1,720,970 research outputs found
Managing ph of organic matrices and new commercial substrates for ornamental plant production: A methodological approach
No full textProfessional peat-free substrates for ornamental plant production are increasingly required by nursery growers. Most promising materials are green compost, coconut coir dust, and woody fibre, used alone or in mixtures. One of the major concerns is pH, usually higher than optimal. In this work, a method based on a three-step procedure was adopted to acidify three organic matrices alone or in mixtures and to individuate the most suitable product, between iron(II) sulphate 7-hydrate and elemental sulphur chips. Firstly, the determination of the buffering capacity by dilution with sulphuric acid was carried out to determine dosages. Afterwards, an incubation trial of 84 (iron(II) sulphate) or 120 days (sulphur chips) was conducted on matrices and substrate mixtures with calculated doses in a climatic chamber maintained at 21◦C. Iron(II) sulphate resulted not suitable because it caused a rapid, but not lasting, pH lowering and an excessive electrical conductivity (EC) increase. Sulphur chips could instead guarantee an adequate and lasting pH lowering. These results were then validated in the open field trial on matrices and substrates. The proposed acidification methodology could be considered in developing new substrates, but the rapidity of pH acidification and EC increase on plant and mineral nutrition should be further investigated
Estimation of pore-water electrical conductivity in soilless tomatoes cultivation using an interpretable machine learning model
Full text linkSoilless culture is widely adopted for improving produce quality and yield and increasing input efficiency. Most of the benefits potentially achievable in soilless systems are possible through precise and continuous management and adjustment of plant nutrition. Under operational conditions, the electrical conductivity (EC) is the main driving parameter leading fertigation strategies, but its measure in the drainage water can be not completely representative of the root zone in the growing medium. Nowadays low-cost sensors can be adopted to measure bulk EC (ECb) in the substrate. The Hilhorst equation is commonly used to convert the ECb into pore-water EC (ECw). This equation is widely calibrated for soil cultivation, but unable to perform properly for soilless substrate with high moisture content and water permittivity. In this work, two cultivation cycles of cherry tomato, managed in a closed-loop soilless system, were used to calibrate and validate two alternative models to the above equation (i.e., generalized additive model - GAM, and extreme gradient boost model - XGBoost). The models predicted ECw from the ECb recorded by substrate sensors. Plants were grown in rockwool using two different strategies for nutrient solution refill achieving different ECw trends during the cultivation. The Hilhorst equation confirmed its unsuitability for ECw prediction in soilless systems. ECw prediction through GAM was not satisfying at low and high ECw values. XGBoost was the most suitable model for ECw estimation, particularly at extreme EC values
Partial Replacement of Peat: Effects on Substrate Physico-Hydrological Properties and Sage Growth
No full textThe transformation of organic by-products derived from waste into value-added resources represents a promising strategy to advance circular economy principles and bolster environmental and agricultural sustainability, especially in soilless cultivation. This study evaluates the viability of three organic by-products-wood fiber (WF), coffee silverskin (CS), and brewer's spent grains (BSGs)-as partial peat replacements in horticultural substrates. Ten growing media formulations were assessed, incorporating increased doses (0-40% v/v as peat replacement-PR) of each alternative by-product. The effects on physical and hydraulic substrate properties, along with plant growth traits, were examined using two ornamental Salvia genotypes, 'Victoria' and 'Amistad'. To synthesize the multivariate growth data into a single, biologically meaningful metric, based on the first principal component, a Growth Index (GI), a PC1-derived index, was calculated, providing a powerful, unified metric to rank substrate efficacy. WF-based substrates exhibited increased porosity and diminished water retention, whereas media enriched with CS and BSG enhanced moisture availability, particularly at 20-40 PR. The bulk density was highest at PR40 for both WF and BSG treatments, and at PR20 in CS-based substrates. Electrical conductivity increased in CS and BSG treatments with rising PR levels. The results on the vegetative growth of ornamental sages have highlighted that differential PR rates are required depending on the specific organic by-product and plant genotype. In 'Victoria', GI indicates that a 20% replacement of peat with BSG provided the optimal conditions for holistic plant development; the lowest GI for WF substrates across nearly all peat replacement levels indicated that it was the most detrimental alternative for this cultivar. In 'Amistad', the analysis of the GI scores revealed that the CS20 and BSG20 of peat replacement yielded the highest overall growth, with GI scores significantly greater than those of the peat control. CS10 and BSG40 also showed high GI scores in 'Amistad'. WF10 had GI scores similar to those of the peat control. In general, the GI-based approach confirms that moderate inclusion of brewer's spent grain (BSG20) is a highly effective peat replacement for both genotypes. At the same time, coffee silverskin (CS) is particularly effective for the 'Amistad' genotype. This analysis underscores that optimal substrate formulation is not only dependent on the amendment type and rate but also critically on the plant genotype
Preliminary study on in vivo rooting of ornamental plants growing on peat-free growing media
No full textStudies on the use of peat-free growing media to grow potted ornamental plants are nowadays increasing, due to environmental concerns around the exploitation of peat, but these kind of studies are lacking with respect to cutting production. In this work, we investigated rhizogenesis on cuttings of four ornamental species (Viburnum rhytidophyllum L., Pyracantha koidzumii × P. coccinea 'Mohave', Prunus laurocerasus L., Euonymus japonicus Thunb., Ligustrum sinense Lour.) planted on the following growing media: 1) peat:pumice 70:30 v v-1 (control); 2) coconut coir dust:pumice 70:30 v v-1; 3) coconut coir dust:green compost 55:45 v v-1; 4) coconut coir dust:green compost: Stabilized wood fiber 40:30:30 v v-1; 5) coconut coir dust 100 v v-1; 6) green compost 100 v v-1; 7) stabilized wood fiber 100 v v-1. Twelve cm-leafed-cuttings (with 4-6 leaves) were prepared and treated with 4000 ppm indole-3-butyric acid (IBA), 4000 ppm 1-naphthaleneacetic acid (NAA), 4000 ppm IBA+NAA or without hormones. After 120 days, rooting and shooting were evaluated considering root dry weight, length and the root area as main performance indicators. Cuttings grown on substrates with green compost and coconut coir dust generally tended to have same performances of cuttings grown on peat-based media while the cuttings grown on stabilized wood fiber media showed lower rooting grown. In general, data showed that green compost and coconut coir dust could represent excellent substitutes and alternatives to peat for the cultivation of cuttings in commercial nursery providing innovation elements regarding the total elimination of peat during the propagation phase of plants
Effects of irrigation treatments on physiological parameters in Photinia × fraseri ?Red Robin' and in Viburnum ?Lucidum' grown under drought conditions
No full textThe aim of this research was to evaluate the effects of different irrigation treatments on plant development and photosynthesis performances of two broadleaf hedge shrubs species, Photinia × fraseri 'Red Robin' and Viburnum odoratissimum, also known as Viburnum 'Lucidum', in order to assess their adaptability to drought stress conditions and to optimise their use in urban hedges. The plants were grown in pots filled with peat and pumice (1:1) inside a greenhouse placed in central Italy during summer-autumn season. Treatments consisted in four different irrigation regimes differentiated by water restitution when substrate moisture reached value of 73%, 66% or 80% of container capacity plus a treatment where the moisture was maintained constantly at 73%. The irrigation was managed automatically by FDR sensors. Net photosynthesis, transpiration, stomatal conductance, water use efficiency, chlorophyll a fluorescence and biometric parameters were periodically monitored during the experiment. A parallel experiment was conducted by growing these two species in open field with different irrigation frequencies with the goal to evaluate their behavior under natural conditions, similar to those typical in urban landscape. Photinia 'Red Robin' showed a higher adaptability to water stress, especially when water supply was reduced in terms of irrigation frequency. On the contrary, Viburnum 'Lucidum' showed a lower adaptability; in fact, less stressed treatments showed more developed plants with respect to the other ones
Substitution of peat in the cultivation of two shrub species used for ecological restoration and recovery of degraded green areas
No full textEnvironmental restoration and recovery of abandoned and degraded urban areas require cares in the choice and cultivation of plants, which must show high adaptability to stressful conditions after transplanting. For these species, standard cultivation methods are often adopted in intensive nursery production. While more sustainable methods of cultivation are required, little is known about the possibility of replacing peat in the growing media. In this work, a one-year cultivation cycle was carried out with two species: Viburnum lantana L., a native deciduous shrub, and Viburnum rhytidophyllum Hemsl. Six different substrates were tested: 1) peat:pumice 70:30 v v-1, as a control; 2) coconut coir dust:pumice 70:30 v v-1; 3) coconut coir dust:green compost 55:45 v v-1; 4) coconut coir dust:stabilized wood fiber 60:40 v v-1; 5) green compost:stabilized wood fiber 30:70 v v-1; 6) coconut coir dust:green compost: Stabilized wood fiber 40:30:30 v v-1. Growing performance was assessed by measuring plant height, collar diameter, biomass accumulation, leaf area, SPAD index, and leaf chlorophyll fluorescence variables. In addition, only for V. lantana L., leaf gas exchange was measured. V. rhytidophyllum Hemsl. and V. lantana L. grown in peat-free substrates showed comparable, or even significantly higher, values for the measured traits in comparison to the control treatment. Similar results were recorded for SPAD index and net photosynthesis for V. lantana L., while no significant differences were found in the measurement of photosystem efficiency, leaf transpiration, stomatal conductance and internal CO2 concentration. Results suggested that V. rhytidophyllum Hemsl. and V. lantana L. can be cultivated in professional nurseries on growing media that are more sustainable and environmentally friendly than peat
Testing sap-flow sensors to predict irrigation of soilless tomato fertigated with saline water
No full textIn Mediterranean vegetable greenhouses, the optimization of fertigation in presence of saline water is a crucial goal. The use of decision support systems, for calculating irrigation water requirements, based on crop evapotranspiration (ETc) models and on soil, plant, climate data and weather forecast, is helpful for greenhouse farmers although not much applied. In soilless systems, evaporation from the substrate is negligible and irrigation can be inferred considering plant transpiration only. Therefore, sap flow sensors are promising tools for estimating plant transpiration in horticulture, so far mainly used in forestry and fruit crops. This work aimed to validate the use of these sensors in tomato (Solanum lycopersicum L.) by comparison with ETc simulation models. Two trials were conducted on cherry tomatoes in the summer-autumn season, in two unheated greenhouses located in the Centre and South Italy, under a closed soilless system. In the first location (Italy), plants were grown on rockwool slabs and drip-irrigated with saline water up to 75 mM NaCl. In the second location (south Italy), plants were grown on coconut fiber slabs and subirrigated with saline water up to 70 mM NaCl. Sap-flow sensors, using the stem heat balance method, were mounted at 30 cm from the collar of the plants. The actual daily water uptake was measured through flow meters in a closed-loop systems. Greenhouse climate was continuously recorded throughout the crop by a meteorological station. Sap-flow sensor estimates showed significant correlations with flow meter data and climate parameters, at the different salinity levels, thus showing the high capability to replace, or integrate, other tools to optimize irrigation in Mediterranean greenhouses
Salt Stress Triggers Distinct Cations Mobilization Strategies in Olive Tree (Olea Europaea L.): A Case Study Featuring Five Newly Selected Cultivars
No full textSoil salinity affects 7% of the Earth’s land surface representing a threat for olive orchards, particularly in the Mediterranean region where the highest amount of worldwide olive oil production is established. This study aimed to investigate the physiological and nutritional responses of five newly developed olive tree cultivars under salinity stress, in an effort to identify potentially suitable varieties for olive tree cultivation in saline soils. Five Olea europaea (L.) cultivars (‘Tosca’, ‘Apollo’, ‘Minerva’, ‘Zeus’, and ‘Diana’) were subjected to a 90-day salt treatment through fertigation with a solution containing 60 mM NaCl, compared to a control irrigated with 0 mM NaCl. The study evaluated biomass parameters, macroelement balances and physiological traits, including net photosynthetic rate, to determine the impact of salinity. Salt treatment reduced biomass accumulation across all cultivars. However, the cultivar ‘Apollo’ displayed a notable resilience. Despite increased Na concentration in shoot and root tissues, ‘Apollo’ maintained nutrient homeostasis, unlike other cultivars that suffered macroelement imbalances under salinity. Additionally, ‘Apollo’ recorded a higher net photosynthetic rate compared to the other varieties, indicating an efficient physiological adaptation. The findings suggest ‘Apollo’ as a promising cultivar for saline environments. Its superior ability to balance nutrient uptake and sustain photosynthesis under salt stress highlights its potential for addressing the challenges of soil salinisation in the context of climate change
Biochar as growing substrate component for potted Murraya paniculata
No full textBiochar soil amendment can boost plant productivity by improving the soil's biological, chemical, and physical properties. Up to date few studies were conducted on the use of biochar as partial substitute of peat in growing substrates for the horticultural and nursey industries, even less for the production of containerized ornamentals. With the aim to evaluate the agronomical performances of conifers wood biochar as a component for peat-reduced soilless substrates for ornamental species, a greenhouse experiment was carried out on potted Murraya paniculata (L.) Jacq. Plants were grown using the following mixtures: 0, 25, and 50% (v/v). Biochar amendment of substrates significantly affected growth and ornamental quality of potted Murrayas as a decrease of plant height, leaf area, leaf numbers, flower production, biomass yield and water use efficiency was recorded when plants were grown with 50% biochar. Highest values were observed with 0 and 25% biochar. Our results seem to suggest that conifers wood biochar could be used up to 25% as component in peat-based substrates for potted Murrayas
The effect of different peat-free growing media and fertilization levels on the plant nutrition of Leucanthemum vulgare (lam.) and (Dianthus barbatus L.)
No full textResearch on peat-free substrates is increasing due to the environmental concerns associated with peat extraction and with the aim of promoting sustainable horticultural practices. Previous research has shown that green compost mixed with coconut coir dust and stabilized wood fiber can be a valuable peat-free alternative for growing media. This study extends this knowledge by exploring the possibility of reducing fertilization levels by exploiting the nutrient content of green compost. In this paper we tested two ornamental herbaceous perennial plants, Leucanthemum vulgare Lam. and Dianthus barbatus L. For each species, we carried out five different substrate mixtures: 1) peat:pumice 70:30 v v−1; 2) coconut coir dust:pumice 70:30 v v−1; 3) coconut coir dust:green compost 55:45 v v−1; 4) green compost:stabilized wood fiber 60:40 v v−1; and 5) coconut coir dust:green compost:stabilized wood fiber 40:30:30 v v−1. For each mixture, we explored three different levels of fertilization: i) no fertilizer application; ii) low dosage of a controlled-release fertilizer at 2 g L−1; and iii) high dosage of the same controlled-release fertilizer at 4 g L−1. Plant biomass, biometric parameters, eco-physiological parameters, and plant mineral content were measured as performance indicators. The results showed that the nutrient surplus provided by the peat-free substrate, particularly when it contains green compost, can enhance the growth potential of the plants. Adding green compost to non-peat substrates can be an opportunity to optimize plant nutrition while reducing the presence of peat in plant nurseries and the use of chemical fertilizers
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