Boron uptake and concentration in cotton and soybean as affected by boron source

Abstract

Continued introduction of new boron (B) fertilizer materials prompted a second examination of the efficacy of foliar‐applied B materials on B content, B uptake, and dry matter yield of cotton (Gossypium hirsutum L.) and soybean (Glycine max L.). Similar to a previous study, this greenhouse study was conducted at four participating universities using 6‐week‐old cotton (Deltapineland 90) and soybean (Pioneer 9761) plants. Sources and rates of B were 1) boric acid (17.5% B) at 0.22 kg ha^‐1,2) sodium borate (Solubor® 20.5% B) at 0.22 kg ha^‐1, 3) Smith & Ardussi Liquid B (10% B) at 0.22 kg ha^‐1,4) Smith & Ardussi Liquid B at 0.11 kg ha^‐1, 5) Borosol 10 (10% B) at 0.22 kg ha^‐1, 6) Borosol 10 at 0.11 kg ha^‐1, and 7) an untreated control. Control plants that did not receive B were sprayed with water. Four plants were grown in each 15‐cm diam. pot in sandy loam soil. Plants were sprayed at 6 weeks of growth and top growth was harvested at eight weeks. Whole‐plant samples were dried (70°C), ground, and analyzed for B content. Uptake of B, plant B concentration, and plant dry weight varied by state, so results were not combined over all states. In every state there were significant differences in B concentration and B uptake by cotton and soybean as affected by B treatment, but effects were not consistent with any one B source. In two of four cases (Alabama and Georgia) cotton plants receiving any B treatment had greater B concentration and B uptake than the water‐sprayed control. In Virginia and North Carolina, application of B treatments rarely affected B uptake by cotton or soybean. No one B source produced consistently greater B uptake than any other B source.