マツ類のさしきの発根に関する研究 : 第1報 発根に及ぼす2, 3の環境因子について

Abstract

The studies were carried out to make clear the influence of the some environmental factors on the rooting of planted cuttings of pines, at the Kamigamo Experimental Forest Station of Kyoto University. This report consists of the following three experiments, and are outlined as follows: Experiment I: Relationship between the physical characteristics of the bed soil and the rooting of cuttings. 1. The cuttings were severed from the parent trees of yearling seedlings and twelve-year-old of Pinus densiflora, P. Thunbergii and P. taeda, and they were also planted in five kinds of soil (Table 1--1a). 2. The ability of the cuttings to root declined in the cuttings obtained from the matured trees of twelve-year-old and also in P, densiflora, P. Thunbergii and P. taeda in the cutting from yearling seedings. The rooting responses were differed according to the planted bed soils, and rooting ability was high in the yellow colored and red colored soils (Table 1--2). 3. The cuttings tend to show a high response for rooting in such soil as the capillary ascent of water in the soil column is high (Fig. 1--2) and the percolation rate is low. The soil class was SL (Table 1--1b), and the ratio of the maximum air capacity to the water holding ones of the yellow Colored and red Colored soils was 1.0/0.6 (Table 1--1c). But it seems that the optimum ratio of rooting ability may be changed by the soil class used for the beds. 4. The growth response of roots formed by the difference of the soil was not obvious (Table 1--3). Experiment II: Relationship between the water content in bed soil and the rooting of cuttings. 1. The cuttings were severed from the parent trees of yearling and three-year-old seedlings, and twelve-year-old P. densiflora, and they were planted in the bed (red Colored soil) prepared for adjusting the water content, which was always kept at 30, 35, 45 and 50% in each plot (Fig 2--1, Table 2--1). 2. The rooting ability of the cuttings tends to decrease with increasing parent tree age (Table 2--2). 3. The cuttings obtained from the yearling seedlings showed the high rooting response when the water content was high, and those from three-year-old seedlings were conversely low in the former conditions. The mutual relations between the water content in the bed soil and the rooting of cuttings was clearly observed in the difference of water supply by the age of parent trees. 4. It seems that the cuttings obtained from the yearling seedlings form the root according to the oxygen contained in flowing water and enough water capacity in the soil, and those from three-year-old tend to increase in activity when the water capacity is comparative, scarce and the oxygen is sufficient. 5. The root growth increased due to low water content in the soil (Table 2--3), but the height of the cuttings conversely decreased under the conditions (Table 2--4). Experiment III: Relationship between the light value of the bed and the rooting of cuttings. 1. The cuttings obtained from yearling and three-year-old seedlings and matured trees of twelve-year-old P. densiflora was planted in red soil and was provided with the light value limited by the blinds. The treatments consisted of three methods of continual, temporal and not blinded (Table 3--1). However, the purposed light value in blinds was not fixed for a short time (Table 3--2). 2. The cuttings from yearling seedlings comparatively showed higher rooting ability than those of not blind when the light value was limited to continual 25, 50 and 75% and temporal 25 and 50%, and those from three-year-old seedlings and from matured parent trees numerously survived in temporal 50% of the light value Table 3--3). 3. The cuttings planted under the temporal 90% limit of the light value showed a great number of survivals than those under the continual 90%. Especially, the effect of temporal blinds have a tendency to increase with the parent tree age. 4. To keep the quantitative equilibrium between the transpiration and the absorption of the cuttings just after planting, the temporal blind tends to be effective in root formation. 5. The root growth increased with light value (Table 3--4).