Tolerance of Anoxia and Ethanol Toxicity in Chickpea seedlings (Cicer arietinumL.)

Abstract

Controversy exists as to whether ethanol ever accumulates to toxic levels in anaerobic tissues of higher plants. In order to manipulate the internal concentrations of ethanol and relate these to anaerobic injury, seedlings of chickpea (Cicer arietinum L.) were incubated under strict anoxia in vessels in which the anaerobic atmosphere either remained static or else was circulated with that of a large anaerobic incubator. Incubation with a circulating, as compared with a static, anaerobic atmosphere doubled the time that the seedlings could be kept under anoxia and emerge in subsequent survival testing in the glasshouse. Circulating the anaerobic atmosphere gave a 13-fold reduction in the accumulation of ethanol in the seedlings. Parallel experiments which varied the ratio of head space relative to seedling number confirmed that the dilution of the volatile products of anoxia.increased survival. These products included carbon dioxide, ethanol and traces of acetaldehyde. While carbon dioxide may play a role in modifying glycolytic activity under anoxia, it is suggested that it is not directly toxic and that it is the reduction in ethanol concentration in the seedlings as a result of head space dilution that contributes to their increased longevity in circulating anaerobic atmospheres.