1952 Volume 20 Issue 3-4 Pages 158-165
1. The studies on the relation between the growth of peach and persimmon seedlings and soil moisture were conducted with methods which had been used in the previous studies at Okitsu. Present studies had another purposes to know the degree of oxygen decreasing in the soil atmosphere owing to the increasing of soil moisture in pots which were sealed excepting upper holes through which the gas for analysis was sampled.
2. Soil moisture showing no increasing of top growth and optimum soil moisture for top growth for peach seedlings were not so much different from those results obtained in previous study at Okitsu. Owing to the out of season for shoot lineal growth of persimmon, the top growth could not be distinguished by the soil moisture regulated.
3. As for fresh weight, peach seedlings showed considerable growth in 15% soil moisture and proper growth in 20% just like as previous studies, but growth of persimmon was rather poor in the soil moisture less than 25%. Owing to the difference from the previous studies at Okitsu which will be due to the difference of soil class between Okitsu and Hiratsuka soil and of soil properties such as waterholding capacity, root growth was not superior to top growth in drying soil moisture.
4. In the first peach experiment oxygen concentration in the pot did not decrease less than 5% because of too poor root development to take place the decrease of oxygen concentration. In the second peach and persimmon experiments, there were some variations in soil moisture in 40% plots in which gas samples of some pots were frequently drawn off as a chain of bubbles in a column of water, indicating that the obtained gas contained less than 5% oxygen. In such case growth of peach seedlings was restrained but those of persimmons were not so much restrained as peach. In the plots or periods in which the growth of seedlings was vigorous (i. e. in 30% and 35% moisture of peach and 25%, 30%, and 35% moisture of persimmon) the oxygen concentration decreased less than 10% but did not so much decrease to restrain the growth of young seedlings. Therefore, it will be concluded in the good aerating soil such as surface soil that decrease of oxygen concentration due to the increase of soil moisture occurs only in the case, in which soil is nearly submerging.
