Effects of substrate and ectomycorrhizal inoculation on the development of two-years-old container-grown Norway spruce (Picea abies Karst.) seedlings

Abstract

The objective of this study was to test the effects of selected peat growth substrates (Agro CS, Gramoflor and Durpeta) and inoculation with commercial ectomycorrhizal inocula (Ectovit and Mycorrhizaroots) on growth, ectomycorrhiza formation, needle nutrients concentration and several physiological parameters of two-years-old containerized Norway spruce seedlings cultivated under standard nursery conditions. The selected substrates differed in origin, composition and nutrient content: Agro CS and Gramoflor were mixtures of various peat types and components with added nutrients, while Durpeta was non-enriched pure peat. Growth parameters of seedlings cultivated in enriched substrates were significantly higher than those grown on the non-enriched substrate. Significant interactions were found between substrate and inoculation treatments. Inoculation with Ectovit stimulated seedling growth in non-enriched substrate but had no effect on seedling parameters in the enriched substrates, and a negative effect on aboveground biomass in Gramoflor. Mycorrhizaroots inoculum significantly decreased shoot to root dry weight ratio, but had no other effect on seedling development. ECM colonization rate of seedlings ranged from 73 to 80%, with no significant effects of the ECM inoculum or growth substrate. DNA analysis revealed a low species diversity of ECM fungi on seedling roots, with a pronounced dominance of the soil-borne ECM species Thelephora terrestris Fr. Chemical analysis of needles and measurement of chlorophyll a fluorescence showed similar trends as seedling growth. Values of chlorophyll a fluorescence parameters and needle N, P, K, Ca and Mg concentrations were higher in both enriched substrates. Ectovit increased (though not significantly) chlorophyll a fluorescence in needles as compared to Mycorrhizaroots- and non-inoculated seedlings, as well as nutrient-uptake (mainly K) in the non-enriched substrate. Our results suggest the importance of the origin and composition of peat-based substrates on the development of container-grown Norway spruce seedlings, while the observed positive effect of the commercial ECM inoculum Ectovit was more probably caused by its physical and chemical properties rather than by its efficiency in promoting ECM fungi symbiosis. The enriched substrates tested appear to be suitable for production of spruce seedlings of acceptable size for outplanting within two growing seasons.

Keywords

• Peat Substrate
• Ectomycorrhizal Inoculation
• Norway Spruce
• Container-grown Seedlings
• Nutrition
• Chlorophyll a Fluorescence
• DNA Analysis