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Dual inoculation of peat based horticulture substrate with a mixture of four species of arbuscular mycorrhizal fungi and fungal biocontrol agent Trichoderma harzianum showed a significant positive effect on the growth and flowering of cyclamen plants. Inoculation substantially decreased plant mortality caused by spontaneous infection by the fungal pathogen Cryptocline cyclaminis. Plant mortality was also reduced by separate inoculation with arbuscular mycorrhizal fungi. Both separately inoculated agents positively affected the plant growth, although to a lesser extent. Very few significant effects of inoculation were observed on the growth of poinsettia plants cultivated from cuttings. Use of arbuscular mycorrhizal fungi together with the introduction of Trichoderma for inoculation of horticultural substrates is suggested to alleviate the inevitable effects of various stresses during the cultivation of horticultural crops. Keywords: Cyclamen persicum; Euphorbia pulcherrima; inoculation; arbuscular mycorrhizal fungi; mycorrhizal growth response; Trichoderma harzianumHorticultural crops and flowers have been used as host plants in several experimental tests as potential target plants for practical use of mycorrhizal inoculation (Chang 1994, Lovato et al. 1995, rámek et al. 2000. The arbuscular mycorrhizal fungi (AMF) can stimulate plant growth especially in soils or substrates with lower fertility and the effect of AMF on plant nutrition mainly due to improved phosphorus nutrition has been documented (Johnson et al. 1982, Smith et al. 1986). The effect of AMF inoculation is generally more pronounced in plants growing under stress conditions, e.g. nutritional deficiency and water stress. Promotion of mycorrhizal colonisation of plant roots by inoculation facilitates adequate P nutrition, higher resistance to some root pathogens and environmental stresses (Smith and Read 1997). Inoculation of plants may increase crop uniformity and reduce transplant mortality (Waterer and Coltman 1988). It has been accepted that an appropriate management of mycorrhizal symbiosis allows reduction of chemical fertilizers and pesticides input (Azcón-Aguilar and Barea 1997).Since in most soils the indigenous populations of AMF are present, the preinoculation of seedlings in AMF free substrates gives the introduced fungal strain a spatial advantage over the indigenous fungi after transplanting (Powell 1981). In soilless substrates lacking the indigenous AMF or under the conditions where soils are fumigated and most of the indigenous AMF are eliminated, mycorrhizal inoculation is often successful (Nelsen et al. 1981, Vosatka et al. 1992, Vosatka 1995. Tissue cultured plants or plants grown from cuttings or small seedlings can be inoculated with pure strains of highly effective AMF with rapid colonisation rates, which allow a successful colonisation of newly formed roots after transplanting (Vosatka and Gryndler 1999).Several strains of T. harzianum have been found to exhibit a positive growth effect on the plants probably due to t...

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This work deals with the effect of two clay products differing in particle size distribution on properties of growing substrate and on growth of containerized woody plants in substrates amended with these clay products. Fine and coarse clay were added to a peat substrate, each at two rates. The peat substrate without clay was used as a control. The substrates were tested in experiments with two woody ornamentals (Thuja occidentalis’Smaragd’andPrunus cistena). Chemical and physical properties of the substrates were measured according to European Standards before planting. Proportion of water categories differing in availability to the plants were calculated from retention curves measured on the sand box. Properties of substrates in containers with and without plants were evaluated in the same way at the end of the culture. Clay addition changed chemical and physical properties of the tested substrates in terms: available nutrients content, particle density, bulk density, total pore volume, easy available water, water buffering capacity, air capacity, and shrinkage. The effect of fine clay was much stronger. In comparison with the clear effect of clay addition on the substrate chemical and physical properties, the effect on the growth and quality of model woody plants was not so explicit.

A glasshouse pot experiment tested the effects of 14 different combinations of substrate type, pH and nutrient treatments on the occurrence and severity of leaf chlorosis in a susceptible variety of petunia. Plants grown at optimal pH level (4.7) in peat substrate with low limestone dose were symptom-free even without added micronutrients. Severe chlorosis occurred in plants grown at high pH in peat substrate with high limestone (pH 6.7) and in peat-barkcompost (pH 6.2); it was associated with decreased Fe and Mn content in leaves. Regular application of nutrient solution with low concentration of Fe, Mn, and other micronutrients as EDTA chelates greatly reduced chlorosis in plants grown in peat-bark substrate and in peat-bark-compost, and it improved Fe uptake. An exception was peat substrate at high pH level and high limestone where chlorosis was only partially reduced by this treatment. Regular application of Fe, Mn, and other micronutrients as sulphates or citrates had no substantial effect; only application of three additional substrate drenches of 30 mg/l Mn from Mn-EDTA and 90 mg/l Fe from either Fe-EDTA or Fe-EDDHA substantially corrected chlorosis and increased foliar Fe and Mn in cases where plants were grown in high limestone peat substrate.