Response to the expanding demand for high-quality citrus saplings plants requires optimisation and a deep understanding of production climate behaviour. In this context, greenhouse production is the most used technique because it allows farmers to effectively monitor plant growth through production condition control, especially climatic parameters. The current work presents an analysis of climate behaviour and plant heat activity of a citrus sapling tunnel greenhouse in the middle region of Morocco. In this regard, a computational fluid dynamic (CFD) model was developed and validated with respect to temperature and relative humidity measured values. The specificity of this model is the inclusion of a new non-grey radiative and heat transfers physical sub-models to couple the convective and radiative exchanges at the plastic roof cover and crop level. The findings showed that using a green shade net increased the greenhouse shadow, and the layering of plastic and shade net significantly reduced solar radiation inside the greenhouse by 50%. Also, the greenhouse airflow speed was deficient; it cannot exceed 0.3 ms−1, hence the dominance of the chimney effect in heat transfer. Despite the previous results, analyses of greenhouse temperature and relative humidity fields clearly showed the greenhouse climate behaviour heterogeneity, where spatial greenhouse air temperature and relative humidity difference values reached a maximum of 29.7 °C and 23%, respectively. For citrus plants, heat activity results showed that a weak fraction (1.44%) of the short wavelength radiation is converted to latent heat, which explains the low plant transpiration under these conditions. While the convective currents are the primary source of temperature and relative humidity heterogeneity inside the greenhouse, the presence of crop rows tends to homogenise the climate inside the greenhouse. We also concluded the necessity of proper condensation modelling near ground surfaces and inside the crop, and the water vapour effect on climate determination.

In Mediterranean basin, citrus culture is expanding rapidly with a growing demand for high-quality saplings. Protected cultivation with fine microclimate conditions control is the best process of citrus saplings growing with the required quality. In this context, the developed microclimate of a tunnel citrus saplings greenhouse and its effects on plant activity parameters, such as leaf temperature and transpiration, were investigated. The findings show that the temperatures of air and plant leaves inside the greenhouse are highly variable between 6 °C and 33 °C and from 8 °C to 30 °C, respectively. Results also show that greenhouse air humidity is very high – more than 80%. The analysis of plant transpiration based on greenhouse microclimate conditions and leaf temperature reveals that (i) plant transpiration varies throughout the day (between 1.9 and 65.7 mg m−2·s−1); (ii) leaf temperature simulation can be used as an indirect indicator of plant water stress; and (iii) the simulated temperature difference between the leaves and the internal air of the greenhouse can be used to define the minimum threshold air temperature for proper plant development under the greenhouse conditions.

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Introduction: The rooting of cuttings is a fundamental step in olive tree production. This preliminary step is favoured by specific environmental conditions, which demand strict and permanent control across the production system. Achieving these conditions poses a major challenge for propagators. In this context, the greenhouse production technique is the best response and most productive method used globally, including in the Mediterranean regions. This study aims to characterize the microclimate of a tunnel-type greenhouse according to Mediterranean wintertime climatic conditions in Morocco’s central region and assess its performance in fostering olive cutting growth. Methods: Evaluation of the efficiency of greenhouse microclimate is based on measured climatic parameters inside and outside the studied greenhouse. Also, we used a statistical data processing SPSS software for the identification regression analysis of the factors and key parameters determining the success of rooting of cuttings. Results: The experimentally obtained results clearly show for the first time that solar radiation is a determining factor for the success of rooting. The studied greenhouse type guarantees a homogeneous microclimate inside the greenhouse and allows a reduction of 66% of the external global solar radiation, which decreases transpiration and prevents leaf wilting. The results also show that the studied greenhouse system ensures an internal greenhouse air relative humidity close to saturation value and generally stable throughout the day, with a favourable value for successful rooting. However, the greenhouse air temperature was too high during the daytime and very low during the nighttime, indicating unfavorable rooting conditions. Conclusion: The results of this study can provide guidelines for propagators to improve greenhouse design and climate control to increase the yield and quality of this crop.

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