アイグロマツ種子の重さのちがいが発芽およびその後の成長に及ぼす影響

Abstract

本実験はアイグロマツ (Pinus densiflora×P. Thunbergii) の種子の重さのちがいが, 発芽や苗木成長にどのような影響を及ぼすかを明らかにする目的でおこなつた｡ 種子は約60年生の母樹より採取し, それらの種子を5つの重量段階に分け, 1956年1月播種した｡ その概要は次のとおりである｡ 1. 発芽率にたいする種子の重さの影響は, きわめて軽いものや, 重いものはわるく中間的なものがややよいように思われた｡ 発芽所要日数においては種子の重さによる差異はみとめられなかつた｡ 2. 種子の重さの影響は発芽後しばらくの間 (50 ~ 100日間) の成長には大いに影響した｡ すなわち, 種子重量段階の大きいもの程よい成長をしめした｡ しかし日がたつにつれて次第にその影響はうすれるようであつた｡ 活着についてはほとんど差異はみとめられず, 床替後の苗木成長にも種子の重さによる影響はみとめられなかつた｡

This report deals with the results of the experiments, which were conducted to make clear what influence the difference of seeds weight of Aiguro-matsu has on their own germinative vigour and the growth of their seedlings. We collected cones from the mother tree (about 60 years old) in October 1956. These seeds were separated by weight into five grades; 1). First grade 5.0 ~ 7.9mg, 2). Second grade 8.0 ~ 9.9mg, 3). Third grade 10.0 ~ 12.9mg, 4). Fourth grade 19.0 ~ 14.9mg, 5). Fifth grade 15.0 ~ 17.9mg, These seeds were sown in sow-bed on January 1956. The outline of the experimental results is as follows; 1) The Foruth, Third and Second grades (for seed weight) showed more favorable germinative vigour than the First and Fifth grades (for seed weight) and we could not find mutual relations between the days spent in germination and the grades of seeds weight. 2) In about 50 ~ 100 days after sowing, the seedling's growth was greatly influenced by seed weight. Namely, the seedlings from heavier seed showed a growth better than those from lighter seeds. From 50 ~ 100 days on after sowing, seedling's growth was hardly influenced by seed weight, but the seedling growth of the First grade was worse than those of the other grades. 3) The correlation between the survival of seedling and seed weight could not be definded in this experiment.