High soil fertility decreases sucrose content and susceptibility of loblolly pine roots to ectomycorrhizal infection by Pisolithus tinctorius

Abstract

Pinus taeda seedlings were grown for 10 weeks without ectomycorrhizae under low and high rates of complete soil fertility, as well as these rates minus N, P, K, or Ca. Seedling growth, inorganic chemical content of needles, and soluble-carbohydrate content of short roots were significantly affected by soil fertility, especially the high rates of N and P. Number and length of lateral and short roots were not affected by soil fertility. Sucrose and fructose contents of short roots were lowest at high levels of N and P; glucose was not detected. Seedlings from each of the 10 fertility combinations were inoculated with vegetative inoculum of Pisolithus tinctorius and incubated for 19 to 21 days at a moderate level of complete soil fertility. Significantly more ectomycorrhizae were formed on seedlings from the complete low fertility rate than on those from the high rates of N and P. Ectomycorrhizal development on seedlings from the other fertility combinations were intermediate from these extremes. Sucrose content of short roots determined before inoculation was significantly correlated with ectomycorrhizal development and accounted for 85% of the variation in susceptibility of short roots to infection by P. tinctorius. Fructose content of short roots was not correlated with ectomycorrhizal development. These results indicate that high levels of N and Pin soil decrease sucrose content of short roots of loblolly pine and decrease their susceptibility to ectomycorrhizal development by P. tinctorius.

Testing the ecological stability of ectomycorrhizal symbiosis: effects of heat, ash and mycorrhizal colonization on Pinus muricata seedling performance

“…This scenario should lead to lower levels of mycorrhizal colonization in N-enriched settings. Nylund (1991, 1992) found that nitrogen fertilization strongly decreased ectomycorrhizal biomass in and around roots of Pinus sylvestris, and suppression of mycorrhizal formation under high N conditions has been reported in other studies (Marx et al 1977;Termorshuizen and Ket 1989). Our results show that heat treatments (which increase mineral N abundance) decreased % ectomycorrhizal colonization.…”

Effects of nitrogen and water limitation and elevated atmospheric CO2on ectomycorrhiza of longleaf pine

“…This suggests that, on the functionally significant scale of the whole plant, adequate nutrition resulted in more mycorrhizas in total, even though high levels of soil N suppressed mycorrhizal colonization. Marx et al (1977) also found that high levels of soil fertility reduced ectomycorrhizal infection, v^hich they associated with lower levels of sucrose in pine roots. However, Lewis et al (1994) found no significant correlation between carbohydrate concentration (either total sugars or starch) and mycorrhizal development on loblolly pine seedlings.…”

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

“…Most commercial nursery treatments add high rates of fertilizers to maximize seedling shoot and total growth to increase establishment and success in the field [59] which is not only expensive, but also suppresses mycorrhiza development of container seedlings [60]. Therefore, endophyte inoculation of seedlings may be considered as a cost-effective technique to increase growth in the early stage for the nursery stock, which can lead to later stage successes in transplanting and establishment after transplanting.…”