林木のつぎ木とその育種への応用 (IV) : Metasequoia とその近縁種属間のつぎ木植物から得た花粉の機能について

Abstract

本実験は Metasequoia とその近縁種属間植物のつぎ木したものからとつた, つぎ木花粉とそのつぎ穂親木花粉ならびに, つぎ木と同年令の実生樹 (対照木) からとつた花粉の形態と花粉発芽のちがいを検討するために行われた｡ 1. 供試花粉は, 次のつぎ木樹種とそのつぎ穂親木ならびにその対照木から採集した｡ a) 2年生の Metasequoia を台木として, Glyptostrobus (約15年生) とSequoia (29年生) の親木よりつぎ穂をとり1954年についだもの｡ b) 2年生の Metasequoia を台木として, Cryptomeria 3年生の実生苗からつぎ穂をとり1954年についだもの｡ c) 500 ppm のジベレリンを撒布して開花した Metasequoia 2. 成木 (15 ~ 29年生) からつぎ穂をとつてついだ Sequoia, Glyptostrobus のつぎ木花粉の大きさは, そのつぎ穂親木花粉にくらべて幾分小さい傾向がみられた｡ またつぎ木個体間においては有意差がみられた｡ 酢酸カーミンによる花粉稔性は両者とも良好であつた｡ 3. Sequoia, Glyptostrobus のつぎ木花粉の発芽率は, そのつぎ穂親木花粉よりも幾分低い傾向をしめしたが, 花粉管の伸長には花粉置床後96時間までは, 両者のあいだに顕著な差異はみとめられなかつた｡ 花粉置床後120時間からはつぎ木花粉の方が, そのつぎ穂親木花粉よりもやや良好のようであつた｡ 4. Cryptomeria の若木 (3年生) からつぎ穂をとつてついだつぎ木花粉の大きさは, 平均においては対照木花粉よりもわずかに大きい傾向がみられ, またつぎ木個体間に有意差が認められた｡ なお約100年生の成木花粉とつぎ木花粉の大きさを比較してみると, 後者は前者よりもわずかに小さいようにみられた｡ 酢酸カーミン染色による花粉稔性は両者とも良好であつた｡ 花粉の発芽率についてはつぎ木花粉はつぎ穂親木と同年令の対照木花粉よりも, 幾分低い傾向をしめしたが大差はなかつた｡ また花粉管の伸長は花粉置床後96時間まではつぎ木花粉は対照木花粉よりも低かつたが, 置床後120時間からはつぎ木花粉の方が対照木花粉よりもやや良好のようにみられた｡ また花粉の発芽率および花粉管の伸長はつぎ木個体によりわずかに異なつていた｡ 5. Metasequoia の花粉はジベレリン 500 ppm の撒布によつて開花したものである｡ 花粉の大きさは酢酸カーミン染色により測定した結果は27.69μ±3.48であつた｡ 花粉稔性は良好であつた｡ 花粉の発芽率および花粉管の伸長は非常に低い値をしめし, また異常形のものがみられた｡ 6. 一般につぎ木花粉はそのつぎ穂親木花粉ならびに対照木花粉と同様に, 花粉の発芽率および花粉管の伸長は良好であつたから, 交雑用の花粉として使用することができると考えられる｡

1. The present work was carried out to examine the morphological and functional characters of the pollen which were taken from the grafted plants between Metasequoia and its related species plants. In 1954, Cryptomeria (3 years old), Glyptostrobus (ca. 15 years old) and Sequoia (29 years old) were grafted on Metasequoia (2 years old); in 1959, the pollens of these trees and the mother trees were collected as materials, and the were used immediatly in the experiment. 2. The pollens of these grafted plants seemed to have a tendency of being a little smaller in size than those of the mother plants, but with regard to the fertility, i. e. the percentage of well-stained pollen grains with aceto-carmine, both showed similary good results. 3. The germination test of these pollens were undertaken by using sucrose-agar medium (agar 1%, sucrose 7% and pH 7.5). 4. In the pollen of the grafted plants, The germination percentage showed a little smaller than those of the mother plants. The growth of pollen tubes was not remarkable between both trees until 96 hours after setting of the pollen, but on the contrary, the growth of pollen tubes seemed to be better than those of the mother plants from 120 hours after setting of the pollen grains. 5. In grafted Cryptomeria, the size of pollen grains was different between individuals that were grafted and between those individuals which were recognized signficance at 1% level. Morever, they seemed to be a little smaller in size compared with the matured tree (ca. 100 years old). The fertility of pollen was good. 6. In the pollen of the grafted plants, the germination percentage was considerably lower than the control. The growth of pollen tubes seemed to be lower than those of the control until 96 hours after setting of pollen grains, but on the contrary, the growth of pollen tubes seemed to be better than those of the mother plants from 120 hours after setting of pollen grains. 7. Metasequoia which were used as stock, flowered by spraying with gibberellin at 500 ppm. The size of pollen grains stained with acetocarmin was 27.69μ±3.48. The fertility of pollen was good. The germination percentage of pollen grains and the growth of pollen tubes was very low. The abnormal form seemed to be in the growth of pollen tubes. 8. The results which were mentioned above lead to the conclusion that the pollens from the grafted plants between Metasequoia and its related species plants have a possibility to be used for breeding.