クロマツおよびアカマツの吸水種子に対するX-線の影響

Abstract

本実験は突然変異誘発を目的として, クロマツおよびアカマツの吸水種子を用い, X-線照射を行い, 幼苗の生存率, LD-50および初期生育調査を行った｡ (1) クロマツ種子は個体別に3本の木 (13年生) から採種し, 吸水後22日目にX-線 (電圧200kV, 電流19mA, 距離55cm, 1.0mmアルミニュームフイルタ) を照射した｡ (2) アカマツ種子は個体別に5本の木 (約60年生) から採種し, 吸水後12日目にX-線 (クロマツと同様) を照射した｡ (3) 線量はクロマツについて100, 200, 300, 400, 600および1200γまで, アカマツは300, 400, 600, 800, 900, 1200, 1600および2000γまで照射した｡ (4) クロマツ吸水種子のX-線照射後, 播種してから220日目における幼苗の生存率は, 個体によってことなるが, 線量の増加にともなって低くなる傾向がみられた｡ LD-50は個体によってかなりことなるが300γと800γとの範囲にあると思われる｡ 苗高についても個体によってことなり一様でない｡ とくに100γおよび300γは無処理よりも高い個体がみられ, 生育は良好である｡ 形質の変形しているものについてはとくに主軸が枝分れしているものがみられた｡ しかしX-線の影響によって出現したかは明確でない｡ (5) アカマツ吸水種子のX-線照射後, 播種してから190日目における幼苗の生存率は, 個体によってことなるが, 線量の増加にともなって低くなる傾向がみられた｡ 1500γ, 1600γおよび2000γでは各個体とも完全に致死である｡ LD-50は個体によってかなりことなるが, 300γと600γとの間にあると思われる｡ 苗高についても個体によってことなり一様でない｡ とくに300γおよび400γは無処理よりも高い個体がみられ, 生育は良好である｡ 形質の変形しているものについてはとくに主軸が枝分れしているものがクロマツと同様に出現した｡

For the purpose of inducing mutation, in this experiment presoaked seeds of Pinus Thunbergii (Japanese black Pine) and Pinus densiflora (Japanese red Pine) were irradiated with X-rays. The influences of X-rays were investigated on survival rates, LD-50 and initial growth of young seedlings. 1. The seeds of Pinus Thunbergii were collected from three trees (13 years old), and they were X-rays irradiated on the 22nd day after soaking. 2. The seeds of Pinus densiflora were collected from five trees (ca. 60 years old), and were irradietd with X-rays on the 12th day after soaking. 3. Presoaked seeds of Pinus Thunbergii were irradiated with 100, 200, 300, 400, 600, and 1200r of X-rays, and presoaked seeds of Pinus densiflora 300, 400, 600, 800, 900, 1200, 1600, and 200r of X-rays. 4. Survival rates, LD-50 and height of young seedlings in Pinus Thunbergii and Pinus densiflora on the 220th and 190th day after X-ray irradiation respectively, were considerably different according to the tree which gave the seeds. But the following tendencies could be observed. In Pinus Thunbergii the survival rate seemed to decrease with increasing dosages, and LD-50 seemed to range between 300r and 800r. And also seedling heights were not uniform. 100r and 300r especially seemed to have a tendency to make seedlings higher than the controls. Among the plants with abnormal characters, those with branching main stem were frequently observed. It is not clear whether this is due to dircet effect of X-rays or not. 5. The survival rates of presoaked seeds of Pinus densiflora seemed to decrease with an increase of dosage as in the case of Pinus Thunbergii, and 1500r, 1600r and 2000r completly killed them. And LD-50 seemed to range beetween 300r and 600r. Also, the seedling heights were not uniform. 300r and 400r especially seemed to have a tendency of making seedlings higher than the controls. Among the plants with abnormal characters, those with branching main stem were frequently observed as in the case of Pinus Thunbergii.