The Effect of Soil Manganese on Japanese Larch (Larix Leptolepis Sieb. and Zucc.) Seedlings in the Greenhouse
Preliminary analysis of 9 year old Japanese larch trees and soil subjected to appliitions of triple ambient annual nitrogen (N) and sulfur (S) deposftfon revealed elevated available soil and foliar manganese (Mn) levels and decreased growth compared to controls. A greenhouse study was conducted in which Japanese larch seedlings were grown in geld collected soil amended with 0, 100,500, and 1000 mg of Mn as MnCI2 per 8362 cm3 of soil to determine the role of Mn in these growth differences. Growth was measured for 73 days. Soil samples were analyzed for magnesium (Mg), Mn and pH and foliar samples collected on day 73 were analyzed for Mn. Total chlorophyll concentrations were also determined. Control Japanese larch seedlings had significantly greater mean chlorophyll concentrations than treated seedlings. Japanese larch seedlings responded to increased Mn supply with increased uptake of Mn. Height and diameter growth were not significantly dffferent (a< 0.05) among the four treatments. However, overall height growth of Japanese larch was 10 percent less in the three treatments compared to the control. These results are supportive of the hypothesis that elevated available soil Mn may have contributed to the observed growth differences between control and treated Japanese larch in the field.