Influence of moisture, heat, and light stress on hydrogen fluoride fumigation injury to soybeans.

Soybean (Glycine max (L) Merr.) plants were exposed to a single fumigation with hydrogen fluoride at concentrations sufficient to cause visible injury within 2 days. They were subjected to soil moisture or osmotic stress prior to, during, or after fumigation. Moisture stress before or during fumigation reduced injury because of stomatal closure and reduced fluoride uptake. Moisture stress after fumigation markedly accentuated the injury resulting from a single fumigation compared to plants kept continually under optimum soil moisture conditions. Full sunlight following the fumigation accentuated injury, while shade reduced it. Higher temperatures following fumigation also increased severity of symptoms.