The Role of Anaerobic Respiration in Germinating Muskmelon Seeds

Five muskmelon (Cucumis melo L.) cultivar seedlots from a commercial source and freshly produced seeds of two cultivars, when artificially aged, were found to differ in their viability and vigour as determined by germination tests. Furthermore, the various commercial seedlots without ageing also exhibit a range of deterioration levels. Low vigour seeds had higher respiratory quotient values than the high vigour seeds as a result of a higher level of CO2 production. This high level of CO2 evolution in low vigour seeds may have been due to anaerobic respiration. Levels of acetaldehyde and ethanol produced by imbibing seeds were negatively associated with seed viability and vigour. After 6 h of imbibition low vigour seeds produced significantly more ethanol and acetaldehyde than high vigour seeds. After 24 h of imbibition, ethanol continued to accumulate in the commercial seedlots up to 10-fold the amount produced after 6 h of imbibition, whereas, acetaldehyde levels increased less. However, in the freshly produced, artificially aged seeds (except the most extreme ageing), ethanol levels were reduced and no acetaldehyde production could be detected, indicating re-utilization of ethanol. It is suggested that ethanol production in the first hours of imbibition can be used as a reliable index to predict germination in muskmelon seedlots.