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

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

中国内蒙古の沙地における緑化・造林樹種としての叉子円柏 (Sabina vulgaris) と樟子松 (Pinus sylvestris var. mongolica) さし穂の吸水傾向(林学部門)

中国内蒙古に広がる沙地上へ, 叉子円柏(Sabina vulgaris)と樟子松(Pinus sylvestris var. mongolica)の組み合わせによる緑化・造林を考えたときに必要となる基礎的なデータを得るため, これら2樹種のさし穂(切枝)の吸水傾向を, 44∿48日間にわたり調べてみた。いずれの樹種もさし付け直後に最大の吸水速度を示すが, その後叉子円柏では, どちらかといえば吸水速度は直線的に, 樟子松では指数関数的に減少していく。この傾向は苗畑でもガラス室内でも, また発根へいたるさし穂でもそうでないものでも同じであった。ただ, 吸水速度はこれらの場所のちがいや発根のあるなしで若干異なったので, これがどのような意味をもつのか, 樹種間の傾向のちがいも含めて今後検討が必要である。Water uptake of cuttings (shoots cut off from their twigs) of Cha Zi Yuan Bai (Sabina vulgaris) and Zhang Zi Song (Pinus sylvestris var. mongolica) were examined for 44-48 days, in order to obtain basic data which are essential for the afforestation of the vast sands in Chinese Mongolia using a combination of these two tree species. Maximum water uptake rate was observed just after their planting in both species, but the rate started to decrease after that rather linearly in Cha Zi Yuan Bai and exponentially in Zhang Zi Song. Different experiments performed at a field and in a glass-house or using the cuttings before and after rooting showed the same species-dependent decreasing tendencies, thought the water uptake rate itself varied slightly depending on these conditions. It is necessary to elucidate significance of these differences in the condition-dependent water uptake rate and the species-dependent decreasing tendency of the rate

ヒノキさし穂切口の水浸漬期間が異なるときの木部圧ポテンシャルおよび発根について(林学部門)

さし穂の切口を, 最も長くて12日間滞水中に浸漬し, 浸漬終了時にさし穂の木部圧ポテンシャル(XPP)を測定した。そのあと, さし穂をポットにさし付け, 1.5∿2か月後に掘り取って発根成績を調べた。このような実験を3回行い, 切口の水浸漬期間とXPPおよび発根との関係を検討した。さし穂の切口が水浸漬されるとXPPは上昇し, 1∿3日間の浸漬で上限値に達する。それより浸漬期間が長くなると, 逆にXPPは低下する。しかし, すぐに下限値に達し, 再びゆっくりと上昇する傾向がみられた。さし穂の含水量の増加がXPP上昇の原因とみられる。特に, 1∿3日間の浸漬でみられたXPPの上昇は, 第一義的に活発な吸水によって生じたのであろう。途中一時的にXPPが低下する原因は不明である。ヒノキの春ざしでは12日間水浸漬されても発根に影響は認められない。しかし, 秋ざしでは6日間以上の浸漬が行われると, 発根がマイナスの影響を受けることも推測される。The cut ends of cuttings were immersed in stagnant water within 12 days of the longest and xylem pressure potential (XPP) was measured after finish of the immersion. And then, cuttings were planted in pots and dug out after 1.5 to 2 months, the result of rooting was investigated. By performing those experiments three times, the relationships between immersion time of cut end and XPP and also rooting were examined. When the cut ends of cuttings are immersed, XPP rises and the upper limit is attained by immersion for one to three days. When the period of immersion is prolonged, XPP falls reversedly. But, the tendency was observed that it soon attains to the lower limit and again rises slowly. It seems that the increase of water content in cuttings is the cause of XPP rise. Especially the rise of XPP observed by the immersion for one to three days would have been brought out by the primarily active water uptake. The cause of temporary lowering of XPP midway is not clear. The effect on rooting in cuttings of Chamaecyparis obtusa in spring is not recognized even if cuttings were immersed for 12 days. But, when cuttings are immersed over 6 days in fall cutting, it is estimated that rooting may be affected negatively

生長要因の性質についての一考察(林学部門)

生長要因をつぎの3つの性質をもつものとして考えた。つまり生長にとってぜひとも必要なものがあるということ(基質性), 与えられる空間量のちがい(空間性), 生長のための時間(指数要因)である。ここではとくに基質量(土壌容積)を一定にして, 空間(植えつけ密度, 土の深さ)の与えかたをかえた場合の重量および直径・樹高生長から, 生長要因のもつ空間性について検討した。個体あたりの占有する土壌容積を7000(cm)^3と一定にして, 15cm(深さ)-22本/m^2(密度), 30-43,50-71,70-100の4段階の処理とした。1年目の重量生長は密な(深い)区ほど平均個体重(w)は小さく, これまでの密度効果試験を再現するものであった。しかし2年目では純同化量は密な区ほど急勾配でふえており, 時間の制限のない場合には処理間の差のちぢまることが予想された。平均地際直径(D^^-), 平均樹高(H^^-)の生長は1年目ではいずれも密な区ほど少ない生長量であった。2年目でもD^^-はこの傾向がひきつづいてあらわれるが, H^^-は1年目の傾向が逆転して密な区ほど高い生長量がしめされた。このことから, D^^--H^^-関係は2年目の生長のすすんだ段階では両対数図上でマイナスの勾配をもつ直線性がしめされた。このように生長要因の空間性は基質量を一定にしたときにあらわれ, 植えつけ密度が直径方向の生長に, 土の深さが樹高方向の生長に影響をおよぼすことでしめされた。Growth factor has three properties, one is that it is essential to growth, another is spacing on the ground and underground, a third is time as exponential factor. This experiment were performed on the character of spacing. Treatment of experiment is as follows; mean soil volume per plant is 7000(cm)^3,and depth of soil is divied into four plots, namely, 15cm (depth)-22 number of plant per m^2 (density), 30-43,50-71 and 70-100 (see Table 1). Besides, cutting of Cryptomoria japonica is used as experimental material (see Table 2). So-called density effect was appeared by growth after one year. After two years, however, density effect was appeared less than after one year, and it was presumed that weight growth may be the same among the treatments. After two years, on the other hand, mean diamter-mean height relation among four treatments had a straight line with minus gradient on the log. diagram (see Fig. 6). The outline of the discussion about result is as follows; when the soil volume per plant is all the same, it is presumed that weight growth may be no difference among the treatments, and diameter growth may be influenced by the density of planting, while height growth may be influenced by the depth of soil