Reuse of waste materials as growing media for ornamental plants

The use of different waste materials: pine bark, coconut fibre and sewage sludge as substrates in the production of ornamental plants was studied, with an special interest on the suitability of coconut fibre as growing substrate for conifer plants. The plant species tested were Pinus pinea, Cupressus arizonica and C. sempervirens and the substrate mixtures were: (1) pine bark, (2) pine bark with 15% of sewage sludge compost, (3) pine bark with 30% of sewage sludge compost, (4) coconut fibre, (5) coconut fibre with 15% of sewage sludge compost and (6) coconut fibre with 30% of sewage sludge compost. Substrates were physically and chemically well characterized, and 75-cm plants were grown on them for one year. Plant and substrate status were periodically tested along the experiment. As biosolid recycling is the main objective of the present work, the mixtures with 30% of composted sewage sludge will be the most convenient substrate to use. For C. sempervirens and C. arizonica, a mixture between pine bark or coconut fibre and 30% of biosolid compost in volume gave the best results, but the lower cost of the pine bark than the coconut fibre substrate indicated the use of the PB+30% CSS. For P. pinea the research of new combinations between waste products is recommended to attain better results.     

Evaluation of a compost obtained from forestry wastes and solid phase of pig slurry as a substrate for seedlings production

A composted material obtained from forestry wastes and solid phase of pig slurry was evaluated as a substrate component for the production of tomato and lettuce seedlings. Four different substrates were tested: compost (100C), a mixture of 75% compost and 25% peat substrate (75C), a mixture of 50% compost and 50% peat substrate (50C), and peat-based substrate (control). Compost increased the pH of the substrate from 6.3 (control) to 6.9 (100C) but did not affect the electrical conductivity (0.26 and 0.27 mScm(-1), respectively, for control and 100C). Germination and growth of lettuce seedlings were not affected by the substrate type, contrasting with tomato seedlings where the highest growth occurred at 100C substrate. Increasing compost percentage on substrate increased nitrogen, calcium and magnesium availability and, consequently, the concentration of these elements in plant tissues increased. On the contrary, potassium and manganese concentration decreased. Results from the study suggest that the compost studied is a good alternative to peat-based substrates for the production of vegetable seedlings.     

蘑菇渣堆肥对华北落叶松移植容器苗生长和营养积累的影响

为缓解草炭大量使用带来的环境问题,在华北落叶松容器育苗过程中添加蘑菇渣堆肥以替代草炭,添加蘑菇渣堆肥体积比例分别为0%(T₀)、15%(T₁)、18.75%(T₂)、25%(T₃)、37.50%(T₄)、50%(T₅)、56.25%(T₆)、60%(T₇),研究不同配比下基质的理化性质以及对华北落叶松1年生移植容器苗生长和营养积累的影响.结果表明: 当蘑菇渣堆肥替代草炭的比例≤50%时,苗木苗高、地径和生物量与常用草炭处理无显著差异,且处理T₂、T₄、T₅苗木体内养分浓度显著高于对照,基质pH值处于微酸性或中性范围,适宜苗木生长;当蘑菇渣添加比例＞50%时,基质pH值偏碱性,苗木生长受到不利影响,苗木质量下降.当蘑菇渣添加比例为15%时,苗木质量最好,苗高、地径和单株生物量达到最大.因此,蘑菇渣替代草炭培育华北落叶松移植容器苗是完全可行的,替代比例最高可达到50%,当添加比例为15%时,可培育出高质量的苗木.     

The inorganic component of green roof substrates impacts the growth of Mediterranean plant species as well as the C and N sequestration potential

Extensive green roofs substrates should meet a list of physicochemical and biochemical requirements to be used as a basis for plant growth: high water holding capacity, good aeration, low bulk density, and proper drainage are some of them. In recent years, the impact of different organic matter doses and the substrate depth on the subsequent plant growth have been deeply studied. By contrast, there are not many publications about the effect of the inorganic component of these substrates on plant development and C and N sequestration potential by the green roof system, and even more under semi-arid Mediterranean conditions. Four substrates were made by mixing the same compost, at 10% by volume, with different inorganic materials: CsB (compost, silica sand, and crushed bricks; 1:1:8), CB (compost and crushed bricks; 1:9), CSB (compost, clay-loam soil, and crushed bricks; 1:1:8), and CsS (compost, silica sand, and clay-loam soil; 1:1:8). These were placed, a depth of 10 cm, on “cultivation tables” in an experimental farm located in the SE of Spain. Two native species were sown in each substrate: Lotus creticus and Asteriscus maritimus. Physicochemical, nutritional, and biochemical properties of the substrates as well as the plant development were evaluated during a 10-month experiment. The CsB and CSB mixtures had good physicochemical properties (high porosity and acceptable water holding capacity) although the levels of C, N, and humic substances were higher in the soil-containing substrates than in the CB and CsB mixtures. The hydrolytic enzyme activity was also promoted in these mixtures. The plant growth pattern showed differences regarding the inorganic composition of the substrate; L. creticus had superior development in the CsB substrate and A. maritimus was able to grow in all tested substrate mixtures, although its cover was low, being a more versatile candidate to establish a green roof cover. The greatest C and N sequestration potential was achieved by the CsS mixture, reaching 1.06 kg TC m⁻² of green roof substrate. Therefore, substrate composition impacts the growth of native plant species as well as the C and N sequestration by the green roof system.     

Assessment of suitability and suppressiveness of on-farm green compost as a substitute of peat in the production of lavender plants

Suppression of root rot diseases of ornamental plants is a potential benefit of formulating soilless container media with compost. A green compost (green nursery compost, GNC), obtained by a circular-economy approach from residues of pruning of woody plants and grass clippings during the nursery activities was analysed for its suppressiveness of root rot diseases using lavender. To this end, a bioassay was develop by formulating potting mixes containing GNC with two rates of peat substitution (25% and 50%) and infested with the root rot pathogens Sclerotinia sclerotiorum, Rhizoctonia solani and Phytophthora nicotianae. Contrasting results were obtained by using both substrates with a significant reduction of root rot by S. sclerotiorum, no effect on the containment of that by P. nicotianae, and an increase of symptoms caused by R. solani. The specific suppressiveness observed may be attributed to the colonisation of compost by specific groups of antagonistic microorganisms. This hypothesis was investigated by the analysis of culturable fungal community, which resulted in the isolation of Trichoderma harzianum and T. atroviride as preponderant fungal species. Trichoderma representative isolates exerted in vitro antagonistic activities against the target pathogens with varying efficiencies indicating the employment of multiple complementary mechanisms, which may have contributed to the observed specific suppressiveness. Both substrates containing GNC resulted suitable for nursery cultivation of lavender, showing a growth performance similar to that obtained with peat-based substrate. Present results indicate that on-farm compost is a suitable component of mixed-peat substrates capable to support plant growth and provide specific disease suppression.     

Growth of ornamental plants in two composts prepared from agroindustrial wastes

Two composts prepared from agroindustrial wastes were assayed as substrates: C1 from brewing waste (yeast and malt) plus lemon tree prunings; and C2 from the solid fraction of olive mill wastewater plus olive leaves. Sixteen substrates were prepared by combining each compost with Sphagnum peat or a commercial substrate (CS) in different proportions. The nutrients (N and K) provided by the composts, which acted as slow-release fertilisers, influenced especially the development of calendula, although the physical and physico-chemical properties such as total pore space and electrical conductivity (EC) were also relevant. On the other hand, in the salt-sensitive calceolaria hybrid, EC and chloride concentration were the main factors influencing growth. Adequate substrates for the development of calendula can be prepared by mixing C1 at up to 75% with peat or at up to 50% with CS, and C2 at up to 50% with peat or CS. For calceolaria, the substrate should have a lower proportion of compost, C1 at up to 50% and C2 at up to 25%, both mixed with peat or CS. Therefore, composts of agroindustrial origin such as these can be used as an alternative to peat and CSs for growing ornamental plants. provided the mixture contains at least 25% peat or CS.     

Effect of arbuscular mycorrhizal colonization and two levels of compost supply on nutrient uptake and flowering of pelargonium plants

Two challenges frequently encountered in the production of ornamental plants in organic horticulture are: (1) the rate of mineralization of phosphorus (P) and nitrogen (N) from organic fertilizers can be too slow to meet the high nutrient demand of young plants, and (2) the exclusive use of peat as a substrate for pot-based plant culture is discouraged in organic production systems. In this situation, the use of beneficial soil microorganisms in combination with high quality compost substrates can contribute to adequate plant growth and flower development. In this study, we examined possible alternatives to highly soluble fertilizers and pure peat substrates using pelargonium (Pelargonium peltatum L’Her.) as a test plant. Plants were grown on a peat-based substrate with two rates of compost addition and with and without arbuscular mycorrhizal (AM) fungi. Inoculation with three different commercial AM inocula resulted in colonization rates of up to 36% of the total root length, whereas non-inoculated plants remained free of root colonization. Increasing the rate of compost addition increased shoot dry weight and shoot nutrient concentrations, but the supply of compost did not always completely meet plant nutrient demand. Mycorrhizal colonization increased the number of buds and flowers, as well as shoot P and potassium (K) concentrations, but did not significantly affect shoot dry matter or shoot N concentration. We conclude that addition of compost in combination with mycorrhizal inoculation can improve nutrient status and flower development of plants grown on peat-based substrates.     

Use of composted sewage sludge in growth media for broccoli

In this study, the use of composted sewage sludge (CSS) as a binary component with peat (P) in growth media for a horticultural crop, broccoli (Brassica oleracea var. Botryti cv. Marathon), was evaluated. Four treatments were established, based on the addition of increasing quantities of composted sewage sludge to peat (0%, 15%, 30% and 50%, v/v). Physical, physico-chemical and chemical analyses of the different mixtures of CSS and P were made. Plant growth, biomass production and macronutrient (N, P, K, Ca, Mg), micronutrient (Fe, Cu, Mn, Zn) and heavy metal (Pb, Ni, Cd, Cr) contents of plants were determined. The addition of CSS to P increased plant nutrient and heavy metal contents of plants and electrical conductivity (EC) and bulk density values of the substrates. The use of CSS did not affect the germination rate, even at 50% compost. For broccoli growth, the highest yield was obtained with the medium prepared by mixing the peat with 30% of compost; however, the mixture with the most sewage sludge compost (50%) had the greatest contents of macro and micronutrients.     

Composted Green Waste as a Substitute for Peat in Growth Media: Effects on Growth and Nutrition of Calathea insignis

Peat mined from endangered wetland ecosystems is generally used as a component in soilless potting media in horticulture but is a costly and non-renewable natural resource. The objective of this work was to study the feasibility of replacing peat with different percentages (0, 10, 30, 50, 70, 90, and 100%) of composted green waste (CGW) as growth media for the production of the ornamental plant Calathea insignis. Compared with 100% peat media, media containing CGW had improved physical and chemical characteristics to achieve the acceptable ranges. Moreover, CGW addition had increased the stability (i.e., reduced the decomposition rates) of growth media mixtures, as indicated by comparison of particle-size distribution at the start and end of a 7-month greenhouse experiment. Addition of CGW also supported increased plant growth (biomass production, root morphology, nutrient contents, and photosynthetic pigment contents). The physical and chemical characteristics of growth media and plant growth were best with a medium containing 70% CGW and were better in a medium with 100% CGW than in one with 100% peat media. These results indicate that CGW is a viable alternative to peat for the cultivation of Calathea insignis.     

Alternative soilless media for growing Petunia x hybrida and Impatiens wallerana: physical behavior, effect of fertilization and nitrate losses

The use of alternative soilless media for the production of potted plants requires knowledge of their physical and chemical characteristics to result in the best conditions for plant growth. We investigated the use of alternative soilless media based on river waste and Sphagnun sp. and Carex sp. from Argentinean peatlands on Petuniaxhybrida and Impatiens wallerana production at two fertilization levels (200 and 400mgl(-1)N). River waste or 'temperate peat' is the name given to a material, resulting from the accumulation of aquatic plant residues under an anaerobic subtropical environment, which is dredged from river banks. Our results showed that alternative substrates based on river waste can be used to grow high quality plants. This result was not fully explained on the basis of established methods to evaluate substrate quality. Highly concentrated fertigation solution decreased the substrate quality parameters and plant growth. Nitrate leaching from the alternative substrates containing river waste was lower than the standard peat-based materials, which makes river waste desirable from a sustainable pot production system perspective. River waste and Carex peat are suitable alternatives to Sphagnum peat from the Northern Hemisphere.     

Physiologic response of Agaricus subrufescens using different casing materials and practices applied in the cultivation of Agaricus bisporus

Casing materials and practices used in the cultivation of Agaricus bisporus were evaluated in the cultivation of Agaricus subrufescens, using the best techniques for optimization of production, including the possibility of re-casing of the compost for the production of a second crop of mushroom. Casing based on peat moss, loam soil or coir was compared to casing material mixed with or without spawn-run compost. Based on the results, we conclude that the casing layer used in the cultivation of A. subrufescens should not necessarily be the same as that used in the cultivation of A. bisporus. For the tested strain cultivated with loam soil as casing layer, the ruffling technique is highly superior to CACing and should be pursued in further research. The re-casing of compost in new cycles showed good results suggesting that the currently used compost could be improved.     

Growth enhancement of Citrus reshni after inoculation with Glomus intraradices and Trichoderma aureoviride and associated effects on microbial populations and enzyme activity in potting mixes

There have been some scientific reports suggesting that dual inoculations with arbuscular mycorrhizal (AM) and saprophytic soil fungi may cause an additive or synergistic growth enhancement of the inoculated host plant. Some Trichoderma spp. have shown antagonistic potential against pathogenic fungi and a beneficial effect on plant growth. Joint inoculations of the mycorrhizal fungus Glomus intraradices Schenck and Smith, isolated from a citrus nursery (Tarragona, Spain) and a strain of Trichoderma aureoviride Rifai, isolated from an organic compost, were tested on a citrus rootstock, Citrus reshni Hort. ex Tan. The interactions between both microorganisms and their influence on mycorrhizal root colonization and plant growth enhancement, the changes produced in the soil microbial activity, like esterase, trehalase, phosphatase and chitinase activities, and on microbial populations were evaluated in three organic substrates: (1) sphagnum peat and autoclaved sandy soil (1/1, v/v), (2) sphagnum peat, quartz sand and perlite (1/1/1, v/v) and (3) pine bark compost (BVU, Prodeasa Product). Substrate characteristics were more important than the AM inoculation treatment in the determination of enzyme activity. In bark compost, the number of bacterial colonies obtained on soil-dilution plates was significantly higher than in peat and sand mixtures. Inoculation with T. aureoviride alone produced no significant effect on growth enhancement of C. reshni. However, dual inoculation with both, T. aureoviride and G. intraradices significantly increased plant growth in two of the substrates used and was the best treatment in pine bark amended compost. The inoculation with T. aureoviride did not affect the development of mycorrhizal root colonization. These results show a synergistic effect of G. intraradices and T. aureoviride on the growth of C. reshni in organic substrates and indicate the potential benefits of using combined inoculations.     

Spent mushroom substrates as component of growing media for germination and growth of horticultural plants

This research work was conducted in order to investigate the possibility of using spent mushroom substrate (SMS) in the production of horticultural seedlings replacing part of the peat in the growing media. Three vegetable species with different salt sensitivities, the less sensitive being tomato (Lycopersicon esculentum var. Muchamiel), the moderately salt-sensitive being courgette (Cucurbita pepo L. var. Afrodite F1) and the most salt-sensitive being pepper (Capsicum annum L. var. Lamuyo F1) were grown in 12 media containing SMS of two types of mushroom (Agaricus bisporus (SMS-AB) and Pleurotus ostreatus (SMS-PO)) or a mixture of both 50% (v/v) (SMS-50), as well as peat in various ratios. The proportions of each residue in the mixtures elaborated with peat were 25%, 50%, 75% and 100% v/v residue. A substrate of 100% peat was used as control. The experiment was arranged in a completely-randomised design with two replicates per treatment under greenhouse conditions. Prior to sowing, some physical, physico-chemical and chemical properties of the growing media were determined and seed germination and fresh weight of seedling were also measured. In most of the cases, the addition of SMS to the growing media produced an increase in the pH values, salt contents, macro and micronutrient concentrations and a decrease in the water holding capacity contents in comparison to peat, whereas great differences were found in the air capacity values between SMS-based substrates and peat. Up to 75% SMS can be used in mixtures with peat for seed germination of the plant species studied. Regarding the most suitable SMS-based substrates for plant growth, any substrate could be used for tomato seedling production. However, all SMS-AB-based substrates and the media containing low dose of SMS-PO and SMS-50 were adequate for growth of courgette and pepper.     

Substitution of peat for municipal solid waste- and sewage sludge-based composts in nursery growing media: effects on growth and nutrition of the native shrub Pistacia lentiscus L

In this study, the effect of a partial substitution of peat for compost on the growth and nutrition of a native shrub (Pistacia lentiscus L.) was tested. Composts were prepared from pruning and municipal solid wastes or pruning waste and sewage sludge. For preparing growing media each compost was added at a rate of 40%, fresh pine bark at 20% or 40% and peat at 20%, 40% or 60%. Aqueous extracts from the substrates did not impair germination of cress (germination bioassay). In relation to plants growing in peat-based substrate (used as a control), plants of the compost-based substrates reached better growth and nutrition, especially when using the sewage sludge-based compost, and the P uptake was notably enhanced. The concentrations of trace elements were far lower than the ranges considered phytotoxic for vascular plants. Detrimental effect derived from using fresh pine bark was not observed.     

Early growth response of container-grown selected woody boreal seedlings in amended composite tailings and tailings sand

Successful reclamation of saline-alkaline sites may be enhanced by revegetating with species that are tolerant to factors that limit normal plant growth. Boreal woody plants tested in this study have shown promise for use in saline habitats. This study was conducted to assess the effects of amendment treatments (peat, pulp waste, agriboost, a combination of pulp waste and fly ash, and mineral fertilizer) on the early growth of three hybrid poplar clones and three coniferous species. Twelve-week and 18-week container-grown hybrid poplar clones and coniferous species, respectively, were monitored for 12 weeks in pot culture in both composite tailings (CTs) and tailings sand (TS) materials obtained from the oil sands plant, Syncrude Canada Ltd., Ft. McMurray, Alberta. These substrates with low nutrients, organic matter, and water-holding capacities, were amended with different organic materials at different rates. Growth, as assessed by the volume increment in both substrates, was generally better for the first 6 weeks than for the last 6 weeks. Growth was reduced during the last 6 weeks due to nutrient depletion over time in these impoverished substrates. Overall, for both substrates, the mineral fertilizer, 20%, 40% and 60% peat were the best amendments treatments for poplar clones with NM-6 being the most productive clone. For coniferous species, 20% and 40% pulp or peat appear to be the best amendment treatments, with lodgepole pine being the most productive species. The inflexion point of the regression functions were found around 30% rate of the amendment materials. The results also indicated that peat and pulp waste were the best amendment treatments for both hybrid poplars and coniferous species whereas the agriboost and mix (combination of pulp waste and fly ash) were the worst.     

Management of nursery practices for efficient ectomycorrhizal fungi application in the production of Quercus ilex

The application of ectomycorrhizal (ECM) fungi on forest nursery production is regarded as part of good management practice. However, before employing large scale inoculations in a nursery the interaction between ECM symbionts, growth substrate and fertilisation input should be studied to select the most suitable nursery practices for promoting plant growth and ECM colonisation. In this study, seedlings of Quercus ilex were inoculated with Paxillus involutus, Hebeloma mesophaeum or Cenococcum geophilum and grown in three different substrates commonly used in forest nurseries: peat-based compost, forest soil or composted pine bark. The effect of various fertilisation regimes was also studied. The choice of substrate had a significant effect on plant growth and ECM colonisation. The most appropriate combination of substrate and ECM fungus for Q. ilex growth and nutrition was peat and H. mesophaeum. Plants grown on a peat-based compost and inoculated with H. mesophaeum had a significantly greater biomass and leaf phosphorus concentration without fertilisation. Composted pine bark was found not to be suitable for growth or for mycorrhization. If the appropriate growth substrate is selected, it is possible to replace the use of chemical fertilisers by inoculation with selected ECM fungi. This results in a significant increase in plant development, and thus ECM fungi can be recommended as a more environmental friendly biotechnological approach to plant management in the nursery.     

Integrative Application of Soil Conditioners and Bio-augmentation for Enhanced Heavy Metal Stabilization from Wastewater and Improved Growth of Nicotiana alata L. and Petunia hydrida L.

Wastewater generated from industries contains numerous contaminants, among which heavy metals (HMs) are non-degradable. This research work highlights the use of commonly used ornamental plants, Nicotiana alata L. and Petunia hydrida L., with compost (C) and peat moss (M), and rhizospheric bacterial augmentation using Pseudomonas japonica, for the phytostabilization of HMs from synthetic wastewater. After plant–soil acclimatization, plants were exposed for 6 weeks to synthetic wastewater, containing cadmium, chromium, copper, lead, nickel, and zinc concentrations (based on the HMs level of wastewaters collected from textile and pharmaceutical industry). Physiological response, biochemical status, and enzymatic fluctuations of plants and the distribution of HMs in plant parts and soil, were quantified. With the combined use (5% each v/v conditioner/soil) of C and M, in bio-augmented soil, physiological response and enzymatic status of both plants improved, with decreased stress injury due to HMs. Further, the plant HMs uptake was reduced, with better stabilization of HM in soil. For better phytostabilization of HMs in wastewater, the use of compost, peat moss, and bacterial augmentation is recommended with Nicotiana alata L. and Petunia hydrida L.

     

Comparative assessment of chelated spent mushroom substrates as casing material for the production of Agaricus bisporus

Spent mushroom substrate (SMS) leached with water or treated with chelating agents to remove metal cations, pasteurised to remove any harmful micro-organisms and mixed with peat has potential as a casing material for mushroom production. The microbial and chemical changes in SMS after treatment with citric acid, ethylene diaminetetraacetic acid (EDTA) and water were compared; treatment with the chelating agents resulted in lower ash content, conductivity and minerals, higher fibre fractions, carbon, hydrogen and nitrogen. The microbial and chemical changes in the materials after treatment with the two chelators and water were compared. Blending peat with the heat-treated materials at a ratio of 1:1 resulted in improved physical properties. The casings prepared from the test materials and the control, consisting of 100% peat, were compared after neutralising with lime for their productivity in a mushroom yield trial. As expected, the compost bags cased with the control were the most productive compared to the other casings. Of the three treated materials, casing prepared from SMS treated with EDTA blended with peat was the most productive. Dry matter of harvested mushrooms from chelated-SMS casings was significantly higher than the control casing. Comparison of the main components of peat and chelated SMS revealed that the major differences were in the proportions of ash, lipid, lignin and fibre fractions. The stability of some of these components, when complexed with metal cations present in lime may play an important role in determining the composition of the cell wall in fruiting bodies leading to high dry matter content. Received: 19 November 1998 / Received revision: 29 March 1999 / Accepted: 6 April 1999     

Use of municipal solid waste compost (MSWC) as a growing medium in the nursery production of tomato plants

Five media prepared from old peat (OP), white peat (WP) and municipal solid waste compost (MSWC) were used to determine optimum growing media for tomatoes (Lycopersicum esculentum Mill. cv "Atletico"). The mixtures of substrates used were: OP (65%)+WP (30%)+perlite (5%), OP (65%)+MSWC (30%)+perlite (5%), WP (65%)+OP (30%)+perlite (5%), WP (65%)+MSWC (30%)+perlite (5%), MSWC (65%)+WP (30%)+perlite (5%). Various seedling indices were measured in order to assess the quality of the nursery-produced plant. Nursery-produced tomato seedlings grown in WP (65%)+MSWC (30%) displayed quality indices similar to those recorded for conventional mixtures of old and white peat sphagnum, due to a correct balance between the compost nutrient supply and the porosity and aeration provided by white peat.     

The Cultivation of Arabidopsis for Experimental Research Using Commercially Available Peat-Based and Peat-Free Growing Media

Experimental research involving Arabidopsis thaliana often involves the quantification of phenotypic traits during cultivation on compost or other growing media. Many commercially-available growing media contain peat, but peat extraction is not sustainable due to its very slow rate of formation. Moreover, peat extraction reduces peatland biodiversity and releases stored carbon and methane into the atmosphere. Here, we compared the experimental performance of Arabidopsis on peat-based and several types of commercially-available peat-free growing media (variously formed from coir, composted bark, wood-fibre, and domestic compost), to provide guidance for reducing peat use in plant sciences research with Arabidopsis. Arabidopsis biomass accumulation and seed yield were reduced by cultivation on several types of peat-free growing media. Arabidopsis performed extremely poorly on coir alone, presumably because this medium was completely nitrate-free. Some peat-free growing media were more susceptible to fungal contamination. We found that autoclaving of control (peat-based) growing media had no effect upon any physiological parameters that we examined, compared with non-autoclaved control growing media, under our experimental conditions. Overall, we conclude that Arabidopsis performs best when cultivated on peat-based growing media because seed yield was almost always reduced when peat-free media were used. This may be because standard laboratory protocols and growth conditions for Arabidopsis are optimized for peat-based media. However, during the vegetative growth phase several phenotypic traits were comparable between plants cultivated on peat-based and some peat-free media, suggesting that under certain circumstances peat-free media can be suitable for phenotypic analysis of Arabidopsis.