Study On Screening Of High Yielding Medicago Sativa Suitable For Rice Rotation And Its Cadmium Tolerance

Research on 15 Medicago sativa varieties suitable for planting in the south of China were selected in the field experiment from April 2016 to 27,and the experiment was carried out on the acid resistant cadmium germination in the light incubator.In this study,15Medicago sativa varieties were compared from the perspectives of forage yield,nutrient quality and root traits;In addition,the Medicago sativa varieties suitable for ecological restoration in rice field were screened from the aspects of cadmium accumulation,acid tolerance and yield.The main results are as follows:1,The field experiment was conducted to study the difference of the yield of 15Medicago sativa varieties in paddy soil.The results show that visitors rank first of total fresh grass yield with the output of 35830kg/hm²;WL525HQ ranked first with 10820 kg/hm² hay production;WL363 has the worst performance with 18610kg/hm² fresh grass yield and5060kg/hm² yield.The fresh yield performance is on the fourth stubble,the third stubble,the first stubble,and the second stubble,among which the fresh grass yield on the fourth stubble accounts for 31%-65%of the total yield.2,We make the forage quality identification of 15 Medicago sativa varieties harvested in field experiment.The results show that there are 13 Medicago sativa varieties with crude protein content of 19.28-24.52%in the first crop,reaching the highest standard.The other species with crude protein content as 18.91%and 18.73%reached the requirement of grade one.There are 10 species with crude protein content between 19.11-23.87%also reached the requirement of the best one in stubble 2.The other species are on the first grade with crude protein content between 17.29-18.64%,reaching the first grade.All the species in stubble 3reach the beat grade with crude protein content between 20.11-25.96%.3,The entropy-right method is used to evaluate the yield and nutritional quality of fifteen Medicago sativa varieties.The results show that WL525HQ is a good variety of rice planting;Sadie 7,Sadie 10,55v12,Jin 5010,55v48 and 5S43 are good varieties of rice paddies;6010,WL363,WL440,WL656HQ,Gannong No.5,56s82,Le Han and tourists,planting varieties are poor in paddy field.4,The root system of the 15 Medicago sativa varieties are compared and we find that the WL656HQ and Sadi 10 has a percentage of 71.60%and 71.12%respectively on the fresh lateral root to whole fresh root,which is much higher than other species.The species whose percentage is more than 60%are Le Han,WL525HQ,5S43,WL363,visitors.Except Sadi 7 whose percentage is 48.60%,other species all have a percentage of 50%.At the same time,when comparing the Root traits and dry matter yield,it is found that there was significant correlation between them.The heavier the root system is,the more lateral roots it has,and the heavier the lateral root weight is,the higher the dry matter yield has.Medicago sativa planting in the rice fields of root morpHology showed inhibition of root growth,but significantly promoted the growth of lateral roots.5,We make laboratory simulation test of acid cadmium stress with 15 species of Medicago sativa in Germination method.Under the stress of CdCl₂ solution of pH5.5,40mg/L,WL525HQ has the hughest germination rate-50.33%,and 6010 has the lowest germination rate-23%.root growth of Medicago sativa is affected under he stress of cadmium.Compared with the control group,the root length was significantly shorter than the control group,27%-62%shorter than the control group.The surface area,volume,number of root tips and the number of branches decreased significantly,but the mean diameter increased significantly.6,Combined with acid cadmium resistance of different Medicago sativa varieties in the germination experiment and Cadmium accumulation of different Medicago sativa varieties in the field experiments,we can divide them into three types by means of Euclidean distance averaging method.Five acid and cadmium sensitive types are WL525HQ,6010,55v48,Gannong No.five,and Jinneng 5010.2 moderately acid cadmium resistant types are 56S82 and 55v12.8 types of acid tolerant cadmium are Yue Han,5S43,Sadie 10,visitors,WL440,Sadie 7,5S43 and WL656HQ.Planting Gannong No.five,55v48,Sadie 7,Sadie 10,WL525HQ,tourists,Jinneng 5010can significantly accumulate cadmium,suitable for use as ecological restoration plant.Sadie 7,Sadie10,visitors and WL656HQ are suitable for use as ecological restoration plants in heavily cadmium contaminated rice fields.