Abstract
The effect of ethylene in the soil atmosphere on soybean and rice seedling growth was investigated. The results obtained are summarized as follows: 1. Ethylene production from dry soil was seven times much more than that from re-dried soil which was dried again just after submerging for two days, when ethylene determination was made from these soils saturated with water at 30°C. When soybean seedlings were grown in these two kinds of soil, the inhibition of root elongation and increase of root dry weight were observed in the dry soil, suggesting the relationship between higher ethylene concentration in root tissue and the growth phenomena mentioned. 2. Tremendous ethylene production was detected from the soil mixed with compost. When soybean seedlings were grown in this soil, the inhibition of root and shoot growth were observed as well as the increase of root dry weight and stem-diameter. 3. Elongation of seminal root and coleoptile in rice seedling was stimulated by ethylene which was evoluted from submerged soil. The ethylene evolution from the submerged soil was observed constantly for twelve to sixteen weeks after submergence. These results suggest that ethylene produced from soil plays an important role for regulating the growth of seedlings.
