Vegetable and ornamental crops require high input demand to adequately support their standard commercial quality and yield. For these crops, a very high level of agronomic use efficiency of many productive factors can be achieved in soilless culture. For example, the benefits derived from the adoption of soilless closed loops for the recirculation of the nutrient solution are well known as a benchmark of excellence for nutrient and water use efficiency. The challenges that we now face are as follows: (i) making soilless systems more inclusive of sustainable and eco-friendly growing substrates, possibly available at a local level; (ii) replacing chemicals with more sustainable products (e.g., organic active compounds) as much as possible for plant nutrition and protection. These goals can be addressed by following different approaches, but the adoption of peat-free organic substrates may play a central role. This work investigates four organic materials, i.e., biochar, coir, green compost, and wood fibers, to assess their role in plant nutrition and protection when used as components for the preparation of growing media in the soilless cultivation of containerized crops. In further detail, the work highlights how these materials may support normal agronomic practices.

Ornamental plant production constitutes an important sector of the horticultural industry worldwide and fungal infections, that dramatically affect the aesthetic quality of plants, can cause serious economic and crop losses. The need to reduce the use of pesticides for controlling fungal outbreaks requires the development of new sustainable strategies for pathogen control. In particular, early and accurate large-scale detection of occurring symptoms is critical to face the ambitious challenge of an effective, energy-saving, and precise disease management. Here, the new trends in digital-based detection and available tools to treat fungal infections are presented in comparison with conventional practices. Recent advances in molecular biology tools, spectroscopic and imaging technologies and fungal risk models based on microclimate trends are examined. The revised spectroscopic and imaging technologies were tested through a case study on rose plants showing important fungal diseases (i.e., spot spectroscopy, hyperspectral, multispectral, and thermal imaging, fluorescence sensors). The final aim was the examination of conventional practices and current e-tools to gain the early detection of plant diseases, the identification of timing and spacing for their proper management, reduction in crop losses through environmentally friendly and sustainable production systems. Moreover, future perspectives for enhancing the integration of all these approaches are discussed.

Low nutrient and high pH of circulating water represent two of the main issues to overcome for a successful combination of aquaculture and hydroponics in aquaponics offering a sustainable and circular economy solution for vegetable production. The purpose of this study was to screen the tolerance of four herbs to high pH and low nutrient concentration in hydroponics, i.e., green and red basils, mint, and rocket salad, with a focus on plant yield and nutraceutical aspects. Results highlighted green basil as the most tolerant species to low nutrient and high pH conditions followed by mint. On the contrary, negative effects from high pH and low nutrient were reported on red basil and especially rocket salad, which strongly affect their marketability parameters. Rocket salad fresh biomass was more than halved under the combination of high pH and low nutrients. Results on green and red basil showed the importance of testing the tolerance to these agronomic conditions at both species and variety levels. Despite the reduction in biomass, leaf pigments were not influenced by high pH and low nutrients and therefore can be considered parameters of minor importance for the evaluation of these species. In conclusion, the tolerance of green basil and mint to high pH and low nutrients under hydroponic conditions has been highlighted. Further investigation coupled with fish farming will be able to reinforce the convenience of using these species for aquaponics.

In the horticultural sector, the achievement of an efficient and eco-friendly sustainable production of plants is nowadays challenging. Indeed, in plant vegetative propagation of woody ornamentals, the substitution of chemical products used to promote rooting of cuttings with natural extracts would be a desirable goal. Thus, the aim of this work was to test the replacement of synthetic phytoregulators, such as auxins and brassinosteroids, with biostimulants, such as seaweed extracts, for the rooting promotion of rose cuttings. The rooting rate and biometric parameters of control cuttings treated with distilled water were compared with those of cuttings treated with synthetic hormones, i.e., auxins or 22(S),23(S)-homobrassinolide, or two commercial products based on low temperature seaweed extracts, i.e., Kelpak^® and Phylgreen. Two scented hybrid tea rose cultivars were used to assess possible genotype-dependent effects, i.e., ‘Michelangelo^®’ and ‘Cosmos^®’. Auxins confirmed their role in root growth enhancement in ornamental plant cuttings. Like these phytoregulators, Kelpak^® improved the survival rate and root biometric parameters of both rose cuttings, highlighting its suitability for the replacement of synthetic products used for rooting promotion in rose propagation. Brassinosteroids showed a species-dependent effect, increasing the root biomass in ‘Cosmos^®’ while it resulted as distilled water in ‘Michelangelo^®’. Phylgreen did not improve the rooting of both rose cuttings, highlighting the necessity of evaluating the applicability and methodology for this product before its use. In conclusions, our results highlighted the possibility to replace chemical products in rose cutting production.

Non-thermal plasma (NTP) appears a promising strategy for supporting crop protection, increasing yield and quality, and promoting environmental safety through a decrease in chemical use. However, very few NTP applications on containerized crops are reported under operational growing conditions and in combination with eco-friendly growing media and fertigation management. In this work, NTP technology is applied to the nutrient solution used for the production of gerbera plants grown in peat or green compost, as an alternative substrate to peat, and with standard or low fertilization. NTP treatment promotes fresh leaf and flower biomass production in plants grown in peat and nutrient adsorption in those grown in both substrates, except for Fe, while decreasing dry plant matter. However, it causes a decrease in the leaf and flower biomasses of plants grown in compost, showing a substrate-dependent effect under a low fertilization regime. In general, the limitation in compost was probably caused by the high-substrate alkalinization that commonly interferes with gerbera growth. Under low fertilization, a reduction in the photosynthetic capacity further penalizes plant growth in compost. A lower level of fertilization also decreases gerbera quality, highlighting that Ca, Mg, Mn, and Fe could be reduced with respect to standard fertilization.