Effect Of Mulched Drip Irrigation Under Regulated Deficit Irrigation On Pepper's Growth And Yield In Hexi Oasis Region

The experiment about mulched drip irrigation under water deficit regulation of pepper?s growth was conducted at Yimin Irrigation Experimental Station during April to September in 2017.The all growth period of pepper was divided into the four periods: seeding,blossom and fruit period,full fruit period and later fruit period.The experiment was composed of three water regulated deficit levels,mild water regulated deficit(65%~75%)moderate water regulated deficit(55%~65%)and severe water regulated deficit(45%~55%)at seedling,and mild water regulated deficit at both full fruit period and later fruit period.Adequate irrigation treatment(75%~85%)was used throughout the growth period as a control.The main studies were about the soil content and temperature in root zone,water consumption characteristics,the pepper growth,fruit yield and water use efficiency in each water treatment at different growth periods.The main conclusions are as follows:(1)Under the circumstance of drip irrigation with film mulching,temperature of the soil that is 5-25 centimeters underground increases first and then decreases with advancement of the growth process.As the depth of soil increases,the temperature changes slightly.The effect of drip irrigation under the membrane is minimal.The temperature of shallow soil is closely related to the change of atmospheric temperature because of external environment.The effect of membrane on soil is obvious in the early stage of pepper?s growth while slight in the later period.The moderate RDI can increase soil temperature.Except for this,average ground temperature will rise by 2 degree Celsius through heavy RDI in the seeding period compared with full irrigation.(2)Compared with full irrigation during the whole growth period,regulated deficit irrigation using drip irrigation under membrane has significant reduction to the pepper?s height,stem thickness,leaf area and dry matter accumulation.Meanwhile,with the deeper adjustment of water deficit irrigation,these nutrition indicators will decrease obviously.(3)Regulated deficit irrigation using drip irrigation has a significant effect on the soil moisture that is 0-30 centimeters underground while the soil moisture that is 30 centimeters under the ground is not effected.Water deficit irrigation can significantly reduce the water consumption.The water consumption is 258.4 mm in the seeding period with moderate RDI and full productive stage with mild RDI,232.2 mm in the seeding period with heavy RDI and full productive stage with mild RDI,272.3 mm in the seeding period with heavy RDI and few fruit stage with mild RDI.The water consumption is decreased by 17.3%,25.7% and 12.8% compared with the control group(P<0.05).The water consumption is 288.56 mm in the seeding period with mild RDI and its water consumption is reduced by 7.6% which has little difference compared with the control group(P>0.05).In addition,water consumption increases first and then decreases with the growth of the pepper.(4)The periods of seedling and full fruit are important for pepper yields form.The yield per plant of treatments T1,T2 and T4 under the moderate and severe water regulated deficit during the seedling period are respectively lower 24.2%,36.9% and 15.5%(P<0.05)than that of the control group CK.Mild water regulated deficit greatly affects single fruit weight(P<0.05)during the periods of full fruit and later fruit;the water regulated deficit during the full fruit period will lead to the decrease of single fruit weight of pepper,while it will not much affect the yield of pepper.(5)RDI in the seeding stage and few fruit stage can increase ground water using efficiency and irrigation water using efficiency which increases 2.8% and 1.1% compared with control group,but RDI in the few fruit stage goes against ground water using efficiency and irrigation water using efficiency.Mild RDI in the seeding stage and few fruit stage can increase ground water using efficiency(12.1 kg/m3)and irrigation water using efficiency(13.3 kg/m3)under the circumstance of keeping up production but has little obvious difference compared with control group.(6)Considering indicators such as pepper yield,round water using efficiency(65%~75%?f)and irrigation water using efficiency(65%~75%?f)the optimized methods of regulated deficit irrigation using drip irrigation under membrane in Hexi Corridor oasis irrigation district are Mild RDI in the seeding stage and few fruit stage.