Ethanol, a Respiratory By-product: An Indicator of Seed Quality

Abstract

Ethanol production by seeds was developed as a rapid biochemical test, and found to be a sensitive indicator of seed quality. Seeds of maize, soyabean, cotton, rice and lettuce were aged at 75% relative humidity and 45 degrees C to obtain five aged samples for each species including a nonaged control. Ageing reduced the percentage germination and the coefficient of the rate of germination (CRG). Samples of differentially aged seed lots were subjected to aerobic and anaerobic conditions. Maize and soyabean seeds were imbibed in distilled water while seeds of cotton, rice and lettuce were imbibed with 50 mM glucose in 5 mM potassium phosphate adjusted to a pH of 5.6. Cotton seeds were ground and particles from 3.35 to 4.76 mm were used, while lettuce was scarified. Ethanol was analysed using immobilized enzyme electrode technology and verified by gas chromatography. Anaerobiosis induced greater amounts of ethanol production compared to aerobic treatments. In general, the ethanol production increased with ageing under aerobic conditions while the reverse trend was measured under anaerobic conditions. The anaerobic to aerobic ethanol ratio (ANA ethanol ratio) was calculated and was correlated with the CRG.