CFD) models. User-defined functions have been implemented to account for the interactions between the plants and the air within the greenhouse. Crop rows and rock bed blocks have been considered as porous media with their dynamic and thermal proprieties. The model’s accuracy was approved by comparing simulated and experimental climate parameter data from the greenhouse. The model’s ability to predict temperature, humidity, and air velocity fields in the greenhouse as well as in the rock bed system during both phases of energy storage and restitution was demonstrated. The thermal, dynamic, and hygric fields were accurately replicated with this numerical model. The growing zone had a vertical temperature gradient between the ground and the greenhouse roof, as well as high humidity. The distribution of temperature fields along the rock bed blocks showed a significant temperature gradient between the air inlet and outlet in the blocks during the two phases of heat storage and restitution. As a result, the model could be useful for sensitivity studies to improve the performance of this thermal storage heating system