Effects Of Planting Pattern With Delayed Irrigation At Jointing Stage On Winter Wheat Growth And Development And Water Use Efficiency

Shandong province is one of the most important agricultural areas in China,and it is the main planting area of winter wheat.The water consumption in the winter wheat growing season is about 300-450 mm,while the precipitation is only 110-180 mm in the winter wheat growing season,which is far from enough to meet the needs of the winter wheat growing season.Without affecting the yield,reducing irrigation water and improving water use efficiency are becoming more and more important for sustainable agricultural development.Therefore,taking winter wheat as the research object,experiments were conducted at the Experiment Station of Shandong Agricultural University during the 2017-2018 and 2018-2019 winter wheat growing seasons.A split-plot design was adopted in this test.The main plots represented the two planting patterns,wide-precision planting pattern(W,sowing and row spacing were 4.8 and 28.0 cm,respectively)and conventional planting pattern(C,sowing and row spacing were 2.2 and 20.0 cm,respectively);the subplots differed in their irrigation treatments,the two irrigation regimes were 60 mm irrigation at the jointing stage(I1)and 60 mm irrigation delayed 10 d at the jointing stage(I2).During the growing seasons,the soil water content of winter wheat,photosynthetically active radiation,chlorophyll content,chlorophyll fluorescence characteristics,leaf water status,leaf enzyme activity,the number of winter wheat population,the accumulation of dry matter above ground and yield were measured.To explore the effects of different planting patterns combined with delayed 10 d irrigation at the jointing stage on water consumption characteristics,growth and development,and water use efficiency of winter wheat.Research indicates:(1)Before irrigation at jointing stage,the soil water content in the 0-20 cm soil layer treated with wide-precision planting pattern was higher than that in the conventional planting pattern.After irrigation at jointing stage,delayed irrigation treatment did not increase deep soil moisture.During the filling stage,the soil water content of the delayed irrigation treatment at the jointing stage was higher than that of the normal irrigation treatment at the jointing stage,indicating that the irrigation delayed 10 d at the jointing stage increased the soil moisture in the later stages of winter wheat growth and was beneficial to the growth and development of winter wheat.The combination of delayed irrigation at jointing stage and wide-precision planting pattern reduced the soil water consumption of winter wheat from jointing to heading stage,reduced ineffective evaporation of soil moisture,and increased soil water consumption from grain filling to maturity.It is conducive to organic matter accumulation and grain maturity.Under the premise of not changing the irrigation amount,combining the wide-precision planting pattern and delayed 10 d irrigation at the jointing stage can reduce the total water consumption during the winter wheat growing seasons,thereby achieving water-saving effects.(2)The combination of the wide-precision planting pattern and delayed 10 d irrigation at the jointing stage increased the PAR capture rate,chlorophyll content of flag leaves and improved chlorophyll fluorescence characteristics.The wide-precision planting pattern can significantly increase the number of single stems of winter wheat compared with the conventional planting pattern,which is conducive to increasing the number of spikes.Delaying irrigation at the jointing stage caused water stress on the winter wheat at the jointing stage,accelerating tiller polarization of the winter wheat,and reducing tillering and extinction in the later growing stage.The combination of the wide-precision planting pattern and delayed 10 d irrigation at the jointing stage significantly increased the contribution of dry matter accumulation during winter grain filling and dry matter accumulation after flowering to grain yield,which was conducive to improving grain yield.(3)The wide-precision planting pattern can significantly increase the number of spikes of winter wheat.Under this condition,delayed 10 d irrigation at the jointing stage significantly increased kernel numbers per spike of winter wheat.The spikes and kernel numbers per spike of the combination of wide-precision planting pattern and delayed 10 d irrigation at the jointing stage was significantly higher than other treatments,and the maximum yield was obtained.During the two-year winter wheat growing seasons,the water use efficiency of the combination of the wide-precision planting pattern and the delayed 10 d irrigation at the jointing stage was significantly improved,thereby achieving the goal of water-saving and stable production.In summary,delaying irrigation at the jointing stage can increase the yield and water use efficiency of wide-precision sowing wheat fields.Our research provides theoretical basis and technical support for determining reasonable irrigation regimes and planting patterns for winter wheat in Shandong province.