The Japanese Iris species, Iris laevigata Fisch., I. ensata Thunb., and I. sanguinea Hornem., have different habitat. However, the physiological basis that can explain the difference in the habitat is not clear. In the present study, the responses in rhizomes to anoxic conditions in the three Iris species were determined. Rhizomes of I. laevigata and I. ensata, which prefer shallow-water areas or wetlands, survived 28 days of anoxia, but those of I. sanguinea, which typically grows on dry land, could not. The activity of alcohol dehydrogenase, a key enzyme in the energy metabolism under anoxia, was detected during anoxic incubation of rhizomes of all the three Iris species, but continued to increase for 28 d only in I. laevigata. Moreover, a substantial increase in the ethanol content of rhizomes was observed only after 7 d of anoxic incubation of I. sanguinea. Although the content of sucrose and storage polysaccharides in the rhizomes of both I. laevigata and I. sanguinea decreased during incubation, the decrease was more pronounced in the latter under anoxia. These results suggest that I. laevigata and I. ensata are successfully adapted to aquatic environment owing to the tolerance of their rhizomes to low-oxygen conditions through the maintenance of energy metabolism.

日本鸢尾品种，燕子花甘草，一ensata藤，和一荪Hornem，有不同的栖息地。但是，尚不能解释栖息地差异的生理基础。在本研究中，确定了三种虹膜物种中根茎对缺氧条件的响应。偏爱浅水区或湿地的la.vige和Is ensata的根茎在缺氧28天后存活，但sanguinea的根茎，通常生长在干燥的土地上，却不能。在所有三种鸢尾属植物的根茎缺氧孵化期间，都检测到了乙醇脱氢酶（一种在缺氧条件下的能量代谢中的关键酶）的活性，但仅在南美白鸢尾中持续升高了28天。此外，仅在缺氧温育意大利血吸虫7天后，观察到根茎中乙醇含量的显着增加。虽然在这两种的根茎蔗糖和存储多糖含量I.金樱子和I.荪孵育期间下降，其下降更为明显在后者下缺氧。这些结果表明I. laevigata和I. ensata 由于其根茎对低氧条件的耐受性，通过维持能量代谢，它们已成功地适应了水生环境。