Compensation Effects Of Winter Wheat Yield Loss And Water Use Efficiency Under Zero-tillage

Zero tillage as one of the conservation tillage,can mitigate greenhouse gases emission,preserve soil water and improve regional ecological environment.But zero tillage affected grain yield due to the reduction of seeding emergence and stem number.This study(begin from 2015,pond cultivate)was conducted at the Experimental Station of Shandong Agricultural University to resolve the reduction of winter wheat yield and water use efficiency(WUE)due to long-term no tillage in the North China Plain.To investigate the regulation mechanism of yield loss compensation and water use efficiency under no-tillage on winter wheat by genotypes,delayed10 days irrigation at the jointing stage and wide-precision planting pattern.To test whether it can better solve the contradiction between water saving and high yield,and then form a TillagePlant-Irrigation model,and provide a theoretical basis for water saving agriculture in the North China Plain.In this study,two tillage methods(no tillage,ZT;conventional tillage,CT)combined with two winter wheat genotypes(Tainong-18,TN18;Jimai-22,JM22),two planting patterns(wide-precision planting,W;conventional planting,G),two irrigation patterns(irrigation at jointing stage,I1;delayed 10 d irrigation at jointing stage,I2,the planting pattern is W),respectively.To investigate the regulation mechanism of yield loss compensation and water use efficiency under no-tillage on winter wheat by soil physical and chemical properties,water consumption,tiller number,dry matter accumulation.And to simulate the soil moisture content(SMC),the actual evaporation(AE),the actual transpiration(AT)and the actual evapotranspiration(AET)under two tillage methods(no tillage,ZT;conventional tillage,CT)and two irrigation patterns(irrigation at jointing stage,I1;delayed 10 d irrigation at jointing stage,I2,the planting pattern is G)by Root Zone Water Quality Model 2(RZWQM2).The main results are as follows:1.Effect of no tillage on grain yield and WUE of winter wheat.Regardless of genotypes,planting patterns and irrigation patterns,compared with CT treatment,ZT increased soil organic carbon(SOC)during whole growing season,increased mean weight diameter(MWD)at 0–20 cm soil layer,increased macro aggregate at 10–30 cm,increased soil moisture content(SMC),decreased soil moisture consumption before sowing(SMCBS)and evapotranspiration(ET),simultaneously,ZT limited the growth and development of winter wheat by increasing bulk density at 0–30 cm,decreased tiller number and dry matter accumulation,reduced the dry matter transfer after anthesis,spike numbers and kernel number per spike,resulted in a yield loss and reduced WUE.2.Compensation effect of Tainong-18 on yield loss and water use efficiency under no-tillageTN18 increased water consumption at shallow soil layer(0–20 cm),decreased water consumption at 30–110 cm and ET.TN18 increased aggregate stability by altered soil physical and chemical properties.Compared to JM22,TN18 decreased bulk density and geometric mean diameter(GMD)at 0–10 cm,increased macro aggregate,MWD and SOC at 0–20 cm.TN18 increased the dominant bacteria which was decreased under ZT at 0–10 cm and increased OTUs,species abundance(Chao and Ace index).Compared to JM22,Shannoneven and Shannon was increased and Simpson was decreased at 0–10 cm.TN18 had higher community distribution evenness and improved the community diversity.TN18 increased the dry matter transfer to grain after anthesis and increased grain yield by increasing spike number and kernel number per spike under ZT.TN18 had a compensation effect on yield loss and improve WUE.3.Compensation effect of delayed 10 d irrigation at the jointing stage on yield loss and water use efficiency under no-tillage.I2 increased spike number and improved grain yield(3.06% and 9.91% in the two growing seasons,respectively).Compared to I1,I2 significant decreased tillering die from jointing to heading stage and increased dry matter accumulation.I2 increased the dry matter transfer to grain after anthesis,and provided fundamental guarantee for yield loss compensation under ZT.Compared to CT,ZT increased SMC at 80–120 cm.Compared to I1,I2 decreased SMC at 80–120 cm(heading,milking and mature stage).I2 can absorb moisture SMC at deep layer.Compared to I1,I2 increased soil moisture consumption at 10–110 cm,ET and WUE.Compared to I1,I2 decreased bulk density and GMD at 10–20 cm,increased macro aggregate and MWD at 10–20 cm,and improved SOC(4.72%–5.99%)from anthesis to mature stage.I2 and decreased soil compaction,increased aggregate stability,and provided the environment for crop growth.4.Compensation effect of wide–precision planting pattern on yield loss and water use efficiency under no-tillage.W decreased soil bulk density,macro aggregate and MWD,but increased microaggregate,GMD and SOC.W increased relative abundance of dominant bacteria at 0–20 cm.Compared to G,Shannoneven was increased under W at 0–10 cm.W had higher community distribution evenness.In the end,W increased tiller number and increased dry matter transfer to grain yield after anthesis by increasing dry matter accumulation.W decreased water consumption at 30–90 cm and ET,obtained higher yield by increasing spike number and kernel number per spike,and improved WUE.It had compensatory effect on yield loss under ZT.5.Effect of tillage methods and irrigation pattern on winter wheat yield and water use efficiency based on RZWQM2.In this study,soil moisture data were used to calibrate the parameters of the model under CTI1.Root mean squared error(RMSE)was 2.85 cm,normalized root mean square error(NRMSE)was 9.24%,mean relative error(MRE)was 6.87,and coefficient of determination(R2)was 0.78.Compared to other layers,the simulation effect of SMC was better at 30-90 cm soil layer.Compared to CT,ZT decreased AE from sowing to mature stage.And AE/AET was lower in ZT than in CT.The results showed that ZT reduced ET mainly by decreasing actual evaporation.I2 increased measured yield and measured WUE,but I2 decreased simulated yield and simulated WUE by RZWQM2.RZWQM2 had some limitations in simulating the effects of mild water stress on crop growth at jointing stage.In conclusion,the inhibition effect was increased on grain yield and WUE under ZT with the increase of planting years.TN18 and W treatments enriched the rhizosphere soil community structure.Meanwhile,TN,I2 and W treatments increased winter wheat yield and WUE by reducing surface soil compaction(bulk density),increasing aggregate stability and SOC,and increasing dry matter transport to grains after anthesis,thus providing compensation for the yield loss of winter wheat.