Effects of simulated acid rain on the growth of agricultural crops

Abstract

Three species of crops, radish, spinach and bush bean, were exposed to simulated acid rain at pH 5.6 (control) to 2.5 throughout their growing periods. Plants were subjected to acid rain treatment three times a week, for one hour with 10mm of precipitation at a time. All the plants exposed to simulated acid rain falls at pH3.0 or below produced visible injury on the leaves. The visible injuries were severe on the cotyledons of radish and spinach and primary leaves of bush bean exposed to rain at pH 2.7 and 2.5, which resulted in the growth reduction of plants at early stages of growth compared to pH 5.6. In none of the cases in this study did treatment at pH 3.0 or higher significantly affect the growth of leaf area or dry weight of whole plants in three species. These results suggest that current ambient levels of rain acidity in Japan, where annual mean pH value is about 4.6, may not affect growth in the three species of crops tested in this study.