Kumari et al.

notȱ affectedȱ significantlyȱ byȱ differentȱ applicationȱ appliedȱmetribuzinȱatȱthreeȱlevelsȱi.e.ȱ0.25ȱkg.ȱha -1 ,ȱ

ratesȱofȱmetribuzin.

0.50ȱkg.ȱha -1 ȱandȱ1.00ȱkg.ȱha -1 ȱwereȱ32.63%,ȱ24.69%ȱ

andȱ11.36%ȱrespectivelyȱatȱthreeȱdaysȱafterȱherbicideȱ

Table 1. Effect of different doses of metribuzin on plant height,

application.ȱTheȱdataȱon%ȱdissipationȱofȱherbicidesȱ

yield attributes and tuber yield of potato

revealedȱ atȱ threeȱ levelsȱ ofȱ metribuzinȱ applicationȱ

i.e.ȱ 0.25,ȱ 0.50ȱ andȱ 1.00ȱ kg.ha -1 ȱ approximatelyȱ 17.9,ȱ

Plant

No. of

Potato

Plant

19.21ȱ andȱ 27.73%ȱ ofȱ metribuzinȱ remainedȱ inȱ soilȱ

Treatments

population haulms/ tuber yield

(cm)

(No /m)

plant

(q. ha -1 )

respectivelyȱatȱ15ȱdaysȱafterȱherbicideȱapplication.

Metribuzin 0.25

55.3

4.7

3.5

200.9

Atȱ 45ȱ daysȱ afterȱ herbicideȱ application,ȱ inȱ allȱ

kg. ha -1

herbicideȱ appliedȱ treatmentsȱ moreȱ thanȱ 90%ȱ

Metribuzin

50

59.8

5.0

4.0

245.2

ofȱ herbicideȱ dissipated.ȱ Perȱ centȱ dissipationȱ ofȱ

kg. ha -1

metribuzinȱ wasȱ 94.20%ȱ inȱ metribuzinȱ 0.50ȱ kgȱ ha -1

Metribuzin 1.00

62.9

5.0

3.7

216.7

followedȱ byȱ metribuzinȱ 0.25ȱ kg.ȱ ha -1 ȱ (91.57%)ȱ andȱ

kg. ha -1

metribuzin1.00ȱkg.ha -1 ȱ(90.90%).ȱTheȱresiduesȱwereȱ

Control

55.8

5.0

3.3

119.9

belowȱdetectableȱlevelȱforȱmetribuzinȱ@ȱ0.25ȱkg.ȱha -1

CD(P=0.05)

NS

NS

NS

35.2

atȱ 75ȱ daysȱ afterȱ herbicideȱ applicationȱ indicatingȱ

thatȱ appliedȱ metribuzinȱ mightȱ haveȱ dissipatedȱ

Weedsȱ inȱ unweededȱ checkȱ (control)ȱ reducedȱ theȱ toȱ 100%ȱ completely.ȱ Howeverȱ theȱ concentrationȱ

tuberȱ yieldȱ byȱ 51.1%ȱ overȱ theȱ bestȱ treatmentȱ i.e.ȱ ofȱ metribuzinȱ 0.50ȱ kg.ȱ ha -1 ȱ wasȱ 0.005ȱ g.ȱ g -1 ȱ andȱ

metribuzinȱ 0.5ȱ kg.ȱ ha -1 .ȱ Theȱ betterȱ tuberȱ yieldȱ i.e.ȱ forȱ metribuzinȱ 1.00ȱ kg.ȱ ha -1 ȱ wasȱ 0.022ȱ g.ȱ g -1 .ȱ Theȱ

245.2ȱq.ȱha -1 ȱowedȱtoȱsuperiorȱweedȱcontrolȱdueȱtoȱ corresponding%ȱdissipationȱforȱmetribuzinȱ0.25ȱkg.ȱ

metribuzinȱappliedȱatȱrateȱofȱ0.5ȱkg.ȱha -1ȱ metribuzinȱ ha -1 ,ȱ 0.50ȱ kg.ȱ ha -1 ,ȱ 1.00ȱ kg.ȱ ha -1 ȱ wasȱ100,ȱ98.47ȱ andȱ

1ȱkg.ȱha -1ȱ beingȱstatisticallyȱatȱparȱwithȱmetribuzinȱ 96.60%ȱ respectively.ȱ Theȱ residuesȱ ofȱ metribuzinȱ

0.25ȱ kg.ha -1ȱ wasȱ theȱ nextȱ bestȱ treatment.ȱ Howeverȱ exhibitedȱaȱdecliningȱpatternȱasȱaȱfunctionȱofȱtime.ȱAȱ

unweededȱcheckȱ(control)ȱresultedȱintoȱsignificantlyȱ perusalȱofȱdataȱasȱevidentȱinȱ(Tableȱ2)ȱrevealedȱthatȱ

lowestȱyieldȱofȱpotatoȱtubers.

metribuzinȱ atȱ threeȱ applicationȱ ratesȱ i.e.ȱ 0.25,ȱ 0.50ȱ

Theȱmethodȱvalidatedȱforȱmetribuzinȱestimationȱbyȱ

andȱ1.00ȱkg.ȱha -1 ȱpersistedȱinȱsoilȱupȱtoȱ60,ȱ75ȱandȱ

gasȱ chromatographyȱ (GC)ȱ gaveȱ theȱ retentionȱ timeȱ

120ȱdaysȱrespectively.ȱThisȱindicatesȱthatȱmetribuzinȱ

ofȱ referenceȱ materialȱ 5.9ȱ minutes.ȱ Theȱ recoveryȱ

atȱhigherȱdosesȱpersistedȱinȱsoilȱforȱlongerȱdurationȱ

experimentȱ conductedȱ withȱ soilȱ andȱ potatoȱ tubersȱ

thanȱlowerȱdoses.ȱMetribuzinȱdidȱnotȱleaveȱresiduesȱ

showedȱ recoveryȱ percentageȱ aboveȱ 80%.ȱ Theȱ

inȱsoilsȱbeyondȱharvestȱofȱtheȱcropȱatȱanyȱofȱappliedȱ

recoveriesȱ ofȱ metribuzinȱ atȱ differentȱ concentrationȱ

doses.ȱ Further,ȱ theȱ examinationȱ ofȱ dataȱ (Tableȱ 2)ȱ

levelsȱwereȱwellȱwithinȱacceptableȱlimits,ȱconfirmingȱ

depictsȱthatȱrateȱofȱdissipationȱofȱmetribuzinȱinȱsoilȱ

aȱgoodȱrepeatabilityȱofȱtheȱmethod.ȱTheȱassayȱresultsȱ

wasȱrapidȱwhichȱcouldȱbeȱattributedȱtoȱtheȱfavourableȱ

ofȱ commercialȱ formulationsȱ Sencorȱ 70%ȱ (WP)ȱ

physico-chemicalȱ parametersȱ likeȱ volatilization,ȱ

revealedȱthatȱtheȱactiveȱingredientȱwasȱ69.3%ȱwithȱ

vapourȱ pressure,ȱ heavyȱ rainfall,ȱ favourableȱ

±ȱ0.3ȱstandardȱdeviation.ȱMetribuzinȱresiduesȱand%ȱ

temperature,ȱhighȱorganicȱmatterȱcontentȱandȱheavyȱ

dissipationȱdataȱinȱsoilȱatȱdifferentȱtimeȱintervalsȱasȱ

textureȱofȱsoil.

detectedȱbyȱGCȱareȱpresentedȱinȱTableȱ2.ȱTheȱinitialȱ (Audusȱ 1964,ȱ Sheetsȱ 1962,ȱ Khouryȱ et al. 2003)ȱ alsoȱ

depositsȱ ofȱ metribuzinȱ inȱ soilȱ immediatelyȱ afterȱ reportedȱ veryȱ intenseȱ andȱ rapidȱ degradationȱ ofȱ

applicationȱofȱmetribuzinȱ0.25,ȱ0.50ȱandȱ1.00ȱkg.ha -1

metribuzinȱ andȱ concludedȱ fromȱ theȱ studyȱ thatȱ

wereȱ0.190,ȱ0.328,ȱ0.660ȱandȱafterȱ3ȱdaysȱofȱherbicideȱ leachingȱbyȱrainfallȱandȱdegradationȱisȱimportantȱinȱ

applicationȱreachedȱtoȱ0.128,ȱ0.247ȱandȱ0.585ȱg.ȱg -1

disappearanceȱofȱmetribuzinȱfromȱsoil.

respectively.ȱ Theȱ correspondingȱ perȱ centȱ lossesȱ ofȱ

452