Effects of growth medium, nutrients, water, and aeration on mycorrhization and biomass allocation of greenhouse-grown interior Douglas-fir seedlings

Abstract

Commercial nursery practices usually fail to promote mycorrhization of interior Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco var. glauca (Beissn.) Franco] seedlings in British Columbia, which may account for their poor performance following planting in the field. We tested the effects of four nursery cultivation factors (nitrogen fertilization, phosphorus fertilization, watering, and soil aeration) and field soil addition on mycorrhization, survival, growth, and biomass allocation of interior Douglas-fir seedlings in a series of greenhouse experiments. Where field soil was added to the growing medium, mycorrhization and root/shoot ratios were maximized at lower levels of mineral nutrient application and aeration. Where field soil was not added, mycorrhization was negligible across all fertilization and aeration treatments, but root/shoot ratio was maximized at lower levels of mineral nutrients and the highest level of aeration. Regardless of whether field soil was added, intermediate levels of soil water resulted in the best mycorrhizal colonization and root/shoot ratios. However, field soil addition reduced seedling mortality at the two lowest water levels. A cluster analysis placed ectomycorrhizal morphotypes into three groups (Mycelium radicis-atrovirens Melin, Wilcoxina, and mixed) based on their treatment response, with all but two morphotypes in the mixed group whose abundance was maximized under conditions common to advanced seedling establishment. For maximal mycorrhization and root development of interior Douglas-fir seedlings, nurseries should minimize addition of nitrogen and phosphorus nutrients, maximize aeration, provide water at moderate rates, and, where possible, add small amounts of field soil to the growing medium.

Increased Biomass of Nursery-Grown Douglas-Fir Seedlings upon Inoculation with Diazotrophic Endophytic Consortia

“…The role of mycorrhizal symbiosis in increasing phosphorous uptake has been studied in a number of conifer species, with recent studies showing how mycorrhizal effects on seedling establishment change with soil conditions [52]. In dry Douglas-fir forests, reduced mycorrhizal diversity and abundance have been associated with reduced survival and growth of newly-planted conifer seedlings [53,54]. Inoculating nursery seedlings with beneficial endophytes may help offset some of these disadvantages.…”

Plant Nutritional Status Explains the Modifying Effect of Provenance on the Response of Beech Sapling Root Traits to Differences in Soil Nutrient Supply

“…Uptake via the mycorrhizal pathway is of major importance for N and P nutrition of trees in temperate zones (Plassard and Dell, 2010;Chalot and Plassard, 2011). While fertilization with P often decreases mycorrhization in inoculation experiments (Garbaye and Wilhelm, 1985;Kazantseva et al, 2009), under field conditions, relationships between soil P availability and measures of mycorrhization or mycorrhizal P uptake are less clear and might differ seasonally (Yang et al, 2016;Spohn et al, 2018). In most studies on the effect of N availability, mycorrhizal colonization increased with decreasing N availability (e.g., Brunner and Brodbeck, 2001;Sun et al, 2010); however, under natural concentration gradients, higher colonization was also found at lower C:N ratios (Hawkins et al, 2015).…”

Local adaptation in migrated interior Douglas‐fir seedlings is mediated by ectomycorrhizas and other soil factors

“…; e.g. Twieg et al, 2007); and c. 95% of Douglas-fir seedlings are nonmycorrhizal when grown under standard nursery conditions for use in forestry in British Columbia (Kazantseva et al, 2009). Although a reasonable amount of information on EMF associations with interior Douglas-fir exists (Jones et al, 1997(Jones et al, , 2010Simard et al, 1997b;Hagerman & Durall, 2004;Durall et al, 2006;Twieg et al, 2007;Teste et al, 2009a), the geographic scope of those studies has been mostly limited to two ecosystem types in south-central British Columbia.…”