Effect of age (position on stolen) on the carotene content of leaf blades and leaf stalks of ladino clover

Ladino clover 茎葉中のCarotene 含量に及ぼすAge(Stolon上の位置)の影響

Takasaki Tetsunosuke

広島大学水畜産学部紀要

Journal of the Faculty of Fisheries and Animal Husbandry, Hiroshima University

　Ladino cloverの葉身，葉柄中のCarotene含量は生育期の如何にかかわらず常に葉身中にその大部分(凡そ90%程度)がみられ，葉柄中には微量(10%程度)にすぎなかった.花(頭花，花梗)は花奮，開花初期，最盛期或は終期等(Flowering stage)により多少差はあったが葉身に比しCarotene含量は甚だしく少なく，同様にStolon も白色を呈しChlorophyll，Carotene 共に殆んど皆無にひとしい.肉眼的に一見同様と見られるLadino cloverの茎葉比率及びCarotene含量はその生育時期即ちStolon 上の位置により相当差がみられ，Stolon先端上の生育初期の茎棄は基部に近くAgeの進んだものに比し葉身きわめて小さく葉柄細く短かい.この時期の葉身の割合は高く全茎薬重量の35-40 %を占めているが，その成長につれて葉身は大きく葉柄もより太く伸びるが葉身の割合は反対に減少して40cm に達する頃全茎葉の凡そ25%程度であった。
　幼時(7.5cm) は葉身未だ開かず葉柄15cm 前後に達する頃半開状となり更らにその生育進み20cmに達する頃完全に開葉する.かかる幼時期(7.5 ~15cm) の葉身は淡緑色を呈し葉柄はその色一層淡く基部は殆んど白色にちかい.かかる葉の形成初期は光，温度等のChlorophyll 生成条件が不十分で未だProto-chlorophyll が完全に変化成熟しない状態にある.従ってChlorophyll が未完成の状態でGrana中に存在する時，常にこれと結合しその普遍的成分である赤樫色色素Carotene も叉少ない.即ち淡緑色を呈する幼葉はChlorophyll，Carotene 共に少ないことが見られた.反対に一定限度内の日照と混度下では漸次その緑色度を増しCarotene 含量も増加して幼時(7.5cm) に比し40cm に達したものは平均凡そ3倍程度Carotene 含量は増加してくる.
　以上の実験結果から実際上Ladino clover の利用に際し余りに若い草地の放牧，刈取等は単に収量減にとどまらず栄養的の損失も多く不得策である.最少限その草丈25cm 以上IZ::仲長させ，叉刈取放牧は何れも5-7cm 以下の低刈或は過放牧等はさける必要がある.

The age of leaves of Ladino clover had a significant effect on both the proportion of leaf blades to leaf stalks and also its carotene content. Young small new leaves harvested from the top of stolons of Ladino clover have a higher percentage of leaf blades in comparison with its stalks than large fully developed old leaves of the same stolons. Leaf blades at any growing stage in general contained almost 90 per cent of the total carotene in the entire leaves. Leaf stalks have only I 0 per cent of the total carotene in Ladino clover. Therefore, the most important part of Ladino clover is the leaf blades which is the best source of Vitamin A for live-stock. If leaves are very young just beginning to grow on the top of stolons, the carotene content is very low and the color of such leaves is pale green. These pale green colored leaves were predominant among leaves under the height of 20 cm. At these stages most leaves are not yet completely opened and are not very green.

A significant relationship exists between the carotene content and the green color, chlorophylls of leaves. It is well known that the more green pigments the leaves possess, the higher the carotene content. If leaves contain a large amount of carotene, they usually have deep green color.

Therefore, the best indicator of carotene content is leaf color; if leaves contain a large amount of carotene, they usually have a good green color. Ladino clover is one of the best sources of carotene. This is to be expected because the leaf blades, leaf stalks and relatively small amounts of flowers are the only parts of the entire plant which are harvested. When the stems of any other legumes or grasses are harvested, stolons of Ladino clover should not be included.

In conclusion, the results of this study indicate that Ladino clover should be allowed to grow to the height of 25 cm after each pasturing and also should not be cut or grazed to the height less than 5 to 7 cm.

植物学 [ 470 ]

英語

広島大学水畜産学部

[ISSN] 0440-8756

[NCID] AN00213563