RESPONSE OF SUNFLOWER(Helium/ms annuusL.)TO VARYING TW/CPE RATIOS IN SUMMER SEASON
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Date
1998
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Professor Jayashankar Telangana State Agricultural University
Abstract
A fieldexperimentwasconductedonsandyloamsoilatCollegefarm,Acharya N.G.RangaAgriculturalUniversity,Rajendranagar,Hyderabadduring 1997—98summer seasontoinvestigatethe“Responseofsunflower(HeliantlzusannuusL.)tovarying IW/CPEratiosinsummerseason”. Thetreatmentsconsistedofdifferentirrigationschedulesbasedonirrigationwater depth (1W) : Cumulative pan evaporation (CPE) ratios viz., 0.6, 0.8, 1.0 and 1.2 throughoutthecr0plifeandtheircombinationsatvegetative andreproductivestages. Besidesthisanirrigationtreatmentbasedonschedulingirrigationsonlyatcriticalgrowth sub periods was included. Thus, constituted twelve treatments were laid out in a randomizedblockdesign withthreereplications. Thetest varietywasMSFH-8. The amountofwaterappliedateachirrigationwasequivalentto50mmdepth(1134litersper plot). Schedulingofirrigationsat 1.0IW/CPE (13)ratiothroughoutcroplife(whichrequired10irrigationsof50mmdeptheachat8daysinterval), 1.2 IW/CPE(L)ratio throughoutcroplife(whichrequired12irrigationsofSOmmdeptheachat6daysinterval) andcombinationof0.6+1.0(16),0.6+1.2(17),0.8+1.002;),0.8—1.2(19),1.0+1.2(110) lW/CPEratios(which required9-12 irrigationsof50mm deptheach withan irrigation interval of6—10days)wereon parand producedsigniticantlx Pig-her 31'.:1:1 itch-:11 lcz1i area/plant drymatteraccumulation/plant,capitulumdiameter totalnumberofseedsper plant,1000-seedweight seedyield/plant oilcontent,seedyield/haandtotaldrymatter/"ha
incomparisonto0.6IIW/CPE(1;)ratiothroughoutthecroplife,0.8IW/CPE(1;)ratio throughoutthecroplifeandcombinationsof0.6+0.8(15)and0.8+0.6(In)IW/CPE ratiosandinigationsatcriticalgrowthstagesonly(112). ThecropETawasmaximum(489.4mm)intreatment1.2IW/CPEratiothroughoutcroplife(14)closelyfollowedby1.0+1.2(110)(486.5mm)and0.8+1.2(19)(478mm) IW/CPE ratios. While lowest ETa (259 mm) was recorded when irrigations were scheduledatcriticalgrowthstages(112). Ontheotherhand,wateruseefficiencywas highest(5.10kg/ha/mm)whenirrigationswerescheduledat0.8+1.0IW/CPEratio(13). As regardsto moistureextraction pattern cropplants in adequate soil moistureregimes [13(1.0IW/CPEratiothroughoutthecroplife),I4(1.2IW/CPEratiothroughoutthecroplife),16(0.6+ 1.0IW/CPEratio),17(0.6+ 1.2IW/CPEratio),18(0.8+ 1.0 IW/CPEratio),19(0.8+ 1.2IW/CPEratio)and110(1.0+ 1.2IW/CPEratio)treatments] extractedmoremoisturefrom0-40cmsoildepthincrement;whilecropplantsinrelatively drytreatments [11 (0.6 TW/CPE ratio throughoutthe crop life), 12 (0.8 IW/CPE ratio throughoutthecroplife),15(0.6+0.8IW/CPEratio),In(0.8+0.6IW/CPEratio),and112 (irrigationsatcritical grtstages)treatments] extractedbulkoftheirmoisture from lowerdepthsi.e.,20—60cm. Crop coefficients for sunflower ETa were developed based on open panevaporation methodandcalculation ofnet irrigationrequirementand gross irrigation requirement usingKcvalueswasdemonstrated. Theseasonalnetirrigationrequirement was 463.2 mm, while the gross irrigation requirement at field inlet and head works amountedto6617m3and 11580m3 respectively.Thepeakim'gationrequirementwas 4232In. ThecropyieldresponsetoseasonalETawasfoundtobe linearwithanR2of0.958. Seedyieldshowedsignificantpositivecorrelationwithplantheight,leafareaper plant,drymatterperplant,diameterofcapitulum,effectiveseedsperplant,totalnumberof seedsperplantandtestweight. Variationofplantwaterstressparametersviz,relativewatercontent,leafwaterpotential, diffusive resistance, transpiration rate andleaftemperature were largely a functionofwaterapplicationi.e.,IW/CPEratiosemployedduringthecropgrowingseason for scheduling irrigations. Seed yield and crop ETa showed significantly positive correlationwithrelativewatercontent,leafwaterpotentialandtranspirationrate,whileit was negativewithdiffusiveresistanceandleaftemperature.
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D5695