(Lens culinaris L.) Agronomy

13 Pages·2017·0.59 MB·English

agronomy
Article
Impacts of Trace Element Addition on Lentil
(Lens culinaris L.) Agronomy
Md.MoshiulIslam1,*,Md.RazaulKarim1,Md.MoinulHosainOliver2,TahminaAkterUrmi3,
Md.AshrafHossain4andM.MoynulHaque1
1 DepartmentofAgronomy,BangabandhuSheikhMujiburRahmanAgriculturalUniversity,
GazipurP.O.Box1706,Bangladesh;[email protected](M.R.K.);[email protected](M.M.H.)
2 DepartmentofAgriculturalEngineering,BangabandhuSheikhMujiburRahmanAgriculturalUniversity,
GazipurP.O.Box1706,Bangladesh;[email protected]
3 DepartmentofSoilScience,BangabandhuSheikhMujiburRahmanAgriculturalUniversity,
GazipurP.O.Box1706,Bangladesh;[email protected]
4 DepartmentofSoilScience,BangladeshAgriculturalResearchInstitute,GazipurP.O.Box1701,Bangladesh;
[email protected]
* Correspondence:[email protected];Tel.:[phone]
(cid:1)(cid:2)(cid:3)(cid:1)(cid:4)(cid:5)(cid:6)(cid:7)(cid:8)(cid:1)
(cid:1)(cid:2)(cid:3)(cid:4)(cid:5)(cid:6)(cid:7)
Received:27May2018;Accepted:14June2018;Published:27June2018
Abstract: Adequate supply of micronutrients is important for the proper growth and yield of
lentil, particularly in poorly fertile soil. This study was carried out to understand the effects of
zinc (Zn), boron (B), and molybdenum (Mo) on the growth and yield of lentil, and how these
elementscanhelpmanagesoilfertilityissues. Inthisregard,themorpho-physiologicaltraitsoflentils
(BARI Masur-7) were collected from two experiments receiving the same treatments carried out
duringconsecutiverabiseasonsof2015–2016and2016–2017. Theexperimentswerelaidoutwitha
randomizedcompleteblockdesignhavingeighttreatments,andwasreplicatedthrice.Thetreatments
wereT (Control),T (Zn kgha−1),T (B kgha−1),T (Mo kgha−1),T (Zn B kgha−1),
1 2 2.0 3 1.5 4 1.0 5 2.0 1.5
T (Zn Mo kgha−1),T (B Mo kgha−1),andT (Zn B Mo kgha−1). Theresultsrevealed
6 2.0 1.0 7 1.5 1.0 8 2.0 1.5 1.0
thattheapplicationofmicronutrientseithersinglyorincombinationhadsignificanteffectsonthe
plantheight,numberofbranchesperplant,numberofpodsperplant,numberofseedsperpod,
thousandseedweight,andtheseedyieldoflentil. Themaximumseedproductionwas,however,
observedinplotsreceivingtreatmentT ,i.e.,thecombinedapplicationofZn,B,andMo. Agronomic
8
biofortificationalsohadsignificantlyincreasedproteincontentoflentilseedswhileaffectingthemacro
andmicronutrientcontentoflentilseed. Theseresultssuggestthatanymicronutrientdeficiencies
mightleadtoayieldlossoflentil,andsuchascenariocouldbeavoidedbyacombinedapplication
ofmicronutrientsataproportionatelevel.
Keywords: micronutrients;lentil;cropcharacteristics;yieldcomponent;seedquality;soilproperties
1. Introduction
Lentil(LensculinarisL.)isanediblepulsethatbelongstothefamilyFabaceae. Humanshave
knownlentilssincethebeginningofcivilization. ItisoneofthepopularpulsecropsinBangladesh.
Lentilseedcontains25%protein,1.1%fat,59%carbohydrate,andisalsorichinimportantvitamins,
minerals, and soluble and insoluble dietary fiber [1]. Due to the overpopulation of the country,
the majority of fertile agricultural lands are occupied with cereal crops. This is why pulse crops
aregrowninmarginalandpoorlyfertilesoilsunderrain-fedconditionsinBangladesh. Oneofthe
majorconstraintsofpulsesproductionisthelackofpropermanagementpracticesthathascausedthe
continuousdepletionofmicronutrientsduetointensivecropcultivation[2].Therefore,theintroduction
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ofpropermanagementpractices,i.e.,balancingthesupplyofmacroandmicronutrients,mayplaya
majorroleinincreasingtheproductionoflentil.
Lentil production is largely influenced by the genotypic potential and the resistance to biotic
andabioticstresses[3]. However,amongvariousedaphicfactors,theavailabilityofadequateplant
nutrientsisofprimeimportance. Inparticular,micronutrientswerereportedtohaveinfluencedthe
growthandyieldoflentil[4,5]. Micronutrientscontributesubstantiallytotheachievementofhigher
productionbyinfluencingthesymbioticnitrogen-fixingprocess,wheremicronutrientdeficienciescan
limitnitrogenfixationbylegume-rhizobiumsymbiosisandinfluencetheeffectiveuptakeofdifferent
plantnutrients. Zinc(Zn),forinstance,playsanimportantroleinthebiosynthesisofplanthormones,
mainlyindoleaceticacid[6]. Manyotherenzymessuchasthealcoholdehydrogenase(EC1.1.1.1),
superoxidedismutase(EC1.15.1.1),carbonicanhydrase(EC4.2.1.1),andRNApolymerase(EC2.7.7.6)
includezincasacofactor. Itis,therefore,evidentthatzincdeficiencymayinhibitproteinsynthesis
in plant. Zn deficiency also reduces the water uptake by plants, affecting water use efficiency [7],
nodulation, and nitrogen fixation [8]. In addition, Zn uptake is positively correlated with organic
mattercontentinsoil[8,9]. Sandysoilswithlessorganicmatterproduceloweryieldsduetothepoor
utilizationofZn[10].
Boron (B) is one of the most import trace elements essential for plants. Boron can influence
theabsorptionofN,P,andK,anditsdeficiencycanchangetheoptimalequilibriumofthosethree
macronutrients. Boronalsoplaysakeyroleinsugartranslocation,nitrogenfixation,proteinsynthesis,
sucrosesynthesis,cellwallcomposition,membranestability,andK+transport[11]. Borondeficiency
leadstosterilityinplantsbythemalformationofreproductivetissuesaffectingpollengermination,
andresultinginincreasedflowerdropandreducedfruitset[12]. Theotherimportantmicronutrient
essentialfortheproperfunctionofnitrogenaseenzymeofRhizobiumbacteriaisMolybdenum(Mo).
Itisalsothecofactorforthenitratereductaseenzymethatisinvolvedinnitrogenassimilation[13].
Molybdenum,beingaconstituentofnitratereductaseandnitrogenaseenzymes,isassociatedwith
ammoniareductionandnitrogenfixation,anditsdeficiencyadverselyaffectsthegrowthandyieldof
crops[11]. InMo-deficientcrops,theflowersproducedarefewerinnumber,smallerinsize,andmany
ofthemfailtoopenortomature,leadingtolowerseedyield[8].
Itisreportedinthescientificcommunitythattheapplicationofmicronutrientsincreasesnodule
formation,micronutrientuptake,andpostharvestsoilproperties[5,14,15]. Severalresearchershave
alsoreportedthattheconjunctiveuseofdifferentmicroandmacronutrientssignificantlyincreases
seedyieldby55–60%,ofwhich20–25%couldbeascribedtothemicronutrients[4,14,15]. Valencianoet
al.[16]foundthatZnapplicationwasmoreefficientinchickpeawhenitwasappliedinconjunction
withboronandmolybdenum. Quddusetal.[17]reportedthatmanysoilsofBangladesharedeficient
inzinc(Zn),boron(B),andmolybdenum(Mo),whichcausespoorcropyields. Thebeneficialeffects
ofthesethreemicronutrientsongroundnut,soybean,chickpea,andmungbeanhavealreadybeen
reported in Bangladesh. However, their effect on lentil production is yet to be fully understood.
Thepresentstudywasthereforeundertakentoevaluatetheeffectsofmicronutrientsonseedyield,
nutrientuptake,andthepostharvestsoilnutrientstatusoflentilfield.
2. MaterialsandMethods
2.1. ExperimentalSiteandSoil
The field experiment was conducted at the research field of the Pulses Research Sub-Station,
BangladeshAgriculturalResearchInstitute(BARI),Gazipur,Bangladesh,duringthewinterseason
(NovembertoFebruary)of2015–2016and2016–2017.Thesiteislocatedat24◦0/Nlatitudeand90◦25/E
longitudeatanelevationof8.4mabovesealevel. Thesoilofthestudyareabelongstothechhiata
seriesundertheagroecologicalzone(AEZ)MadhupurTract(AEZ-28). Theexperimentalsitehasa
subtropicalhumidmonsoonclimaticcondition. Itischaracterizedbycomparativelyhighmonsoon
rainfall,highhumidity,andhightemperature,longdayswithlessclearsunshine,andsometimesthe
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skyremainscloudyforheavyrainfallduringtheperiodfromApriltoSeptember. Scantyrainfall,low
humidity,lowtemperature,shortdays,andmoreclearsunshinecharacterizetheperiodfromOctober
toMarch. Theaveragetemperaturerangesfrom15.0–36.1◦Candaverageannualrainfallvariesfrom
1500–2200mmaroundtheyear. Initialsoilsamples(0–15cmdepth)werecollectedfromdifferentspots
oftheexperimentalfieldandthecharacteristicsoftheexperimentalsoilaregiveninTable1.
Table1.Physicalandchemicalpropertiesofthesoilusedintheexperiments.
SoilProperties Value
Sand% 26.28
Silt% 38.20
Clay% 35.52
Texturalclass(0–15cm) Clayloam
Particledensity(gcm−3) 2.51
Bulkdensity(gcm−3) 1.35
Porosity(%) 46.22
pH 6.6
ExchangeableK(meq.100g−1) 0.11
ExchangeableCa(meq.100g−1) 6.01
ExchangeableMg(meq.100g−1) 2.02
Organicmatter(%) 1.28
TotalN(%) 0.057
AvailableP(µgg−1) 23.5
AvailableS(µgg−1) 26.0
AvailableZn(µgg−1) 1.31
AvailableB(µgg−1) 0.16
AvailableMo(µgg−1) 0.072
2.2. ExperimentalDesignandTreatments
The experiment was laid out in a randomized complete block design (RCBD) with eight
treatmentsandthreereplications. Theplotsizewas4m×3m. ThetreatmentswereT (Control),
1
T (Zn kgha−1),T (B kgha−1),T (Mo kgha−1),T (Zn B kgha−1),T (Zn Mo kgha−1),
2 2.0 3 1.5 4 1.0 5 2.0 1.5 6 2.0 1.0
T (B Mo kgha−1),andT (Zn B Mo kgha−1). Basalapplicationoffertilizerwasmadewith
7 1.5 1.0 8 2.0 1.5 1.0
15 kg nitrogen (N), 20 kg phosphorus (P), 30 kg potassium (K), and 10 kg sulfur (S) ha−1 in all
plots. Fertilizersofeachtreatmentwereappliedtotheirrespectiveplotsatthefinallandpreparation.
ThesourcesofN,P,K,S,zinc(Zn),boron(B),andmolybdenum(Mo)wereurea,triplesuperphosphate
(TSP),muriateofpotash(MoP),gypsum,zincsulfate,boricacid,andsodiummolybdate,respectively.
Disease-free vigorous lentil (BARI Masur-7) seeds were sown on 8 November 2015 and 2016 with
thespacingof30cm×5cm. Theseedratewas30kgha−1. Standardcropmanagementpractices
wereemployed. Nopestsanddiseaseswereobservedduringtheexperimentalperiod. Cropswere
harvestedatmaturity. Dataonyieldcontributingcharacterswererecordedfrom10randomlyselected
plantsfromeachplot. Theseedyield(kgha−1)wasrecordedbythewholeplottechnique. Theseed
yieldwasadjustedto10%moisturelevel[18]. Theadjustedseedyieldat10%moisturelevelperplot
wasconvertedtoseedyieldaskilogramperhectare.
2.3. ProteinPercentage
Theproteinpercentageinlentilseedwascalculatedconsideringthepulsesfoodfactor5.30[19].
Theproteincontentwasmeasuredbymultiplyingthe%Ncontentofseedwiththepulsesfoodfactor
5.30(%N×5.30).
2.4. ChemicalAnalysisofPlantSamples
The collected grain and straw were air-dried in ambient conditions and then oven-dried at
65–70◦Cfor72h. ThedriedsampleswerefinelygroundbyusingaWiley-Millwithstainlesscontact
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pointstopassthrougha60-meshsieve. Groundplantsamplesweredigestedwithdi-acidmixture
(HNO HClO )(5:1)asdescribedbyPiper(1966)[20]forphosphorus(P),potassium(K),sulfur(S),
3 4
zinc(Zn),andboron(B).TotalnitrogenwasdeterminedusingKjeldhalsystems[21]. Phosphoruswas
determinedcolorimetricallyusingthevenadomolybdateblueascorbicacidmethodbydoublebeam
spectrophotometry(Modelno. 200-20,Hitachi,Tokyo,Japan)[22]. Potassiumandzincconcentrations
inthedigestweredirectlymeasuredbyatomicabsorptionspectrophotometry(ModelNo.VARIAN
SpectrAA55B,Adelaide, Australia)andthesulfurconcentrationwasdeterminedbytheturbidity
methodusingBaCl byspectrophotometry[23]. Theboronconcentrationwasalsodeterminedby
2
spectrophotometryfollowingtheazomethine-Hmethod[23].
2.5. SoilAnalysis
Soilsampleswerecollected(upto0–15cmdepth)attheinitialstageandalsoafterharvestfrom
fourdifferentspotsineachplot. Thecompositesoilsampleofeachplotwasbroughttothelaboratory
fordifferentsoilanalyses.
Particlesizeanalysisofthesoilwasconductedusingthehydrometermethod[24]. Thetextural
classwasdeterminedusingMarshall’sTriangularCoordinatesoftheUSDAsystem.
Particledensitywasdeterminedbythevolumetricflaskmethod[24]usingthefollowingformula:
Ms
Particledensity(Dp) = gcm−3
Vs
where
D =Particledensity(gcm−3);
P
Vs=Volumeofsoilsolid(cm−3);
Ms=Weightofsoilsolid(g).
Bulkdensitywasdeterminedbythecoresamplermethod[24]usingthefollowingformula:
Ms
Bulkdensity(Db) = gcm−3
Vt
where
Db=Bulkdensity(gcm−3);
Ms=Massofsoilsolid(g);
Vt=Totalvolumeofsoil(cm−3).
Soilporositywascalculatedfromtheresultsofparticledensityandbulkdensityas:
Dp−Db
Soilporosity= ( )×100
Dp
where
Dp=Particledensity(gcm−3);
Db=Bulkdensity(gcm−3).
SoilpHwasmeasuredwiththehelpofaglasselectrodepHmeterusingasoilwatersuspension
of1:2.5asdescribedbyReference[23]. Organiccarbonwasdeterminedfollowingthewetoxidation
methodasdescribedbyReference[23]andtheorganicmattercontentwascalculatedbymultiplying
the%organiccarbonwiththeVanBemmelenfactor1.73[25]. Totalnitrogenwasdeterminedusing
Kjeldhalsystems[21]. Calciumandmagnesiumweredeterminedbytheammoniumacetateextraction
method[26]. Phosphoruswasdeterminedcolorimetricallyusingthevenadomolybdateblueascorbic
acid method by double beam spectrophotometry (Model no. 200-20, Hitachi, Tokyo, Japan) [22].
Potassium and zinc concentrations in the digest were directly measured by atomic absorption
Agronomy2018,8,100 5of13
spectrophotometry(ModelNo.VARIANSpectrAA55B,Australia)andthesulfurconcentrationwas
determinedbytheturbiditymethodusingBaCl byspectrophotometry[23]. Theboronconcentration
2
wasalsodeterminedbyspectrophotometryfollowingtheazomethine-Hmethod[23].
2.6. StatisticalAnalysis
Thecollecteddatawereanalyzedtoassesstheirstatisticalsignificance. Statistix10programwas
usedtoperformstatisticalanalysis(www.statistix.com). Meanswereseparatedbytheleastsignificant
difference(LSD)testata5%levelofsignificance[27].
3. ResultsandDiscussion
3.1. EffectofMicronutrientsonMorpho-PhysiologicalCharactersofLentil
3.1.1. PlantHeight
Plantheightisthemostimportantcharacteristicofthemorpho-physiologywhichalsoactsasa
keytoshootyieldaswellastotalbiomassproduction. AgronomicbiofortificationwithZn,B,and
Mosignificantlyincreasedtheplantheightoflentil(Table2). Thehighestplantheight(35.9cm)was
recordedfromtheT treatmentwhichwasstatisticallysimilartoT ,andthelowest(31.8cm)was
8 5
recordedfromtheT (control)treatment(Table2). Aswithotherleguminouscrops,Znapplication
1
resultedinmorevegetativegrowth[28],leadingtohigherplantheight. Differentmicronutrientsmight
havehelpedinthesynthesisoftheauxinindoleaceticacidandincreasedtheplantheight.
Table2.EffectofZn,B,andMoapplicationsongrowthandyieldcharactersoflentil.Averagesfrom
threeindependentexperimentsareshown(meanof2yearsofdata).
Plant 1000 Seed Seed
Branches Pods Seeds
Treatments Height Plant−1 Plant−1 Pod−1 Seedswt. Yield Protein
(cm) (gm) (Kg/ha) (%)
T =Control 31.8e 2.54c 36.9e 1.62d 17.3c 822d 20.8b
1
T =Zn2.0kgha−1 34.7bc 2.74b 51.1bcd 1.77bc 18.7b 1081bc 24.8a
2
T =B1.5kgha−1 34.1cd 2.76b 48.2cd 1.80b 18.6b 1066c 24.6a
3
T =Mo1.0kgha−1 33.5d 2.69bc 48.0d 1.76bc 18.3b 1015c 25.3a
4
T =Zn B 35.1ab 3.04a 62.0a 1.88a 19.6a 1203ab 25.2a
5 2.0 1.5
T =Zn Mo 34.9bc 2.85b 52.9b 1.79bc 18.4b 1105bc 25.6a
6 2.0 1.0
T =B Mo 34.8bc 2.84b 52.4bc 1.78bc 18.2b 1096bc 25.8a
7 1.5 1.0
T =Zn B Mo 35.9a 3.06a 65.0a 1.90a 19.7a 1256a 26.7a
8 2.0 1.5 1.0
CV(%) 1.70 3.33 4.72 1.46 1.55 6.61 6.71
LSD(0.05) 1.04 0.164 4.29 0.046 0.504 1.27 2.92
Valueswithinacolumnhavingsameletter(s)donotdiffersignificantly(p=0.05).
3.1.2. BranchesPlant−1
Micronutrients have a significant effect on the number of branches per plant (Table 2).
Themaximumnumberofbranchesperplant(3.06)wasrecordedfromtheT treatment,whichwas
8
statistically similar to the T treatment. The minimum (2.54) was recorded from the T (control)
5 1
treatment, which was statistically similar to T (Table 2). A significant increase in number of
4
branchesperplanthasbeenreportedfollowingtheapplicationofdifferentmicronutrients[29–32]and
micronutrientmixtures[33]indifferentcrops.
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3.2. EffectofMicronutrientsonYieldComponentsofLentil
3.2.1. NumberofPodsPlant−1
The number of pods per plant is the most influential yield component, and is most closely
correlatedwithseedyield. Itisalsothemostvariablecomponent[34]. Dataregardingpodsperplant
oflentilasinfluencedbydifferentmicronutrientapplicationsisshowninTable2. Analysisofthedata
revealedthattheeffectofthetreatmentswassignificantonthenumberofpodsperplant. During
thesingleapplicationofZn,B,andMo,thehighestnumberofpodsperplant(51.1)wasobtained
fromtheT treatmentandthelowest(48.0)wasobtainedfromtheT treatment(Table2). However,
2 4
amongallofthetreatments,thehighestnumberofpodsperplant(65.0)wasrecordedfromtheT
8
treatment,whichwasstatisticallysimilartotheT treatment,whilethelowest(36.9)wasrecorded
5
fromtheT (control)treatment(Table2). Theresultsindicatethatmicronutrientshaveapositiveeffect
1
onthepodsetoflentils. Thepodsetwasincreasedby76.15%inT overthecontrol. Thiscouldbe
8
duetothegreaterroleofmicronutrientsintheproductionofindoleaceticacid(IAA),whichmay
haveresultedinmorepodsperplant[35]. Micronutrientsalsoincreasethenumberofbranchesdueto
theformationofstamensandpollens[36]. Theenhancingeffectofzinc,boron,andmolybdenumon
podsperplanthasbeenreportedinmungbean[37],chickpea[38],greengram[39],frenchbean[40],
andcowpea[15]. Theresultsofthisstudycontributetothegrowingbodyofknowledgeaboutthe
effectofthesemicronutrientsonlentils.
3.2.2. NumberofSeedsPod−1
The number of seeds per pod is the least variable yield component. It was also significantly
influencedbyagronomicbiofortification(Table2). Thehighestnumberofseedsperpod(1.90)was
obtainedfromtheT treatment,whichwasstatisticallysimilartotheT treatment,andthelowest(1.62)
8 5
wasrecordedfromtheT (control)treatment(Table2). Similarresultshavebeenreportedinthecase
1
ofmungbean[37]andgreengram[39],showingtherelevanceofthepresentstudy,andinferringthe
factthatagronomicbiofortificationmighthaveenhancedtheseedsettingthatresultedinanincreasing
numberofseedsperpod.
3.2.3. ThousandSeedWeight
Seed weight is an important quality attribute of crops. Although this character is genetically
controlled,thegrowingconditionalsoexertsconsiderableinfluenceonitsexpression. Inthepresent
study,thethousandseedweightoflentilswassignificantlyinfluencedbytheapplicationofZn,B,
andMo. Thehighestthousandseedweight(19.7g)wasobtainedfromtheT treatment,whichwas
8
statistically similar to the T treatment, and the lowest (17.3 g) was obtained from the T (control)
5 1
treatment(Table2). Thiscouldbeduetothehighermobilizationofphotosynthatestothedeveloping
seedsinT causedbytheagronomicbiofortificationofZn,B,andMo.Theresultsofthisstudyconform
8
withthefindingsofanumberofpreviousreports[37,39]formungbeanandgreengram.
3.2.4. SeedYield
Seedyieldisanimportantconsiderationforanystudyrelatingtothecommercialcultivationas
wellastheseedproductionofacrop. Seedyielddependsonthenumberofpodsperplant,seeds
perpod,andseedweight. TheresultsfromTable2indicatedthattheapplicationofmicronutrients
either singly or in combination had a significant effect on the seed yield of lentil. However, the
maximumincreaseinseedyieldwasobservedfollowingthecombinedapplicationofZn,B,andMo.
Allothertreatmentswerefoundtohavemoderatetoloweffectsinenhancingtheseedyieldofthis
crop. The increase in seed yield varied from 23.48 to 52.80% at different treatments compared to
thecontrols(Table2). Thisindicatesthefactthatagronomicbiofortificationmayhavefosteredthe
photosynthesis process and translocation of photosynthetic products to the seed as a result of an
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increaseinenzymaticactivity. Theplotslackinginoneofthemicronutrients(T ,T ,andT treatments)
5 6 7
showed lower seed yield than T treatments where Zn, B, and Mo were applied in combination.
8
Ontheotherhand,whenZn,B,andMowereappliedindividuallytosoil,theincreaseinseedyield
wasmarginalbutstatisticallydifferentfromthecontrol. Thisresultindicatesthatanymicronutrient
deficienciesmayresultinyieldloss,andthiscouldberecoverediftherelevantmicronutrientsare
applied. Thebestresultswouldthereforebeachievedifmicronutrientsareappliedinconjunction
with macronutrients to favorably influence the plant vigor, morphology, and metabolic processes.
Theresultsofthisexperimentareinagreementwiththefindingsofanumberofpreviousresearch
endeavorsinvolvingothercrops[38,40–43]. Yangetal.[44]forinstance,reportedthatthecombined
application of B with Mo or Zn resulted in higher seed yield than the application of B, Mo, or Zn
alone,andthecombinedapplicationofB,Mo,andZnincreasedtheseedyieldby68.1%comparedto
thecontrols.
3.3. EffectsofMicronutrientsontheProteinContentofLentilSeed
AgronomicbiofortificationwithZn,B,andMohadasignificanteffectontheseedproteincontent
of lentil (Table 2). The highest seed protein content (26.7%) was obtained from the T treatment,
8
whichwasstatisticallysimilartoT (25.8%),T (25.6%),T (25.2%),T (25.3%),T (24.6%),andT (24.8%).
7 6 5 4 3 2
Thelowest(20.8%)proteincontent,however,wasobtainedfromtheT (control)treatment(Table2).
1
Ithasbeenreportedthattheproteinpercentageingrainofmothbean(Vignaaconitifolia(Jacq.)Marechal)
increasedsignificantlyfollowingMoapplication[45].BarikandRout[46]alsoobservedthatagronomic
biofortificationwithMo,Zn,B,K,andSenhancedtheseedproteincontentofpulses. Thisisbecause
an increase in micronutrient availability enhances N uptake by plants through nodule formation,
whichincreasestheproteincontentinseeds[47].
3.4. EffectsofMicronutrientsontheNoduleFormationofLentil
Theresultsoftheconsecutiveexperimentsofthisstudyshowthatthenumberofnodulesperplant
wasgraduallyincreasedfrom32daysafterseeding(DAS)to62DAS,andthendecreasedregardlessof
treatment(Figure1). Theresultsalsoindicatethateverymicronutrienthasanimportantroleinnodule
formation. Thehighestnumberofnodulesperplant(58.5)wasrecordedforT after62daysofsowing,
8
whichwasstatisticallysimilartoT ,andthelowestnumberofnodulesperplant(13.7)wasrecorded
6
forT (control)at32DAS(Figure1). Fromtheresultsofdifferentdates, wefoundthatthelowest
1
numbersofnodulesperplantwererecordedat32DASand77DASwhilethehighestnumbersof
nodulesperplantwererecordedbetween47and62DAS.Itseemsthatthehighestnumberofnodules
formationoccurredduringearlytomid-floweringstages.Afterflowering,nodulesformationefficiency
wasreduced. Micronutrientsplayimportantrolesasconstituentsoforganicstructures,constituentsor
activatorsofenzymes,electroncarriers,andinosmoregulation. Micronutrientsmayalsoinfluence
N fixation in legumes and nonlegumes at various levels of the symbiotic interactions: infection
2
andnoduledevelopment, nodulefunction, andhostplantgrowth[48]. Bolanosetal.[49]studied
the effect of boron on Rhizobium-legume cell-surface interaction and nodule development in pea.
Inboron-deficientplants,thenumberofRhizobiainfectingthehostcellsandthenumberofinfection
threadswerefoundtohavereduced. Moreover,theinfectionthreadshaddevelopedmorphological
aberrationsandreducedthenodulenumber. IthasbeenreportedthattheFe-Mocofactor(FeMoco)of
nitrogenaseconstitutestheactivesiteofthemolybdenum-containingnitrogenaseproteininN2-fixing
organisms[50]. Althoughatalowsupply,molybdenumisanessentialtraceelementandisvitalforthe
synthesisandactivityofmolybdoenzymessuchasnitrogenassimilationenzyme-nitratereductaseand
thenitrogen-fixingenzyme-nitrogenase,thekeyregulatorycomponentfortheinitiationofnodulation
andthemaintenanceofnitrogenfixationinlegumes[51]. Thepresentresultsareinagreementwith
thesepreviousstudiesthatexplainedthereasonforlownoduleformulationatlaterstagesinlentils.
Agronomy2018,8,100 8of13
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Figure 1. Effects of Zn, B, and Mo on number of nodules per plant of lentil at different days after
Figure1. EffectsofZn,B,andMoonnumberofnodulesperplantoflentilatdifferentdaysafter
seeding. Averages from three independent experiments are shown. Error bars represent the SEM.
seeding. Averagesfromthreeindependentexperimentsareshown. ErrorbarsrepresenttheSEM.
Means followed by uncommon letter(s) are significantly different from each other at the 5% level of
Meansfollowedbyuncommonletter(s)aresignificantlydifferentfromeachotheratthe5%level
ofssiiggnniifificcaannccee.. NNootete: T:1T = C=oCntoronlt,r To2l ,=T Zn= 2.Z0 nkg2 .h0a−k1g, Th3 a=− B1 ,1.T5 k=g hBa−11., 5T4k =g Mhao− 11.0, Tkg h=aM−1, oT51 =.0 Zkng2.0hB1a.5−, 1,
T6 = Zn2.0Mo1.0, T7 = B1.51Mo1.0, T8 = Zn2.02B1.5Mo1.0. 3 4
T =Zn B ,T =Zn Mo ,T =B Mo ,T =Zn B Mo .
5 2.0 1.5 6 2.0 1.0 7 1.5 1.0 8 2.0 1.5 1.0
3.5. Effects of Micronutrients on the N, P, K, S, Zn, and B Content of Lentil
3.5. EffectsofMicronutrientsontheN,P,K,S,Zn,andBContentofLentil
The uptake of N, P, K, S, Zn, and B by lentil (grain and straw) was markedly influenced by
agTrhoneoumpitca bkieofoofrtNifi,caPt,ioKn, (ST,aZblne,s a3n adndB 4b).y Thleen rteilsu(gltrsa sihnoawnedd tshtraat wag)rwonaosmmica brkioefdorlytifiincafltuioenn hcaedd ab y
agrsoingonmificicanbti oinfoflruteifinccea toionn th(eT aNb lceosn3teannt dof 4le).nTtihl (esereedsu alntsd sshtroawwe).d Tthhea htiagghreosnt oNm ciocnbteinotf o(5rt.0ifi4%ca tinio sneehda d
a siagnndi fi1c.7a4n%t iinnfl sutreanwc)e woans tohbetaNinecdo nfrtoemnt tohfe lTe8n ttriela(tsmeeednt,a wndhischtr awwas). stTahtiestihciagllhye ssitmNilacro tnot Ten7 (t4(.858.0%4 %
insaenedd 1a.6n7d%1).,7 T46% (4i.8n3s%tr aanwd) 1w.6a4s%o),b Tta5 i(n4e.7d6%fr)o, mT4 t(h4.e78T%8)t,r Tea3 t(m4.6e5n%t,),w ahnidc hT2w (4a.6s8s%ta)t, iwsthicialel ltyhesi mlowilaerstt o
T7(N4. 8c8o%nteanntd (31.9.627%% i)n, Tse6e(d4 .a8n3d% 1a.1n8d%1 i.n6 4s%tra),wT)5 w(4a.s7 o6%bt)a,inTe4d( 4fr.7o8m% t)h,eT 3co(n4.t6ro5%l (T),1a tnredatTm2e(n4t.6) 8(T%a)b,lwesh 3i le
thealnodw e4s).t INt hcaosn bteenent (r3e.p9o2%rteidn tsheaetd thaen dag1r.o1n8o%miinc sbtiroafwor)tiwficaastioobnt aoifn gedrafinro lmeguthmeecso innt rfoiell(dT cotnredaittimonesn t)
1
(Tabinlecsre3asaensd N42) f.ixIatthioans abnede nnordeuploer mteadsst,h raetsuthlteinagg irno nhiogmheicr Nbi ocofonrtteinfitc iant igornaino f[5g2r,a5i3n]. le gumes in field
conditionsincreasesN fixationandnodulemass,resultinginhigherNcontentingrain[52,53].
2
Table 3. Effect of Zn, B, and Mo applications on N, P, K, S, Zn, and B content in lentil seed. Averages
from three independent experiments are shown (mean of 2 years of data).
Table3.EffectofZn,B,andMoapplicationsonN,P,K,S,Zn,andBcontentinlentilseed.Averages
fromthreeiTndreeaptemndenentst experiNm e(%nt)s arePsh (o%w)n (mKea n(%of) 2yeSa r(s%o)f daZtan). (μg g−1) B (μg g−1)
T1 = Control 3.92 b 0.22 e 0.61 c 0.13 d 59.0 d 31.2 d
TTr2e =a tZmne n2.t0s kg ha−1 N4(%.68) a 0P.2(%9 c)d 0K.6(2% c) 0.S15( %cd) Z7n0.(8µ agbg −1) 3B2.3(µ dg g−1)
T1=CTo3 n=t rBo l1.5 kg ha−1 3.942.6b5 a 00.3.202 becd 00.6.691 bcc 00.1.143 dd 655.96. 0c d 37.53 1c. 2d
T2=ZTn4 =2 .0Mkog 1h.0a −k1g ha−1 4.648.7a8 a 00.2.928c dd 00.7.662 acb 00.1.175 ccdd 677.50 .8bca b 32.73 2d. 3d
T3=BT15 .=5 Zkgn2h.0aB−1.15 4.645.7a6 a 00.3.303b acbdc 00..7699 abbc 0.02.104 bdc 70.06 5a.b6cc 40.1 3a7b.5 c
T =Mo1.0kgha−1 4.78a 0.28d 0.76ab 0.17cd 67.5bc 32.7d
4 T6 = Zn2.0Mo1.0 4.83 a 0.31 bcd 0.77 ab 0.23 b 69.3 abc 38.7 bc
T =Zn B 4.76a 0.33abc 0.79ab 0.20bc 70.0abc 40.1ab
T5=ZTn7 2=.0 BM11o..55Mo1.0 4.843.8a8 a 0.03.134b cadb 00..7871a ab 00.2.253 bb 686.19 .a3bacb c 40.63 a8.b7 bc
6 2.0 1.0
T =BT8 =M Zon2.0B1.5Mo1.0 4.858.0a4 a 0.03.436a ba 00..8861 aa 00.3.245 ab 7628.4.1 aa bc 41.450 a.6 ab
7 1.5 1.0
T =ZCnV (B%) Mo 5.064.a79 0.93.614a 07.8.864a 01.03.42 a 37.823.4 a 3.2451 .5a
8 2.0 1.5 1.0
LSD (0.05) 0.56 0.049 0.102 0.076 4.56 2.10
CV(%) 6.79 9.14 7.84 10.2 3.83 3.25
LSD(0.05)Values within a co0l.u5m6n havin0g.0 s4a9me lette0r.1(s0)2 do not0 d.0if7f6er significa4n.5t6ly (p = 0.05). 2.10
Valueswithinacolumnhavingsameletter(s)donotdiffersignificantly(p=0.05).
Agronomic biofortification with Zn, B, and Mo had a significant effect on the P and S content in
lentil (seed and straw). The highest amount of P (0.36% in seed and 0.18% in straw) was obtained
AgronomicbiofortificationwithZn,B,andMohadasignificanteffectonthePandScontent
from the T8 treatment, which was statistically similar to T7, and the highest amount of S (0.34% in
inlentil(seedandstraw). ThehighestamountofP(0.36%inseedand0.18%instraw)wasobtained
seed and 0.54% in straw) was obtained from the T8 treatment, which was not statistically similar to
fromtheT treatment,whichwasstatisticallysimilartoT ,andthehighestamountofS(0.34%in
any oth8er treatment. The lowest amount of both P and7 S was recorded from the T1 (control)
seedand0.54%instraw)wasobtainedfromtheT treatment,whichwasnotstatisticallysimilarto
treatment (Tables 3 and 4). Regarding K content,8 the highest K content in lentil seed (0.86%) was
anyothertreatment. ThelowestamountofbothPandSwasrecordedfromtheT (control)treatment
1
Agronomy2018,8,100 9of13
(Tables3and4). RegardingKcontent,thehighestKcontentinlentilseed(0.86%)wasobtainedfrom
theT treatment,whichwasstatisticallysimilartoT ,T ,T ,andT . ThehighestKcontentinlentil
8 7 6 5 4
straw (0.72%) was also obtained from the T treatment, which was not statistically similar to any
8
othertreatment. Ontheotherhand,thelowestKcontent(bothinseedandstraw)wasfoundforthe
T (control)treatment(Table3). ThehighestZncontentinlentil(72.4µgg−1inseedand49.1µgg−1
1
instraw)wasobtainedfromtheT treatment. whichwasstatisticallysimilartoT (68.1µgg−1inseed
8 7
and48.5µgg−1instraw),T (69.3µgg−1). andT (70.0µgg−1). Thelowest(59.0µgg−1inseedand
6 5
42.1µgg−1instraw)Zncontentwas. however,obtainedfromthecontrol(T treatment). Thehighest
1
Bcontentinlentil(41.5µgg−1inseedand31.7µgg−1instraw)wasrecordedfromtheT treatment,
8
whichwasstatisticallysimilartoT (40.6µgg−1inseed)andT (40.1µgg−1inseed). ThelowestZn
7 5
andBcontent(seedandstraw)wasobtainedfromcontrol(T treatment)(Tables3and4). Increasesof
1
theZnandBcontentinbothstrawandseedsgoalongwithZnandBapplicationstothesoil. Similar
resultshavebeenreportedinpreviousstudiesinvolvingdifferentcrops,wheremicronutrientswere
showntohaveinfluencedtheuptakeofN,P,K,S,Zn,andB[54–58].
Table4.EffectofZn,B,andMoapplicationsonN,P,K,S,Zn,andBcontentinlentilstraw.Averages
fromthreeindependentexperimentsareshown(meanof2yearsofdata).
Treatments N(%) P(%) K(%) S(%) Zn(µgg−1) B(µgg−1)
T =Control 1.18e 0.12e 0.59e 0.45e 42.1d 25.6d
1
T =Zn2.0kgha−1 1.42d 0.17a 0.63d 0.49d 48.2ab 26.1d
2
T =B1.5kgha−1 1.41d 0.16ab 0.64d 0.50cd 43.3cd 28.1c
3
T =Mo1.0kgha−1 1.52cd 0.15bc 0.65cd 0.48d 44.5cd 27.6c
4
T =Zn B 1.59bc 0.14cd 0.69b 0.52b 47.8ab 30.0b
5 2.0 1.5
T =Zn Mo 1.64abc 0.13de 0.68b 0.51bc 45.8bc 28.0c
6 2.0 1.0
T =B Mo 1.67ab 0.16ab 0.67bc 0.50cd 48.5ab 29.2b
7 1.5 1.0
T =Zn B Mo 1.74a 0.18a 0.72a 0.54a 49.1a 31.7a
8 2.0 1.5 1.0
CV(%) 4.62 6.17 2.56 1.90 3.48 1.93
LSD(0.05) 0.123 0.016 0.030 0.017 2.82 0.960
Valueswithinacolumnhavingsameletter(s)donotdiffersignificantly(p=0.05).
3.6. EffectsofMicronutrientsonPostharvestSoilProperties
ThepHofpostharvestsoilsslightlyincreasedinallofthetreatments(Table5)afterthe2years
of consecutive experiments. This was the result of the incorporation of lentil stover in soil. It has
beenreportedthatorganicmatterfromcropresidueincreasesthesoilpHstatusbyimprovingthe
soilbufferingcapacity[59]. Organicmatterincreasesthecationexchangecapacity,whichcontributes
toahighbasesaturationofthesoil. Asthebasesaturationincreases,therelativeamountofcations
neutralizes. Ourresultsweresupportedbymanyotherresearchers[60–62],whoreportedanincrease
of soil pH resulting from increased organic matter. It was also reported that plants can alter soil
pHbyreleasingrootexudates, suchasorganicacidanions, toenhancemineralnutrientsolubility,
aswellasbytheliberationofH+andOH− (orHCO − resultingfromOH− carbonation)inorderto
3
counterbalancecationsoranionsenteringtheroots. Thedecompositionoforganicacidanionscanalso
fosterprotonconsumptioninthedecarboxylationprocess,whichmayresultintheincreaseofsoilpH,
whichexplainstheresultsofourstudy.
TheresultsofthisstudysuggestthattheapplicationofZn,B,andModidnotaffectthemacro
andmicronutrientcontentofthesoil,nordiditaffecttheorganicmattercontent(Table5). Nonetheless,
the highest amount of organic matter (1.50%) was obtained from the T treatment and the lowest
8
(1.35%)wasfromtheT treatment. Inmostofthecases,thehighestmacroandmicronutrientcontent
1
ofthepostharvestsoilwasrecordedfromtheT treatmentandthelowestwasfromtheT treatment.
8 1
TheresultsalsoshowedthatagronomicbiofortificationwithZn,B,andMohadaprominenteffecton
theavailabilityofnutrientsinthesoil. Ithasbeenreportedthattheincorporationofpulsesstoverin
soilafterthepickingofpodsresultedinaneconomyofabout23kgN/hainthesucceedingcrop[63].
Agronomy2018,8,100 10of13
Itwasfoundthatthepulsesreceivingoptimumfertilizerhadmorepronouncedresidualeffectbothfor
macroandmicronutrientsinthesucceedingcrops[64,65]. Regardlessofthetreatmentsofthisstudy,
theconsecutiveexperimentsyieldedsimilarresultsthatmayhelpthescientificcommunitytobetter
understandthedynamicsofmicronutrientsinlentilproduction. Ourresultsalsoshedlightsonhow
suchmanagementpracticescanhelpincreasethefertilitystatusofpoorlyfertilesoils.
Table5.EffectofZn,B,andMoapplicationsonpostharvestsoilpHandthestatusofdifferentnutrients.
Averagesfromthreeindependentexperimentsareshown(meanof2yearsofdata).
Ca Mg K P S Zn B
Treatment pH OM(%) TotalN(%)
meq.100g−1 µgg−1
Initial 6.61 1.28 0.057 6.01 2.02 0.11 23.5 26.0 1.31 0.16
Criticallevel 0.12 2.0 0.80 0.20 10.0 10.0 0.60 0.2
T =Zn B Mo 6.71 1.35 0.062 5.90 2.00 0.10 24.0 25.2 1.28 0.14
1 0 0 0
T =Zn 6.78 1.45 0.064 6.01 2.00 0.11 24.5 25.3 1.41 0.15
2 2.0
T =B 6.77 1.38 0.065 6.01 2.01 0.11 24.6 25.5 1.31 0.20
3 1.5
T =Mo 6.82 1.39 0.067 6.00 2.02 0.10 24.8 25.8 1.32 0.16
4 1.0
T =Zn B 6.93 1.47 0.069 5.89 2.00 0.11 24.6 25.7 1.43 0.23
5 2.0 1.5
T =Zn Mo 6.93 1.47 0.068 5.91 2.01 0.10 24.7 25.6 1.44 0.17
6 2.0 1.0
T =B Mo 6.96 1.49 0.070 5.92 2.02 0.10 24.6 25.7 1.36 0.26
7 1.5 1.0
T =Zn B Mo 7.01 1.50 0.072 5.88 2.00 0.11 24.7 25.9 1.45 0.27
8 2.0 1.5 1.0
NS NS NS NS NS NS NS NS NS NS
NS:notsignificant.
4. Conclusions
ThisstudywascarriedouttounderstandtheroleofZn,B,andMointheproductionoflentils
and how the application of these elements can help manage soil fertility issues. In this regard,
themorpho-physiologicaltraitsoflentilswerededucedfromtwoexperimentsreceivingthesame
treatments carried out during consecutive seasons in 2015–2016 and 2016–2017. The agronomic
biofortificationhadinfluencedtheplantheight,branchperplant,and,importantly,thenumberof
nodulesperplant. Suchanintroductionofmicronutrientswasfoundtohavetriggeredmorepod
settingandmoreseedsperpod,whichultimatelyenhancedtheseedyield. TheconjunctiveuseofZn,
B,andMoalsohadasignificanteffectontheproteincontentofseeds. Thesepromisingresultssuggest
thatagronomicbiofortificationwithZn,B,andMomayberecommendedforahigheryieldoflentilin
marginalandpoorlymanagedsoilsunderrain-fedconditions.
AuthorContributions: M.M.I.,M.M.H.andM.A.H.conceivedanddesignedtheexperiments;M.M.I.,M.R.K.
andT.A.U.performedtheexperiments;M.M.I.,M.A.H.,T.A.U.andM.R.K.analyzedthedata;M.M.I.andM.A.H.
contributedreagents/materials/analysistools;M.M.I.,M.R.K.,M.M.H.O.,T.A.U.,M.A.H.andM.M.H.wrote
thepaper.
Funding:Thisresearchreceivednoexternalfunding.
Acknowledgments: TheauthorswouldliketothanktheBangladeshAgriculturalResearchInstitutefortheir
facilities,inwhichtheexperimentwasconducted.
ConflictsofInterest:Theauthorsdeclarenoconflictofinterest.
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