Experimental Research On Soil Water Diagnostic Indexes Of Crop Water Deficit Under Localized Irrigation

The key to develop water-saving agriculture is to improve water use efficiency of crops,local irrigation has advantages to increase water use efficiency. For researches on soilmoisture index of deficit of crops are not sufficient, it is important to precisely regulating soilmoisture and increasing the crop water use efficiency with studying the rule of the root zoneof corn and its physiology and growth under different local water supply ways，and establish arelationship between physical and growth index and soil moisture of partial root zone space.Based on corn as the experimental material, and using pot and vertical soil columnthrough experiment in greenhouse, this research studied the effect on growth, physiology, andhormone of corns, and partial soil moisture index to direct water stress of corn under differentirrigation of different horizontal and vertical root zone space, conclusions are drawn asfollows:(1) Under the conditions of horizontal partial root zone irrigation, height, stem diameter,and leaf area show different under different growth period and different irrigation low bounds.Height, stem diameter, and leaf area increase first, and then decreases with low bounds rising;height, stem diameter, and leaf area of treatment70%θF(T2) as low bound show the highestones. Photosynthetic rate of corn during the day appeared to be a bimodal curve; it risesslightly after14:00,70%θF(T2) as low bounds during seeding and jointing stages got highestextent; transpiration rate decreased compared to normal treatment, and it decreased with lowbounds decreased.(2) Due to vertical research on root zone, photosynthetic rate of one-layer only irrigationare all lower than normal irrigation, bottom layer only irrigation shows the lowest, then themiddle. Middle layer only irrigation of80%θFas low bound shows no significant differenceto normal irrigation, top layer only treatments’ photosynthetic rate are similar to normalirrigation’s, all are unimodal curves, peak appears earlier and decreases little than normalirrigation; transpiration rate of middle layer only treatments appear like bimodal curves, butnot significant, and decrease with the low bound decreases; transpiration rate of bottom layeronly doesn’t change with low bound, they all appear like unimodal curves.（3）Under the conditions of horizontal partial root zone irrigation, length and surface area of root less than0.6mm diameter promoted appeared to normal irrigation, root vigor ofcorn during seeding stage is higher than normal irrigation, and it decreases with low bounddecreases, but root vigor of corn during jointing stage has no significant difference comparedto normal irrigation treatment, except root vigor of T2whose low bound is70%θFis thehighest one; Treatment with lowest irrigation water has the lowest root vigor duringpustulation period and mature period, but has no significant differences.(4) Under the conditions of horizontal partial root zone irrigation, T1has the same lowbound as normal irrigation treatment has lower yield, at the same time, other treatments allhave higher yield, and T3treatment has the highest yield. WUE of T1, T2, T3, T4treatmentincreased by14.35%,25.35%,5.26%and7.18%respectively compared to normal irrigation.Due to vertical research on root zone of corn during jointing stage, weight of dry matter aboveand below ground is higher than normal irrigation treatment; top layer only treatment has thebiggest root shoot ratio, and at the same time, bottom layer only treatment has the highestwater use efficient, different irrigation has no significant difference with each other.(5) Under the conditions of horizontal partial root zone irrigation, we establish therelationship. Pn,Tr, Gs, WSD, Pro and SS，yield and WUE; there are several leavesphysiological characteristics can reflects crop water deficit, this physiological characteristicsare reduced with increasing irrigation limit, the Pro is the most sensitive response to irrigationlower limit, Because the slope of the relationship between proline and the irrigation lowerlimit is the maximum.（6）The paper presents the lower level of partial root-zone irrigation indicators，Seedling was65%, jointing and heading filling period was70%, which could reduce the waterdeficit on maize growth, will help to improve the structure of root growth and raise the yieldand water use efficiency; vertical partial root zone moisture regulation should be increasedmiddle soil moisture, the surface which is frequent wet will increase evapotranspiration, it isnot fully meet the growing needs of jointing stage，which the deep soil have high moisture.