| The current important issue in the field of sustainable agricultural development is how to adjust crop planting systems through agronomic measures,improve water resource utilization efficiency and annual productivity,and adapt to climate change.This study is based on plastic film mulching,through exploring the optimal combination of winter wheat sowing dates and summer maize varieties to improve the annual productivity of the "winter wheat-summer maize" rotation system and adapting to climate change.In 2017-2019,this study carried out field trials of optimized sowing dates for winter wheat and preferred varieties of summer maize under mulching conditions at the Irrigation Experimental Station of Northwest A&F University,Yangling,Shaanxi.In the experiment,6 treatments were set respectively.In the mulching(PM)and bare land(CK)planting modes,the winter wheat variety "Xiaoyan 22" was selected and three sowing dates were set,namely the traditional sowing date(0)and the late sowing 10 Day(10),late sowing 20 days(20);in the summer maize growing season,three varieties were selected,namely Zhengdan 958(ZD),Huanong138(HN),and Dr.He 122(HBS).This study researched on the soil water and heat,root growth,yield and other aspects of the two crops.The main results are as follows:1.Effects of film mulching on soil water heat and plant growth in root zone of winter wheat at different late sowing dates(1)The average soil moisture content of 0-100 cm of 2 years before the greening period of PM0,PM10 and PM20 treatments was 5.16%,8.13% and 13.94% higher than the corresponding bare land treatments,respectively.The effect of mulching on the temperature of winter wheat in the three sowing dates is mainly manifested before the overwintering period and it is most obvious in the 30-42 d after sowing.Under the mulching measures of winter wheat,the three sowing date treatments had a cooling effect after the greening period,and the cooling effect had a certain lag with the sowing date and soil layer.(2)The mulching measures promoted the growth of the root system of winter wheat.The root parameters and above-ground biomass of PM0 treatment were both the largest in different growth period.Film mulching has a certain acceleration effect on the root growth of late sowing winter wheat,so that the RLD,RSD and root biomass of PM10 and PM20 treatments were higher than those of CK0 treatment during the greening and flowering stages,respectively.2.Effects of plastic film mulching on soil water heat and plant growth in root zone of summer maize of different varieties(1)Film mulching treatment significantly increased the 0-100 cm soil water storage of summer maize in the early growth period.Improved the water consumption law of maize throughout the growth period.The warming effect of plastic film mulching on soil temperature was mainly reflected in the early growth stage,with the largest increase at the depth of 5 cm.(2)Compared with different varieties,the root and shoot growth of Zhengdan 958 and Huannong 138 was significantly better than Dr.He122,and the root and shoot growth of Zheng Dan 958 had the best adaptation effects to plastic mulching.Plastic film mulching significantly improved the root growth of Zheng Dan 958 and Huanong 138 before the flowering period,and promoted the absorption and utilization of soil moisture and nutrients by the roots.3.Effects of film mulching on yield and WUE of winter wheat with different late sowing dates and summer maize with different varieties(1)Film mulching measures significantly improved the yield and water use efficiency of winter wheat.Compared with CK0 treatment,the yields of PM0 and PM10 treatment for2 years were increased by 28.92% and 14.35%,and water use efficiency was increased by17.87% and 7.90%,respectively.The root parameters of winter wheat in the greening period were significantly positively correlated with yield and water use efficiency(P<0.01).(2)The grain yields of ZDPM,HNPM and HBSPM treatments were 9.78%,5.67% and3.19% higher than the corresponding bare soil treatments for 2 years,and WUE was 7.37%,6.51% and 4.71% higher,respectively.Among them,film mulching had the most significant effect on Zhengdan 958,and its grain yield and WUE after film mulching were higher than those of the other two varieties.(3)The yield and water use efficiency of the PM0+ZDPM and PM0+HNPM combinations were significantly higher than those of the other combinations.Compared with the CK0+ZDCK combination,the PM0+ZDPM and PM0+HNPM combinations increased production by 18.48% and 16.86%,improved water use efficiency by 19.38% and 7.57%,and reduced water consumption by 18.23 mm and 12.06 mm,respectively.Among them,PM0+ZDPM combination had the highest yield and water use efficiency.In summary,in order to improve the annual productivity of the "winter wheat-summer maize" rotation system in the Loess Plateau and adapting to climate change,it is recommended to choose“PM0+ZDPM”combination treatment,that is to say,to plant the winter wheat around October 10 and summer maize “Zhengdan 958" under the film mulching to increase the annual yield of "winter wheat-summer maize" rotation system.It can also effectively reduce annual water consumption and improve crop water use efficiency. |
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