Seasonal changes in respiratory rates of cultivated cuttings of Cryptomeria japonica after root initiation (Forestry)

呼吸量を知るうえで基礎的な資料となる呼吸速度(mgCO_2/g dry weight/hour at 25℃)を, スギのさし木苗を用いて, 発根直後から約2年間にわたり, 1ヵ月間隔でもとめた。測定は個体と部分(0年生, 1年生, 2年生の各葉, 主軸, 地下主軸, 根)にわけて行なった。呼吸速度は個体, 各部分のいずれについても, 春と秋に急激に増加し, 春から夏, 秋から冬にかけて緩慢に減少した。しかし, 根だけはこの傾向がやや異っており, 5ヵ月の間隔をおいて規則的に呼吸速度の増減をくりかえし, 冬にも呼吸速度の増加がみられた。春と秋における呼吸速度の増加は, スギ苗の生長の盛んな時期が春と秋にあるという週期的な生理活性の消長が大きく影響をおよぼした結果であると考えられる。また, 秋に比較的高い呼吸速度がみられたのは, 日おいをはずしたことによる一時的な光の強い照射が1つの原因とも考えられる。葉の呼吸速度は葉令が進むとともに減少しており, 葉の生理活性が年々低下することが推察された。さらに葉令が4,5年とふえる場合には, 呼吸速度は季節的な週期性に影響されず, 温度依存による基礎代謝だけか, あるいは落葉するということが考えられる。呼吸作用が本来, 温度に依存することから, 秋から冬への呼吸速度の減少は温度依存的な現象であると思われる。一方, 春から夏へは, この期間で盛んに物質生産が行なわれており, 物質の蓄積が続くが, 呼吸基質は一定量を維持するわずかの増加しかないため, 単位乾重あたりで呼吸速度をもとめた場合, 物質生産が続くかぎり減少傾向となることが考えられる。しかし, 週期の一環としての生長の開始直前では, 何らかの作用により物質の変化, 転流などがあって, 呼吸基質の増加や活性化の起ることが予想される。また, 地下部分の呼吸速度が地上部分のそれよりも遅れて増加したり, 季節変化に若干のちがいがあることから呼吸基質となる物質の苗体内での流れが考えられる。The respiratory rates (mgCO_2/g dry weight/hour at 25℃) are used as data when we estimate the amount of respiration. In this experiment, the respiratory rates of cuttings of Cryptomeria japonica were measured at intervals of one month during about two years from immediately after root initiation. The rates of individual and six sections, such as zero year old leaf, one year old leaf, two years old leaf, terrestrial-stem, subterranean-stem (inserted stem under the ground for cutting) and root were measured. The respiratory rates, in both case of individual and sections, showed the tendencies to increase rapidly in spring and fall, and to decrease gradually from spring to summer and from fall to winter (see Figure 1,2 and 5.), too. However only the rates of root somewhat differed from these tendencies, its respiratory rates showed the tendencies to increase also in winter and to increase regularly at intervals of five months (see Figure 6.). It is considered that these seasonal changes in respiratory rates were influenced considerably by the rise and fall of periodic physiological activity, seeing that growing season of Cryptomeria japonica exists in spring and fall. And it is supposed as one reason that the rates of fall observed relatively high values were affected by the strong irradiation of sunlight because sun-shade was taken off September. The respiratory rates of leaf decreased with the lapse of time, namely, with the lapse of leaf-age. For this reason, it is estimated that physiological activity of leaf falls every year. When leaf passes for four to five years in the future, it is supposed that the rates of leaf do not depend on seasonal periodicity, and leaves live only basic metabolism at various temperatures, or defoliate. It is considered that the gradual decrement in respiratory rates from fall to winter depends on the temperature, on the other hand, the gradual decrement from spring to summer is due to a series of dry matter production without accompanied by respiratory substances. Because, when dry matter production continues without accompanied by increment of respiratory substances, or respiratory activity, if the respiratory rates are given by \u27per unit dry matter weight\u27, then the rates are indicated necessarily by the tendency of decrement. But it is supposed that just before beginning of growth, respiratory substances are increased and activated by the changes and the translocations of material, seeing that the rates increase rapidly in spring and fall. And if the respiratory rates are compared leaf and terrestrial-stem (above the ground) with subterranean-stem and root (under the ground), then it is recognized that the seasonal changes in the respiratory rates are slightly different. Therefore, it is estimated that respiratory substances translocate the interior of plant. The respiratory rates of individual and those of total section did not agree. The rates of total section were extremely high values than those of individual. It is considered that in each section, large amounts of CO_2 were released by the excision of plant organs

コナラ成熟林における繁殖器官各部の乾物生産と種子生産における花粉粒及びめ花数の関係(林学部門)

樹齢100∿150年生のコナラ成熟林において1982,83年の繁殖器官各部の生産量を測定し, 考察した。この林分斜面は南向きで急傾斜(平均34度)である。花粉以外の各部生産量はリタートラップ法により, 花粉は開やく前の雄花序につく花粉量調査を併用し, 乾重と個数について推定した。乾物生産量は1982年が300kg/ha・y, 1983年750kg/ha・yで, 雄性も雌性の部分も1983年の方が多く, とくに種子の増加が著しかった。豊作年には乾物生産量全体に占める雌性部分の割合が高く(55%), 凶作年には低かった(20%)。1983年の種子豊作は開花しため花数が増加したこと(2.6倍)と結実率が高かったこと(2倍増加)によりおこった。この結実率の増大は花粉粒の生産個数のそれ(1.2×(10)^⇾1.6×(10)^no./ha・y)に対応していた。一方, め花数に対する花粉粒数の比には両年度の違いは小さく, これはスギ, ヒノキ, オニグルミの林分で認められている結果と一致した。Annual production rates (by dry weight and number) of each component of reproductive organs in a Konara oak (Quercus serrata THUNB.) mature stand, which consisted of trees 100-150 years old, were measured in 1982 and 1983 and analyzed. The slope of the studied stand faced south and was steep (mean inclination : 34°). Production rates per 1-ha stand for each component except pollen were determined using ten litter traps (each measuring 0.5×0.5m), while for pollen, this was done together with measurement of the amount of pollen contained in catkin samples before anther opening. The dry matter production rate of all reproductive parts including pollen in 1982 and 1983 amounted to 300 and 750kg/ha・y, respectively; the increase in 1983 was recognized in both male and female parts, especially acorns. In abundant crops the proportion of female parts to the total production was high (50%), while in poor crops, the proportion was low (20%). The higher production of acorns in 1983 compared with 1982 was caused by an increase in both the potential number of female flowers (2.6 times) and the ratio of fruits which matured (2 times). Changes in the seed-maturing ratio, i.e., the proportion of female flowers developing into mature and sound acorns, was related to the pollen production rate, which varied from 1.2×(10)^ to 1.6×(10)^ grains/ha・y. Little difference between the two years in the ratio of the number of pollen grains to female flowers was found, which agreed with our previous findings for Sugi (Cryptomeria japonica), Hinoki (Chamaecyparis obtusa) and Siebold walnut (Juglans ailanthifolia) stand

生殖器官の生産量からみたシイ林の有性生殖(林学部門)

松尾大社(京都市嵐山)の境内のシイ成熟林において, リタートラップ法で1986年∿1989年の生殖器官の生産量(林分当たり)を測り, また花粉生産量は開花前の雄花序当たり花粉量を基に推定した。これらの諸量を検討し, 有性生殖についてえた主な結果は次の通りである。花粉生産量は重量(218∿359kg (ha)^ (yr)^)では最大クラス, 粒数(64.2∿103×(10)^(ha)^ (yr)^)では突出して多く, しかも年次変動が小さかった。この莫大な花粉数は, しかし, 胚珠数に見合ったものであった(花粉/胚珠の数比, 4.1∿8.3×(10)^5)。花粉粒は小形であるから(1.94∿4.30×(10)^mg), 同化産物の花粉への流れは節約されている。開花年ごとの乾物量は1609∿1803kg (ha)^で, 雄性と雌性の部分量は逆比例の関係にあった。年度ごとの乾物生産量は1237∿2204kg (ha)^ (yr)^の範囲で, これは種子の並作∿凶作の年の値である。この生産量の多少と各部分の割合との間には, 一定の傾向はなかった。これは種子成熟に2カ年を要することに関係がある。また, 当年生と1年生の部分の生産量は等しくなる年が多かった。結実率は低いが(5.5%∿10.6%), ほかの種と大略等しい。年々の種子数は結実率と並行して推移し, 総雌花数も種子生産に関係があるようだ。種子対投資の重量比は種子の並作年に3倍, 凶作年6倍で, これはほかの重力散布種子の種の値と一致した。In a mature stand of Shii chinkapin (Castanopsis cuspidata SCHOTTKY) at Matsuotaisya shrine, Arashiyama, Kyoto, annual production rates of reproductive organs were studied using 20 litter traps (each 50cm×50cm in mouth area) in 1986-1989,and those of pollen were estimated by multiplying the number of fallen male catkins per ha per year by the mean amount of pollen per catkin before anthesis. The main results were as follows. The pollen production rate of 218-359kg d. w. (ha)^ (yr)^ was one of the highest among other species, and that of 64.2-103×(10)^(ha)^ (yr)^ was by far the largest number; moreover, these showed small year-to-year fluctuations. Such a huge number of pollen grains, however, was balanced by the number of ovules in a stand (numerical ratio of pollen grains to ovules : 4.1-8.3×(10)^5). The light pollen grains (1.94-4.30×(10)^mg d. w.) save the assimilation products invested in pollen formation. Dry matter of reproductive organs by the year of anthesis was within the range 1609-1803kg d. w. (ha)^, and those of male and female parts were inversely proportional to each other. Annual production rates were within the range 1237-2204kg d. w. (ha)^ (yr)^, equivalent to values in years of average to poor seed crop. There was no relationship between the annual production rates (by weight) of male and female parts, because fruit maturation requires two growing seasons. In three years among four, the 0-and 1-yr-old parts showed equal dry weight allocation. Seedmaturing ratios or numerical ratios of mature nuts to total female flowers were small (5.5%-10.6%), being approximately equal to those of other species. The year-to-year trend in nut production (by number) parallelled those of seed-maturing ratio and the number of female flowers. Mean nut weight vs. assimilation products necessary for producing a single nut, calculated by dividing the drymatter production rate of overall parts by the number of nuts, was 1 : 3 in a year with an average seed crop, and 1 : 6 in a year with a poor crop. This seed production effort was similar to those of five other barachorous species

東向き及び西向き斜面のミズナラ老齢林における花粉, 雌花及び種子生産の比較(林学部門)

林分1haあたりの雄花序, 花粉, 雌花及び種子の生産量(乾重と個数)について, 老齢ミズナラ林分の東向き斜面と西向き斜面とを比較検討し, 種子生産に関係する要因を考察した。各部分の生産量はトラップ法で測定し, 花粉については開花前の雄花序試料に含まれる花粉量と林分の開花雄花序数をかけて推定した。調査は1984年と85年に行った。両年度は種子豊作年と判断した。両林分の2年間の乾物生産は450∿500kg/ha・yrで, ここに占める雄性部分の割合は東向き林分が1/4,西向き林分は1/8であった。種子生産は西向き林分の方が多く, これは雌花数が多いためであった。種子生産の年変化は結実率に支配され, 雌花数自体の変化は無関係であった。この結実率は, 雌花に対して花粉の生産が多い年度に高くなった。花粉/種子の数比に年変化が認められなかったことから, 花粉生産量が結実率をとおして種子生産を支配したといえる。花粉/種子の数比は, 種子生産の少い東向き林分(19×(10)^6個)の方が西向き林分(5∿6×(10)^6個)より4倍程度多いが, 両林分の結実率は等しかった。このように, 向かい合って接する東向き及び西向き林分における雄性と雌性部分の生産量及び両者の両割合は異ることがわかった。A comparison of east- and west-facing slopes with regard to the production rates of male flowers, pollen, female flowers and seeds in aged stands of Japanese white oak (Quercus mongolica FISCH. var. grosseserrata REHD. et WILS.) was made and the factors affecting seed production were discussed. Annual production rates (by dry weight and number) per 1-ha stand for each reproductive component except pollen were determined using ten litter traps (each 50cm×50cm in mouth area), while for pollen, this was done together with measurement of the amount of pollen contained in catkin samples before anther opening. The study was conducted in 1984 and 1985,years in which the seed crop was abundant. Dry-matter production rates for all reproductive parts including pollen in the two stands for the two study years were in the range of 450∿500kg/ha・yr, the proportion of male parts being one-fourth for the east-facing stand and one-eighth for the west-facing one. Seed production of the west-facing stand was higher than that of the east-facing one, due to the number of female flowers. Yearly changes in seed production were dependent on the seed-maturing ratio, i.e., the numerical ratio of sound acorns to female flowers, and not on the number of female flowers. The high seed-maturing ratio corresponded to the year in which a large amount of pollen was available for fertilization. Judging from the negligible difference between the two years in the numerical ratio of pollen to seeds, i.e., the number of pollen grains necessary for the formation of one acorn, seed production appears to be dependent on the number of pollen grains released into the air. There were no differences between the two stands in the seed-maturing ratio, while the numerical ratio of pollen to seeds in the east-facing stand (19×(10)^6), which had a low seed production, was about four times higher than that in the west-facing stand (5-6×(10)^6). Remarkable differences between the two stands, either neighboring or face to face, were found in the numerical proportion of male to female parts

シイ林における生殖器官各部の生産量と種子生産に影響する要因(林学部門)

京都盆地をとりまく低山帯のシイ5林分を対象にして1982,83年の林分あたり雄花, 花粉, 果実の生産量(乾重と個数)をトラップ法で調査し, 開花∿種子散布の過程を解析した。花粉生産量は既報4樹種より多く, 粒数では2.6×(10)^ha^y^を記録した。雄花の生産量は林分の生育段階の進行に伴い増加するが, 果実にはこの傾向が認められない。生殖器官全体の生産量は10資料のすべてが1t ha^y^をこえ, うち3林分は3∿5.5t ha^y^に達した。1982年開花に由来する生殖器官部分の乾物割合は雄性 : 雌性が1 : 1の3林分と1 : 3の2林分にわかれ, この関係は花粉粒数P/め花数Fの比によって整理できた。前者3林分のめ花数には2倍の較差があるが結実率(21%)は等しかった。P/F比が前者の半分しかない後者2林分では結実率が高い林分(31%)と低いもの(17%)とがあった。若い林分ではP/F比が小さいが, 結実率は高い傾向がみられる。シイ種子生産を決定する要因にはめ花数と結実率の二つが認められた。Annual production rates (per 1-ha stand; by dry weight and number) of catkins, pollen and fruits of five chinkapin (Castanopsis cuspidata SCHOTTKY) stands in the mountain zone around the Koyto Basin were measured in 1982 and 1983 using litter traps, and analyzed from the process of flowering to seed dispersal. The pollen production rates were larger than those of the four species previously reported, i.e., Japanese red pine, Cryptomeria, Chamaecyparis and Siebold walnut; the maximum value reached 2.4×(10)^ grains/ha・y. Catkin production increased with developing growth stage of stands, while fruit production varied among stands. Ten estimations (five stands in two years) of the production rates of all reproductive organs including pollen showed values of over 1t/ha・y, in which all six estimations for three stands amounted to between 3 and 5.5t/ha・y. The distribution ratio of male and female organs within the total dry matter production of parts derived from flowering in 1982 was 1 : 1 for three Stands B, D and E, and 1 : 3 for two Stands A and C, corresponding to the ratio of the number of pollen grains (P) to female flowers (F). In the former stands, a two-fold difference in the numbers of female flowers was recognized, while there was no difference in the seed-maturing ratio (21%), i.e., the proportion of female flowers developing into ripe and sound nuts. Of the latter stands having half the P/F Ratio of the former, young Stand A showed a high ratio (31%) while Stand C showed a low ratio (17%). It was concluded that the seed-maturing ratios in mature stands are related to the P/F Ratio, while in young stands, the former tends to be high in spite of a low P/F Ratio

京都市北部の貧弱な天然生ヒノキ林の純生産速度(林学部門)

B_B残積土にある天然生の, 貧弱な林相のヒノキ林(樹齢85-108年)の純生産速度を調査し, 経済林であるヒノキ人工林と比較検討した。貧弱な調査林の特徴は, 林分葉量, 現存量密度, 林分樹高あたりの幹現存量, 純生産速度および幹重量成長速度は, いずれも人工林にくらべ小さいことである。また, リターフォール速度が小さいのにくらべ, 林内空間の枯枝や枯木量およびA_0層の有機物量は多くて物質循環は悪かった。ほかの測定量や生産構造は人工林の範囲内にあって, 貧弱な調査林の特徴はとくに認められなかった。ヒノキ林の調査報告と比較検討したところ, 冬季の林分葉量10t/haが閉鎖したヒノキ林の下限であることがわかった。また地上部純生産速度7.77t/ha・yもヒノキ林の下限とみられ, これは成長良好な人工林の約50%にあたった。Estimates were made of the aboveground biomass, litterfall rate and net production rate for the natural regenerated forest of Chamaecyparis obtusa S. et Z. growing on the poor site. The height of dominant tress, which ranged from 85 to 108 years of age, was 10.2m, and the largest tree 11.8m in height. Total basal area equaled 34.5m^2/ha. Leaf biomass was 12.4t/ha in summer or about 10t/ha in winter after leaffall. After a discussion on the average of 13.1±0.9t/ha of leaf biomass in winter, it was determined that the 10t/ha of winter leaf biomass was minimum in various Chamaecyparis obtusa forests with the close canopy. Annual leaffall rates for 4 years ranged from 1.65 to 2.72t/ha・y. Net production rate of aboveground parts was estimated 7.77t/ha・y, which accounted to about 50% of some plantations of the maximum growth

コナラの花および堅果数とその枝直径の関係(林学)

コナラの枝につく雄花序, 雌花および堅果の個数と1年枝の直径との関係を検討した。雄花序は直径とは関係がみられず, 雌花は直径の大きいクラスで多く着いていた。堅果はある程度の直径をこえた太い枝に残っていた。1年枝に着く当年枝数は太い枝で多かったことから, 太い枝では資源量が多いことがいえる。これらより雄性器官は枝の資源量とは関係なく着生し, 雌性器官は枝の資源量に影響されて着生していることがわかった。The relationships between the numbers of male flowers, female flowers and acorns produced on shoots and shoot diameter were studied in two 75-yr-old Quercus serrata trees. There was no relationship between the number of male flowers per current year shoot and the diameter of 1-yr-old shoots, while an increase was recognized in the number of female flowers per current shoot with increasing shoot diameter. The acorns survived on 1-yr-old shoots that exceeded a certain diameter. The number of current shoots on each 1-yr-old shoot increased with shoot diameter, suggesting an increase of resources in shoots with increasing size. Although no relationship between production of male flowers and shoot resources was found, there was a relationship between shoot resources and female flower-bearing and acorn development

ヒノキ テンネン コウシン ノ キソ シケン 1 チジュ ノ ハッセイ オヨビ ショウシツ リンガク ブモン

ヒノキの稚樹発生ならびに消失の基礎試験を学内の苗畑と八瀬の林内試験地で行った。1. ヒノキの稚樹は平均気温が15℃ほどになると発生しはじめる。試験地では4月の中・下旬であった。そして7月ころには大部分の発生を終る。2. 温度と土壌水分がヒノキのタネの発芽に十分であれば, 相対照度30%くらいが発芽に最も適し, 100%では抑制され, 5%以下では困難なようである。3. 稚樹の消失時期は7∿8月ころが多く, 消失原因は林内環境で差がある。八瀬試験地のようにA_0層が少なく, A層が浅いところでは雨による倒伏, 埋没, 流失の害が多くなる。A_0層の厚い林地では雨による被害より虫害や乾燥害の多くなることが予想される。越冬稚苗の寒さの害は比較的少ないようである。4. ヒノキのタネの発芽環境と生育環境は異なるので, さらにこの研究が必要である。Basic studies on the germination and the mortality of HINOKI (Chamaecyparis obtusa ENDL.) seedlings were performed on the nursery of the Kyoto Prefectural University and the forest land of Yase, Sakyo-ku, Kyoto. The results obtained are as follows : 1. The seedling of HINOKI begins to germinate when the average temperature comes to about 15℃ (it is in the second and the third ten days of April in the forest land of Yase), and the greater part of germination comes to an end in July. 2. When the temperature and the soil moisture are sufficient for the germination, the relative lux about 30% is most suitable for it. It is restrained at 100% lux, and seems to be difficult under 5%. 3. The mortality of seedlings is highest from July to August, and the causes for the mortality are different according to the forest environment. In the place where A_0 layer is thin and A layer is shallow as the Yase experimental plot, the runing-off, burial and fall of seedlings caused by rain come to increase. In the forest land where A_0 layer is thick, it is assumed that insect and drought damage becomes more than that caused by rain. The frost damage for hibernal seedlings seems to be comparatively little. 4. Future study is necessary because the environment for the germination of the seeds of HINOKI differs from the environment of growth

樹幹の振動および固定がハンノキ属 2 種の成長におよぼす影響(林学部門)

落葉広葉樹ハンノキ属の2樹種の若木について, 3とおりの機械的刺激 : 振動, 固定, および自然(対照)を樹幹に与えて, 約1生育期間の成長への影響を調べた。実験結果を要約するとつぎのとおりである。1)振動によって樹高成長は減少, 直径成長は増加し, そしてH/Dは減少した。生枝下部の幹断面積成長は, 振動で下方ほど著しく促進された。しかし樹冠内では振動の影響はあらわれない。固定すると生枝下部で減少し, 樹冠内での増加が著しい。2)処理期間中の年輪成長幅は, 振動方向の増加が樹幹全体であらわれた。この傾向は下方ほど大きい。3)根重および根の割合は振動によって増加した。とくに支持根で著しい傾向があり, しかも振動方向に発達して耐振動性が大きくなった。4)全樹体, 地上部, 幹枝葉の各重量に対する処理の影響はばらばらであったが, 振動で乾物生産が減少することはなかった。幹枝葉のしめる割合は振動によって顕著な変化があらわれない。T/Rはヤシャブシで処理効果がなく, ヤマハンノキの実験では振動自然>固定で各10%差だった。The effects of three mechanical stimulations : shaking, staying, and free-swaying (control), on the growth and development of young alder trees were studied. The period of the treatments was from 72 to 108 days. The summary of the results are as follows. 1) The shaking reduced height growth, enhanced diameter growth, and consequently decreased the ratio of height to diameter. Stem crosssectional area increment on clear bole was markedly increased by shaking, with the increase toward the stem base. The stayed trees showed a pronounced upward shift of increment, at the expense of downward stem parts. 2) Trees responed to unidirectional shaking by producing larger diameter increment along the shaking direction throughout their length, with increasing on the lower stem. 3) The effects of shaking affected growth by altering weight and percentage of roots, especially for larger roots more than 0.2cm in diameter. The root system was reflected by the development in direction to the stem shaking. 4) Although the evident tendency of the effects of the mechanical treatments on the dry weight of stem, branches, leaves, above-ground parts, and a whole tree has not become visible, the shaking did not reduced dry matter production. With the exception of root growth, the shaked and stayed trees did not alter the distribution of dry weight of each organ within the tree. The ratio of above-ground parts to root of a Alnus firma tree was not affected by shaking, but for A. hirsuta var. sibirica, the value resulted in decrease for shaken trees and in increase for stayed. 5) In the stayed treatment where A. hirsuta var. sibirica trees were prevented from swaying throughout their length, the stem bending was observed after the tree stakes were removed. Mean bulk density of stems spaned a range from 0.37g/(cm)^3 for shaking to 0.31g/(cm)^3 for staying

ヒノキのさし穂の吸水と発根(林学部門)

ソイルポトメータを用いてヒノキのさし穂の吸水量を測定した一連の実験の結果を次のように総括した。さし穂の吸水速度(ml/さし穂・日, あるいはml/g(さし穂乾重)・日)の経時変化のパターンは, 相対的に高い値を示すが変動の大きい第一段階, ついで連続的な低下を示す第二段階, 最後に低下傾向の停止による横ばい, もしくは上昇の傾向を示す第三段階の, 3つの段階を区別することができる。この吸水速度の経時変化は, 切口部分の通水の抵抗, および発根量のそれぞれの要因に, 気象条件の影響が加わってあらわれたものとみられる。吸水量が多くなることは発根にとって望ましい条件となるので, ヒノキのさし木を行なうにあたっては, 吸水量を高めるように水分環境, とくに土壌水分条件に考慮をはらわなければならない。Water absorption of Chamaecyparis obtusa cuttings was measured by using soil potometers for several years, and relation between water absorption and rooting of cuttings was investigated. Three typical stages for water absorption rate (ml/cutting・day, or ml/g d.w.・day) were observed. Namely, water absorption rate showed relatively high values in the early stage, then decreased continuously (second stage), and lastly remained on the same level or conversely increased gradually (third stage). It was considered that above-mentioned changes in water absorption rate arose from following three factors, those were resistance of cut base for that water passes, rooting results, and weather conditions. Active water absorption is one of the conditions necessary to obtain desirable rooting results. When cutting of Chamaecyparis oblusa is carried out, careful consideration for external moisture condition, especially soil water condition is needed