Effects Of Different Cultivation Measures On Yield And Quality Of Forage Rape In Coastal Saline Soil

Rape（Brassica napus L.）is the second largest oil crop in the world.In recent years,it has been used as fresh grass feed to alleviate the shortage of forage for livestock in winter and spring.The area of salt and alkali land in Tianjin is large and groundwater exploitation is limited,which seriously restricts the development of planting industry.The existing researches on saline-alkali resistance of rape mainly focus on molecular technology and breed new variety,but there are few researches on cultivation measures to regulate the yield formation and quality of rape in saline-alkali land.In order to provide theoretical basis and technical support for high-yield,high-efficiency and high-quality rape cultivation in coastal saline-alkali land,this study explored the regulatory effects of variety,sowing date,N/K interaction and ridge and brackish water irrigation with brassica napus on overwintering and salt stress resistance,fresh grass yield,forage quality and fertilizer utilization.The main results are as follows:1.Compared with Brassica napus L.,the growth period of Brassica campestris L.was shortened,the overwintering rate was increased and the density was increased.The fresh forage yield（FFY）and dry forage yield（DFY）of Brassica napus L.were significantly higher than those of Brassica campestris L.but the forage quality of Brassica napus L.was significantly better than that of Brassica napus L.Photothermal resources increased the overwintering rate and density of rape before overwintering,which was positively correlated with FFY and DFY.However,the lower the overwintering temperature was,the lower the overwintering rate of rape was,and the photothermal resources were negatively correlated with FFY and DFY during overwintering and after regreening.Crude protein,fat and total fatty acid were negatively correlated with temperature before overwintering and sunshine duration,but positively correlated with temperature during overwintering and after regreening,sunshine duration and rainfall during overwintering.Milk productivity was significantly positively correlated with temperature,sunshine duration and rainfall during overwintering period,while relative feeding value and relative forage quality were significantly positively correlated with maximum temperature and rainfall.2.With the delay of sowing date,the average daily temperature and effective accumulated temperature during the growth period of rape were increased,the growth period of rape before flowering was shortened,but the growth period after flowering was prolonged,and the total growth period was shortened.The fresh forage yield of rape decreased with the delay of sowing date,and the yield was more than 35×10~3kg hm^-2before March 28.The fresh forage yield of Huayouza 62 was significantly higher than that of other cultivars.The forage yield and quality of fresh rape were significantly negatively correlated with fiber content,and the neutral detergent fiber content was significantly negatively correlated with effective accumulated temperature at seedling stage,and significantly positively correlated with vegetative growth and effective accumulated temperature after flowering.3.The annual fresh forage yield and dry forage yield of rape were significantly increased by N application rate,K application rate and seasonal interaction with N fertilizer.With the increase of N application rate,Nitrogen Partial Factor Productivity（PFPN）and Agronomic Use Efficiency of Nitrogen（ANUE）decreased,but Potassium Partial Factor Productivity（PFPP）and Agronomic Use Efficiency of Potassium（APUE）increased.Increased K fertilizer application increased PFPN and APUE,but decreased ANUE and PFPP.The PFPN,ANUE,PFPP and APUE were significantly increased by N/K interaction.The contents of crude protein（CP）and starch increased,while the contents of water-soluble carbohydrate（WSC）decreased.Under K fertilizer treatment,starch content decreased while WSC increased.CP,acid detergent fiber,neutral detergent fiber,total digestible nutrient,starch content and milk productivity were significantly increased under N/K interaction treatment.4.Ridge culture treatment reduced soil p H（p>0.05）at the flowering end stage,1～2 g L^-1brackish water irrigation treatment significantly reduced the total soluble salt content by7.6%～45.2%at the flowering end stage.Irrigation water salinity and cultivation mode significantly affected the forage yield（FFY）,root biomass,taproots diameter and root number,and the interaction between irrigation water salinity and cultivation mode also significantly affected FFY and root number.FFY and root traits of brassica napus L.were significantly increased by 1～2 g L^-1brackish water irrigation treatment and these interaction effect.Compared with flat culture（CK）,ridge culture（RW40）treatment increased FFY,root biomass and root shoot ratio,and decreased taproot length,taproot diameter and root number.With the increase of salinity of irrigation water,crude protein and starch contents of 4 g L^-1treatment were significantly increased by 9.7%～21.3%and 25.3%～105.0%compared with others,and fiber content of 1 g L^-1treatment was higher than other treatments.In conclusion,the results of this study showed that the fresh forage yield of Brassica napus L.Huayouza 62 could be significantly increased by apply 225 kg hm^-2N and 90～135kg hm^-2K in spring sowing period from March 8 to March 18,adopting ridge culture and 1～2g L^-1irrigation water treatment.To improve forage quality and realize high efficiency,high yield and high quality of rape in North China Plain.