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factor that may influence plant growth in subirrigation systems. Substrates with 60% sphagnum peat were shown to provide the best capillary rise and growth of privet ( Ligustrum sp. L.) and viburnum ( Viburnum L.) ( Caron et al., 2005 ). Similarly

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Pine wood components are increasingly being used in soilless substrates to produce floriculture crops in the United States, particularly as a substitute for peat and perlite ( Drotleff, 2018 ; Harris et al., 2020 ). Sphagnum peatmoss is the major

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experimentally measured acidity when plants were grown with an ammonium-based, water-soluble fertilizer in a peat/perlite substrate. Materials and Methods Greenhouse substrate experiments In Spring 2007, a 70%:30% (v:v) peat:perlite substrate was mixed

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Abstract

Spagnum peat, perlite, vermiculite, and six media formulated (by volume) from these constituents (2:1, 1:1, 1:2 peat: perlite; 2:1, 1:1, 1:2 peat: vermiculite) were limed with 0, 0.9, 1.8, 2.7. 3.6, 5.4, 7.2, and 9.0 kg∙m−3 dolomite [CaMg(CO3)2]. Media were wet to container capacity with distilled/deionized (d/d) water, incubated at 25° ±3°C, and pH determined at day 0, 2, 5, 7, 14, 28, 56, and 84. Liming reactions in mixes could not be predicted from reactions occurring in sphagnum peat, perlite, and vermiculite constituents alone. Although sphagnum peat made the major contribution to liming reactions, both perlite and vermiculite were found to contribute to liming responses of media in which they were incorporated. The major portion of pH change due to incorporation of pulverized dolomite in peat-based media occurred within 2 days. Change in pH was complete within 14 days.

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, 1988 ; Nelson, 1998 ). One of the most common materials used in the formulation of substrates is sphagnum peat (peat). Environmental concerns ( Barkham, 1993 ; Buckland, 1993 ; Robertson, 1993 ) in the European Union and cost in markets, such as

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greenhouse vegetable species grown in hydroponic culture ( Bar-Yosef, 2008 ; Conesa et al., 2009 ; Ikeda and Osawa, 1983 ; Imas et al., 1997 ; Savvas et al., 2006 ; Sonneveld and Voogt, 2009 ). Edible crop species are also grown in peat-based soilless

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Canadian sphagnum peat moss has long been the preferred base for growing media of horticulturists in North America and Europe. Growers, horticultural scientists, and soil media producers have been using peat moss for several decades with excellent results. In the past 5 years, there has been some concern raised, especially in the U.K., that harvesting peat is harmful to the environment. The situation in Canada is far different from that in Europe. The Canadian peat industry is a world leader in restoration research because of its efforts to find the best ways to return harvested bogs to functioning wetlands. The first stage of research just completed by Laval Univ. shows that peat bogs can be effectively, economically, and easily restored. Additional research findings will be described in this paper. But, the conclusion is clear: Peat moss is a safe, environmentally friendly growing medium. This paper also will describe the state of resource in Canada as outlined by an independent environmental group, the steps taken by the Canadian Sphagnum Peat Moss Assn. to ensure that resource development is sustainable, as well as the process of how peat is harvest and how bogs are restored to functioning wetlands.

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Problems of inconsistent initial pH in peat moss-based substrates that are created using standard formulas for limestone additions, and pH drift from the target in those substrates may be due to variations in the CEC and BS of peat moss. This study was conducted to determine whether such variation exists. Sixty-four peat moss samples were obtained from several bogs across Alberta, Canada. Adsorbed cations on each peat moss sample were displaced with hydrochloric acid (HCl), and flushed out with three deionized water washes. The displacing/flushing solution was collected and later analyzed for concentration of bases (Ca, Mg, K, and Na) using atomic absorption spectrometry. After cations were removed, the peat moss exchange sites were saturated with barium acetate [Ba(OAc)2] to displace the H+, which were then collected by a second flushing with deionized water. This second displacing/flushing solution was titrated with measured amounts of NaOH to a phenolphthalein end point. Base saturation and CEC were calculated. There were significant variations in CEC (ranging from 108.12 to 162.25 cmol·kg-1) and BS (ranging from 13.52% to 63.97% of CEC) among the peat moss samples. Ca accounted for 78.08% of the BS. For a given peat moss, the higher the BS, the lower the neutralization requirement to achieve a target pH. Also, high CEC peat mosses may have greater buffering capacity than those with low CEC, which may result in less pH drift.

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Kenaf is an alternative fiber crop being evaluated in Mississippi. Kenaf, primarily grown in Asia, can be used in the manufacture of paper, fiber board, acoustical tiles and compost. The bark is the source of the fiber used, leaving the fiber core or pith for use as a paper additive, poultry litter, or is discarded. The objective of this study was to evaluate the potential use of kenaf fiber core as a vermiculite substitute in a sphagnum peat moss-based medium.

Plugs of Celosia argentea, Viola × wittrockiana, and Impatiens wallerana were transplanted into 10 cm pots containing 5 different sphagnum peat moss-based media modified with the milled fiber core (pith) of kenaf (Hibiscus cannabinus) and/or vermiculite. The media were as follows: 5 peat: 0 kenaf : 5 vermiculite (v/v/v); 5 peat : 1 kenaf : 4 vermiculite (v/v/v); 5 peat : 2 kenaf : 3 vermiculite (v/v/v); 5 peat : 3 kenaf : 2 vermiculite (v/v/v); 5 peat : 4 kenaf : 1 vermiculite (v/v/v); and 5 peat : 5 kenaf: 0 vermiculite (v/v/v). Water holding capacity, pore space, pH and media shrinkage were monitored throughout the study along with plant growth and plant quality.

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Paclobutrazol drench applications of 0, 2, and 4 mg a.i./pot were applied to `Pacino' potted sunflowers (Helianthus annuus L.) and `Red Pigmy' tuberous rooted dahlias (Dahlia variabilis Willd.) grown in substrates containing 50%, 60%, 70%, or 80% (by volume) sphagnum peat or coir, with the remainder being perlite, to study the efficacy of paclobutrazol (Bonzi). Potted sunflower plant height differed significantly for peat- and coir-based substrates, with greater plant height being observed in coir-based substrates. Plant diameter was significantly greater at higher percentages of peat or coir in the substrate at 2 and 4 mg of paclobutrazol. Inflorescence diameter also was significantly decreased as paclobutrazol concentration increased. When the percent of height control from the untreated plants for potted sunflower was compared between coir and peat-based substrates, the percent height reduction was similar for peat- and coir-based substrates at 2 mg of paclobutrazol and height control was greater at 4 mg of paclobutrazol in coir-based substrates. The differences in plant growth observed in peat- and coir-based substrates can be attributed to differences in physical properties of these substrates. Dahlia plant height, diameter, and number of days until anthesis were not influenced by substrate type or percentage. However, dahlia growth was significantly reduced as paclobutrazol concentration increased. Coir-based substrates did not reduce the activity of paclobutrazol drenches compared to peat-based substrates, although to compensate for the greater amount of plant growth in coir-based substrates, paclobutrazol concentrations may need to be increased slightly to achieve a similar plant height as with peat-based substrates.

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