Background-Why HortiMED?

In the Mediterranean Basin, the world’s major vegetable production area, the area under protected cultivation has been rapidly developed in the last decades, with more than 120.000 ha of greenhouses and large tunnels, and more than 300.000 ha if low tunnels are also considered (Pardossi et al, 2004). Nevertheless, there is an urgent need for technological updating of greenhouse industry to face the increasing competition arising from globalisation of both production and marketing (Pardossi et al, 2004); and to minimize the environmental impacts reported by intensive horticulture (discharge of nutrients and growing eutrophication trends, intensive water use, excessive pesticide use…).

Food products, crop and fish yields are projected to decline in many Mediterranean areas (by 2050 yield reductions by 40% for legume production in Egypt have been estimated) due to climatic and other stress factors (Cramer et al, 2018). Besides, irrigation demands in the Mediterranean region are projected to increase between 4 and 18% by the end of the century due to climate change alone; while population growth, and increased demand, may escalate these numbers to between 22 and 74%. Furthermore, those areas at extremely high risk are predominantly located in the Southern Mediterranean region, including Algeria and Egypt (Zittis, G. et al, 2015). Likewise, the expected global atmospheric temperature increase of 2 °C will probably be accompanied by a reduction in summer precipitation of around 10–15% in Northwestern Spain (Vautard, R. et al., 2014). Besides, the increased application of fertilizers accompanied by extreme drought periods can increase salinization of the available water in Southern Mediterranean areas (Fernández et al, 2018), which is critical considering that about 30% of the irrigated farmlands in Egypt are already affected by salt intrusion (Hegazi et al, 2005). Another major constraint is the increased water competition in the Mediterranean region. In Algeria, water availability per capita is 600 m³/hab/year, placing Algeria in the category of poor countries in water resources under the shortage threshold set by the UNDP or by the World Bank (Sahnoune et al. 2013); while Egypt’s water needs are expected to surpass available water resources by 2030.

Furthermore, under semi-arid growing conditions like those found in Mediterranean regions, greenhouse crops are usually over-irrigated so that growers prevent water and nutrient shortages. The excess (about 40%) nutrient solution contains not only fertilisers but also residues from the agrochemicals used in the greenhouse (EIP-AGRI 2019-Circular horticulture). In fact, greenhouse industry applies more fertilizer and water per unit of production area compared to other cropping systems (Colla et al. 2015; Rouphael et al. 2016). This excess, when discharged to the surroundings or filtrated to deeper soil levels, results in environmental pollution including contamination of aquifers and eutrophication of surface waters (De Pascale et al., 2017). Besides, greenhouse vegetable production is the most energy-intensive agricultural sector, with energy cost in greenhouses representing between 20-40% of the total cost (Salazar et al. 2014). Furthermore, the intensification of greenhouse production has created favourable conditions for many devastating pests & diseases that can cause a cost of about 15% of the potential income for a typical greenhouse.This has significantly increased the need for pesticide applications, at the time that legislative measures and standards requirements related to quality and safety of vegetables have become increasingly demanding. Consumer awareness has risen and the demand for pesticide-free and organic products is a reality, which cannot be ignored.

In view of this, optimal greenhouse management is required to ensure unrestricted growth at a yield close to the maximum potential, while minimizing unsustainable exploitation of resources, especially energy, soil & water.