Effects Of Different Planting Patterns On Growth And Annual Yield Of Rice And Oilseed Rape In Rice-oilseed Rape Rotation System

Rice-oilseed rape rotation system is the main rotation system of the Yangtze River,and it is an important measure to ensure the safety of food and oil in China.Compared with the traditional transplanted rice-transplanted oilseed rape rotation planting pattern（TTR-TPO）,direct seeded rice-oilseed rape rotation planting pattern is a lighter and simplified rotation cultivation mode,which has the advantages of ensuring yield,saving labor and water.However,there is a lack of systematic research on the comparison between different direct-seeded rice-oilseed rape rotation systems and TTR-TPO.Therefore,six different rice-oilseed rape rotation planting patterns were set up in this experiment,which including dry direct seeded rice-direct seeded oilseed rape rotation planting pattern（DDSR-DSO）,wet direct seeded rice-direct seeded oilseed rape rotation planting pattern（WDSR-DSO）,traditional transplanted rice-direct seeded oilseed rape rotation planting pattern（TTR-DSO）,dry direct seeded rice-transplanted oilseed rape rotation planting pattern（DDSR-TPO）,wet direct seeded rice-transplanted oilseed rape rotation planting pattern（WDSR-TPO）and TTR-TPO.Therefore,the objectives of the current study were:to compare the differences in yield,resource utilization efficiency of rice,oilseed rape and annual between different planting pattern of rice-oilseed rape rotation system,and to discover the high-efficiency cultivation techniques of rice and oilseed rape in rice-oilseed rape rotation planting patterns and to provides theoretical support for rice-oilseed rape rotation production in the middle and lower reaches of the Yangtze River,and then to better guide the production of rice and oilseed rape.Firstly,the yield of WDSR was the highest,and which was significantly higher than that of TTR and DDSR,mainly resulted from WDSR had higher total spikelet per unit area,but there was no significant difference in rice yield between TTR and DDSR.Secondly,the oilseed rape yield of DDSR-DSO was the highest,which was 3.70 and 3.42 t ha^-1 in 2019and 2020,respectively,which was significantly higher than that of WDSR-DSO and TTR-DSO.However,there was no significant difference in the oilseed rape yield between DDSR-TPO,WDSR-TPO and TTR-TPO.Thirdly,the annual yield of WDSR-DSO and WDSR-TPO was the highest,and which was significantly higher than that of TTR-TPO and TTR-DSO,but there was no significant difference in the annual yield compared with DDSR-DSO and DDSR-TPO.Fourthly,the total water consumption in rice-oilseed rape rotation system was indicated that WDSR-DSO and WDSR-TPO>TTR-DSO and TTR-TPO>DDSR-DSO and DDSR-TPO,which was mainly caused by the difference of irrigation times,irrigation amount and the amount of water consumption during the process of soil preparation of different rotation systems in rice season,and the performance was consistent in two years.Fifth,the water use efficiency（WUE）of DDSR-DSO and DDSR-TPO were significantly higher than those of other rotation systems,while WUE of WDSR-DSO,WDSR-TPO and TTR-DSO were lower than TTR-TPO,and the performance were consistent in two years.Among them,the WUE of DDSR in rice growth season was significantly higher than that of WDSR and TTR,and which was 51.9%and 45.9%higher than that of TTR and WDSR,respectively.However,there was no significant difference between WDSR and TTR.The WUE of DDSR-DSO in oilseed rape growth season was significantly higher than that of WDSR-DSO and TTR-DSO,but there was no significant difference in WUE among DDSR-TPO,WDSR-TPO and TTR-TPO.Finally,the economic benefits of DDSR-DSO was the highest,followed by DDSR-TPO,WDSR-DSO and WDSR-TPO,while TTR-TPO and TTR-DSO were the lowest.Among them,the economic benefits of DDSR-DSO and DDSR-TPO were significantly higher than that of TTR-TPO,and which were increased by 15.2 and 8.7%as compared with TTR-TPO,respectively.The reason for the high economic benefits of DDSR-DSO and DDSR-TPO was related to the low input of labor and irrigation.Here we show that DDSR-DSO is an alternative to TTR-TPO in central China due to higher WUE and net economic return,less water consumption and similar annual yield,which is a high-yield and high-efficiency rice-oilseed rape rotation planting patterns that suitable for planting in those regions of drought,water shortage and less rainfall.In addition,compared with TTR-TPO,WDSR-DSO and WDSR-TPO had higher annual yield and economic benefits,but their water consumption was large during the whole growth stage.Therefore,WDSR-DSO and WDSR-TPO may be suitable for regions where water levels are high for soil puddling during land preparation and rainfall is sufficient in the rice growth season.