Growth of Hedera helix L. Container Plants in Compost Substrates Made with Miscanthus ogiformis Honda Straw and Various N-Sources

Ammonium sulfate or urea were added as N-source to shredded straw of Miscanthus ogiformis ‘Giganteus’ and water was included as control. The combined materials were composted for seven months, and the resulting composts were tested as growth substrates for nursery container plants and compared with fertilized and unfertilized peat substrates. The pH was below recommended level for the compost substrate made with ammonium sulfate and for the unfertilized peat substrate throughout the experiment. Electrical conductivity and concentrations of most nutrients were low and decreased throughout the experiment for all growth substrates. Shrinking of the growth substrates after 4, 12 or 17 months was larger for compost substrates than for peat substrates. Bulk density increased in compost substrates and decreased in peat substrates, while the total loss of C was greater in compost substrates than in peat. Water retention was lower and air volume greater for compost substrate made with ammonium sulfate than for fertilized peat. Algae and mosses did not occur on Miscanthus compost growth substrates in contrast to peat substrates. The shoot length and dry matter of Hedera helix, produced after four and 12 months of growth, and five months following cut back, showed that plants can grow well in compost substrates made of Miscanthus straw and ammonium sulfate or urea. However, the compost substrates could not fully substitute for fertilized or unfertilized peat substrate with respect to dry matter production.     

Vermicomposting leachate as liquid fertilizer for the cultivation of sugarcane (Saccharum sp.)

In vermicomposting, the main product is the worm casts, but a leachate is generated that contains large amounts of plant nutrients. This leachate is normally diluted to avoid plant damage. We investigated how dilution of vermicompost leachate combined with different concentrations of nitrogen (N) - phosphorus (P) - potassium (K) triple 17 fertilizer, and polyoxyethylene tridecyl alcohol as dispersant and polyethylene nonylphenol as adherent to increase efficiency of fertilizer uptake, affected sugarcane plant development. The vermicomposting leachate with pH 7.8 and electrolytic conductivity 2.6 dS m^?1, contained 834 mg potassium (K) l^?1, 247 mg nitrate (NO₃^?) l^?1 and 168 mg phosphate (PO₄^3?) l^?1, was free of pathogens and resulted in a 65% germination index. Vermicompost leachate did not inhibit sugarcane growth and mixed with 170 g l^?1 NPK triple 17 fertilizer resulted in the best plant development. No dispersant or adherent was required to improve plant height and stem development.     

Using Thermal Sensitivity Analysis to Determine the Impact of Drainage on the Hydrochemistry of a Tropical Peat Soil from Malaysia

Peat from an area of pristine swamp in Malaysia and from an area of that swamp drained 10 years earlier for agriculture was incubated along a temperature gradient from 0 to 20 °C to simulate microbial activity through changes in temperature. With increasing temperature, nitrate availability decreased in the pristine peat but increased in the drained peat, suggesting that drainage has altered the principle nitrate transformation process from denitrification to nitrification. Sulfate concentrations in the pristine peat exhibited a greater proportional decrease with increasing temperature than in the drained peat, suggesting that drainage has decreased the influence of sulfate reduction over sulfate availability at this site. With the exception of phosphate, nutrient concentrations in the drained site were significantly greater (P < 0.05) than in the pristine site. Biogeochemical models should consider that drained peatlands may respond very differently to the temperature change predicted by current climate change models.     

Does Compost Selection Impact Green Roof Substrate Performance? Measuring Physical Properties,Plant Development,and Runoff Water Quality

Six green roof substrate blends were created by using composts sourced from local suppliers and the Michigan State University Student Organic Farm. Bulk density, field capacity, total porosity, and saturated hydraulic conductivity were determined for each substrate and compared to an un-amended expanded shale aggregate. Significant differences were detected in all measured physical properties. A plant growth study was conducted in a greenhouse. Ocimum basilicum (basil), Sedum floriforum (sedum), and Carex eburnea (bristleleaf sedge) were grown in a depth of 10 cm of all six substrates for 6 months. The greatest dry shoot masses in bristleleaf sedge and sedum were twice those of the smallest masses. The largest wet harvest of basil was four times greater than the smallest harvest. Runoff water was collected after simulated precipitation events on regular intervals during the plant growth study and analyzed for nitrate and phosphate concentrations. Ion concentrations were greatest on the first measurement date and decreased rapidly with time. Compost selection had a strong impact on initial nitrate and phosphate concentrations, but the influence of compost on concentrations diminished with time. Overall, compost selection was found to have measureable and meaningful impacts on green roof substrate performance.     

Differences in nitrogen‐assimilating enzyme activity in halophyte species are habitat‐related

The chemical form and content of available nitrogen (N) in salt marsh substrates varies considerably. On the western coast of Ireland, habitats designated as Ombrogenic Atlantic salt marshes were formed on ombrogenic peat substrate. The peat substrate in these systems has three times more ammonium than substrate from adjacent salt marsh habitats on sand and mud substrate. This study examined the extent to which the high concentration of ammonium in peat salt marsh substrate influences the N‐ assimilating enzyme activity of halophytes and the extent to which N metabolism differs between species. Specifically, this work investigated whether plants from peat salt marshes are more likely to assimilate ammonium than plants from non‐peat substrates. Four halophyte plant species—Armeria maritima, Aster tripolium, Plantago maritime, and Triglochin maritime—were sampled from various saltmarsh habitats including three sites on peat substrate and three on non‐peat substrate, comprising sand, mud and sand/mud. The activities of N‐metabolising enzymes—glutamine synthetase (GS), glutamate synthase, glutamate dehydrogenase (GDH), and nitrate reductase (NR)—were quantified in shoot and root parts. Root GS activity in Armeria maritima and shoot GS activity in Triglochin maritima were positively correlated with increasing soil ammonium levels. Root NR activity in Aster tripolium and shoot NR activity in Plantago maritima were significantly higher in plants grown on non‐peat substrates than peat substrates. The shoot : root GS activity ratio in Triglochin maritima on peat substrate was more than double the ratio on non‐peat substrates. It is concluded that all species tested displayed differences in N‐metabolising activities depending on the chemical form and/or concentration of N in the substrate, while three out of the four species were capable of taking advantage of the high levels of ammonium in peat substrates.     

Lime Rate Affects Substrate pH and Container-grown Birch Trees

Nursery production of birch (Betula nigra L.) trees commonly occurs in containers using a soilless substrate such as pine bark or peat moss. Birch trees have been reported to suffer from pH-induced micronutrient deficiencies in landscapes; thus, they are recommended to be planted in low-pH soils (<6.5). Little research has addressed the influence of substrate pH on birch trees during container production. Therefore, the objective of this research was to determine if substrate pH influences birch tree growth and development. Birch (Betula nigra ‘NBMTF’) liners were transplanted into 11.4 L plastic nursery containers filled with an 80 pine bark: 20 sphagnum peat moss (v:v) amended with either 0.6 kg.m^?3 of elemental sulfur (S) or 0, 1.8, 3.5, or 7.1 kg.m^?3 dolomitic lime. Substrate pH ranged from 4.8 to 7.3. There were only a few and minor differences in leaf chlorophyll content and no differences in plant growth. Differences in leachate and plant tissue nutrient concentration occurred for some elements, although these differences were not enough to affect plant growth. Container-grown birch trees can be grown over a wide range of substrate pH (4.8 to 7.3) with little or no effect on their growth.     

Use of Acacia Waste Compost as an Alternative Component for Horticultural Substrates

The rising cost of peat and pine bark has boosted the demand for alternative organic materials for container growing media. Here, composts of invasive acacia (Acacia longifolia and Acacia melanoxylon) residues were evaluated as alternative organic materials for horticultural substrates. Compost bulk density was less than 0.4 g cm^?3 and total pore space was more than 85 percent of the total volume, as established for an ideal substrate. The matured acacia compost air capacity, easily available water, buffering capacity, and total water-holding capacity were also within acceptable recommended values. With increased composting time the physical characteristics of the composts were improved, but the same was not true for chemical characteristics such as pH and electrical conductivity. The replacement of pine bark compost by acacia compost in a commercial substrate did not negatively affect either lettuce emergence or lettuce growth, suggesting that acacia compost can be successfully used as an alternative component for horticultural substrates.     

Standardization of media and nutrient concentration for coleus (Plectranthus barbatus Andr.) under substrate culture

Coleus (Plectranthus barbatus Andr.) is a medicinal herb whose roots contain forskolin. Incidences of soil-borne diseases, wilt complex and nematodes are the major limiting factors for growing this crop under soil media. Hence, an investigation was initiated for the standardization of soilless growth media and nutrient solution concentration in coleus. Coco peat, vermiculite, sand and their combinations were used as potting media with different concentrations of nutrients based on the recommended dose of fertilizers for soil media (1,080 mg plant^?1 nitrogen, 960 mg plant^?1 phosphorous and 1200 mg plant^?1 potassium). Among the different media and nutrients, plants grown under coco peat media with 80% of the recommended dose of fertilizer for soil (864 mg plant^?1 nitrogen, 768 mg plant^?1 phosphorous and 960 mg plant^?1 potassium) recorded significantly higher root yield (17.10 tha^?1) and quality parameters (0.98% forskolin). Benefit–cost ratio was also recorded maximum (4.25) in the same treatment.     

Effect of peat on mycorrhizal colonization and effectiveness of the arbuscular mycorrhizal fungus Gigaspora margarita

Abstract

The influence of the addition of Chinese peat and Canadian peat on arbuscular mycorrhizal colonization, mycorrhizal effectiveness and host-plant growth was investigated in a pot experiment. Chinese peat or Canadian peat was mixed with Masa soil (weathered granite soil) at different levels (0, 25, 50, 100, 150 or 200 g kg^?1) into which an arbuscular mycorrhizal fungus (AMF) Gigaspora margarita Becker & Hall was inoculated, and seedlings of Miscanthus sinensis Anderess were planted. There was a significant increase in plant growth with increasing amounts of Chinese peat. The growth-promoting effect of the AMF on the host was enhanced when the addition of Chinese peat was increased from 25 to 100 g kg^?1. Root colonization and the number of spores proliferating increased with increases at low levels of Chinese peat (from 25 to 100 g kg^?1), and decreased gradually with higher Chinese peat increments. Although plant growth and root colonization with the addition of Canadian peat increased slightly, Canadian peat suppressed mycorrhizal effectiveness. In contrast to Canadian peat, the addition of Chinese peat improved considerably the physical and chemical properties of the soil, which might result in the promotion of AM formation and mycorrhizal effectiveness.     

Effects of Different Substrate Ratios on the Growth and Physiology of Sequoia sempervirens Container Seedlings

Abstract

Container technology can effectively control soil environment and nutrient status to obtain the optimal plant growth condition. Peat, green waste compost (GWC), soil and perlite were used as substrate materials to study the effects of different substrate ratios on growth and physiology of 1.5-year-old Sequoia sempervirens container seedlings. The optimal substrate ratio of S. sempervirens container seedlings was obtained by L₉ (3⁴) orthogonal design and was finally evaluated by principal component analysis. The volume ratio of peat: GWC: soil: perlite of 4: 1.5: 1: 2 was the best substrate ratio for S. sempervirens across all parameters, whose porosity, bulk density (BD) and gas-water ratio (GWR) were within the ideal ranges. The concentrations of total nitrogen (TN) of 1.40% and total phosphorus (TP) of 0.13% were the highest among the nine different substrates. The total potassium (TK) and electrical conductivity (EC) were 0.13% and 0.70?ms cm^?1, respectively. In addition, the plant height and ground diameter growing in the substrate were increased by 28% and 39% compared to their respective initial values. The content of peat and GCW had significant effects on growth (p?<?0.01). The GWR in T2 (peat: GWC: soil: perlite = 6: 1: 0.5: 2) and T6 (peat: GWC: soil: perlite = 4: 0.5: 0.5: 1) are not suitable for S. sempervirens container seedlings. The PCA ranking of the 9 groups of substrates is: T8?>?T1?>?T4?>?T3?>?T2?>?T5?>?T7?>?T9?>?T6. The combination of peat, GWC, soil and perlite in an appropriate ratio could provide a good environment for S. sempervirens container seedlings.     

Manganese in substrate clays—harmful for plants?

Mixtures of peat and substrate clays are commonly used as growth media for horticultural plant production. A quality protocol for substrate clays defines a threshold value of active manganese (Mn_act = sum of exchangeable and easily reducible Mn) in substrate clays of < 500 mg kg^–1 to prevent toxic reactions of plants. This threshold value was tested in experiments with peat‐clay blends under various growth conditions, and nutrient solution experiments were additionally conducted to investigate the effects of silicic acid and dissolved organic matter on the occurrence of Mn toxicity. Common bean (Phaseolus vulgaris L.) and hydrangea (Hydrangea macrophylla) plants were cultivated in different peat‐clay substrates and in peat under different moisture and pH levels. The clays varied in their Mn_act content from 4–2354 mg kg^–1. The results of the substrate experiments reveal that a threshold value for Mn in substrate clays is not justified, as plants grown in all peat‐clay substrates did not develop any Mn toxicity even at high substrate moisture or low pH conditions which are known to increase the Mn availability. The extraction of active Mn did not well reflect the Mn concentrations in plant dry matter and substrate solution. As plants tolerated high Mn concentrations in the substrate solution compared to the nutrient solution without toxicity symptoms, the influence of silicic acid and dissolved organic matter (DOM) on Mn toxicity was characterized in a nutrient‐solution experiment. Manganese toxicity was clearly diminished by silicic acid application, but not by DOM. The former effect probably explains the tolerance of bean plants in peat substrates where high silicon concentrations in the substrate solution were observed. Peat‐clay blends even provided up to five times more silicon to plants than pure peat.     

The Use of Spent Mushroom Substrate (SMS) as an Organic Manure and Plant Substrate Component

The effect of the addition of SMS to soil on the growth of perennial ryegrass was studied in a pot experiment. SMS raised the analyzed levels of P, K, Mg and Electrical Conductivity (EC) but not the level of NO₃-N. At the first harvest, there was a positive response of growth up to a rate equivalent to 50 t/ha but above this growth declined. By the final harvest, there was a positive response of dry matter production up to the highest rate, 400 t/ha. The calculated nitrogen efficiency of dry matter production for SMS averaged 3.1 as against 21.1 for calcium ammonium nitrate. Leaching an SMS/peat column with distilled water at 10 day intervals over a 60 day period recovered 94 percent of the K in the leachate, 33 percent of the P and only 15 percent of the N. In SMS/peat mixes, early growth of tomato seedlings did not respond to rates above five percent of SMS by volume and was reduced when the SMS rate was above 20 percent. When the plants were grown on to a more mature stage, there was a response up to 20 percent SMS. In three experiments, SMS was used as a single nutrient source to supply N, P and K respectively. When used as a source of P and K, there was little benefit from increasing the rate of SMS above five percent. However, when used as a source of N, plant growth increased up to a rate of 25 percent SMS. There was no response to the addition of trace elements to SMS/peat substrates. When an SMS/peat substrate, containing five percent SMS by volume was supplemented with extra N, plant performance was as good as in a peat substrate with inorganic fertilizers.     

Phosphorus dynamics in peat‐based substrates

The mobility of nutrients in soils is well characterized, whereas little information is available for common horticultural substrates based on peat. Aim of the current study was to investigate the mobility and dynamics of phosphorus (P) as well as the parameters involved in P transport to plant roots in peat‐based substrates. A series of experiments was run to determine the impedance factor (f) and the buffer power (b). The impedance factor was determined for black peat and black peat mixed with 20% and 40% (v/v) of mineral component at volumetric water content (θ) of 40%, 50%, 60%, and 70% and at different diffusion time. Buffer power was calculated for black peat and black peat mixed with 20% (v/v) of seven different mineral components. Phosphorus was applied at rates of 0, 35, and 100 mg (L substrate^–1), respectively. The impedance factor was not affected by addition of the mineral component to peat. However, f increased from 0.03 to 0.2, by increasing θ from 40% to 60%, indicating that water content has a significant effect on this parameter. Substrate‐solution P ranged from 0.3 to 27 and from 1 to 95 mg P (L solution)^–1 for the P‐application rate of 35 and 100 mg P (L substrate)^–1, respectively. Buffer power of the substrates ranged from 1 to 17.25 depending on the mineral component, and it was positively correlated with oxalate‐soluble Fe and Al in the substrate. The calculated effective diffusion coefficient for P in the substrate was in the range of 10^–7 to 10^–8 cm² s^–1. This high value could be attributed mostly to the low buffer power rather than to the high impedance factor.     

Nitrous oxide emissions from three ecosystems in tropical peatland of Sarawak,Malaysia

Abstract

Nitrous oxide (N₂O) emissions were measured monthly over 1 year in three ecosystems on tropical peatland of Sarawak, Malaysia, using a closed-chamber technique. The three ecosystems investigated were mixed peat swamp forest, sago (Metroxylon sagu) and oil palm (Elaeis guineensis) plantations. The highest annual N₂O emissions were observed in the sago ecosystem with a production rate of 3.3 kg N ha^?1 year^?1, followed by the oil palm ecosystem at 1.2 kg N ha^?1 year^?1 and the forest ecosystem at 0.7 kg N ha^?1 year^?1. The N₂O emissions ranged from –3.4 to 19.7 µg N m^?2 h^?1 for the forest ecosystem, from 1.0 to 176.3 µg N m^?2 h^?1 for the sago ecosystem and from 0.9 to 58.4 µg N m^?2 h^?1 for the oil palm ecosystem. Multiple regression analysis showed that N₂O production in each ecosystem was regulated by different variables. The key factors influencing N₂O emissions in the forest ecosystem were the water table and the NH⁺ ₄ concentration at 25–50 cm, soil temperature at 5 cm and nitrate concentration at 0–25 cm in the sago ecosystem, and water-filled pore space, soil temperature at 5 cm and NH⁺ ₄ concentrations at 0–25 cm in the oil palm ecosystem. R² values for the above regression equations were 0.57, 0.63 and 0.48 for forest, sago and oil palm, respectively. The results suggest that the conversion of tropical peat swamp forest to agricultural crops, which causes substantial changes to the environment and soil properties, will significantly affect the exchange of N₂O between the tropical peatland and the atmosphere. Thus, the estimation of net N₂O production from tropical peatland for the global N₂O budget should take into consideration ecosystem type.     

Production and Interior Performances of Tropical Ornamental Foliage Plants Grown in Container Substrates Amended with Composts

Three representative Florida composts were mixed by volume with sphagnum peat and pine bark to formulate 12 container substrates. After physical and chemical characterization, the substrates, along with a control, were used to grow containerized Cordyline terminalis ‘Baby Doll’, Dieffenbachia maculata ‘Camille’, and Dracaena fragans ‘Massangeana’ cane. All substrates were able to produce marketable plants, but only five or seven, depending on plant genus, of the 12 compost-formulated substrates resulted in plants comparable or superior to those of the control substrate. The five also had substrate shrinkage equal to or less than the control. Plants were then moved to an interior evaluation site to determine the suitability of compost-formulated substrates in sustaining foliage plant growth under an interior environment. During a six-month interior evaluation, the plants maintained their aesthetic appearances. Based on plant growth parameters and quality ratings as well as substrate shrinkage both in production and interior evaluation, five of 12 compost-formulated substrates were identified to be equal or superior to the control. This study showed that the three composts, after being appropriately mixed with sphagnum peat and pine bark, can be used as container substrates in every phase of tropical foliage plant production and utilization.     

Use of Composted and Fresh Spent Tea Grinds As a Potential Greenhouse Substrate Component

In the United States, the market for freshly brewed, ready-to-drink tea has grown exponentially during the last 20 years. Along with generating more product, tea brewers have also produced more waste. Spent tea grinds (STG) are the finely ground waste product of the tea brewing process. STG's high water-holding capacity and organic nature make it a potential replacement for common substrate components such as pine bark (PB) and peat moss (PM). In an experiment, Lantana camara L. 'New Gold' and Nephrolepis exaltata L. 'Bostoniensis', were grown in various substrates for 10 weeks on a raised bench in a greenhouse. Four substrates, which were 100% STG, 1:1 mixture of cocomposted PB:STG, Fafard® 3B, and a composted 1:1 mixture of PB:STG, were evaluated in this experiment. Substrates either contained a preplant incorporated, complete fertilizer ^(+F), or contained no exogenous fertilizer ^(?F). Lantanas grown in tree bark compost (TBC)^+F and a 1:1 mixture of PB:STG^+F had the greatest growth index at harvest, while STG^+F was not different than TBC^+F. Lantanas grown in TBC^+F, Fafard® 3B^+F, and a 1:1 mixture of PB:STG^+F had the highest shoot dry weights at harvest. No differences existed in growth index or shoot dry weight of boston fern. Substrate leachate pH was at the high end, or slightly above, a recommended range for the duration of the experiment for substrates containing TBC, but plant growth was not reduced.     

D-最优混料设计优化草菇菇渣复合基质的黄瓜栽培配方

应用D-最优混料设计方法，以黄瓜植株的农艺性状、果实品质和产量为评价指标，探索了草菇菇渣、草炭和珍珠岩不同配比复合基质对黄瓜栽培的影响，建立了各配比基质与黄瓜植株响应值之间的回归模型，考察了配方中各基质的相互作用对黄瓜植株各响应值的影响。试验结果表明：菇渣营养丰富，但电导率和酸碱度偏高；草炭呈酸性，持水性、透气性强，可降低pH；珍珠岩吸水能力强，透气性好。草炭、珍珠岩复配的基质EC、pH较低，而含草菇菇渣的复配基质EC和pH随菇渣添加量的增加而升高，最终优化得到的最优基质配比为草菇菇渣32.02%、草炭60.00%、珍珠岩7.98%，该配方的理化性质良好，适宜黄瓜生长；经验证该配方生长的植株株高、茎粗、维生素C含量、可溶性糖含量、单株产量和硝酸盐含量分别为350.00 cm、11.74 mm、101.01 mg/kg、1.31%、2 123.33 g和351.04 mg/kg，与草炭相比，株高、茎粗、维生素C含量、可溶性糖含量和单株产量分别提高20.69%、1.73%、12.79%、14.79% 和41.56%，硝酸盐含量降低14.66%，且生产成本可节省约33%。可见，通过混料设计将草菇菇渣复合基质进行优化，可解决单一基质存在的电导率、酸碱度偏高等问题，栽培效果更佳，将草菇菇渣应用于黄瓜无土栽培是完全可行的。     

Nitrogen uptake efficiency of finger millet grown in hydroponic culture

The optimum nitrogen requirement along with nitrogen uptake efficiency of finger millet (Eleusine coracana) for obtaining plants of a high phenotypic quality was studied in this research using hydroponic culture. 20 days old seedlings were transferred in nutrient solution containing all the essential macro and micro nutrients. Plants were subjected to three treatments of nitrate viz. 0.05 mM, 0.1 mM and 0.5 mM by dissolving it in the nutrient solution. Plants grown in nutrient solution devoid of nitrate were treated as control. Plants grown in 0.5 mM nitrate conc. attained more height compared to other low nitrogen treatments (0.1 mM and 0.05 mM). Similarly plants of 0.5 mM nitrate treatments possessed more number of lateral roots, surface area of leaves, dry weight of plants and chlorophyll content compared to other low nitrogen treatments. Specific activity of nitrate reductase in plants treated with 0.5 mM concentration was found nearly 3 times higher than that of control plants; similarly, specific activity of nitrite reductase in 0.5 mM treated plants was also high compared to other low nitrogen treatments followed by control. The results of the present investigation therefore indicate that nitrogen uptake efficiency as revealed by the activities of nitrate reductase and nitrite reductase was high in 0.5 mM nitrate treatment. It also shows that 0.5 mM nitrate is optimum nitrogen concentration for the growth of finger millet in hydroponic condition.     

Tomato seedling development is improved by a substrate inoculated with a combination of rhizobacteria and fungi

Chile's seedling production industry has been growing for the last 10 years, and demand has actually reached 1250 million seedlings per year. This system has special relevance due to the high cost of seeds. In addition, there is an increasing demand for substituting synthetic agrochemicals. Therefore, the potential use of plant growth-promoting rhizobacteria (PGPR) in tomato production has been investigated. Before sowing, the micro-organisms provided by Biogram S.A. were inoculated into the substrate diluted in 250 mL/L unchlorinated water. The experiment was laid out in a ‘split-plot’ design with the two plant substrates as main plots and the inoculants as subplots, including six replicates per treatment. Tomato seedlings were grown using two different plant substrates: a mixture of 70% peat and 30% perlite by volume, and a substrate with 20% peat, 20% perlite and 60% compost by volume, both inoculated with Bacillus subtilis or Pseudomonas fluorescens or Bioroot®, which is a commercial product containing B. subtilis, P. fluorescens, Trichoderma harzianum, yeast, algae and Nocardia. For control, uninoculated tomato seedlings were grown on the respective plant substrates. Variance analysis did not identify significant interactions between substrate type (main plots) and inoculation treatment (subplots), P ≤ 0.05. There were significant differences between inoculants (P ≤ 0.05). Means were compared by using the Tukey's multiple range test. Tomato growth in terms of leaf area (cm²/plant) and shoot and root dry weight (g/10 plants) was improved for the seedlings grown on the substrate with 70% peat and 30% perlite, compared to the compost containing an alternative that is valid for both uninoculated perlite peat and all inoculated treatments where perlite peat was outstanding. Inoculation with Bioroot® improved the leaf area, shoot dry weight, root dry weight, radical contact area, volume of roots and root forks compared with the control without inoculation, when both plant substrates were analysed together. Thus, inoculation with Bioroot® can be recommended as an alternative to tomato seedling growers' dependence on synthetic agrochemicals.     

Effect of Compost Age and Concentration Of Pig Slurry on Plant Growth

Shredded straw of Miscanthus ogiformis Honda ‘Giganteus’ was composted with addition of water or aqueous solutions with 3, 10, 30 or 100% pig slurry. After 3, 6, 9, 12 and 15 months of composting the composts were tested as pot plant growth substrates for Hedera helix L. in comparison with enriched and nonenriched peat substrates. During the first week of composting temperatures rose to higher levels with stronger pig slurry solution except for the compost made with 100% pig slurry solution which suffered from oxygen depletion. Plants grown in compost substrates made with M. ogiformis and 10 or 30% pig slurry solution produced the same shoot lengths and dry matter as plants grown in enriched or nonenriched peat substrates. Plants in compost substrates made with water or 3% pig slurry solution produced slightly shorter shoots and less dry matter. Many plants in the compost substrate made with 100% pig slurry solution failed to grow, and for the remaining plants in that treatment, shoot and dry matter production was very low at all five ages of compost. Nutrient concentrations were suboptimal for compost substrates made with water or 3% pig slurry solution, near optimal with 10% pig slurry solution, above recommended concentrations with 30% pig slurry solution and supraoptimal with 100% pig slurry solution. The pig slurry concentration had little effect on water retention in 6 months old compost substrates while in older compost substrates increasing pig slurry concentration increased the water retention capacity. In six month old compost substrates water retention was lower than in peat substrates while in 12 months old composts the water retention was greater in the compost substrates than in the peat substrates. Total porosity was above 92% and similar for all substrates. Air volume was greater in compost substrates than in peat substrates. It is concluded that compost substrates made of Miscanthus ogiformis straw and diluted pig slurry can be used successfully as a substitute for peat substrates. An aqueous solution of 10 to 30% pig slurry solution added as nitrogen source before composting is optimal. Three months of composting is sufficient for optimal plant growth.