60Co-γ射线辐照对茉莉花种子萌发和幼苗生长及生理的影响

以6种不同剂量（0、20、40、60、80、100 Gy）的⁶⁰Co-γ射线辐照处理茉莉花Jasminum sambac (L.) Ait]果实,观测其对茉莉花种子萌发、幼苗生长及生理的影响。结果表明：（1）低剂量（20~40 Gy）⁶⁰Co-γ射线辐照加快茉莉花种子萌发;高剂量（60~100Gy）辐照推迟萌发,并极显著降低茉莉花种子生根率、根长及成苗率;随着辐照剂量的增加,幼苗株高先增后降,不同处理间差异显著,茎粗有降低的趋势,但除80Gy剂量处理外,其他处理与对照差异不显著。（2）随着辐照剂量的增加,幼苗叶片中超氧化物歧化酶（SOD）活性先升后降,过氧化氢酶（CAT）活性极显著降低（P<0.01）,过氧化物酶（POD）活性先降后升,丙二醛（MDA）含量出现波动,对照的含量与所有辐照处理均无显著差异。（3）茉莉花种子幼苗叶片内叶绿素a、叶绿素b、叶绿素a+b均随着辐照剂量的增加呈先降低后上升趋势,不同处理间差异极显著。（4）横县双瓣茉莉花种子的⁶⁰Co-γ射线辐照半致死剂量（LD₅₀）为73.51 Gy,临界剂量（LD₄₀）为81.71 Gy。综上,低剂量率（1.0 Gy/min）条件下,⁶⁰Co-γ射线辐照诱变茉莉花果实的适宜辐照剂量为73.51~81.71 Gy。

Effect of 60Co-γ Irradiation on Seed Germination and Seedling Growth and Physiology in Jasmine [Jasminum sambac (L.) Ait]

To identify the effects of ⁶⁰Co-γ irradiation in jasmine Jasminum sambac (L.) Ait] and determine suitable radiation dose for jasmine seed mutation, the mature berries of J. sambac were irradiated at a different dose of gamma rays viz., 0, 20, 40, 60, 80 and 100 Gray (Gy), which dose rate is 1.0 Gy/min. The peel and pulp of the mature berries were removed to obtain dark brown seeds, and then the seeds were sown, the sowing substrate was peat soil, and the sowing depth was 0.5-1.0 cm.The changes of seed germination, seedling growth and physiology of the seed from the berries were analyzed. Low dose (20-40 Gy)⁶⁰Co- γ irradiation accelerated the seed germination (11.8-15.3 d), high dose (60-100 Gy) irradiation delayed seed germination (23.3-32.8 d), and CK was13.8 d. High dose (60-100 Gy) irradiation also significantly reduced the rooting rate, root length and seedling rate of jasmine seeds. With the increase of irradiation dose, the height of seedlings increased firstly and then decreased, and the difference was significant among different treatments. The height of seedlings was the highest at 60 Gy. The stem diameter decreased, but there was no significant difference between other treatments and the control except 80 Gy. With the increase of ⁶⁰Co- γ irradiation dose, the activity of superoxide dismutase (SOD) increased firstly and then decreased, and reached the highest at 60 Gy. The activity of catalase (CAT) decreased significantly (P<0.01), the activity of peroxidase (POD) decreased firstly and then increased, and reached the lowest at 80 Gy. The content of malondialdehyde (MDA) in seedling leaves fluctuated, and there was no significant difference between the control and all irradiation treatments. chlorophyll a, chlorophyll b and chlorophyll a+b in the leaves of jasmine decreased at first and then increased with the increase of irradiation dose, and the differences among different treatments were extremely significant, both chlorophyll b and chlorophyll a+b were the highest at 80 Gy and chlorophyll a was the highest at 100 Gy. The radiation damage effect of seeds was determined by relative seedling rate, and the optimal radiation dose range was between half lethal dose (LD₅₀) and critical dose (LD₄₀). In this paper, the half lethal dose (LD₅₀) and critical dose (LD₄₀) of ⁶⁰Co- γ irradiation was 73.51 Gy and 81.71 Gy, respectively. Thus, when the dose rate is 1.0 Gy / min, the suitable radiation dose range for jasmine seed mutation is 73.51-81.71 Gy.