The incidences of suspected Boron (B) deficiency have increased recently in Kentucky tobacco fields, potentially due to recent changes in management practices. The symptoms observed in the field include; hollow stalk, stunted growth, deformed or no bud formation, small slits on the lower leaf midrib and uncontrollable breaking of the midrib approximately two inches from the stalk. B is a micronutrient tobacco needs in minute amounts, however excessive additions of B could cause toxicity. The objectives of this work were to 1) establish critical points for B sufficiency, 2) describe and define B deficiency and toxicity symptoms and 3) develop field strategies to aid in the mitigation of B deficiency. A general nutrient response curve was generated utilizing solution culture experiments. The peak of the response curve appeared to occur at solution B concentration of 100 µM. Trace-levels of B contamination and small plant size in the solution culture limited the development of deficiency symptoms. Toxicity was observed at solution concentrations of 400 µM and above. Despite choosing sites with a history of B deficiency, deficiency symptoms were not observed during this study. Toxicity was observed when 0.56 kg B/ha or greater was applied as simulated transplant water treatments. No toxicity was observed when B was applied as a soil broadcast or foliar application. Recommendations are to apply B with caution as a broadcast application to avoid potential problems with toxicity. Additional research is required to refine the nutrient response curve and better understand B deficiency.
| Identifer | oai:union.ndltd.org:uky.edu/oai:uknowledge.uky.edu:pss_etds-1053 |
| Date | 01 January 2014 |
| Creators | Frakes Mitchell, Laura Ann |
| Publisher | UKnowledge |
| Source Sets | University of Kentucky |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations--Plant and Soil Sciences |
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