Study On The Characteristics Of Seed Germination And Seedling Growth Of Jacaranda Mimosifolia

Seed germination is the premise of seedling growth, and seedling growth is critical and important period in the life cycle of plants. Seed germination is not only determined by the genetic characteristics and environmental factors, but also has relationship with the endogenous inhibitor of seeds and plant hormones. The growth and characteristics of aboveground and underground part of plant related to the quantity and quality of seedlings production. To understand the characteristics of seed germination and improve seeds germination and seedlings growth has an important practical significance to production of nursery stock and application of garden plants. However, the seed germination rate of Jacaranda mimosifolia was too low, which lead the shortage of seedlings resources. But there were strong demand for its landscaping and application. Hence, it is particularly important to research the characteristics of seeds germination and seedlings growth of Jacaranda mimosifolia.This study took the seeds and seedlings of Jacaranda mimosifolia as experimental materials. Through the experiment of seed germination and seedling growth of Jacaranda mimosifolia in aim to improve the seed germination rate and growth increment, and systematic studied the characteristics of seed germination and seedling growth of Jacaranda mimosifolia, including the relationship between seed germination with temperature and light, the influence of exogenous hormones on seeds germination and the dynamic situation of seedling growth in two years. What’s more, it discussed and analyzed the activity of seed endogenous inhibitor and its relationship with seed germination. The preliminary results are as follows:1. The seed morphological characteristics of Jacaranda mimosifoliaThe fruits of Jacaranda mimosifolia were hard wood and flat in broadly ovoid capsule. The shell was smooth with6～7cm long,4～5cm wide and1.5～2cm thick. Every fruit contained about50～80seeds. The seed covered with membranous transparent wings was flat-heart or subcordate, which had brown color. It was5.7～6.4mm long,4.8～5.5mm wide. The fruits of Jacaranda mimosifolia began to appear after flowering with green color in outside, and the immature seeds also appeared light green. In the next year of February, the color of fruit and seed gradually became brown, and gradually crack in March. The seed thousand seed weight was9.039g, seed vitality was32.7%on average.2. The seed germination characteristics of Jacaranda mimosifoliaSeeds germination of Jacaranda mimosifolia showed the optimum temperature was25℃. Germination temperature range was15-35℃. In the range of temperature, with the increasing of temperature, the germination rate increased first but decreased subsequently. Light culture could promote seed germination. Especially in low temperature environment, it could significantly improve seed germination. However, under the condition of the20-35℃, there was no significantly difference between light culture or not on seeds germination. Temperature and illumination treatment had no significant interaction effect on seed germination. The main effect of seed germination was temperature, but Light culture could promote seed germination.It showed that the seed germination rate and potential significant improved with IAA or NAA treatment and promoted more obviously with the increase of the concentration. Germination of IAA treatment were not concentrated and appeared three germination peak. The germination peak of NAA treatment appeared on day8-9achieved5-8seeds, and showed higher germination consistency. However, in the same concentration conditions, IAA showed more significant promotion on seed germination. There was significant difference between100,200mg·L-1and other IAA treatment, but only200mg·L-1NAA treatment had significant difference among others.3. The activity of seed extracts endogenous inhibitor of Jacaranda mimosifoliaIn the seed coat and seed embryo of Jacaranda mimosifolia, there contained many endogenous inhibitory substances, which significantly inhibited the seed germination and the radicle and hypocotyl growth of seedling of Brassica pekinensis. Inhibition was enhanced with the increase of the concentration of the extracts. Test showed that the inhibitory effect of extracts from seed coat was stronger than that of extracts from embryo. It indicated that the seed coat contains more endogenous inhibitory substances than that of embryo. However, extracts of seed coat in0.10g/mL promoted the growth of radicle. The reason maybe the seed coat of Jacaranda mimosifolia contained some substances that could promote the growth of radicle.The study also showed that the seed coat tissues contained some substances which could affect the SOD, POD, CAT activity of cabbage seedlings. With the increasing concentrations of the seed coat extracts, the POD and SOD activity of Cabbage showed increase first and decrease after. The CAT activity decreased with the increasing concentrations of the seed coat extracts. Low extracts concentration of seed coat could activate SOD and POD of cabbage seedlings, and high extracts concentrations could cause POD activity decreased rapidly, but had little impact on SOD.4. The seedling growth characteristics of Jacaranda mimosifoliaThe seedling growth characteristics of aboveground and underground part of Jacaranda mimosifolia showed that, in the first year of growth, the height of aboveground part was significant less than the length of underground part. But after two years growth, the height of aboveground part was significant higher than that of underground part. This indicated that, in the early growth of seedling, the growth of underground part came first, after that the height of aboveground rapidly grew.From the different culture substrate conditions we could conclude that, in the first year of growth, the growth length of humus was significantly different than the length of garden soil and mixed soil, but there were no significant difference between them. After two years growth, the growth length of garden soil was significant difference between humus and soil mixtures, but there were not significant on humus and mixed soil.View from the biomass of two years growth, the biomass of seedlings cultivated by garden soil was most, humus came to second and the mixed soil was the less one, and there were significant differences among them. Taking the biomass distribution of different parts to see, the accumulation of aboveground biomass was greater than the underground part and were significant difference. The root-shoot ratio of humus was the largest one, followed by the mixed soil and garden soil. In summary, the low seed germination rate of Jacaranda mimosifolia had relevant with seed vigor and endogenous inhibitor. The optimum temperature for Seeds germination was25℃, and temperature range was between15℃and35℃. Light culture could promote seed germination. IAA or NAA treatment could significant improve the seed germination rate and potential. The seed coat and seed embryo contained many endogenous inhibitory substances, and the seed coat contained more endogenous inhibitory substances than that of embryo. What’s more, the seed coat tissues contained some substances which could affect the SOD, POD, CAT activity of cabbage seedlings. The characteristics of seedling growth showed the underground grew fast in the first year and the aboveground grew fast in the second year, and the growth of aboveground was greater than that of underground part. However, this experiment did a preliminary study on the characteristics of seed germination and seedling growth. The substance change in seed germination process, physiological changes under the influence of the environment and the specific relationship between dynamic changes of seedlings growth and the nutrients are need further study.