Application of soilless culture technologies in the modern greenhouse industry – A review

Abstract

Soilless culture systems (SCS) are increasingly adopted as a major technological component in the modern greenhouse industry. The core advantage of soilless culture, frequently referenced to as "hydroponics", is the independence of the crop from the soil which, as a natural medium, is heterogeneous, accommodates pathogens, tends to degrade in monoculture systems, and may be infertile, saline or sodic. The cultivation on horticultural growing media (GM) such as rockwool, perlite, and coconut is worldwide the most frequently used SCS for production of fruit vegetables and cut flowers. Water culture systems such as floating hydroponics, Nutrient Film Technique and aeroponics are mainly used for production of leafy vegetables. Modern, fully automated fertigation heads are used for the preparation and timely supply of nutrient solution (NS), which serves both the nutrition and irrigation of the plants. In soilless culture, the NS that drains out of the root zone can be easily collected and recycled, thereby considerably increasing the water use efficiency and minimizing environmental impacts arising from fertilizer residues. The spread of pathogens via the recycled effluents is a challenge that can be encountered by introducing a suitable system for their disinfection before reusing, based mainly on UV radiation, slow sand or membrane filtration, or a chemical treatment (mainly O 3 , H 2 O 2 or chlorination). In SCS, the NS composition has to be adapted to the composition of the water used for its preparation, the plant species and even the cultivar, the growth stage, the season of the year and the current climatic conditions, and this is a challenge that can be encountered by using modern information and computer technologies. Last but not least, the frequency of irrigation in GM-grown crops is high due to the limited volume of rooting medium per plant and has to be efficiently controlled. Suitable automation technologies are mostly based on real-time measurement of parameters related either to the greenhouse microclimate (e.g., solar radiation, vapor pressure deficit, air temperature) or to the GM water status (water tension or content).

Increasing Sustainability of Growing Media Constituents and Stand-Alone Substrates in Soilless Culture Systems

“…This is due to the inherent space, nutrient, and water use efficiencies of this production method; all of which are higher than soil-grown crops [9]. At present, life cycle analysis (LCA) is used for the classification of growing media constituents, based on their environmental impact and sustainability, environmental protection, and the application of "green technologies" for their production [7,16]. Mugnozza et al [43] determined, using LCA, that soilless cultivation reduced the environmental impact by more than double, due to lower levels of fertilizers and pesticides emitted to the environment, compared to soil cultivation.…”

“…However, there is no universal substrate or mixture that is valid for all plant species and in all situations of cultivation [11,14,23]. Gruda et al [14], Barrett et al [24], Savvas, and Gruda [16] also speak for the performance of growing media. Here, they included not only substrate properties, but also the ability to perform well in real growing conditions.…”

“…In the horticultural industry, generally, mixtures of growing media constituents and additives are used. Organic or inorganic materials can be used as constituents, while additives include fertilizers, liming materials, and bio-control or wetting agents [14][15][16].…”

“…Commercial applications include lawn and garden soil amendments, potting soils, and turf maintenance on golf courses [21]. The extensive use of peat as a basic and main component of substrates is due to relatively low costs in these areas, its excellent chemical, biological, and physical properties with low nutrient content, low pH, a unique combination of high water-holding capacity by high air space and drainage characteristics, light weight, and freedom from pests and diseases [14,16,21]. The unique microporous properties of Sphagnum peat and its resistance to degradation are matched by few other growing medium constituents [22].…”

Investigating the Suitability of Pressmud and Coir Pith for Use as Soilless Substrate by Sem, Xrf, Uv-Vis and Ftir Spectroscopy Techniques

“…2 Growbag cultivation is one of the simplest and most user-friendly soilless cultivation techniques, 3 which could be adopted to achieve prompter harvest from a small piece of land, alleviating the environmental risks associated with soil-based cultivation systems. [4][5][6][7] The selection of an appropriate substrate composition based on technical and economic feasibility is a vital aspect of research and key to success in any soilless production system. 8 The composition of growbag media may be either inorganic (e.g.…”