Oak trees are deciduous trees that can live up to 200 years and face a variety of environmental stresses. Like all plants, oak trees need nutrients which vary under different stress conditions. We study nitrogen as an essential element in the growth of plants. Most nitrogen is found in chlorophyll molecules of a leaf, and we are interested in understanding how nitrogen concentration varies oak species with different responses to flooding. The objectives of this study are to: (1) Determine the relationship between leaf chlorophyll and leaf nitrogen concentration for five different species of oak (bur oak, pin oak, swamp white oak, northern red oak and shumard oak) and (2) assess how flood tolerance affects the above relationship. The relationship between total leaf nitrogen concentration and chlorophyll of bur oak (Quercus macrocarpa), pin oak (Q. palustris), northern red oak (Q. rubra), shumard oak (Q. shumardii), and swamp white oak (Q. bicolor) were determined. Each tree species was represented by seedlings raised from acorns collected from both upland and lowland sites with the exception of northern red oak, which was represented by seedlings from a single location. A SPAD-502 Meter (Minolta Corporation ltd., Osaka, Japan) was used to measure chlorophyll in 135 individual seedlings for 5 consecutive weeks. A single leaf was repeatedly sampled on each seedling in each flooded and non-flooded (control) treatment over 5 replications in a greenhouse. The harvested leaves were oven dried for 72 hours and nitrogen analysis was conducted in the lab by combusting the sample in an induction furnace and measuring the nitrogen via thermal conductivity.
Results/Conclusions
The SPAD-502 Meter could be a useful tool that determines leaf N level of a plant by increasing it's overall health and production yield. However, Users of SPAD meter should know that the SPAD-502 Meter does not tell you how much N should be applied but the need for additional N in the leaf. If used with other known N Management practices, the SPAD-502 Meter can be an excellent tool. The preliminary results of this experiment indicate a close correlation between the SPAD readings and nitrogen content (r=0.6214*) confirming the effectiveness of this tool. The flooded oak species used in this study also showed a substantial decrease in the N content compared to the non-flooded oak species. Therefore, the SPAD-502 Meter can be proven to be an effective tool when it comes to decision making.
