Response of Oak and Maple Seed Germination and Seedling Growth to Different Manganese Fertilizers in a Cultured Substratum

Kaile Mai,Roger A Williams

doi:10.3390/f10070547

Abstract

Oak regeneration failures have been causing a slow decline in the occurrence of oak forest ecosystems in eastern North America. Accordingly, our study sought to determine a means of creating more vigorous and competitive oak seedlings by the addition of manganese (Mn) fertilizers. Seeds of northern red oak (Quercus rubra L.), chestnut oak (Quercus prinus L.), and red maple (Acer rubrum L.), one of oak’s major competitors in North America oak forest ecosystems, were sown in 0.7 liter pots that contained a growing medium mixture of peat moss, perlite, and sand in a ratio of 2:1:2, and germinated in a greenhouse. Three different chemical compound Mn fertilizer treatments—manganese chloride (0.16 mg L−1 Mn, MnCl2·4H2O), nanoparticle manganese in the form of manganese hydroxide (0.01 mg/L Mn, nanoparticle Mn(OH)2), and manganese hydroxide (0.01 mg L−1 Mn, Mn(OH)2)—and a treatment of Hoagland solution were applied to the planted seed. These treatments were compared to a control consisting of water, and treatments were applied twice a week over a 12 week period. Germination rates and seedling growth were measured over this period of time. At the end of 12 weeks seedlings were harvested, separated into roots, stem, and foliage for the purpose of biomass and nutrient analysis by seedling component. Northern red oak displayed a 100% germination success rate with MnCl2·4H2O and Mn(OH)2 treatments, while red maple germination was reduced with the MnCl2·4H2O and nanoparticle Mn(OH)2 treatments with only a 32% and 24% germination rate, respectively. The MnCl2·4H2O treatment produced the largest overall seedling size (basal diameter squared times the seedling height) of red maple with a 191.6% increase; however, the MnCl2·4H2O treatment produced the largest overall seedling size (basal diameter squared times the seedling height) of northern red oak and chestnut oak with an increase of 503.7% and 339.5%, respectively. The greatest increase in overall seedling size for northern red oak was with the Mn(OH)2 treatment at 507.2%, and 601.2% for chestnut oak with the nanoparticle Mn(OH)2 treatment. MnCl2·4H2O treatment significantly increased the oak foliar nitrogen (N) content. It appears that the application of Mn fertilizer can increase the germination and growth of these oak species while suppressing or having a lesser effect on red maple, thus creating a competitive advantage for oak over its competitor.

Highlights

Oak (Quercus sp.) is an important tree species in forest ecosystems of North America
The purpose of this study was to determine effects of Mn fertilizer applied in different compositions on the germination, seedling morphology, and mineral nutrition of northern red oak (Q. rubra L.), chestnut oak (Q. prinus L.), and red maple (Acer rubrum L.)
Most of the northern red oak germinated during the second week after being sown whereas chestnut oak germinated mainly during the third and the fourth week

Summary

Introduction

Oak (Quercus sp.) is an important tree species in forest ecosystems of North America. Oak forests have been shrinking due to various problems it experiences when regenerating, causing it to lose its dominant status in the Central Hardwoods Region of the eastern United States [1]. Oak seedlings typically have low survival during the first year as compared with their shade tolerant red maple competitor. For which prescribed fire has been used to help get seedlings established, are fire tolerant while its competitors are not [5,6,7,8,9]. In the absence of burning it is critical that there exist an adequate number of competitive oak seedlings

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