XVII th World Congress of the Interntionl Commission of Agriculturl nd Biosystems Engineering (CIGR) Hosted y the Cndin Society for Bioengineering (CSBE/SCGAB) Quéec City, Cnd June 13-17, 2 SOIL MOISTURE, ELECTRIC CONDUCTIVITY AND TEMPERATURE DYNAMICS AND MAIZE GROWTH UNDER ALTERNATE FURROW IRRIGATION LI CAI-XIA 1,2, CHEN XIAO-FEI 3, SUN JING-SHENG 1,2,*, LI FU-SHENG 4, GAO YANG 1,2, ZHOU XIN-GUO 1,2 1 Frmlnd Irrigtion Reserch Institute, Ministry of Wter Resources/Chinese Acdemy of Agriculturl Sciences, Xinxing, Henn 4533, P.R.Chin <* jshsun623@yhoo.com.cn> 2 Key L of Crop Wter Requirement nd Regultion of Ministry of Agriculture, Xinxing, Henn 4533, P.R.Chin 3 College of Wter Conservncy, Shenyng Agriculturl University, Shenyng, Lioning 1161, P.R.Chin 4 Agriculturl College, Gungxi University, Nnning Gungxi 535, P.R.Chin CSBE1679 Presented t Section 1: Lnd nd Wter Engineering including EnviroWter 2 ABSTRACT To investigte the effect of lternte furrow irrigtion (AFI) on wter sving nd yield in northestern Chin, field experiment ws crried out to study the dynmics of soil wter, electric conductivity temperture, grin yield nd wter use efficiency (WUE) of mize with AFI in Shenyng region in 25. Field experiment comprised of three tretments: CFI (conventionl furrow irrigtion), AFI1 nd AFI2. Results showed tht AFI hd more spce for lterl seepge of soil wter nd lower evportion loss. Higher irrigtion mount of single furrow in AFI tretment decresed surfce soil electric conductivity, i.e. surfce soil temperture ws higher in AFI tretment, especilly in non-irrigted furrow nd ridge, which ws eneficil for crop growth t the seedling stge. AFI2 incresed WUE nd grin yield y 22.2% nd 4.8%, respectively. Although AFI1 improved WUE y 28.5%, it significntly decresed grin yield. Therefore, the AFI with pproprite irrigtion quot (AFI2) cn increse oth grin yield nd WUE nd chieve wter sving nd yield incresing simultneously. Keywords: lternte furrow irrigtion, mize, electric conductivity, temperture, wter use efficiency INTRODUCTION Currently, surfce irrigtion is still the min irrigtion method nd ccounts for 9 percent of glol irrigtion re (Crevoisier et l. 28). In Chin, surfce irrigtion even ccounts for 98 percent of ntionl irrigtion re. Furrow irrigtion nd order irrigtion re mostly dopted for min dry lnd crops such s whet, mize nd cotton (Li et l. 23). Surfce irrigtion cn chieve higher wter use efficiency (WUE) with etter mngement (Kng 1991; Mihol 27). Fcing the scrcity of wter resources nd lower efficiency of irrigtion wter, new surfce irrigtion such s deficit irrigtion, limited irrigtion nd regulted deficit irrigtion hd een conducted y mny experts to improve grin yield nd WUE simultneously, ut these irrigtion methods CIGR XVII th World Congress Quéec City, Cnd June 13-17, 2 1
only considered optiml wter lloction timely nd did not tke optiml distriution of irrigtion wter in crop root zone, regultion function of scisic cid (ABA) on lef stomtl perture nd WUE into ccount. Therefore, sed on physiologicl function of the integrted effect of crop roots nd ABA theory on WUE improvement, lternte prtil root zone irrigtion (APRI) ws proposed with reltionship etween photosynthesis, trnspirtion nd stomtl perture y Kng et l. (1997), which improved the trditionl furrow irrigtion. Mny studies on wine grpe (De souz et l. 23), tomto (Zege et l. 24), soyen (Wkrim et l. 25), cotton (Du et l. 26) nd potto (Shhnzri et l. 27) with lternte furrow irrigtion (AFI) were crried out in recent yers. The results showed tht AFI ws promising wter-sving irrigtion method. Du et l. (26) indicted tht AFI incresed cotton yield nd WUE, nd it respectively incresed cotton WUE y 17.2% nd 18.6% when compred to CFI (conventionl furrow irrigtion) nd FFI (fixed furrow irrigtion). Du et l.(28) studied on tle grpe irrigted with ADI (lternte drip irrigtion), nd indicted tht ADI reduced irrigtion wter, improved WUE nd fruit qulity without detrimentl effect on yield. Ling et l. (2) pointed out tht AFI significntly reduced evportion loss nd improved irrigtion wter efficiency, sved wter y 33.3% without detrimentl effect on mize yield. Pn et l. (2 nd 22) lso indicted tht AFI could sve wter y 33.3% nd reduce deep percoltion. Since AFI ws proposed, mny reserchers minly focused on the effects of AFI on grin yield nd WUE, ut furrow irrigtion hd certin influences on soil slt nd energy udget in surfce soil (Xie et l. 1997. Soil electric conductivity could represent slt content in the soil (Liu et l.21). Plenty of rdition het ws dissipted during wter evportion, surfce soil chrcteristics ffected rdition sorption (Wng 2). Soil het with furrow irrigtion ws ffected y meteorologicl fctors such s wind direction (Yng 1996). Ren et l. (28) showed tht furrow irrigtion significntly incresed soil temperture, which promoted mize growth. Li et l. (21) indicted tht surfce soil temperture nd nutrient use efficiency were improved with suitle proportion of furrow to ridge under furrow irrigtion. Up to now, there re few studies on surfce soil electric conductivity nd energy udget with AFI. Therefore, mize, s one of min food crop in northestern Chin, ws selected s n experimentl crop. The ojectives of this study were to: (1) investigte the distriution of soil wter, electric conductivity nd temperture with AFI, nd nlyze wter use nd consumption, nd vrition of electric conductivity resulted from wter trnsfer with AFI; (2) investigte the effect of AFI on mize growth, grin yield nd WUE. MATERIALS AND METHODS Experimentl site description Experiment ws conducted from June to Septemer in 25 in n experimentl field of Wter Conservncy College of Shenyng Agriculturl University (N 41 44, E 123 27, ltitude 44.7 m). Climtic records in mize growing seson in the region yielded the mximum temperture of 32.2, the minimum temperture of 6.4, nd the men temperture of 21.6, the sunshine durtion of 815 h nd rinfll of 595.5 mm. The soil is clssified s rown soil, with the ulk density of 1.38 g cm -3, the field cpcity of.33-.41 cm 3 cm -3, nd PH-vlue of 7.9. The soil ws smpled for the -3 cm depth efore sowing in 25 with.75 g kg -1 soil orgnic mtter, 6.84 mg kg -1 ville N, 48. mg kg -1 ville P nd 14.84 mg kg -1 ville K. The wter tle ws out 4.8 m during the experimentl period. CIGR XVII th World Congress Quéec City, Cnd June 13-17, 2 2
Experimentl design The experiment comprised of three tretments with three replictions. Three tretments included CFI (conventionl furrow irrigtion, CFI), lternte furrow irrigtion (AFI1 nd AFI2). Irrigtion quot of ech tretment ws shown in Tle 1. Tretment Tle 1 Irrigtion quot of ech tretment Before jointing Jointing-tsseling After tsseling Irrigtion quot (m 3 /hm 2 ) Irrigtion for single furrow (m 3 ) Irrigtion quot (m 3 /hm 2 ) Irrigtion for single furrow (m 3 ) Irrigtion quot (m 3 /hm 2 ) Irrigtion for single furrow (m 3 ) CFI 3.18 45.27 5.3 AFI 1 15.18 225.27 25.3 AFI 2 2.24 3.36 33.4 The lower limit of irrigtion ws 65% of the field cpcity. Mize needed to e irrigted when soil wter content t the root zone of the ridge reched to the lower limit. Field experiment ws conducted in cuoid lysimeters under movle rin shelter. Length, width nd depth of the lysimeters re 1.2 m, 1. m nd 1. m, respectively. Ridge plnting nd furrow irrigtion were dopted in the lysimeters with north-south direction. The cross section ws trpezoidl, nd the dimension ws shown in Fig. 1. In ech lysimeter, 4 plnts of mize (Ze mys L. cv. Shenyu 171.2 plnts m -2 ) were plnted on My 28, 25 nd hrvested on Septemer 28, 25. The row spcing is 6 cm nd the plnt spcing is 4 cm. Mize 8cm Furrow 2cm cm cm 2cm Ridge 2cm cm Mize 4cm cm 12cm 12c Fig. 1 Profile digrm of the lysimeter () nd ly out of mize () in the lysimeter Mesurements Soil wter content nd electric conductivity Soil wter content (θ) ws mesured with time domin reflector (TDR) every six dys. TDR ccess tues were locted in the irrigtion furrow nd ridge of CFI tretment, respectively. For AFI1 nd AFI2 tretment, CIGR XVII th World Congress Quéec City, Cnd June 13-17, 2 3
the tues were locted in the irrigted furrow, ridge nd non-irrigted furrow, respectively. Soil wter content were mesured every 2 cm in 2-8 cm soil lyer. The surfce soil wter content nd electric conductivity in -2 cm soil lyer were mesured y proe type TDR ( cm). Surfce soil temperture Surfce soil tempertures were mesured using the portle infrred thermometer. Soil tempertures of furrow nd ridge in ech loction were mesured four replictions, nd then men vlues were clculted. Soil evportion nd evpotrnspirtion Soil evportion (E) ws mesured y microlysimeter with inner nd outer tues. The tue ws mde of iron sheet of glvnize with 1 mm thickness. The dimeter of the inner tue hd two types: cm nd 8 cm. The corresponding dimeters of the outer tue were 12 cm nd cm, respectively. The former ws plced in furrow nd the ltter in ridge. Replcement of soil core nd weight ws performed t 16: everydy. Evpotrnspirtion (ET) is estimted sed on soil wter lnce eqution s follows (Hillel 1998): ET = P e + I + U R D w S 1 Where, ET is crop evpotrnspirtion (mm), S the chnge of soil wter stored in -8 cm soil lyer (mm), P e the effective precipittion (mm), determined y USDA soil conservtion services method, I irrigtion quot (mm), U the upwrd cpillry flow into the root zone (mm), R the runoff (mm), D w the downwrd dringe out the root zone (mm). The upwrd nd downwrd flow estimted using Drcy s lw (Kr et l. 27; Medeiros et l. 25) indicted tht the two items were negligile t the experimentl site. Runoff ws lso negligile ecuse of lower irrigtion quot nd sheltering from rinfll during the growing seson. Growth index, yield nd yield components Lef length, lef width, plnt height nd stem dimeter fter emergency were mesured using the ruler t 7- dys intervls. Two plnts were smpled in ech plot. Lef re ws determined y following formul: lef re = lef length the gretest lef width.75 (Zhng et l. 26). Three representtive plnts for ech tretment were selected t the commencement of filling stge. Ten seeds, smpled in one row of the er t ech smpling, were tken from the er of the smples t four dys intervls, After smpling, the er ws wrpped crefully, so tht effects of smpling on other seeds were reduced. The seeds were dried t 8 to constnt dry weight. At hrvesting, eight plnts were selected to mesure grin weight per er, -seed weight, er length, re top length, er dimeter, row numer per er, nd so on for ech tretment. CIGR XVII th World Congress Quéec City, Cnd June 13-17, 2 4
Wter use efficiency nd hrvest index Wter use efficiency (WUE) cn e clculted s follows: Y WUE= ET grin (2) Y WUE = iomss iomss ET (3) Hrvest index (HI) is clculted s follow: Y HI = Y grin iomss (4) where, Y grin is grin yield t hrvest (kgm -2 ), WUE iomss wter use efficiency y crop iomss (kgm -3 ),Y H-iomss iomss t hrvest (kgm -2 ), ET totl ctul evpotrnspirtion over the growing seson (mm). Dt nlysis Dt were nlyzed with SAS (Sttisticl Anlysis System) soft pckge (SAS Institute, 1999), nd significnce test ws conducted with LSR (lest significnt rnge test) method. RESULTS Dynmics of soil wter, electric conductivity nd temperture Soil wter content dynmic in the profile Soil wter content (θ) t jointing stge ws chosen to nlyze soil wter dynmic in the irrigtion furrow fter the irrigtion (Fig. 2). CIGR XVII th World Congress Quéec City, Cnd June 13-17, 2 5
Soil moisture (cm 3 /cm 3 ) 38 34 3 26 22 18 14 6-Jul. CFI. -Jul 14-Jul 18-Jul 22-Jul 26-Jul Dte Ridge Electricl conductivity Irrigtion furrow.14.12..8.6.4.2 38 34 3 26 22 18 14. AFI 1.14.12..8.6.4.2. 6-Jul -Jul 14-Jul 18-Jul 22-Jul 26-Jul Dte Ridge Irrigtion furrow Electricl conductivity (s/m) Non-irrigtion furrow Electricl conductivity Soil moisture (cm 3 /cm 3 ) 38 c. AFI 2.14 34.12 3. 26.8 22.6 18.4 14.2. 6-Jul 11-Jul 16-Jul 21-Jul 26-Jul Dte Ridge Non-irrigtion fu Irrigtion furrow Electricl conduc 6-Jul d. Electricl conductivity of CFI, AFI 1 nd AFI 2.14.12.1.8.6.4.2 -Jul 14-Jul 18-Jul 22-Jul 26-Jul Dte AFI1 AFI2 CFI Electricl conductivity (s/m) Fig. 2 Chnges of soil wter content nd electric conductivity t surfce soil lyer (- cm) Soil wter movement nd redistriution occurred in the irrigtion furrow within 2 dys fter the irrigtion. Soil depth with mximl wter content in the profile ws different t the 1st dy fter irrigtion, AFI t the - cm nd CFI t 4-6 cm soil lyer. Irrigtion wter cn move to the dry re in AFI plot ecuse of lterl infiltrtion. Becuse two djcent furrows in the CFI plot were irrigted, wter ws rpidly moved to the deep lyer ecuse of lower soil wter potentil. At the 1st dy fter irrigtion, the depth of the wet front ws 4-6 cm for CFI nd AFI2 tretments nd 2-4 cm for AFI1 tretment. At the 8th dy fter irrigtion, the depth with mximl wter content ws 6-8 cm. Soil wter content ws grdully decresed due to the evportion nd root uptke. At the 2th dy fter irrigtion, the verge soil wter content in the whole profile of CFI tretment ws 26.4%, while tht of AFI tretment reched to the lower limit of irrigtionfig.3. Seeing from the dynmic of verged wter content in the soil profile, from the 1 st dy to the 2 th dy fter irrigtion, soil wter content vried from 38.1% to 26.4% in CFI, 32.9% to 24.1% in AFI 2 nd 31.1% to 23.8% in AFI 1. Therefore, CFI cn mintin higher soil wter content fter irrigtion, ut its soil wter content vried gretly t ech time intervl. Soil wter content in AFI vried slightly t ech time intervl, especilly t 6-8 cm soil lyer. Soil electric conductivity dynmic in surfce soil lyer Soil electiric conductivity t - cm lyer t the jointing stge ws chosen to nlyze the chnge of soil electiric conductivity within 2 dys fter irrigtion. Soil electiric conductivity ws firstly higher nd then decresed to e reltively constnt with the chnge of soil wter nd the pek CIGR XVII th World Congress Quéec City, Cnd June 13-17, 2 6
soil electiric conductivity occurred t the 3rd dy fter irrigtion for ll wter tretments. Soil electiric conductivity in the AFI1 nd AFI2 tretments vried slightly during the mesurement period. The electric conductivity in the CFI tretment ws higher thn those of AFI1 nd AFI2 tretments. El ect r i cl conduct i vi t y( m/ s). 1. 8. 6. 4. 2. CFI Fur r ow Ri dge. 4m/ s El ect r i cl conduct i vi t y( m/ s) El ect r i cl conduct i vi t y( m/ s). 5-1 Jul 2- Jul 4- Aug 19- Aug 3- Sep 18- Sep I r r i gt i on f ur r ow. AFI 1. 8 Ri dge Non- i r r i gt i on f ur r ow. 6. 36m/ s. 4. 2. 1 5- Jul 2- Jul 4- Aug 19- Aug 3- Sep 18- Sep c. AFI I r r i gt i on f ur r ow 2. 8 Ri dge Non- i r r i gt i on f ur r ow. 6. 33m/ s. 4. 2 5- Jul 2- Jul 4- Aug 19- Aug Dt e 3- Sep 18- Sep Fig. 3 Soil wter content of CFI (), AFI 1 () nd AFI 2 (c) In the CFI tretment, the electric conductivity of the irrigtion furrow ws the mximum t the 1st dy fter irrigtion. Occurrence of the mximl electric conductivity in the ridge lgged ehind in the furrow, the electric conductivity in the ridge reched its mximum vlue t the 4th to 6th dy fter irrigtion, thus soil slt content in the ridge ws higher thn tht of the furrow. Averge electric conductivities of oth ridge nd furrow were.43 nd.37 sm-1 over the whole growing seson, respectively. In the AFI 2 tretment, the mximum electric conductivities occurred t the 1 st, 4 th nd 7 th dy fter irrigtion for the irrigted furrow, ridge, nd non-irrigted furrow, respectively. After the mximum vlue, soil electiric conductivity in ech site grdully decresed to e constnt. Averge electric conductivities during the whole growing seson were.31,.36 nd.35 sm -1 for the irrigted furrow, ridge nd non-irrigted furrow, respectively Vrition of soil electric conductivities in AFI 1 ws similr to tht of AFI 2. Averge electric conductivities over the whole growing seson ws.33,.37 nd.39 sm -1 for the irrigtion furrow, ridge nd non-irrigtion furrow, respectively (Fig.4). CIGR XVII th World Congress Quéec City, Cnd June 13-17, 2 7
2 3 4 5 6 7 8 Wter moisture (cm 3 /cm 3 ) 15 2 25 3 35 4 45 c. AFI 2 Fig. 4 Chnges in electric conductivity nd men vlues t different sites of ech tretment Dynmic of surfce soil emperture Vrition of temperture over surfce soil Vrition of temperture over surfce soil in the irrigted furrow, ridge nd non-irrigted furrow nd men soil tempertures of ll irrigtion tretments were shown in Fig.5, respectively. Men soil temperture of ech tretment ws in order of CFI<AFI 2 <AFI 1. And men soil tempertures over the whole growing stge were 24.21 nd 25.22 for the furrow nd ridge of the CFI tretment, 25.21, 25.85 nd 25.86, nd 25.64, 26.2 nd 26.34 for the irrigted furrow, ridge nd non-irrigted furrow of AFI 2 nd AFI 1, respectively. Soil temperture in the irrigted furrow reduced fter irrigtion. In the CFI tretment, the difference in men soil temperture etween the furrow nd ridge ws out 1. In the AFI 2 tretment, the difference in men soil temperture ws.64 etween the furrow nd ridge, nd.65 etween the irrigted nd non-irrigted furrows, respectively. In the AFI 1 tretment, the difference in men soil temperture ws.56 etween the furrow nd ridge,.7 etween the irrigted nd non-irrigted furrows, respectively. Thus AFI cn increse soil temperture, ut reduce the difference of soil temperture etween the furrow nd ridge when compred to CFI. CIGR XVII th World Congress Quéec City, Cnd June 13-17, 2 8
Temper t ur e( ) 35 3 25. CFI 2 Fur r ow 15 Ri dge 24. 72 5- Jul 2- Jul 4- Aug 19- Aug 3- Sep 18- Sep Temper t ur e( ) 35 3 25. AFI 1 2 I r r i gt i on f ur r ow Ri dge 15 Non- i r r i gt i on f ur r ow 26. 6 5- Jul 2- Jul 4- Aug 19- Aug 3- Sep 18- Sep Temper t ur e( ) 35 3 25 2 15 c. AFI 2 I r r i gt i on f ur r ow Ri dge Non- i r r i gt i on f ur r ow 25. 64 5- Jul 2- Jul 4- Aug 19- Aug 3- Sep 18- Sep Dt e Fig. 5 Chnges in soil temperture nd men vlues t different sites of ech tretment SOIL EVAPORATION Soil evportion nd irrigtion quot of ech tretment were shown in Fig. 6. Totl irrigtion over the whole growing seson ws 373 mm, 248 mm nd 314 mm for the CFI, AFI1 nd AFI2 tretments, respectively. And totl soil evportion over the whole growing seson ws 81.6 mm, 42.9 mm nd 55.8 mm for CFI, AFI1 nd AFI2, respectively, indicting tht AFI cn reduce soil evportion. CIGR XVII th World Congress Quéec City, Cnd June 13-17, 2 9
Irrigtion(mm) 9 6 3 AFI2 AFI1 CFI Soil evportion(mm) 23-My 3-My 9-Jun 24-Jun 13-Jul 26-Jul 13-Aug 31-Aug 24-Sep 5 4 3 2 1 Dte 23-My 3-My 9-Jun 24-Jun 13-Jul 26-Jul 13-Aug 31-Aug 24-Sep Dte Fig. 6 Soil evportion nd irrigtion of ech tretment AFI1 CFI AFI2 Soil evportion over the growing seson ws influenced y mny fctors, e.g. crop cnopy, meteorologicl fctors nd soil wter content. In order to eliminte the effect of meteorologicl fctors on soil evportion, the reltive soil evportion intensity, E/ET, ws introduced to sustitute soil evportion. ET ws the reference crop evpotrnspirtion, estimted using Penmn-Monteith eqution recommended y FAO (Allen et l. 1998). The E/ET incresed with the incresing θ for ll irrigtion tretments, which ws in order of AFI 2 > AFI 1 >CFI. Bsed on the mesured dt, the reltionships etween E/ET nd θ cn e expressed exponentilly s follows: CFI AFI 2 AFI 1.8θ 2 E / ET =.16e R =.7493 5 5.686θ 2 E / ET =.95e R =.7127 6 17.242θ 2 E / ET =.4e R =.8228 7 where, ET is the reference crop evpotrnspirtion (mm), θ soil wter content (cm 3 cm -3 ). LAI hd less effect on E/ET in CFI thn tht of AFI. The reltionships etween E/ET nd LAI cn e expressed in the negtive exponentil function s follows: CFI AFI 2 AFI 1.2897LAI 2 E / ET =.727e R =.823 8.2757 LAI 2 E / ET =.571e R =.9594 9.3788 LAI 2 E / ET =.131e R =.7745 CIGR XVII th World Congress Quéec City, Cnd June 13-17, 2
MAIZE GROWTH AND DEVELOPMENT Chnges in stem dimeter, plnt height nd LAI over the whole growth stge were showed in Tle 2. Lef growth speed, lef length nd width minly depended on the division nd extension of cells tht were ffected y soil wter (Xin 1992). During the vegettive growth stge (efore July 3), the stem dimeter, LAI nd plnt height were significntly incresed. After the vegettive growth stge, the growth indices went successively into the stle growth stge. At the mturity stge, AFI2 ws the gretest stem dimeter, while AFI1 ws the lowest. And CFI hd the gretest plnt height nd LAI. The growth rte of stem dimeter in CFI lgged ehind tht of AFI, indicting tht AFI ws eneficil for strong seedling nd lodging resistnce. The CFI tretment hd greter plnt height nd lef re, ut AFI ws helpful for controlling the redundnt growth. Dte (dd/ mm) Tle 2 Plnt height, stem circumference nd lef re index of ech tretment Plnt height (cm) Stem circumference (cm) LAI (cm) CFI AFI 1 AFI 2 CFI AFI 1 AFI 2 CFI AFI 1 AFI 2 6/6 13.2 13. 2 13. 2 2.3 2.3 2.3.1.1.1 14/6 28.33 27.9 28.3 4. 3.8 3.9.3.4.3 2/6 58.77 61.9 59.3 6.2 c 7.5 6.9.7.9.9 27/6 72. 73.4 82.. 9.5 9.2 2.1 2.2 2.1 3/7 88.8 89.7 92.6 11..6 11.1 3.2 3.4 3.3 16/7 19.2 176.4 c 182.6 11.1.6 11.2 6.4 5.8 6.3 24/7 258. 249.6 c 255. 11.1.7 11.3 6.7 6.4 6.5 8/8 264.6 259.7 263.8 11.2.8 c 11.4 7.1 6.6 c 6.7 27/8 27.7 26.7 c 266. 11.2.8 c 11.4 7.1 6.7 6.9 Different smll letters (,, c) in the sme column indicte significnt difference t P.5 level. Crop reproductive growth nd senescence were ffected y wter stress. The filling speed of mize firstly incresed, then decresed for ll irrigtion tretments, nd CFI firstly reched the mximum vlue. AFI 2 hd higher filling speed thn CFI, nd AFI 1 hd the lowest filling speed. The verge filling speed ws.91,.92 nd.84 g dy -1 for CFI, AFI 2 nd AFI 1. Chnges of yellow leves per plnt during the growing seson were shown in Fig. 7(). AFI 2 hd the lowest yellow leves per plnt, ut AFI 1 hd the highest. CIGR XVII th World Congress Quéec City, Cnd June 13-17, 2 11
mi l k- f i l l i ng r t e( g/ d). 18. 15. 12. 9. 6. 3 AFI 1 AFI 2 CFI ( ) Yel l owe l eves 8 6 4 2 ( ) CFI AFI 2 AFI 1 13- Aug 21- Aug 29- Aug 6- Sep 14- Sep 22- Sep Dt e 17- Jul 6- Aug 26- Aug 15- Sep 5- Oct Dt e Fig. 7 Effect of different irrigtion tretments on the progress of milk-filling rte () nd lef senescence rte () of mize MAIZE YIELD COMPONENTS AND YIELD Compred to AFI 1 nd CFI, AFI 2 significntly incresed the -seed weight nd yield (Tle 3). The er length, grin numer per plnt, seed weight per plnt, core weight per plnt, -seed weight nd yield in AFI 1 were significntly lower thn those of AFI 2. Compred to CFI, AFI 2 incresed grin yield of mize y 4.7%, nd AFI 2 nd AFI 1 incresed hrvest index (HI) y 8.5% nd 5.2%, respectively, indicting tht AFI cn improve grin output rtio. Tle 3 Mize yield, yield components nd HI of ech tretment Er length (cm) Er circumfere -nce (cm) ld hed length (cm) Er rows (rows) Row grins Grin numer per spike CFI 23.4 AB 18.6 A 2.3 B 15.6 A 44.9 A 7.8 A AFI 2 23.9 A 19.6 A 2.9AB 16.5 A 42.7 AB 74.9 A AFI 1 22.4 B 18.7 A 3.3 A 15.5 A 4.3 B 624.7 B Tretment Tretment Grin weight per plnt (g) Er xsis weight per plnt (g) -seed weight (g) Y grin (kg/hm 2 ) Y iomss (kg/hm 2 ) CFI 272.3 AB 34.6 AB 39.2 B 9156. B 23154.2 A.39 AFI 2 288. A 4.2 A 4.8 A 9599.7A 22354.2 B.43 AFI 1 254. B 3.3 B 39.4 B 8466.4C 2354.17 B.42 Different smll letters (,,c) nd cpitl letters(a,b,c) in the sme line indicte significnt difference t P.5 nd P.1 level, respectively. WATER USE EFFICIENCY (WUE) Compred to CFI, AFI significntly incresed WUE nd WUE iomss, AFI 2 nd AFI 1 incresed WUE y 22.2% nd 28.5% nd WUE iomss y 12.4% nd 22.3%, respectively, indicting tht AFI cn improve wter use efficiency of mize. In summry, AFI 2 my improve the contriution of irrigtion wter to grin production (Tles 3 nd 4). HI CIGR XVII th World Congress Quéec City, Cnd June 13-17, 2 12
Tle 4 The evpotrnspirtion nd wter use efficiency of ech tretment Tretment ET (mm) WUE (kg/m 3 ) WUE iomss (kg/m 3 ) CFI 247.7 2.7 5.23c AFI 2 231.8 2.53 5.89 AFI 1 192.6c 2.66c 6.4 Different smll letters (,, c) in the sme column indicte significnt difference t P.5 level DISCUSSION Soil electric conductivity could represent wter nd slinity content in the soil (Liu nd Yng, 21), nd is n importnt index of soil productive potentility. On one hnd, excessive fertiliztion nd irrigtion incresed ccumultion nd migrtion mount of slt in the soil; on the other hnd, frequent irrigtion nd crop trnspirtion incresed the trnsport of soil slt to the surfce soil y evportion, which could influence soil electric conductivity in the soil (Xie et l. 1997). In this study, soil electric conductivity in surfce soil lyer incresed t the 1 st dy fter irrigtion, nd then soil electric conductivity in surfce soil lyer decresed s the result of soil wter infiltrtion. Wter infiltrtion nd soil evportion in CFI ws greter thn these in AFI, ecuse CFI hd more irrigtion. Men vlue of soil electric conductivity in furrow nd ridge ws.4 s m -1 during whole growing seson. Men vlue of soil electric conductivity in AFI 1 nd AFI 2 ws.33 nd.36 s m -1, respectively. The results indicted tht the increse of soil electric conductivity in surfce soil lyer in CFI mye result from greter evpotrnspirtion force. There ws more spce for wter lterl movement in AFI with lower evpotrnspirtion pull. Wter trnsported to the ridge nd dry furrow with lower wter potentil, which resulted soil electric conductivity in ridge nd dry furrow higher thn tht in wet furrow (Fig.4). In pot mize experiment, soil slinity hd inhiitory effect on mize LAI nd height 35 dys fter emergence, ut soil slinity hd slight effect on LAI during the lter growing seson (Liu 24). Zhng et l. (1999) indicted tht soil slinity ffected the growth of mize seedlings when slt content ws 3 g L -1. In this study, the growth rte of plnt height, LAI nd stem dimeter in the AFI tretments ws fster thn those of the CFI tretment within 36 dys from sowing nd fter 81 dys from sowing, which my result from the comined effect of wter nd slinity. Soil temperture is n importnt fctor influencing iologicl ctivity nd crop growth, nd it represents soil het condition. In griculturl production, soil temperture in the cultivted horizon not only ffects the growth of roots nd seedlings, ut lso directly nd indirectly influences the trnsport nd trnsform of wter nd nutrients (Lei et l. 1988). And soil temperture is relted to soil het trnsport, crop growth nd yield etc. Under full irrigtion nd fertilizer, there ws liner reltionship etween lef elongtion rte nd soil temperture (Zhng et l. 21). In this study, AFI incresed the temperture over surfce soil, which cn provide dequte het t the seedling stge nd reduce frost injury t the lter growing seson. Ling et l.(2) indicted tht lternte drying nd wetting in the soil hd the compenstory effect on lef growth of mize. Yng et l. (23) showed tht lternte irrigtion could sve irrigtion wter, nd hd slight effect on mize height nd lef growth. In this study, the stem dimeter of AFI 2 ws significntly greter thn tht of CFI t the seedling nd mturity stges, which ws eneficil for strong seedling nd lodging CIGR XVII th World Congress Quéec City, Cnd June 13-17, 2 13
resistnce. Compred to CFI, AFI 2 hd slight difference in plnt height ut significnt difference in LAI t the mturity stge. Thus CFI promoted the growth of mize height nd LAI. However, AFI inhiited the redundncy growth of mize. At the erly growth stge, mize with CFI firstly reched the mximum filling rte, however, t the lter growth stge, mize with AFI 2 hd greter filling rte thn CFI. Moreover, AFI 2 hd lower yellow leves, indicting AFI cn keep more green leves nd higher filling rte t the lter growth stge. In the CFI tretment, soil wter minly infiltrted to the deep lyer nd soil wter content in the sme depth ws the mximum t the sme stge, indicting tht soil wter my increse the deep percoltion. But in the AFI tretment, the infiltrtion nd lterl leching simultneously fter irrigtion my reduce the deep percoltion nd improve WUE, which ws in greement with the result of Pn et l. (2). Ling et l. (2) nd Kng et l. (21) suggested tht AFI could sve wter y more thn 33.3% without yield reduction when compred to CFI. This study indicted tht lternte drying nd wetting in the soil significntly reduced evpotrnpirtion ut improved yield components nd significntly incresed mize yield. Compred to CFI, AFI 2 incresed WUE, WUE iomss nd yield y 22.2%, 12.4% nd 4.8%, respectively. However, AFI 1 significntly reduced grin yield lthough it sved irrigtion wter nd improved WUE. Soil slt content nd temperture were seprtely nlyzed for different irrigtion methods in this study. However, crop growth nd yield were influenced y the interction of wter, het nd electric conductivity, which needs further reserch. CONCLUSIONS Alternte furrow irrigtion incresed the spce for wter infiltrtion nd reduced soil evportion loss. Reltionships etween soil evportion nd soil wter content nd LAI were shown in the exponentil functions. AFI hd lower electric conductivity in the - cm soil lyer. Het resource ws efficiently utilized y mize with AFI, which ws eneficil for crop growth. The redundnt growth ws inhiited, mize-lodging tolernce ws improved, nd WUE ws significntly incresed under AFI with suitle irrigtion mount. Compred to the CFI tretment, AFI 2 incresed yield nd WUE y 4.8% nd 22.2%, respectively. ACKNOWLEDGEMENTS We cknowledge the finncil supports from the Ntionl Nturl Science Foundtion of Chin (42722, 577971), the Ntionl High-Tech 863 Project of Chin (26AA23). REFERENCES Allen, R.G.., Pereir L.S., Rse, D., Smith, M., 1998. Crop Evpotrnspirtion. Guideline for Computing Crop Wter Requirements, Irrigtion nd Dringe, Pper no.56. FAO, Rome. Crevoisier, D., Popov, Z., Milhol, J.C., Ruelle, P., 28. Assessment nd simultion of wter nd nitrogen trnsfer under furrow irrigtion. Agriculturl Wter Mngement, 95(4), 354-366. De Medeiros, G.A., Arrud, F.B., Ski, E., Fujiwr, M., 21. The influence of crop cnopy on evpotrnspirtion nd crop coefficient of en (Phseolus vulgris L.). Agriculturl Wter Mngement, 49, 211-224. De Souz, C.R., Mroco, J.P., Dos Sntos, T.P., Rodrigues, M.L., Lopes, C.M., Pereir, J.S., Chves, M.M., 23. Prtil root zone drying: regultion of stomtl perture nd CIGR XVII th World Congress Quéec City, Cnd June 13-17, 2 14
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