桃の忌地に関する研究(第4報)

生育地土壌及び桃葉抽出液の稀釈が桃実生の生育に及ぼす影響 (1)

抄録

1. Old peach soil was diluted by virgin soil from 10^0.5 to 10⁵ times (for example, the soil dilut-ed to 10 times consists of 1 part of peach soil and 9 parts of virgin soil) and peach seedlings were planted in 6-inch pots containing those soils. As the result, the growth in original peach soil was inferior to the control (virgin soil), and the more diluted the soil, the more excellent the growth, and the maximum growth was in 10³ times plot. But in the case the soil was more diluted than in this plot, the growth was gradually reduced, and approached to the growth level in virgin soil.
2. On pouring the peach leaf extracts diluted by water from 3 to 1000 times respectively (ori-ginal extract was prepared by immersing the fresh leaves in 10 times water for 24 hours), the peach seedling showed the minimum growth in original extract plot and the maximum in 100 times plot.
3. In sand culture, the ether extract of peach leaves (original extract was prepared by extracting 50g of fresh leaves with ether, and evaporating ether, then dissolving the residue with 50ml of nutrient solution) and its solutions diluted from 10 to 10⁵ times by nutrient solution, were poured on peach seedlings respectively. As a result, the peach growth responses showed the same tendency as in the two tests stated above. The growth in 10 times plot was far inferior to the control (ether extract not supplied) and the growth in 104 and 105 times plot was superior.
4. Generally in these experiments, when peach seedlings were grown in old peach soil or in soil supplied with peach leaf extracts, the seedling growth showed depression, and on the contrary, showed promotion in more diluted plots. It seems that one of its causes is in the presence of some substances which are not nutrient.