Peat Substrate Research Articles

Nutrient Use Efficiency and Cucumber Productivity as a Function of the Nitrogen Fertilization Rate and the Wood Fiber Content in Growing Media.

A peat substrate is made from peat from drained peatlands, which is a limited resource. A realistic estimate is that 50% of the world's wetlands have been lost. Peat is used in horticulture, especially for the cultivation of vegetables in greenhouses. The consequences of peatland exploitation are an increase in the greenhouse effect and a decrease in carbon stocks. Wood fiber can be used as an alternative to peat. The chemical properties of growing media interact and change continuously due to the small volume of growing media, which is limited by the growing container. This study aims to gain new knowledge on the impact of nutrient changes in the microbial degradation of carbon compounds in wood fiber and mixtures with a peat substrate on the content and uptake of nutrients required by plants. The cucumber (Cucumis sativus L.) variety 'Dirigent H' developed in the Netherlands was cultivated in growing media of a peat substrate and wood fiber: (1) peat substrate (PS); (2) wood fiber (WF); (3) wood fiber and peat substrate 50/50 v/v (WF/PS 50/50); (4) wood fiber and peat substrate 25/75 v/v (WF/PS 25/75). The rates of fertilization were the following: (1) conventional fertilization (CF); (2) 13 g N per plant (N13); (3) 23 g N per plant (N23); (4) 30 g N per plant (N30). The experiment was carried out with three replications. As the amount of wood fiber increased, the humidity and pH of the growing media increased. The fertilization of the cucumbers with different quantities of nitrogen influenced the nutrient uptake. The plants grown in the 50/50 and 25/75 growing media had the best Cu uptake when fertilized with N23. When the plants grown in the wood fiber media and the 50/50 media were fertilized with N13, N23, and N30, the Mn content in the growing media at the end of the growing season was significantly lower than the Mn content in the media with conventional fertilization. Thus, nitrogen improved the uptake of Mn by the plants grown not only in the wood fiber, but also in the combinations with a peat substrate. Growing plants in wood fiber and fertilizing them with N13 can result in the optimum uptake of micronutrients. The number and biomass of cucumber fruits per plant were influenced by the amount of wood fiber in the growing media and the application of nitrogen fertilizer. The highest number of fruits and biomass of fruits per plant obtained were significantly higher when the cucumbers were grown in WF/PS 50/50 growing media with additional N13 fertilization.

From Waste to Plant Production: Cattle Dung Compost as an Alternative Nursery Substrate to Commercial Peat for Producing Lettuce Plants

The limited availability of peat-based substrates, a nonrenewable resource, and the negative environmental impacts associated with their extraction require the conservation of this resource. We assessed the use of cattle dung compost as a stand-alone nursery substrate, replacing peat substrate for the production of lettuce (Lactuca sativa L.) seedlings. A completely randomized design was employed, using cattle dung compost (C) and commercial peat (P, control treatment) in various combinations (100% P; 25% C/75% P; 50% C/50% P; 75% C/25% P; 100% C) to assess their effects on different growth parameters of lettuce. Twenty-eight parameters (e.g., seed germination, seedling survival, diameter, height, biomass growth) were assessed, corresponding to the time when the seedlings are transplanted. All treatments achieved 100% seed germination and seedling survival; indicating the successful establishment of lettuce seedlings across all tested substrates. However, seedling growth was found to be significantly influenced by substrate type. Seedling diameter was significantly increased by 10.8% in the 50% C/50% P substrate, while seedling height was significantly increased by 7.7, 6.8, and nearly 10%, respectively, within the 25% C/75% P, 50% C/50% P and 100% C substrates, relative to the control. Other substrate treatments were not significant. Similar or significantly higher values than the control were also observed for biomass growth under the tested substrates, indicating the beneficial effect of cattle dung on the initial growth of plants during the nursery phase. Cattle dung compost, used as a growing substrate, demonstrated similar or superior results to commercial peat, suggesting its potential as a viable alternative potting medium for sustainable horticulture.

Exploring the role of pedological and climatic aspects in the medium-term decline of green roofs hydrological performance: an experimental study in a Mediterranean environment

ABSTRACT In the realm of sustainable strategies for urban flooding risk mitigation, green roofs (GRs) emerge as a key solution. The complex relationship between hydrological, pedological, and climatic aspects poses several challenges in the definition of GRs’ medium-term behaviour, emphasizing the imperative for further research. Embedding pedological and climatological evidence, this study focuses on relevant observed changes in the hydrological performance and behaviour of two extensive GR test beds located in southern Italy over a 7-year monitoring period. Experimental rainfall and runoff data, at the event scale, point to a reduction of approximately 12% in the stormwater retention capacity (RC) of monitored GRs. Additionally, a comparative analysis of RC values in two specific time windows revealed how, in an early stage, it was controlled by soil moisture content whereas it is currently (aged state) mainly related to rainfall characteristics. After excluding climate variability as a potential driver for observed RC changes, a pedological experimental campaign highlights variations in the physical and hydraulic parameters of the peat substrate, which, in turn, is addressed to affect the retention and detention capabilities of the GRs.

Improving restoration outcomes of boreal Sphagnum-dominated peatlands after peat-extraction: The key role of phosphorus fertilization

Fertilization is a common and effective restoration practice for some ecosystems. However, there are still knowledge gaps about the long-term effectiveness and impact of phosphorus fertilization during the restoration of degraded boreal Sphagnum peatlands using the Moss Layer Transfer Technique. Data gathered from 114 peatland sectors restored 1 to 25 years ago, encompassing around 2900 surveyed plots in Eastern Canada, were analyzed to investigate the influence of fertilization on plant re-establishment (cover, height, and aboveground biomass accumulation) and community composition. Fertilization with a low phosphorus dosage (1.64 g P m−2) of granular phosphate rock (P2O5; NPK 0–13-0) proved to accelerate peatland vegetation recovery by favoring a shift in plant community composition towards a Sphagnum dominance. This shift was encouraged by the fast colonization of Polytrichum strictum after fertilization, a nurse plant that stabilizes the peat substrate and facilitates the subsequent establishment of Sphagnum. Phosphorus fertilization increased by 42 % Sphagnum cover 25-year post-restoration and increased approximately by 15 % aboveground biomass accumulation 20-year post-restoration. Conversely, without fertilization, the success of restoration and long-term vegetation trajectories were uncertain. Phosphorus fertilization led to an increase in plant richness in the first 5 to 10 years after restoration and enhanced spatial heterogeneity in species composition throughout the later stages of restoration (20–25 years), suggesting that fertilization may foster dynamic, diverse plant communities. This study emphasizes fertilization's key role in restoring boreal Sphagnum peatland plant communities, especially in areas prone to episodes of freeze-thaw cycles, strongly advocating for the mandatory inclusion of phosphorus fertilization in the restoration process.

Aquaponic growth of basil (Ocimum basilicum) with African catfish (Clarias gariepinus) in standard substrate combined with a Humicacid Fiber-Substrate (HFS)

A major challenge in agriculture, horticulture and aquaponics practices is the reduction of mineral fertilisers and peat to reduce CO2 emissions and increase sustainability. This study used a three-phase-natural fertiliser, the Humicacid Fiber-Substrate (HFS), made from natural regenerative organic and mineral-fractions (Humus-Mineral-Complex), to reduce the peat content in plant pots for aquaponics farming. Basil (Ocimum basilicum) growth was compared with i) 100% standard media substrate ("Einheitserde", white peat 80%, clay 20%), and ii) 85% "Einheitserde" and 15% of HFS under irrigation with aquaculture process waters from an extensive and intensive production of African catfish (Clarias gariepinus) under coupled aquaponic conditions. The substitution with 15% HFS and use of intensive fish water resulted in comparable plant growth to a fertiliser solution as control, and in higher leaf width and leaf green weight and lower root dry weight compared with the standard media substrate "Einheitserde". Basil leaf chlorophyll content from the aquaponics was higher compared with local market plants. This suggests the possible substitution of the peat substrate "Einheitserde" with at least 15% HFS to reduce the natural peat fraction. Further studies on crop-specific substrates are needed to reduce peat in aquaponics farming plant cultivation.

Flaxseed oil cake improves basil (Ocimum basilicum L.) yield under drought stress by increasing herb biomass and quality of essential oil

Oil cakes are agro-industrial wastes produced in large quantities, with still untapped potential in plant production. Basil is one of the most economical essential oil crops cultivated worldwide, requiring sustainable production methods. This greenhouse experiments evaluated the effects of flaxseed oil cake (FOC) added to peat substrate at the rates of 5, 10, and 20 g dm−3 on herbal yield, content of bioactive compounds and mineral elements, antioxidant activity, and essential oil composition of basil (Ocimum basilicum 'Dark Opal'), grown under well-watered and drought stressed conditions. Two-way ANOVA, principal components analysis (PCA), and correlation networks were applied to associate the data. PCA analysis indicated variability in basil responses to the different treatments, with each treatment forming distinct clusters. The study revealed the beneficial effect of FOC on basil herb yield under water stress. Applying 10 g dm−3 FOC was the most effective in mitigating drought stress in basil. Under drought stress conditions, FOC at the rate of 10 g dm−3 increased fresh weight by 63.9 % and herb dry weight by 59.9 % compared with the peat-only substrate plants. As FOC rates increased, the nitrogen level of plant tissues and substrates increased while reducing sugars, total polyphenols, and total flavonoids content decreased. GC-MS analysis of basil essential oil showed that the main compounds were τ-cadinol (10.79–12.54 %), linalool (4.93–10.01 %), methyl eugenol (4.11–6.71 %), α-bergamotene (3.11–5.48 %) and eugenol (2.10–5.05 %). Drought stress lowed the linalool, methyl eugenol and α-bergamotene concentrations compared with the well-watered plants. However, adding FOC increased the accumulation of linalool and methyl eugenol in all of the FOC treatments under drought stress. Analysis of the differential network showed that the fresh and dry weight and the methyl-eugenol content as “hub” parameters correlated with most traits of basil grown under well-watered and drought stress conditions. In conclusion, using FOC at appropriate levels can effectively reduce plant herb yield loss caused by water stress.

Soil Type and Associated Microbiome Influence Chitin's Growth Promotion Effect in Lettuce

Chitin amendment of peat substrate has been proven effective in promoting lettuce growth and increasing phenolic compounds in lettuce seedlings. However, the effect of chitin soil amendment on lettuce growth in mineral soil remains unexplored. The effect of chitin amendment of mineral soil on lettuce growth and metabolite changes was investigated for the first time in the present study in comparison with chitin-amended peat substrate. Our findings showed that chitin addition in peat substrate increased lettuce head weight by approximately 50% at harvest, whereas this increase was 30% when chitin was added to mineral soil. Targeted metabolomics analysis indicated that chitin addition affected the phenolic compounds in lettuce seedlings, but this effect varied between soil types. Moreover, untargeted metabolomics analysis suggested that using peat substrate or mineral soil had a greater influence on produced lettuce metabolites than chitin addition. Rhizobiome analysis showed that specifically Mortierellaceae family members, known for chitin degradation and plant growth promotion, significantly increased in peat substrate upon chitin treatment. In mineral soil, three bacterial genera and five fungi, including known plant-growth-promoting genera, were significantly more abundant upon chitin treatment but Mortierellaceae family members were not. We assume that the observed effects primarily stem from soil characteristics and from chitin-induced alterations in rhizobiome composition, particularly the presence of Mortierellaceae members, leading to promoted lettuce growth. Despite the variability, chitin remains an environmentally friendly alternative to synthetic fertilizers in lettuce production, but its beneficial effects are dependent on rhizobiome composition, which should be considered before chitin application. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Replacing traditional nursery soil with spent mushroom substrate improves rice seedling quality and soil substrate properties.

Currently, large quantities of spent mushroom substrate (SMS) are produced annually. Because SMS has high water retention and nutrients, it has great potential to replace traditional topsoil for raising seedlings in agricultural production. However, few studies have examined the effects of substituting SMS for paddy soil on rice seedling growth and soil nutrients. SMS was mixed with rice soil in different proportions (20%, 50%, and 80%), and chemical fertilizer, organic fertilizer, and peat substrate were added in addition to equivalent nitrogen as a traditional seedling nursery method for comparison. Compared to traditional paddy soil (CK), the seedling qualities of the three SMS ratio treatments were all higher. Adding SMS at different ratios promoted rice seedling root growth, elevated the soluble protein concentration, and amplified the superoxide dismutase (SOD) enzymatic action in rice seedlings. Total porosity and aeration porosity of the soil increased by 17.40% and 32.90%, respectively. Soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) increased by 21.26-118.48%, 50.44-71.68%, and 23.08-80.17%, respectively. Besides, the relative abundance of Bacillus, Bacteroidetes, and other bacteria as well as the abundance of Ascomycota were all significantly increased. Adding 50% SMS increased the abundance of Pseudomonas by 8.42 times. The seedling quality of the 50% SMS treatment was even higher than chemical fertilizer and organic fertilizer treatments, only second to the peat substrate treatment. In summary, partial substitution of paddy soil with SMS can ameliorate substrate properties, improve seedling quality, and increase microbial diversity, indicating the suitability of SMS as a replacement for rice soil in seedling substrates. The 50% SMS ratio is the best. This study provides a basis for SMS to replace traditional rice soil in seedling cultivation.

Organic matter decomposition in mountain peatlands: effects of substrate quality and peatland degradation

Abstract Background and Aims Peatlands occupy only 3% of Earth’s terrestrial lands but store about one-third of global soil carbon. However, these large carbon stocks are currently under threat due to peatland degradation, where altered hydrological balance could enhance peat oxidation; thus releasing large amounts of CO2 into the atmosphere. We investigated the interactive effects of substrate quality, peat depth and peatland degradation on the decomposition rate of organic matter in peatlands by way of a field incubation experiment. Methods We incubated high-quality fresh peat and a lower-quality degraded peat substrate at three different depths (5, 15, and 30 cm) in two (intact and degraded) mountain peatlands for 18 months. Our results indicated that there is a significant interactive effect of substrate quality, peat depth, and peatland type on the peat decomposition rate. Results The fresh peat showed significantly higher decomposition rates than the degraded peat substrate, likely due to the high percentage of bioavailable carbon in the fresh moss substrate. In the degraded peatland, fresh peat at 30 cm showed no mass loss during the incubation period, likely due to the high-water table creating anaerobic conditions. The fresh peat incubated in the intact peatland showed a higher decomposition rate than the same substrate incubated in the degraded peatland due to the comparatively lower water table in the intact peatland. Conclusions Our findings indicate that the quality of the substrate being decomposed and the depth of the water table act as the main factors affecting the decomposition rate in mountain peatlands.

Specific surface area and microstructure of the surface of soil solid substrates of different genesis

The sorption characteristics of sand, peat, the arable layer of Moscow urbanozem and a mixture of these substrates were studied in conjunction with the surface topography of their solid phase, studied by scanning electron microscopy (SEM). The arable layer has the greatest ability to absorb nitrogen, and the peat substrate showed very low values of the sorbed gas. A different picture of the mutual arrangement of substrate sorption isotherms is observed when water vapour is used as a sorbing gas. Peat is distinguished by high values of sorbed moisture in the entire studied range of relative humidity. This leads to differences in the ranking of substrates by specific surface area in descending order of its values. So, the specific surface area by water sorption in the series: peat / arable layer / mixture / sand was: 420 / 72 / 45 / 4 m2/g, respectively. The given surface was ranked according to nitrogen sorption in a different sequence: 8.31 / 2.41 / 1.45 / 0.55 for the series: arable layer, mixture, peat and sand, respectively. The analysis of microstructural characteristics by the SEM method at various magnifications revealed the most developed, rough surface in the arable layer. It turned out to be geometrically the most diverse, even at magnification of ×20 000. The variety and heterogeneity of the relief of the interface of the phases leads to the appearance of hysteresis of the sorption/desorption curves. Its severity in the range of nitrogen vapor concentration in which hysteresis is detected, and in the maximum width of the hysteresis loop, also turned out to be the most significant in the arable layer. The very low nitrogen specific surface of peat, which is close to a sandy substrate, is associated with the presence of organic films draping and leveling the surface of peat particles, which was revealed by analyzing images obtained by scanning electron microscopy. The sorption of water showed their high hydrophilicity, which led to high values of substrate humidity in the entire studied range of relative humidity.

Trichoderma atroviride Enhances Impatiens walleriana Hook. f Growth and Flowering in Different Growing Media.

Trichoderma spp. are widely reported to regulate plant growth by improving nutrient uptake, photosynthesis, and abiotic stress tolerance. However, their possible application for bedding plants is little explored, especially when comparing different growing media. Considering that coconut coir dust is finding broader application in the ornamental plants sector as a peat substitute, this work was aimed to test the combination of Trichoderma atroviride AT10 and coconut coir dust on Impatiens walleriana plants. Four treatments were tested as a mix of: (i) two growing media (70:30), peat:perlite or coconut coir dust:perlite; and (ii) the absence or presence of a T. atroviride treatment. At the end of the production cycle, the biomass and ornamental parameters, leaf pigments, nutrient content of the plant tissues, and Trichoderma abundance were assessed. The results revealed that T. atroviride can readily colonize coir, and the same positive effects of inoculum were found in plants grown on both substrates. The biostimulant effect of T. atroviride was observed as an increase in the aboveground biomass, number and weight of flowers, pigments and nutrient concentration, thereby improving the commercial quality of I. walleriana. Thus, T. atroviride has shown its potential in making bedding plant cultivation more sustainable and improving the yield and aesthetic parameters of plants grown on peat and coconut coir dust substrates.

The effect of peat replacement in horticulture media by willow (Salix viminalis L.) biomass compost for cucumber transplant production.

This research evaluated the usefulness of horticultural substrates prepared on the basis of compost from chipped willow without additives and with the addition of nitrogen and decomposing mycelium of the cellulose-lignin fraction of wood in the cultivation of cucumber seedlings. The produced composts were mixed in different proportions: mixture 1 (W1) - the proportion of compost without additives and compost prepared with the addition of nitrogen and mycelium was in the ratio of 50:50, mixture 2 (W2) - the proportion of compost without additives and compost prepared with the addition of nitrogen and mycelium was in the ratio of 75:25. The starting mixtures were used to prepare horticultural substrates with different components (peat - P, vermicompost - V) and additives: basaltmeal - B, biochar from deciduous wood - C. The components were added in varying proportions. A total of 29 different substrates were subsequently tested in the study. Plant showed that the traits assessed varied to a greater extent under the effect of the test factors than at earlier growth stages. It was demonstrated that cucumber grown on substrates with 75% or 50% willow compost had a unit weight at the same statistical level as when grown on peat substrate (P). The plants with the highest unit weight (8.5- 10.4 g), belonged to the same homogeneous group and derived from sites W1P1B2, W2P1, W1P1B1, W2P2, W1P1C1, P, W1P1, W2B1, W2P2B2. High-quality cucumber transplant should characterise well develop, optimal height-to-stem thickness ratio, short hypocotyl, thick green leaves and cotyledons.

Impacts of forestry drainage on surface peat stoichiometry and physical properties in boreal peatlands in Finland

Management of drained peatlands may pose a risk or a solution on the way towards climate change mitigation, which creates a need to evaluate the current state of forestry-drained peatlands, the magnitude of degradation processes and indicators for carbon (C) loss. Using a large dataset (778 profiles, 891 peat samples, collected between 1977 and 2017) from peatlands having different fertility classes across Finland, we investigate whether the surface peat profiles of undrained and forestry-drained peatlands differ in C:N, von Post and dry bulk density. The utility of element ratios (C:N:H stoichiometry) as site indicators for degradation were further analyzed from a subsample of 16 undrained and 30 drained peat profiles. This subsample of drained sites had carbon dioxide (CO2) and methane (CH4) fluxes measured allowing us to link peat element ratios to annual C gas effluxes. Element ratios H:C, O:C and C:N and degree of unsaturation (combining C, N, H changes) were found widely valid: they captured both differences in the botanical origin of peat as well as its potential decomposition pathway (C lost via a combination of dissolved organic C and C gas loss and/or the gaseous loss predominantly as CO2). Of the stoichiometric indexes, peat H:C ratio seemed to be the best proxy for degradation following drainage, it indicated not only long-term degradation but also explained 48% of the variation in annual CO2 emission. The O:C ratio positively correlated with annual CH4 flux, presumably because high O:C in peat reflected the availability of easily degradable substrate for methanogenesis. The differences in C:N ratio indicated notable decomposition processes for Sphagnum-dominated peatlands but not in Carex-dominated peatlands. Degree of unsaturation showed potential for an integrative proxy for drainage-induced lowering water table and post-drainage changes in peat substrate quality.

Peat Substrates Amended with Wood-based Biochar Do Not Influence the Efficacy of Paclobutrazol Drenches

Various soilless substrate components have been evaluated for many years to identify sustainable resources that do not negatively impact plant growth. Biochar is a carbon-based material that has been evaluated for use as an alternative aggregate in peat-based soilless substrates. In addition, the use of carbon adsorption for compound removal is widely used in groundwater remediation, municipal water filtration, and volatile organic compounds. Experiment one aimed to determine the impact of coarse biochar (<6 mm) on paclobutrazol efficacy when incorporated at 15% or 30% by volume in a peat-based substrate when compared with a perlite-amended substrate at the same incorporation volumes. In Expt. 1, a single paclobutrazol drench application of 0, 0.5, 1.0, 2.0, and 4.0 mg·L−1 was applied to ‘Princettia Red’ and ‘Princettia White’ poinsettias (Euphorbia pulcherrima × Euphorbia cornastra). In Expt. 2, two different biochar particle sizes of coarse (<6 mm) and extra coarse (>6 mm) were examined at the same incorporation volumes as Expt. 1 and compared with a perlite-amended substrate at the same incorporation volumes. However, during Expt. 2, continual drench applications at times of irrigation of 0.0, 6.25, 12.5, 25.0, 50, and 100 μg·L−1 (ppb) paclobutrazol were applied to pansy (Viola ×wittrockiana) ‘Matrix Blue Blotch’ and begonia (Begonia ×hybrida) ‘Big Red Bronze Leaf’. The efficacy of paclobutrazol drenches for controlling growth in all species was unaffected by the substrate composition regarding aggregate type or aggregate incorporation rate. Thus, even though biochar is often used for bioremediation and wastewater treatment, it did not negatively impact the efficacy of paclobutrazol drenches at the concentrations used. This research suggests that when biochar is used as an amendment to peatmoss it will not influence paclobutrazol drench efficacy when incorporated up to 30% by volume for the examined species.

Effect of various doses of birch-derived biochar on the growth of Helianthus annuus L.

Although biochar (BC) is expected to improve soil properties and plant growth, few studies have confirmed its effect on Helianthus annuus L. (sunflower). The effects of four different concentrations of birch-derived BC (2.5, 5, 7.5, and 10%) on the biometric growth parameters of sunflower were studied in a 60-day pot-scale experiment. In addition, the physicochemical properties and elemental composition of the birch-derived BC and peat substrates were examined. It is noted that birch-derived BC was characterized by a slightly acidic pH (about 6.4), lower electrical conductivity and 3.4 times higher water-holding capacity compared to the control substrate. Moreover, the percentage of carbon in BC was 1.4 times higher, while the content of hydrogen and oxygen, on the contrary, was lower in 1.5 and 2.0 times than in the control substrate. In most cases, adding BC to the peat substrate improved H. annuus growth parameters such as shoot height, root length, leaf area, as well as total fresh and dry biomass. The best results were obtained by adding 5% BC, which had a positive effect on all biometric parameters of H. annuus plants, while 10% BC had the least impact.

Usage of different planting schemes for mini-tubers potato growing under North Ossetia-Alania republic conditions

The purpose of the research is to study the effect of different planting schemes of the base lines on the quantitative yield of mini-tubers in the conditions of Republic of North Ossetia-Alania. The object of the research was microplants and microtubers of new promising potato varieties Gulliver, Sadon and Varyag. The experiments were carried out in 2020-2022, laid on a peat substrate using planting patterns 25x25 cm in plastic pots, 25x30 and 25x15 cm in the ground. Growing mini-tubers according to the scheme 25x25 cm in pots contributed to the formation of from 139.4 to 155.5 pcs/m2 with a standard seed fraction yield of 88-94%. An increase in the nutrition area as a result of planting the base lines into the soil according to the 25x30 cm scheme reduced the number of formed mini-tubers by 19.4-49,0 pcs/m2 with a standard yield of 77-85%. According to the 25x15 cm scheme, the total yield of mini-tubers increased by 19-35 pieces/m2, but the yield of the standard fraction decreased to 57-74%. In the original seed production of potatoes, an important indicator in the cultivation of mini-tubers is the yield of a fraction of more than 20 mm in transverse diameter. The maximum yield of mini-tubers with such dimensional characteristics was noted when planting micro-plants according to the scheme 25x25 cm - 113.7 pcs/m2. The use of micro-tubers according to this scheme reduced the number of mini-tubers with a fraction of more than 20 mm to 91.7 pcs/m2 or by 19%. As a result of applying the schemes of 25x30 and 25x15 cm, the quantitative yield of mini-tubers with a fraction of more than 20 mm did not depend on the origin of the base lines and amounted to 58.5-65.6 pcs/m2. Based on the studied planting schemes in protected ground in the Republic of North Ossetia-Alania, the maximum yield of mini-tubers with the best dimensional characteristics was obtained as a result of planting the base lines according to the 25x25 cm scheme in plastic pots. Reducing the feeding area according to the 25x15 cm scheme reduced the yield of mini-tubers of a fraction of more than 20 mm by 1.8-1.9 times.

Micronutrient Fe and Mn uptake from peat by marigold and petunia

Peat substrates have the potential to function as micronutrient sources such as iron (Fe) and manganese (Mn). Typically, when planning fertilization program for crops, the components of peat substrates are not taken into account. The objective was to quantify potentially plant-available micronutrients of Fe and Mn from peat substrates by floriculture species when no additional Fe and/or Mn were applied in the fertilizer solution. Greenhouse experiments were conducted using Tagetes erecta ‘Atlantis Primrose’ marigold (iron-efficient) and Petunia x hybrida ‘Celebrity Pink Morn’ petunia (iron-inefficient) to compare extractable Fe and Mn from two peat sources with actual plant uptake of these nutrients by the plants. In Experiment 1, marigold was grown hydroponically in plastic tubs using four different nutrient solutions: complete, without Fe, without Mn, and without both Fe and Mn. Within a period of less than two weeks after transplant, the absence of Fe and Mn severely limited marigold growth. The hydroponic study highlighted the importance of providing both Fe and Mn nutrients immediately after sowing to support normal marigold growth. In Experiment 2, both marigold and petunia were grown from seed in two peat substrates (Blackmore seedling peat “BM peat” and Sunshine Professional Black Bale peat “SG peat”) and an acid-washed sand substrate. Each peat was limed at 3 g.L−1 of reagent grade CaCO3 resulting in an initial substrate-pH of 5.0 for SG peat and 5.5 for BM peat. Four nutrient solutions [(a) complete, or complete with (b) no Fe, (c) no Mn, and (d) no Fe or Mn] were applied with each irrigation without leaching. Initial substrate nutrient levels were extracted using the SME (saturated medium extract) method using either water (SMEW) or 0.005 M DTPA (diethylenetriamine-pentaacetic acid, SMED) as extractants. Over a 5-week period (during the vegetative, non-blooming stage), peat substrates provided sufficient Fe and Mn for marigold, but iron deficiency symptoms were observed in marigolds grown in sand without Fe fertilizer. Petunia plants developed iron deficiency symptoms in all substrates without Fe fertilizer. The absence of Mn fertilizer, however, did not have a significant impact on petunia growth and health, indicating that peat substrates likely provided adequate Mn for non-symptomatic petunia plant growth. The micronutrient Fe and Mn budget analysis suggested that the SMEW method underestimated the availability of Fe and Mn to the plants, whereas the SMED method may have overestimated the extractable Fe and Mn levels in relation to the actual tissue uptake. Overall, the peat substrates showed a high potential for providing Fe and Mn in quantities sufficient for the initial growth of iron-efficient marigold, but was inadequate for iron-inefficient petunia.

Mangrove peat and algae leachates elicit rapid and contrasting molecular and microbial responses in coastal waters

As sea level rises, previously sequestered blue carbon can be exported offshore as particulate or dissolved organic matter where it may be re-mineralized or sequestered. The priming effect, or interactive effects of organic matter turnover with a mixed substrate, is well described in soils, but still debated in aquatic systems. Priming may contribute to enhanced blue carbon re-mineralization in coastal environments. Here we examined mangrove-derived dissolved organic matter turnover in a lab incubation, with leachates from mangrove peat, 13C-labeled algae, and peat+algae (primed). Particulate and dissolved organic matter were assessed; microbial metatranscriptomes were evaluated; and dissolved organic matter was characterized with high resolution mass spectrometry. Stable isotopes indicated rapid allocation of algal-derived dissolved organic matter into particulate organic matter. The algal treatment had the greatest increase in carbon dioxide, but primed and peat treatments had the greatest loss of dissolved organic carbon, greater RNA concentrations, and similar changes in total carbon dioxide. This suggests that, while total carbon dioxide did not increase under priming conditions, the addition of a peat substrate may promote microbial biomass production relative to carbon dioxide production. This work highlights that more targeted studies investigating the specific mechanisms of priming are necessary to address the molecular and microbial transformations associated with priming in aquatic systems.

SEED GERMINATION AND GROWTH DYNAMICS OF SEEDLINGS OF SCOTS PINE (PINUS SYLVESTRIS L.) WITH A CLOSED ROOT SYSTEM ON DIFFERENT SUBSTRATES

The relevance of the study is due to the great needs of growing high-quality planting material in a short time for forestry reclamation on disturbed lands both during oil and gas exploration and during oil and gas production. The paper presents the results of studies of germination energy, germination and growth dynamics of Pinus sylvestris L. seedlings grown in RKL-81 cassettes in a greenhouse in 2022 and 2023. At the same time, the renewal of forests is possible after the technical and biological stages of recultivation when creating forest crops from indigenous forestforming species. In 2022 and 2023, experiments were conducted on different types of peat-based substrate, differing in density, nutrient content and additional components from a complex of humic acids and salts, mineral fertilizers, trace elements, strains of friendly soil microflora and mycorrhiza. Pre-sowing seed treatment and agrophysical properties of substrates affected the energy of seed germination and germination, as well as an increase in the total number of germinated seeds during the first month. Good germination results were obtained in 2022 with pre-sowing seed treatment with Borogum-M, Rich-Micro, Bionex-Kemi preparations in low-density peat, filled with the starting composition of fertilizers. However, the biometric indicators of seedlings were slightly higher on the substrate with the addition of humic acids and salts, mineral fertilizers, trace elements, strains of soil microflora and mycorrhiza. In 2023, agroperlite was added to one of the peat substrates to reduce density and increase porosity. The germination energy, germination rate and dynamics of the emergence of seedlings on this substrate turned out to be the highest (from 93 to 100%). It is proposed to grow pine seedlings during one growing season on low-density peat with the addition of agroperlite and a complex of mineral and organic components, including soil microflora and mycorrhiza. This will speed up the process of obtaining the planting material of scots pine for forestry reclamation on disturbed lands both during oil and gas exploration and during oil and gas production.

Adaptation of plum home (<i>Prunus domestica</i>) micro plants to <i>in vivo</i> conditions

The aim of the research was the possibility of using zeolite for the adaptation of micro plants of plum home variety Kazanskaya under in vivo conditions. The control was a substrate for experiments based on grassroots peat (manufactured by JSC “Udmurttorf”, Udmurt Republic, Russia). In the studied variants, zeolite (Tatarsko-Shatrashanskoe deposit, Republic of Tatarstan, Russia) was added to peat in 60, 90, and 120 g/l doses. Microplants were also planted on a 100% zeolite substrate. It has been established that the survival rate of domestic plum micro plants to non-sterile conditions in a grassroots peat substrate with the addition of zeolite in all doses is significantly higher than in the control variant (78.3%) and varies within 86.7–99.2%. The survival rate of domestic plum micro plants in a 100% zeolite substrate was 80.8% at the control indicator’s level. At the first stage of adaptation, the growth length of micro plants in the bottom peat substrate with the addition of zeolite at doses of 60 and 90 g/l increased significantly. It amounted to 1.9 and 3.3 cm, respectively, with 1.2 cm in control. Compared with the maximum allowable duration of adaptation according to GOST R 54051-2010 of 45 days, the transformation of home plum was 21 days in general. At the same time, in the variants with the addition of zeolite to the substrate based on grassroots peat at doses of 60: 90 and 120 g/l, the growth length of home plum micro plants was, on average, 6.0, 8.0, and 5.3 cm, respectively, and the height of adapted micro plants to the end of the second stage of adaptation were 7.0; 9.0; 7.3 cm, which exceeded the performance of State Standard (SS) R 54051-2010.