Effects of Fertilization on the Growth and Mycorrhizal Development of Container-Grown Jack Pine Seedlings

Abstract

Abstract Jack pine seedlings were grown in 65-cc containers filled with a peat: vermiculite mixture or pure peat and inoculated with either Laccaria proxima, Pisolithus tinctorius, Sphaerosporella brunnea, and E-strain isolate or left uninoculated. Seedlings in peat: vermiculite were fertilized twice weekly for 17 weeks with complete fertilizer solutions containing either 15, 30, or 60 mg N/1. Seedlings in pure peat were only fertilized at the 15 mg N/1 rate. Differences in plant growth and mycorrhizal formation were minimal between the two growing media. Root weights in peat: vermiculite were not affected by fertilizer levels, but the high level of fertilizer reduced the total number of short roots produced. Shoot growth was increased by using 30 mg N/1, but not further increased by using 60 mg N/1. Inoculation with the E-strain fungus reduced shoot growth 35 percent over all fertilizer treatments. Infection by E-strain exceeded 95 percent in all treatments, whereas infection by Laccaria proxima was reduced when 60 mg N/1 was used. Mycorrhizal colonization by Pisolithus tinctorius was highly variable but some infection occurred in all treatments. Mycorrhizae formed with Sphaerosporella brunnea occurred only when the lowest amount of fertilizer was applied. Forest Sci. 30:828-835.