1. Department of Biology, College of Science, University of Baghdad, Baghdad, Iraq
2. Department of Horticulture and Forestry, University of Arkansas, Fayetteville, Arkansas, USA.
3. Department of Botany and Microbiology, University of Arkansas, Fayetteville, Arkansas, USA.
4. Department of Agronomy, University of Arkansas, Fayetteville, Arkansas, USA
ABSTRACT
The Bedford soybean cultivar was grown under field conditions in a low boron content soil and fertilized with 0 to 4 kg . ha-1 borate. Leaf analysis showed higher boron uptake and lower phenolic content with increasing boron rates. HPLC showed most of the phenolics to be quercetin and kaempferol, with only 8% of the total being simple phenolic acides such as ferulic, caffeic, vanillic, p-coumaric and others. Of the complex phenolics, quercetin was most affected by boron levels, while vanillic acid was most affected among the simple acids. Analysis of the hydroponic solution in a second study showed that, in general, the roots lost more simple phenolics into the solution under both deficiency and toxicity levels of boron than at sufficient levels, an no complex phenolics were lost. These results suggest that boron may have an important role in membrane maintenance.