Seed Germination Characteristics And Seeding Effects Of Several Caragana Species In Xinjiang

Seed germination is a critical stage in the plant life cycle and the key link of plant population regeneration and expansion.Short-term dry storage is one of the factors affecting seed vigour and germination,which determines whether seeds can be used in vegetation restoration.Seed emergence and seedling survival are also important stages of plant life cycle.Caragana Fabr.have several ecological functions of nitrogen fixation,wind protection and sand fixation,soil and water conservation.It is also regarded as a potential candidate species for vegetation restoration.In this study,C.spinosa,C.aurantiaca,C.soongorica,C.tekesiensis,C.roborovskyi,C.polourensis,C.dasyphylla as the research objects,the response of fresh mature seeds and the germination of seeds stored indoors to the second year of spring to changing temperature.And choose the more drought-tolerant C.dasyphylla,C.roborovskyi,C.leucophloea,C.arborescens and C.korshinskii to sow under different site conditions of mining iron ore in Awei irrigation ditch in Qinghe County without irrigation.The main results of the research are as follows:(1)The seeds of C.soongorica and C.tekesiensis were the heaviest,while the seeds of C.spinosa were the lightest.The water absorption of C.aurantiaca seeds were the highest(72.6%),and that of C.roborovskyi seeds were the lowest(9.5%).It showed that the seeds of C.aurantiaca in river wetlands need to absorb more water to start germination,and the seeds of C.roborovskyi in the desert could germinate with less precipitation.(2)The seed germination percentages of fresh and mature seeds of C.tekesiensis,C.roborovskyi and C.polourensis were 13%-73% under four different temperature conditions,and the germination percentages increased to 28%-96% after dry storage in the spring of the second year,indicated that dry storage at room temperature could break the physical dormancy of some seeds and thus improve the germination percentages of seeds.The seeds of C.soongorica,C.tekesiensis,C.roborovskyi and C.polourensis after dry storage had higher germination percentage(39%-96%)at high temperature(25/15? and 30/15?),but lower germination percentage(10%-66%)at low temperature(15/5? and 20/10?).These results indicated that the seeds of the four species of Caragana germinated better and could be sown in summer.After dry storage,the seeds of C.spinosa,C.aurantiaca and C.dasyphylla could germinate in spring,summer and autumn.The germination percentages of the fresh mature seeds and dry stored seeds of C.spinosa,C.aurantiaca and C.dasyphylla were 74% to 100% under four temperature conditions,which indicated that the seeds of the three species could germinate in spring,summer and autumn,and could be sown in any season of the growing season.(3)On the abandoned mining areas of sand ore without irrigation conditions,on the flat ground,C.roborovskyi showed the highest seed emergence percentage(44.7%)in spring.On the sunny slope,the emergence percentage of C.arborescens was 50.7%.It showed that when the temperature rises in spring,C.roborovskyi and C.arborescens could use the snowmelt water in spring to emerge.C.roborovskyi and C.leucophloea showed that higher seedling rate(90.3%-92.6%)on the flat ground,and C.korshinskii,C.roborovskyi,C.arborescens showed the highest seedling survival rate(95.8%-100%)on sunny slope.It indicated that the seedlings of these four species of Caragana were drought-tolerant and could survive the summer high temperature and drought.