クロマツ、アカマツのサシキの発根におよぼす用土の理学的性質の影響

Abstract

This experiment was carried out in order to make clear the effects of the physical characteristics of the propagating media upon the rooting responses of cuttings of Pinus densifiora and P. Thunbergii. The cuttings were taken from one year seedlings and planted on April 28, 1959. The author selected the kanuma soil as the propagating medium, in this experiment deviding it into five classes according to the sizes of soil grains. A-medium･･･1mm. B-medium･･･1 ~ 2mm. C-medium･･･2 ~ 3mm. D-medium･･･3 ~ 4mm E-medium･･･4 ~ 6mm. The temperature, at 3cm under the surface of each medium, read every seventh day just before the watering at ten o'clock is given fig. 1. The physical characteristics of the each propagating medium is shown in table 1 and table 2. The author removed all the cuttings on July 30 (93rd day aftar planting) and investigated the percentages of survival cuttings, rooted cuttings, the average mumber of main roots and the total length of main roots per rooted cutting etc. The rooting responses were observed, to vary considerably in accordance with the kinds of the propagating media as shown in table 3 and table 4. There seems to have been almost no, or if any, little influences of the differences of temperature upon the differences of the rooting responses, there being no distinct variation in the soil temperatures of each propagating medium as is illustrated in fig. 1. This variation of rooting, therefore, seems to have risen chiefly from that of the physical characteristics of the media. The mutual relations between the water content of medium and the rooting of cuttings was not clearly observed in this experiment. This is probably because every medium contained enough amount of moisture for rooting. The results of this investigation show that, when the medium contains enough moisture for the rooting of cuttings of P. densiflora and P. Thunbergii, its air content is one of the factors which affect their rooting. The ratio of moisture content to air content of propagating medium seems to be a reliable measure of the condition which renders the moisture and air in soil in the fittest situation for the rooting of the cuttings. For the rooting of P. densiflora cuttings, the results of the experiment suggest that when the media contain enough moisture in them, the best ratio is about 1.0 : 1.0. For the rooting of P. Thunbergii cuttings, these experimental results showed that the best ratio is about 1.0 : 0.5.