STUDIES ON WATER DAMAGE IN MUNG BEAN .2. ELECTRICAL-CONDUCTIVITY OF SEED LEACHATE AS AN ASSAY OF LEVEL OF DAMAGE

Weather-damaged seeds of mungbean are unsuitable for the production of bean sprouts and some other food uses. The breeding of resistant cult ivars requires an understanding of the weathering process and the use of suitable criteria for measuring the degree of weather damage. The a im of this research was to describe the effect of weathering on the el ectrical conductivity of leachate from exposed seeds and to evaluate t his technique as a means of discriminating among levels of weather dam age. Seeds were weathered in the field or immersed in water in the lab oratory for varying durations during one or more cycles of wetting and drying. Leachate conductivities generally increased with increasing v isual damage and decreasing viability of seeds. When measurements of c onductivity were delayed, the results appeared to be confounded by the extent to which solutes were lost during previous exposure/s to weath ering. Measurements soon after immersion tended to reduce this effect and to better reflect the level of weather damage in seeds of mungbean . It was concluded that leachate conductivity technique can provide a reliable assay of weather damage in mungbean. When seeds have been exp osed to severe weathering, however, the relationship breaks down, and the technique can give misleading results.