The Studies On Irradiation Effects Of ⁶⁰Co-? Ray On Zanthoxylum Schinifolium Seedlings

Radiation mutagenesis is one of the effective ways to obtain new germplasm resources,having the advantages of high mutation rate,breaking genetic linkage and short breeding cycle.Zanthoxylumschinifolium is an important perfume tree species and medicinal plants,and has an important scientific and economic value.In order to enrich the germplasm resources and broaden the variation types of Z.schinifolium,and lay a foundation for genetic breeding and improvement of Z.schinifolium,we selected some indices including the seeds germination rate,seedling height,diameter and leaf numbers,physiological and biochemical as well as photosynthetic characteristics of different radiation dose,to explore the effects different radiation dose on growth situation of Z.schinifolium determined⁶⁰Co-gamma irradiation's suitable irradiation dose range of Z.schinifolium.The main research results were as follows:?1?The effects of different irradiation doses on the germination rate of Z.schinifolium were different.With the increase of radiation dose,the number of seeds germinated gradually decreased,and the seed germination rate showed a downward trend as a whole.The highest germination rate was 52.67%and the relative germination rate was 81.24%at the dosage of 25Gy.The semi-lethal dose of gamma rays to Z.schinifolium ranged from50Gy to 100Gy.?2?With the increase of radiation dosage,the seedling height and diameter of Z.schinifolium showed a single peak change trend.The peak value appeared at 25Gy radiation dosage,which was 21.25 cm and 0.24 cm,respectively.Leaf length and width showed a tendency of off-peak variation under different radiation dose gradients,and the peak value was consistent with seedling height,and radiation dose?>25Gy?had a negative effect on leaf morphological growth,and the leaf morphological variation was the greatest when radiation dose was 150Gy.?3?The highest MDA content was found in 100Gy irradiationdose,with a value of17.96,so the damage of plant cell membrane was serious and the degree of plant injury was high.POD and SOD activity were small at low and moderate radiation doses,and with the increase of radiation doses,both increased sharply.But at 200Gy radiation doses,both enzyme activity decreased.?4?The response of chlorophyll a,chlorophyll b and total chlorophyll content to radiation doses were different after irradiation.Chlorophyll a and chlorophyll b content were the highest at 25Gy radiation doses.The contents of chlorophyll a and chlorophyll b were lower than those of the control.The maximum of net photosynthetic rate appeared at12:00 and 25Gy radiation dose,and the diurnal variation of net photosynthetic rate showed a single peak,the peak appeared at about 12:00.In conclusion,radiation dose within a certain range could inhibit seed germination rate,seedling height,ground diameter and leaf morphology of Z.schinifolium.The highest MDA content showed the plant membrane was damaged and the plantdamaged seriously,so the protective enzyme system could stimulate self-protection mechanism,so that Z.schinifolium couldsurvive of adverse conditions,chlorophyll and photosynthetic rate were also affected by the degree of irradiation.The semi-lethal dose of ⁶⁰Co-gamma rays ranged from 50Gy to 100Gy,and the optimum dose ranged from 0Gy to 25Gy.On this foundation,we can consider the specific doseaccording to the actual situation,providing theoretical support for screening superior varieties of Z.schinifolium improving seedling efficiency.