1950 Volume 19 Issue 3-4 Pages 185-194
1. Young apple, chestnut, persimmon (D. Lotus Linn.) seedlings and grape cuttings were planted in 4-litre, 8cm deep glazed porcelain crocks. Soil moisture was regulated every day, to 10, 15, 20, 30, 40 and 50%, of dry weight of soil by watering the volume of water lost during the day.
After shoot growth of the seedlings was measured at 5 days intervals, these seedlings were investigated on the top and root fresh weight and leaves of every plot were analysed. Some of the another seedlings were dried to wilting and not watered to scorching of leaves.
2. Soil moisture in which the leaves showed definite wilting was 7.3% for apple trees, 9.3% for chestnut, 9.0% for persimmon and 5.6% for grapes and soil moisture showing no increasing of top growth was 15% (39% of water capacity) for apple trees and 10% (2_??_% of water capacity) for chestnut, persimmon and grape. Grape showed proper growth at the 20% as peach seedlings of previous study and also chestnut made compara tively proper top growth at the same soil moisture percentage.
Optimum soil moisture of the top growth was from 20 to 40% for grape and from 30 to 40% (79-105% of water capacity) for another trees studied but latter top growth was superior in 30% to 40% soil moisture. At 50% top growth gradually decreased and leaf color turned pale and yellowish by injury of excessive soil moisture.
3. The roots production of grape was best in 20% soil moisture, in which apple and persimmon roots were less than half of these in 30% soil moisture, but chestnut roots in 20% actually weighed same with those in 30%.
In general, root growth was superior to top growth in drying soil moisture and the top and root ratio showed smaller as the soil moisture more decreased.
Though the growth of the trees was vigorous in 30-40%, the amount of growth, except chestnut, was more in 30%. Moreover, blackening and partial death of root tips and appearance of lenticels and decrease of white new roots were slightly found in 40% soil moisture as 50% soil moisture in which those unprofitable abnormalities were very remarkable.
Nitrogen content of apple, chestnut and persimmon leaves was highest in 20% soil moisture but grape leaves only showed the exceptional nitrogen content shown in Fig. 7.
