臺灣におけるキナ樹の收穫學的研究

Abstract

1. The average precipitation in Formosa is tremendously heavier than at Cinchona planations in Java and at those places in South America where the plants originally grow. It will, therefore, be recommendable to prefer an indigenous plants as cover-plants that it may not be washed away by heavy rainfalls. 2. The northern side of a hill is better than the southern for preserving the change of temperature, earth-surface temperature, evaporation, light, and moisture of soil at minimum in the dry season. The writer, therefore, asserts that the northern side of a hill is preferable for the Cinchona planting. It has been proved from the fact that growth of Cinchona planted on that side was much faster and better than that on the opposite side. 3. The growth of Cinchona is less in the cold dry season than in the warm wet one. According to the writer's survey for four years from 1935 to 1938, the biggest increment of the plant was seen twice a year, that is, between June and July and between September and October. This may suggest it recommerable to plant the Cinchona in August in a year when it happens to be too dry for its planting from March to April. 4. From the writer's weekly obsevation, it was found that the correlation coefficient between increase of height and temperature was rather low and that between growth of height and precipitation, low and negative. 5. The writer's obsevation reached the following conclusion regarding the growth of Cinchona: a) The height of its stand in Formosa is not so inferior to that in Java. b) The circumference of the plant in Formosa is averagely larger than that in Java. There grow 5, 000 to 10, 000 of Cinchonas per ha in Java while only 4, 500 in Formosa. 6. The correlation coefficients between circumference and height were 0.54, 0.65, and 0.71 respectively in three different stands of which the writer made an investigation. The reason why so small were the coefficients as mentioned above would be due to the irregularity of stands based on the geographical conditions in Formosa. 7. The results of the writer's survey regarding the Cinchona bark are indicated as follows: a) The bark is unexceptionally thickest near root and becomes thinner toward the top. b) The ratio of bark to wood in disk is smaller toward the lower part of the plant. c) Denser the stand is, the thinner, the bark. This is seen both in Java and Formosa. d) The correlation coefficient between circumference and thickness of bark is 0.83. e) The yield of dry bark from stem, branch and root increases in proportion to the age of Cinchona, of 5 to 10 years old. f) The growing stock and total increment of Cinchona dry bark per ha are less in Formosa than those of stands of Tjiniroean l and Letter B in Java. However, this difference is not so significant. 8. According to the writer's survey, the quinine sulphate contents is as follows: a) No correlatinn is found between circumfereence and content of quinine sulphate. That is to say, the latter is independent from the size of plant. Therefore, a careful selection of plant will be an important problem to study in the future. b) The quinine sulphate content is highest near the root and diminishes toward the top. This is, however, the case of trees at and under the age of five years. Of the older trees, the content is the largest at around 1 meter high from the ground surface. c) The bark of stem has the highest content of quinine sulphate. The root bark comes next and then the branch bark. 9. Summarizing the writer's susvey, he has produced the following table regarding the yield of quinine sulphate: [Table omitted]