Effects Of Melatonin Seed Soaking Combined With Stalk Rot Agent Application On Rapeseed Growth,and Yield Under Rice Straw Returning

In order to achieve high and stable yield of rapeseed,the technology of improving the quality of rapeseed emergence and cultivating strong seedling was explored under the rice straw returning condition.In this paper,the effects of melatonin(MT)seed soaking and straw rot agent application on the emergence quality,seedling growth and development,seedling physiological characteristics and yield components of Brassica napus cultivar "Fengyou 737" were studied.The main results are as followings:(1)The rapeseed seed germination were not affected by seeds soaked with Low concentration(50 μmol/L)and high concentration(400 μmol/L)MT.Compared with control condition,the germination potential,germination rate and germination index of rapeseed seeds soaked with 100 μmol/L MT,were significantly increased by 13.4%,19.4%and 2.0%,respectively.In addition,the root development,SOD and CAT enzyme activities under low temperature and drought conditions of rapeseed seeds soaked with 100μmol/L MT,were also significantly enhanced.Thus the tolerance of rapeseed to low temperature and drought were significantly enhanced by 100 μmol/L MT soaking at germination stage,Therefore,the concentration of melatonin was used for seed soaking in the field test.(2)Under field conditions,the seedling rate of rapeseed was significantly reduced by 17%under rice straw returning condition.While under rice straw returning condition,the emergence rate of rapeseed was significantly increased by 7% after seed soaking with 100μmol/L MT compared with the control.The plant height,the root neck thickness the biomass accumulation of rapeseed were also significantly increased after100 μmol/L MT soaking at seedling stage.At mature atage,number of pod per plant and yield were significantly increased by 7.6% and 8.8% for rapeseed soaked with 100 μmol/L MT compared with control.(3)The soil bulk density was significantly reduced,the soil porosity was significantly increased after application the straw rot agent,under rice straw returning condition.After MT seed soaking combined with stalk rot agent application,The plant height and leaf area of rapeseed were significantly increased by 41.2%,64.2% and 31.7%,8.2% at seedling stage and overwintering stage,respectively.At the same time,the treatment of MT soaking seeds combined with straw rot agent application also significantly improved the photosynthetic efficiency.Compared with the control condition,The shoots and roots biomass of this treatment was significantly increased by 120.5% and 114.3%,respectively.In summary,application of straw rot agent can improve soil structure under rice straw returning condition.MT soaking seeds combined with straw rot agent application can effectively increase the emergence rate,seedlings quality,root development and leaf photosynthetic efficiency,which play important roles in high yield of rapeseed.