Influence of fertilization on nutrient status and size of bare-root Pinus taeda L. seedlings
Abstract
The purpose of this study was to evaluate the influence of varying types and amounts of fertilizer on loblolly pine ( inns taeda L.) seedlings. Morphological traits as well as nutritional status were measured. A comparison of the effects of constant versus increasing applications of fertilizer was included in this study. In addition, an effort was made to evaluate the influence of different treatment histories on two separate nursery compartments. Seedlings grown in a southern forest nursery were fertilized with either pre-plant nitrogen, top-dress nitrogen or top-dress magnesium. Nitrogen was supplied as ammonium nitrate(NH,N03) and magnesium as magnesium sulfate(MgSO,*7H20)' Seedlings were evaluated after ten weeks for shoot length, root length, and stem diameter, and again after one growing season for the aforementioned plus tissue concentrations of N, P, Y, Ca, and Mg. Ten week analysis showed no statistically significant results, perhaps due to lack of tissue differentiation over the short growing period. Sampling performed after one growing season showed that pre-plant applications of N had no effect on the seedlings except for mean needle:stem weight. Top-dress applications of Mg had no significant effect on seedling morphology, but did significantly increase Mg and N foliage concentrations. Top-dress N application in compartment 4 resulted in higher needle to stem and needle to root weight, and higher N concentrations in foliage and stem tissue. Increasing applications of N resulted in significantly higher K stem and Mg root concentrations. Applications of N in compartment 7a increased mean needle weight, N concentrations, P foliar concentrations, and K stem and root concentrations. Application of N at an increasing rate significantly increased concentrations of N, Mg, and K. Comparison between top-dress applications of N in compartment 4 and 7a showed that 7a seedlings had higher stem caliper, shoot length, stem weight, and needle weight. Lower root measures in compartment 7a were probably due to heavier soil that caused loss of roots upon lifting. As a result, needle:root and shoot:root ratios were increased. Tissue concentrations of N and P were significantly higher for compartment 4 seedlings, whereas K and Mg concentrations were higher for compartment 7a.The results of this study indicate that production of quality seedlings can be enhanced through minor changes in nursery practices that are currently already in place. Manipulation of seedlings by fine-tuning fertility levels can, in combination with existing moisture management, result in optimum seedling growth.
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Citation
Wall, Margot Marie (1994). Influence of fertilization on nutrient status and size of bare-root Pinus taeda L. seedlings. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1994 -THESIS -W1875.