Mutagenic Effects Of ⁶⁰CO-γ Ray Irradiation Treatment On The Seed Of Bauhinia Variegate

Bauhinia variegata is a typical species of Lingnan,mainly grows in the south of China.Its flower is colored beautifully,with a long flowering period and rapid growth.It has extensive research and utilization prospects.However,the research on germplasm resources is lagging behind.Employing the method of ⁶⁰Co-γray treatment of Bauhinia variegata,this paper studies on the determination of seed germination,seedling growth,physiological and biochemical indicators and chromosome characteristics,aiming to obtain mutant plants and select new varieties that are suitable for the needs of the garden and steadily hereditary.The research results are as follows:（1）Mark the death rate of contrast as 0%,the research showed the half lethal dose of Bauhinia variegate was about 358 Gy.（2）Irradiation has obvious effect on the morphology,growth and seed germination of the radicle.The greater the radiation dose,the more serious the damage.The 400 Gy（gray）dose irradiation treatments resulted in seed embryo damage and morphological aberration,which showed a decrease in the elongation of the radicle,the morphological thickening,and the obvious inactivation and Browning of the root tip growth point.With the increase of the treatment dose,the germination rate of the seeds gradually decreased,the growth of the radicle was inhibited with the increase of dose.（3）Irradiation has a significant effect on seedling diameter and seedling height growth.200 Gy,300 Gy dose irradiation dosages is conducive to the growth of seedling ground diameter and seedling height,of which 300 Gy maximum ground diameter and seedling height growth,diameter and seedling growth minimum 400 Gy dose,irradiation treatment had dwarf effect.At the same time,the irradiation can change the shape of the blade to a certain extent,which causes the blade to be wrinkled and incomplete.Irradiation has different effects on the fresh weight of the seedlings.（4）Irradiation treatment has obvious effect on chlorophyll,carotenoid,SOD enzyme,soluble protein and MDA in seedling leaves.When processing time 24 hours,all kinds of pigment content reached the maximum;SOD enzyme activity,soluble protein content,MDA content increased with the increase of irradiation dose,are in decline after rising first,200 Gy dose processing SOD enzyme activity,MDA content,the largest 300 Gy dose to handle the soluble protein content of the largest.（5）The daily variation curves of the net photosynthetic rate of each treated leaf showed bimodal.200 Gy dose value maximum net photosynthetic rate(9.54μmol·m^-2·s^-1),400 Gy dose net photosynthetic rate of the minimum value(2.59μmol·m^-2·s^-1),300 Gy dose change of net photosynthetic rate,magnitude and change trend are close to with control group,400 Gy dose of diurnal change of net photosynthetic rate trend is consistent with the control group.200 Gy and 300 Gy dose processed the photosynthetic effect of its leaves.After 400 Gy dose processing,its photosynthesis decreased significantly,and its overall value decreased by 68.02%.At the same time,irradiation treatment influences the stomatal conductance,intercellular CO₂ concentration and transpiration rate,and the higher the radiation dose,the greater the inhibition effect.（6）Irradiation has mutagenic effect on chromosomes.With the increase of irradiation dose,the frequency of chromosome variation in seedlings increased,and the variation patterns and types showed a variety trend.At the same time,the aberration rate of chromosomes increased with the increase of dose.The variation rate of chromosome morphology and quantity of 400 Gy dose was 20.6%.