タケノコ時代の形状と, 成竹となつたときの稈の形状との関係について

Abstract

本報告は, タケノコ時代の形状と, そのタケノコが成竹となつたときの形状との関係を知るため, 京都大学上賀茂試験地のモウソウチク林において調査した結果を取りまとめたものである｡ その結果を要約するとつぎのとおりである｡ 1. タケノコが地上10cmに伸長したときの地ぎわ直径と, そのタケノコが成竹となつたときの目通り直径, 根元直径, 竹稈長, 枝下高などとのあいだは相関係数+0.71 ~ +0.95を示し, つよい相関関係が認められた｡ したがつて, タケノコの大部分が地中にあつて, その先端部の10cmが地上にあらわれたときの地ぎわ直径を測定することによつて, そのタケノコが成竹となつたときの形状を予測することができる｡ この結果を応用することによつて, 稈の細い不良竹となるタケノコを, 早期に間引くことができるので不良竹林の改善や良竹材の増産に役立つとともに, 堀りとつたタケノコを食用に供することができる｡ 2. タケノコが地上30cmに伸長したときの地ぎわ直径と, そのタケノコが成竹したときの目通り直径, 根元直径などとのあいだにも, 正のつよい相関関係が認められた｡ この結果は人工四角竹をつくるうえに役立つ｡ すなわち, 四角竹をつくるために板框をタケノコにはめこむとき, その板框のサイズは, そのタケノコの地ぎわ直径よりも1.5cmぐらい小さくすれば良いことがわかる｡ 3. さらに, タケノコの先端がやや曲つているもの, 縮小葉がやや開いて黄緑色のもの, 籜耳や小舌の毛が黄色味をおびたタケノコは, 直立状のもの, 縮小葉が開いて黄褐色のもの, 籜耳や小舌の毛が褐色, 紫色のものよりも, 稈の太い良い成竹となる傾向がみられるから, タケノコの地ぎわ直径の大きさによつて, 成竹となつたときの形状を予測するときの参考にすることができよう｡

In order to make clear the relation between the shape of young bamboo sprouts and the shape and quality of matured culms, this report deals with the results of investigation in Mosochiku (phyllostachys edulis) grove of Kamigamo Experimental Forest Station of Kyoto University. The outline of the results is as follows: 1. Among the relation of the diameter at the base of sprouts 10cm high above the ground to the diameter at eye height, diameter at base, culm length and clear length of culms when the sprouts are mature, there are recognized close positive correlations. Therefore, using the diameter at the base of sprouts when their height is 10cm high above the ground, it is possible to estimate the shape and quality of matured culms. This estimation helps improve poor groves and increase the yield of good culms, as it facilitates an early thinning of poor sprouts that are likely to develop into culms of inferior quality. At the same time these sprouts dug out early can be used for food. 2. The relations of the diameter at the base part of sprouts 30cm high above the ground to the diameter at eye height and at the base of culms when the sprouts are mature, also show close positive correlations. This relationship is of use for producing artificial quadrangular culms. Because, such culms are produced by placing wooden frames over young sprouts when they are about 30cm high above the ground. It can be understood by the result (Table I ) that the size of the frames should be smaller by about 1.5cm than the basal diameter of sprouts. 3. There is a tendency that sprouts with slightly crooked types, opened and yellowish green sheath blades and yellowish hair on Iigules and auricles, develop into culms of better quality than sprouts of upright type with opend and yellowish brown sheath blades and brown or purple hair on ligules and auricles. But since it does not necessarily follow that growth conditions of sprouts are better just because they belong to the former type, the dimensions of sprouts must always be taken into consideration together.