Effects Of Different Soil Layer Depths In Supplemental Irrigation On Water Consumption Characteristics, Grain Yield And Its Physiological Basis In Wheat

Field experiment was conducted in order to examine the effects of different soil layerdepths in supplemental irrigation and relative soil moisture content on water consumptioncharacteristics, grain yield and its physiological basis in wheat. In2009–2010wheat growingseason, the field experiments were conducted with Jimai22. The irrigation treatments weredesigned as no irrigation (W0);80%of relative soil moisture content in0~140cm soil layersat Over-wintering,70%at jointing, and65%at anthesis (W1);85%at Over-wintering,70%atjointing, and65%at anthesis (W2);80%at Over-wintering,70%at jointing, and70%atanthesis (W3);85%at Over-wintering,70%at jointing, and70%at anthesis (W4),respectively. In2010–2011wheat growing season, the field experiments were conducted withShannong15and the irrigation treatments were designed based on relative soil moisturecontent in four different soil layer depths which were0-20cm(D1),0-40cm(D2),0-60cm(D3)and0-140cm(D4). The irrigation treatments were designed as no irrigation (W0′),65%ofrelative soil moisture content in the desingned soil layer depths at jointing and75%atanthesis (W1′),70%at jointing and75%at anthesis (W2′),75%at Over-wintering,70%atjointing and75%at anthesis (W3′),80%at Over-wintering,70%at jointing and75%atanthesis (W4′),70%at jointing and80%at anthesis (W5′), respectively.1Effects of relative soil moisture content on water consumption characteristics and grainyield and its physiological basisThe ratio of precipitation to total water consumption amount in W2treatment was higherthan that of W3and W4treatments, the irrigation amount and the ratio of irrigation amount tototal water consumption amount were present as W4＞W2or W3＞W1, whereas a oppositechange occurred in the ratio of soil water consumption amount to total water consumptionamount. The above results indicate that under the lower soil relative moisture contentconditions, it was advantage of increasing the amount of soil water consumption. Water potential and relative water content of flag leaves in W2treatment had nosignificant differences with other treatments at early grain filling stage, but which were higherthan those of W1and W3treatments and had no significant differences with W4treatment atlate grain filling stage. The above results indicate that W2and W4treatments were advantageof improving grain yield.Dry matter amount after anthesis and the amount of grain dry matter accumulation in W2treatment had no significant differences with W4treatment were higher than other treatments.The amount of plant nitrogen accumulated at anthesis and the amount of grain nitrogenaccumulation at maturity in W2and W4treatments were higher than other treatments. Thetranslocation ratio of nitrogen from vegetative organs after anthesis to grain in W2treamentwas higher than treatment W4. The above results indicate that W2treatment was beneficial toincrease the amount of nitrogen accumulation in the plant at anthesis and maturity and theefficiency of nitrogen translocation from vegetative organs to grain.The spike number, grain number per spike, weight per grain and grain yield for W2andW4treatments were higher than other treatments, but water use efficiency and irrigationbenefit for W2were higher than W4treatment.In conclusion, under the condition of this experiment, as far as grain yield, water useefficiency and irrigation benefit be concerned, the most appropriate irrigation regimerecommended is W2treatment.2Effects of soil layer depths in supplemental irrigation and relative soil moisturecontent on water consumption characteristics, grain yield and its physiological basis2.1Effects of soil layer depths in supplemental irrigation and relative soil moisturecontent on water consumption characteristicsThe soil water consumption amount during over-wintering to anthesis in W4′treatmentwas lower than other treatments, but during anthesis to maturity was higher than otherirrigated treatments. It suggests that W4′treatment was favorable to increase the waterabsorption from the soil by wheat after anthesis.The soil water consumption amount during sowing to jointing was no significantdifferences between the treatments under W1′, W2′and W5′conditions, and during jointingto anthesis in D2treatment had no significant differences with D3were lower than othertreatments, and during anthesis to maturity in D2treatment had no significant differences with D3were higher than D1, lower than D4treatment. The soil water consumption amount duringsowing to over-wintering was no significant differences between the treatments under W3′and W4′conditions, and during jointing to anthesis in D2treatment was higher than D3treatment, but during anthesis to maturity was lower than D3treatment. It suggests that underW1′、W2′and W5′conditions, D2and D3treatment were favorable to increase the waterabsorption from the soil by wheat after anthesis; under W3′and W4′conditions D3treatmentwas favorable to increase the water absorption from the soil by wheat after anthesis.2.2Effects of soil layer depths in supplemental irrigation and relative soil moisturecontent on water potential and relative water content of flag leavesUnder D1conditions, Water potential and relative water content of flag leaves in W4′treatment were higher than other treatments and had no significant differences with W3′treatment at grain filling stage. Under D2, D3and D4conditions, Water potential and relativewater content of flag leaves in W4′treatment were higher than other treatments at milddle andlate grain filling stages. It suggests that W4′treatment was favorable to improvephotosynthesis and grain filling.Under all the relative soil moisture content conditions, relative water content of flagleaves in D2treatment had no significant differences with D3were higher than othertreatments at grain filling stages and water potential of flag leaves in D2treatment had nosignificant differences with D3were higher than other treatments at milddle and late grainfilling stages. It suggests that D2and D3treatments were favorable to improve photosynthesisand grain filling which was the physiological basis of high-grain weight.2.3Effects of soil layer depths in supplemental irrigation and relative soil moisturecontent on carbon metabolism of wheatThe amount of grain dry matter accumulation at maturity from vegetative organs beforeanthesis, the amount of dry matter accumulation after anthesis and the amount of grain drymatter accumulation in W4′treatment had no significant differences with W3′were higherthan other treatments under D1conditions. The amount of grain dry matter accumulation atmaturity from vegetative organs before anthesis, the amount of dry matter accumulation afteranthesis and the amount of grain dry matter accumulation in W4′treatment were higher thanother treatments under D2, D3and D4conditions. The above results indicate that W4′ treatment was beneficial to increase the amount of dry matter accumulation in the plant afteranthesis and the efficiency of dry matter translocation from vegetative organs to grain whichwas one reason of high grain yield.The amount of grain dry matter accumulation at maturity from vegetative organs beforeanthesis in D2and D3treatment had no significant differences with D1were higher than D4treatment under W1′conditions. The amount of grain dry matter accumulation at maturityfrom vegetative organs before anthesis in D2and D3treatment were higher than othertreatments under W2′, W3′, W4′and W5′conditions. Under all the soil relative moisturecontent conditions, the amount of grain dry matter accumulation at maturity were higher thanother treatments. The above results indicate that D2and D3treatments were beneficial toincrease the amount of dry matter accumulation in the plant before anthesis and the efficiencyof dry matter translocation from vegetative organs to grain, and they were advantage ofimproving grain yield.2.4Effects of soil layer depths in supplemental irrigation and relative soil moisturecontent on nitrogen metabolism of wheatThe amount of plant nitrogen accumulated and the amount of grain nitrogenaccumulation at maturity in W4′treatment had no significant differences with W3′treatmentwere higher than other treatments. The amount of plant nitrogen accumulated at anthesis andthe amount of grain nitrogen accumulation at maturity in W4′treatment had no significantdifferences with W3′treatment were higher than other treatments under D1, D2and D3conditions. The amount of plant nitrogen accumulated at anthesis and the amount of grainnitrogen accumulation at maturity and its from vegetative organs after anthesis were higherthan other treatments under D4conditions. The above results indicate that W4′treatmentwas beneficial to increase the amount of nitrogen accumulation in the plant at anthesis and theefficiency of nitrogen translocation from vegetative organs to grain.The amount of plant nitrogen accumulated and the amount of grain nitrogenaccumulation at maturity in D2treatment had no significant differences with D3treatmentwere higher than other treatments under W1′, W2′and W5′conditions. The amount of plantnitrogen accumulated and the amount of grain nitrogen accumulation at maturity in D2treatment were higher than other treatments under W3′and W4′conditions. The amount of plant nitrogen accumulated at anthesis and the amount of grain nitrogen accumulation atmaturity from vegetative organs after anthesis in D2treatment had no significant differenceswith D3treatment were higher than other treatments under W1′and W4′conditions. Theamount of plant nitrogen accumulated at anthesis and the amount of grain nitrogenaccumulation at maturity from vegetative organs after anthesis in D3treatment were higherthan other treatments under W2′and W5′conditions. The amount of plant nitrogenaccumulated at anthesis in D2treatment had no significant differences with D3treatmentwere higher than other treatments, and the amount of grain nitrogen accumulation at maturityfrom vegetative organs after anthesis in D3treatment were higher than other treatments. Theabove results indicate that D2and D3treatments were beneficial to increase the amount ofnitrogen accumulation in the plant at anthesis and the efficiency of nitrogen translocationfrom vegetative organs to grain.2.5Effects of soil layer depths in supplemental irrigation and relative soil moisturecontent on grain yield and water use efficiencyThe grain yield in W4′treatment was higher than other treatments. Water use efficiencyin W4′treatment had no significant differences with W1′, W2′, and W3′treatments washigher than W0′treatment but lower than W5′treatment under D1and D3conditions. Wateruse efficiency in W4′treatment had no significant differences with W2′treatment was higherthan W3′, W1′and W0′treatments but lower than W5′treatment under D2conditions.Water use efficiency in W4′treatment was higher than other treatments under D4conditions.The above results indicate that W4′treatment was beneficial to gain higher grain yield andwater use efficiency.The grain yield in D2treatment had no significant differences with D3treatment washigher than other treatments. Water use efficiency in D2treatment had no significantdifferences with D1and D3treatments were higher than D4treatment under W1′, W2′andW3′conditions. Water use efficiency in D2treatment had no significant differences with D3treatment were higher than D4treatment, but lower than D1treatment under W4′conditions.Water use efficiency in D2treatment had no significant differences with D1treatment werehigher than D3and D4treatments under W5′conditions. Water use efficiency of irrigationand irrigation benefit were higher than D3treatment. The above results indicate that D2 treatment was beneficial to gain higher water use efficiency of irrigation and irrigation benefitthan D3treatment.In conclusion, under the condition of this experiment, as far as the above factors beconcerned, the most appropriate irrigation regime recommended is that the soil layer depth ofsupplemental irrigation was0~40cm (D2) and relative soil moisture content was80%atOver-wintering,70%at jointing and75%at anthesis (W4′).