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Planting Date and Straw Mulch Affect Biomass Yield,Oil Yield and Oil Quality of Japanese mint (Menthaarvensis L.) Harvested at Successive IntervalsS.K. Brara, B.S. Gilla, A.S. Brara & Tarundeep Kaura

a Department of Agronomy, Punjab Agricultural University, Ludhiana 141004 Punjab, IndiaPublished online: 17 Sep 2014.

To cite this article: S.K. Brar, B.S. Gill, A.S. Brar & Tarundeep Kaur (2014) Planting Date and Straw Mulch Affect BiomassYield, Oil Yield and Oil Quality of Japanese mint (Mentha arvensis L.) Harvested at Successive Intervals, Journal of EssentialOil Bearing Plants, 17:4, 676-695, DOI: 10.1080/0972060X.2014.958549

To link to this article: http://dx.doi.org/10.1080/0972060X.2014.958549

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Planting Date and Straw Mulch Affect Biomass Yield, Oil Yield and Oil Qualityof Japanese mint (Mentha arvensis L.) Harvested at Successive Intervals

S.K. Brar, B.S. Gill, A.S. Brar * and Tarundeep KaurDepartment of Agronomy, Punjab Agricultural University, Ludhiana 141004 Punjab, India

Abstract: In northwest India Japanese mint is being cultivated during spring season and faces both theextremes of temperature. The present investigation was planned to find out the optimum time of planting andharvesting with and without application of mulch to realize high quality essential oil. The experiment was laidout in split plot design keeping combinations of four date of planting (Jan 1, Jan 15, Jan 30 and Feb 15) and twostraw mulch levels (No mulch and mulch @ 6 t/ha) in main plots and three harvesting schedules (120, 135 and150 days after planting) in sub plots. Japanese mint planted on Feb 15 recorded maximum fresh herb, dry herband oil yield, which were statistically at par with that planted on Jan 30 but were significantly higher than Jan15 and Jan 1 plantings. Application of straw mulch resulted in significant improvement in fresh herb, dry herband oil yield of Japanese mint. Fresh herb, dry herb and oil yield were significantly higher in crop harvested at150 DAP than 135 and 120 DAP. Menthol content in mint oil did not influence with change in planting date orharvesting schedules while, menthone content decreased significantly with delay in harvesting from 120 to 150DAP. A strong positive and linear relation was observed between emergence count and delay in planting ofJapanese mint. Oil yield was positively correlated with plant height, stools count and fresh herbage production,while leaf to stem ratio has positive relation with oil content.

Key words: Mentha arvensis L., planting date, harvesting schedule, straw mulch, oil yield,quality traits.

IntroductionJapanese mint or menthol mint (Mentha

arvensis L.) is an essential oil bearing industrialcrop. The aerial parts of the herb on distillationyield essential oil containing a large number ofaroma chemicals. Japanese mint is a potentialsource of natural menthol and other constituentslike mint terpenes, menthone, isomenthone,methyl acetate, etc which are widely used in thepharmaceutical, cosmetic, food and flavorindustries. Among the mint species Japanese mint(Mentha arvensis L.), peppermint (Menthapiperita L.), bergamot mint (Mentha citrataEhrh.) and spearmint (Mentha spicata L.) arereported to be cultivated on large scale in Brazil,

Japan, China, USA and India. India is currentlyproducing more than 18000 tonnes of mint oilagainst world production of 22,000 tonnes peryear and emerged as a major supplier of mint oiland menthol 3. In India, mint is mainly cultivatedin Uttar Pradesh, Punjab and Haryana over morethan 10.163 million hectares of agricultural land14. In Punjab, only two species namely, M.arvensis and M. spicata are grown on an areaabout 15,000 hectares 2, spread over districts ofLudhiana, Jalandhar, Hoshiarpur, Roopnagar,Kapurthala, Shaheed Bhagat Singh Nagar andFerozepur in sub mountain plain and central plainagro climatic regions of the state. Out of thesetwo cultivated mint species; M. arvensis occupies

ISSN Print: 0972-060XISSN Online: 0976-5026

*Corresponding author (A.S. Brar)E-mail: < braras@pau.edu > © 2014, Har Krishan Bhalla & Sons

Received 07 March 2014; accepted in revised form 12 May 2014

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predominant position and contributing more than80 per cent of total production of essential oil inPunjab. Fresh herb of M. arvensis contains 0.5 to0.8 per cent of oil, which is source of naturalmenthol (70 to 85 per cent) and number ofterpenoids of economic importance. The majorconstitutes identified in Japanese mint oil are:menthol, p-menthone, L-menthol, (+)-isomenthol, neomenthol, methyl acetate, andseries of other trace compounds 5. However,proportion of various constitutes varyconsiderably according to genetic makeup,geographical, ecological conditions and growthstage of the crop 10.

Herbage and oil yields of the Japanese mint aredependent on the technology used in raising thecrop and the prevailing climatic conditions. Outof the various agronomic practices, time ofplanting and harvesting stage are most importantfor potential yield realization in Japanese mint.Production efficiency of a crop greatly differsunder different date of planting depending uponfoliage characteristics and canopy structure. Acrop which can attain optimum leaf area indexand retains it for a longer period, is consideredmore efficient for harvesting of solar energyduring the crop season. Though the solar radiationis not a limiting factor in tropic and sub-tropics,but in north India mint crop is grown during springseason and faces low temperature along with shortday length during early stage of the crop, whichadversely affects germination and early vegetativegrowth. These climatic conditions can be easilymanipulated through change in time of plantingand application of straw mulch. Application ofmulch creates conducive micro climatic condi-tions through buffering the low soil temperaturefor emergence and early crop growth. Mulchingalso plays multipurpose role through smotheringthe weeds by cutting light penetration, conservingmoisture, improving the micro organismpopulation and nutrient dynamics whichfavourably affects the crop yield 11,15. Akhtar, et.al., 1 observed bright sun light with 30°C daytemperature as conducive climatic conditions forbetter leaf, stem and dry matter productionregardless of night temperature at various growthstages of Japanese mint. Similarly, stage of

harvesting also has great bearing on oilproductivity in Japanese mint because delayed orearly harvesting leads to reduction in oil contentin plant parts. Solomon and Beemnet 13 reportedhighest leaf to stem ratio under early harvestingthan the delayed and Guenther 9 reported leaf asthe primary source of essential oil production inmint. However, Beemnet, et. al., 4 observedsignificantly increase in fresh and dry herb yieldunder delayed harvesting up to 150 days afterplanting (DAP), which ultimately influences theoil yield per unit area. Ellis and Gaylard 8 reportedthat full bloom stage of the crop is more conduciveto obtain good quality mint oil. Therefore, presentinvestigation was planned to find out the optimumtime of planting and harvesting for higher herband quality oil in Japanese mint raised with andwithout application of mulch.

Material and methodsLocation and climate

A field experiment was conducted during springseason of 2010 and 2011 at Research Farm,Department of Agronomy, Punjab AgriculturalUniversity, Ludhiana (Punjab) India. Ludhiana issituated in trans-gangetic agro-climatic zone,representing the Indo-Gangetic alluvial plains at30° 56' N latitude, 75° 52' E longitude and analtitude of 247 m above mean sea level. This tracthas four distinct seasons namely; spring, summer,autumn and winter. The climate of this region ischaracterized as sub-tropical semi-arid with hotsummer and very cold winter. The meanmaximum and minimum temperatures showconsiderable fluctuation during summer andwinter. Maximum temperature above 38°C iscommon during summer and frequent frosty spellsare experienced during winter, especially inDecember and January. The average annualrainfall is 705 mm, approximately 80 % of whichis received during July to September. Duringwinter, rains are scanty but a few showers ofcyclonic rains are received during December-January or late spring.

MethodologyThe experiment was laid out in split plot design

in randomized block arrangement with four

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planting dates and two mulch levels in main plotsand three harvesting schedules in sub plots. Allthe treatments were replicated three times and plotsize was 2.25 m x 6 m. Soil at experimental sitewas well drained, loamy sand (79.7 % sand), withnormal reaction (pH 8.2) and electricalconductivity (0.29 dS/m), low in organic carbon(0.35 %) and available nitrogen (116.5 kg/ha),medium in available phosphorous (20.2 kg/ha)and potassium (253.6 kg/ha). Seed bed wasprepared with two cultivations with disc harrowand two ploughing with cultivator followed byplanking. Local cultivar “Kosi” was used forplanting at different dates (Jan 1, 15, Feb 1 andFeb 15) using 5.0 q/ha suckers having 2-4 nodes.Before planting suckers were dipped in 0.1 percent carbendazine 50 WP for 5-10 minutes andlaid end to end at depth of 4-5 cm in openedfurrow made with the help of single tined drilland then covered with soil. Rice straw mulch wasapplied @ 6 t/ha as per the treatments immediatelyafter the planting of suckers. A basal dose of 37.5kg N/ha, 40 kg P2O5/ha and 40 kg K2O/ha wereapplied through Urea, DAP and MOP and 37.5kg N/ha was applied at 40 days after planting astop dressing. First irrigation was appliedimmediately after planting to ensure propermoisture conditions for sprouting of the suckersand thereafter irrigation was assured accordingto need of the crop. Pendimethaline at 2.5 l/hawas applied after planting as pre emergence andtwo weeding were done at 50 and 80 DAP to keepthe proper check on weeds. To check the attackof termite and cut worm, chloropyriphos 20 ECat 5.0 litre/ha was applied twice with irrigationwater and one foliar sprays of endosulfan 35 ECat 2.5 litre/ha was also applied to check the attackof gram caterpillar. The crop was harvestedmanually with sickle about 5 cm above the groundlevel as per the harvesting schedule (120, 135 and150 DAP) and fresh weight from net plots wastaken immediately and then a sample of 500 gfresh herb was kept in oven at 60 °C temperaturetill constant weight to convert the yield on dryweight basis. Data on emergence and periodicstool count was recorded from two spots of onemetre row length selected randomly in each plot.Periodic plant height was recorded from randomly

selected five plants in each plot. To record theperiodic dry matter data plants from half metrerow length were harvested and then dried in ovenat 60°C temperature till a constant weight. Weedbiomass data was recorded from one square metrearea at 50 DAP before weeding from each plotsand then kept in oven at 60°C temperature till aconstant weight.

Essential oil content in 500 g of fresh herb fromeach plot was extracted with Clevenger’sapparatus at harvesting of the crop. Oil percentagewas calculated on v/w basis on fresh herb weight.The oil samples were dried using anhydroussodium sulphate and stored at 5°C in sealed grassvials prior to the analysis of essential oil profile.The oil samples from each plot were chemicallyanalyzed on gas chromatography using capillarycolumn (30 m x 0.25 mm, 0.25 μm). Thetemperature of oven and injector was kept at250°C and that of detector at 270°C. Thetemperature was programmed as: injectortemperature 250°C; column temperature wasraised from 60 to 270°C at 4°C/min and then heldat 270°C for 5 min; carrier gas N2; ignition gasH2; injection volume 2 μl. Standard compoundsof menthol and menthone were used to identifyretention time for peaks of both constitutes in theoil while using acetone as solvent for preparationof the standard curve to check the reproducibilityof the results.

Compound identification was calculated basedon retention time of standard compounds(Menthol and menthone). Relative amounts (peakarea percent basis) of menthol and menthone werecomputed from peak area without FID responsefactor corrections. Physical properties viz.specific gravity, optical rotation and refractiveindex and chemical properties viz. acid, ester andsaponification value of M. arvensis oil weredetermined according to the specification ofIndian Standard Institution (IS: 326-1968).

Statistical analysisAnalysis of variance was performed on growth,

yield, and quality parameters using PROC GLMprocedure of SAS software version 9.3 of the SASsystem for windows. The difference betweenmeans of various treatments was compared with

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Fishers’ least significant difference test at 5 %probability level. Since trends in results weresimilar during both the years, data was pooled,keeping years as main factor to increase theprecision for main plot (Main plot = Planting datesx Mulch levels). Significant interaction betweenvarious parameters was observed using either alinear or quadratic regression model expressedas:

All the regression fit were produced using SPSS18.0 software (SPSS Institute Inc.).

ResultsWeather parameters

The weather parameters did not differ muchduring 2010 and 2011 crop season except therainfall (Fig. 1 & 2). Total rainfall during cropseason (1st to 28th standard meteorological week)was 383 mm in 2010 and 521 in 2011 with welldistribution pattern. The minimum temperatureranged between 5.5 to 29.1°C and 4.1 to 29.2°Cwhile maximum temperature ranged between 27.9to 41.7°C and 29.1 to 41.9°C and meantemperature remained between 11.9 to 35.5°C and11.0 to 36.7°C during 2010 and 2011, respecti-vely. The lowest minimum temperature wasrecorded in 3rd and 4th meteorological weeks andthe highest maximum temperature was recordedin 25th and 20th meteorological weeks during 2010and 2011, respectively. The mean relativehumidity ranged from 30.6 to 92.4 per cent and39.6 to 89.6 per cent during 2010 and 2011,respectively.

Soil temperatureThe average soil temperature regimes

experienced by crop increased with delay inplanting and soil temperature of 15.1, 13.0, 10.4and 9.2°C per day was recorded in crop plantedon Feb 15, Jan 30, Jan 15 and Jan 1 from plantingof the suckers to start of the emergence (Fig. 3),respectively. Crop planted on Feb 15 and Jan 30experienced 4.7 & 5.9 and 2.6 & 3.8°C per dayhigher temperature regimes as compared toplanted on Jan 15 and Jan 1 from planting of the

suckers to start of the emergence, respectively.Average soil temperature was also remainedhigher in later planting dates from start tocomplete of the emergence and crop planted onFeb 15 and Jan 30 availed 2.9 & 3.5 and 1.1 &1.7°C per day higher temperature as compared toplanted on Jan 15 and Jan 1 (Fig. 4), respectively.Soil temperature was also remained 1.6°C per dayhigher in crop raised with surface straw mulchfrom planting to start of emergence than no mulchplots and corresponding figure was 1.1°C per dayhigher from start to final emergence count (Fig 3& 4). A positive and linear relationship wasobserved between delay in planting date andaverage soil temperature with R2 value of 0.976and 0.980 for crop raised with and without mulchfrom planting to start of emergence, respectively.The corresponding values of R2 remained 0.931and 0.952 for with and without mulch treatmentsfrom start to complete of emergence, respectively.

EmergenceThe number of days to start emergence decrea-

sed progressively with delay in planting date fromJan 1 to Feb 15 (Fig. 3). The crop planted on Jan1, Jan 15, Jan 30 and Feb 15 took 24, 17, 10 and7 days to start emergence, respectively. Similarly,crop planted on Jan 1, Jan 15, Jan 30 and Feb 15took 20, 13, 11 and 10 days from start to completeemergence, respectively (Fig. 4). Japanese mintraised without application of straw mulch took 3days more to start emergence as compared to cropraised with mulch. Similarly, mulched plots alsotook 3 less from start to complete emergence anda constant population of Japanese mint wasrecorded at 40, 27, 19 and 15 DAP in mulchedplots and planted on Jan 1, Jan 15, Jan 30 andFeb 15 as against 48, 32, 23 and 18 days weretaken by crop raised without mulch (Fig. 3 & 4),respectively. A strong linear but negative relationwas observed between delay in planting date anddays taken to start and complete of emergence(Fig. 3 & 4). However, a curvilinear relation wasobtained between average soil temperature anddays taken to start and complete of emergenceboth for mulched as well as no mulched plots (Fig.5 & 6).

Emergence count per square metre increased

y = β0 + β1x + εy = β0 + β1x + β1x

2 + ε

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significantly with delay in planting from Jan 1 toFeb 15 and maximum plant count per unit areawas observed in Feb 15 planted crop. Emergencecount was 48.6 & 37.3 and 67.2 & 54.5 per centhigher in Jan 30 and Feb 15 planted crop ascompared to that of Jan 1 and Jan 15 (Fig. 7),respectively. Similarly, emergence count at

constant population was also 10.2 per cent higherin mulched plots as compared to no mulched plots,respectively. A positive and linear relation wasobserved between emergence count and delay inplanting date with R2 value of 0.938 and 0.948for crop raised with and without mulch,respectively.

Fig. 3. Effect of date of planting on average soil temperature and days tostart emergence of Japanese mint raised with and without mulch

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Weed dry matterWeed dry matter increased significantly with

delay in planting dates and a positive linearrelation was observed between weed dry matterand delay in planting date with R2 value of 0.987and 0.990 in crop raised with and without mulch(Fig. 8), respectively. However, significantreduction in weed dry matter was observed in crop

raised with surface straw mulch than no mulchplots.

Growth parametersPlant height, stools count and dry matter

accumulation in Japanese mint were influencedsignificantly with change in planting dates at 60,90 DAP and at harvest (Table 1 & 2). At 60 DAP,

Fig. 4. Effect of date of planting on average soil temperature and days tocomplete emergence of Japanese mint raised with and without mulch

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Fig. 5. Relation between days taken to start emergence of Japanese mintraised with and without mulch and average soil temperature

plant height, stools count and dry matteraccumulation were increased significantly andprogressively with each delay in planting fromJan 1 to Feb 15, while at 90 DAP differences wereat par between Jan 30 and Feb 15 planted crop.At harvest, maximum value of growth parameterswas observed in crop planted on Feb 15 which

was statistically at par with crop planted on Jan30 but both were significantly superior to cropplanted on Jan 15 and Jan 1.

Application of straw mulch had significanteffect on growth attributes of mint at all thegrowth stages of crop. At 60, 90 DAP and atharvest, crop raised with surface straw mulch

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Fig. 6. Relation between days taken to complete emergence of Japanese mintraised with and without mulch and average soil temperature

resulted in significantly taller plants with higherstools count and dry matter accumulation ascompared to crop raised without mulch. At 60DAP, interaction effects of planting dates andmulch levels were found to be significant for plantheight and dry matter accumulation (Fig. 9). Plantheight and dry matter accumulation wasmaximum in crop planted with mulch on Feb 15

which was significantly higher than all othercombination of mulch levels and planting dates.However, crop planted on Jan 30 with mulch gavestatistically at par plant height and dry matter tothat planted on Feb 15 without application ofmulch. Plant height, stools count and dry matteraccumulation also increased significantly witheach delay in harvesting from 120 to 150 DAP.

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Fig. 7. Effect of planting dates on emergence count ofJapanese mint raised with and without mulch

Fig. 8. Effect of planting dates on weed dry matter (50 DAP)in Japanese mint raised with and without mulch

Interaction between planting dates and harvestingschedules was also found to be significant for allthree growth parameters (Fig. 10). The maximumplant height, stools count and dry matteraccumulation was observed in crop planted on

Feb 15 and harvested at 150 DAP which wasstatistically at par with that planted on Jan 30 andharvested at 150 DAP but both were significantlyhigher than all other combinations of planting dateand harvesting schedule. Leaf to stem ratio was

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Fig. 9. Interactive effect of planting dates and mulch levels on plant heightand dry matter accumulation at 60 DAP in Japanese mint

not influenced significantly with change inplanting dates at all growth stages. At 60 DAP,Jan 1 planted crop gave significantly higher leafto stem ratio than all later planting dates, while at90 DAP and at harvest differences were nonsignificant. Leaf to stem ratio was significantlyhigher in crop raised without mulch at 60 and 90

DAP while differences were statistically at par atharvest between mulched and no mulched plots.There was a decreasing trend in proportion ofleaves was observed with delay in harvesting from120 to 150 DAP. The maximum leaf to stem ratiowas observed in crop harvested at 120 DAP andfurther delay in harvesting decreased the leaf to

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Table 1. Effect of planting date and mulch levels on periodic plant height, stools count, drymatter accumulation and leaf to stem ratio of Japanese mint (pooled data of 2010 and 2011)

Treatment Plant height Stools count Dry matter Leaf : Stem(cm) (no./m2) (g/ m2)

60 DAP 90 DAP 60 DAP 90 DAP 60 DAP 90 DAP 60 DAP 90 DAP

Planting date1 Jan (D1) 14.7 33.7 31.5 39.3 64.7 294.5 2.15 1.3915 Jan (D2) 17.8 44.0 36.4 49.5 88.0 381.1 1.89 1.3430 Jan (D3) 22.7 59.2 49.8 63.4 97.6 465.4 1.86 1.3115 Feb (D4) 27.8 62.8 57.5 67.6 107.0 495.9 1.80 1.28LSD (p=0.05) 1.6 4.0 2.2 4.1 3.4 21.7 0.15 0.07Mulch levelNo mulch 16.7 45.9 40.8 50.9 82.5 392.8 1.99 1.36Mulch (6 t/ha) 24.7 53.9 46.7 58.9 96.2 425.7 1.86 1.30LSD (p=0.05) 1.1 2.8 1.6 2.9 2.4 15.3 0.11 0.05Interaction S NS NS NS S NS NS NS

stem ratio significantly.

Herb yield, oil content and oil yieldFresh herb, dry herb and oil yield increased

successively and significantly with each delay inplanting from Jan 1 to Feb 15 while differenceswere at par between Jan 30 and Feb 15 planting(Table 2). However oil content was not influencedwith change in planting dates. Crop raised withstraw mulch gave significantly higher fresh herb,dry herb and oil yield with no difference in oilcontent than crop raised without mulch. All thethree yield parameters also increased significantlyand successively with delay in harvesting from120 DAP to 150 DAP with no difference in oilcontent. Interaction effects of planting dates andharvesting schedules was also found to besignificant for fresh herb, dry herb and oil yield(Fig. 11). The maximum value of yield parameterswas obtained in crop planted on Feb 15 andharvested at 150 DAP which was statistically atpar with crop planted on Jan 30 and harvested at150 DAP but significantly better than all othercombination of planting dates and harvestingschedules. Data further manifested that cropplanted on Jan 30 or Feb 15 and harvested at 135DAP gave significantly higher yield parametersas compared to crop planted on Jan 15 andharvested at 150 DAP despite the 15 days less

field duration.

Quality parametersPhysical properties of mint oil viz. optical

rotation, specific gravity and refractive index didnot vary with planting dates, mulch levels andharvesting schedules (Table 3). Among thechemical properties of oil, acid value decreasedsignificantly with delay in planting dates,harvesting schedules and application of strawmulch while reverse was true for ester value.However, maximum saponification value wasrecorded in oil extracted from Feb 15 planted cropwhich was at par with Jan 30 but significantlybetter than Jan 1 and Jan 15. Similarly, applicationof straw mulch and delay harvesting also resultedin significant improvement in saponification valueof mint oil. Menthol and menthone content in herboil did not vary with change in planting dates andmulch application. However, menthone contentdecreased significantly with delay in harvestingfrom 120 to 150 DAP.

Correlation studiesCorrelation matrix was analysed among six

growth and yield attributes of Japanese mint atharvest under different treatments (Table 4). Theoil yield having a very strong and positive relationwith plant height, stools count, fresh herb and dry

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Fig. 10. Interactive effect of planting dates and harvesting schedules on plant height,stool count and dry matter accumulation at harvest in Japanese mint

herb yield. However, leaf to stem ratio showedvery strong negative relation with oil yield andpositive with oil content in fresh herbage of mint.Stools count per square meter at harvest havingstrong and positive relation with plant height and

negative with leaf to stem ratio and oil content.Thus, all the parameters those having positiverelation with herbage production have shownnegative relation with oil content and leaf to stemratio.

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Fig. 11. Interactive effect of planting dates and harvesting scheduleson fresh herb, dry herb and oil yield of Japanese mint

DiscussionIn north-western India spring season is

considered from January to end of the June andruns through the both the extremes of temperature.In this region spring crop faces extremely lowtemperature during emergence and early

vegetative growth period and high temperatureduring maturity. In the view of the above saidconsideration the present study was conductedwith hypothesis to manipulate the micro climaticcondition of Japanese mint with the change indate of planting and harvesting schedule with

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Tabl

e 2.

Eff

ect o

f pla

ntin

g da

tes,

mul

ch le

vels

and

har

vest

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sche

dule

on

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rb,

dry

herb

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ld, o

il co

nten

t and

oil

yiel

d of

Jap

anes

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int (

pool

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ata

of 2

010

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2011

)

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ant h

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tSt

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cou

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Ste

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esh

herb

Dry

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bO

il co

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tO

il yi

eld

(cm

)(n

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2 )yi

eld

(q/h

a)yi

eld

(q/h

a)(%

FW

B)

(l/ha

)

Plan

ting

date

(A)

1 Ja

n (D

1)55

.955

.00.

9721

5.7

55.8

0.67

141.

915

Jan

(D2)

66.1

66.8

0.95

246.

163

.00.

6616

1.6

30 Ja

n (D

3)81

.681

.40.

9229

2.2

74.7

0.63

183.

715

Feb

(D4)

85.5

85.5

0.90

297.

877

.50.

6318

6.9

LSD

(p=0

.05)

4.0

3.4

NS

13.7

3.0

NS

9.2

Mul

ch le

vel (

B)

No

mul

ch68

.467

.50.

9425

2.5

64.1

0.66

163.

2M

ulch

(6 t/

ha)

76.1

76.8

0.93

273.

471

.30.

6417

3.8

LSD

(p=0

.05)

2.8

2.4

NS

9.7

2.1

NS

6.5

Har

vest

ing

sche

dule

(C)

120

DA

P55

.255

.11.

0122

9.3

57.7

0.66

150.

213

5 D

AP

75.2

73.7

0.94

261.

968

.30.

6516

9.1

150

DA

P86

.587

.70.

8629

7.7

77.2

0.63

186.

3

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Tabl

e 3.

Eff

ect o

f pla

ntin

g da

tes,

mul

ch le

vels

and

har

vest

ing

sche

dule

on

phys

ic-c

hem

ical

prop

ertie

s and

com

posi

tion

of J

apan

ese

min

t oil

(poo

led

data

of 2

010

and

2011

)

Trea

tmen

tPh

ysic

al p

rope

rtie

sC

hem

ical

pro

pert

ies

Oil

com

posi

tion

(%)

Opt

ical

Spec

ific

Ref

ract

ive

Aci

dE

ster

Sapo

nific

atio

nM

enth

olM

enth

one

rota

tion

grav

ityin

dex

valu

eva

lue

valu

eC

onte

ntC

onte

nt

Plan

ting

date

(A)

1 Ja

n (D

1)-3

7.2

0.89

561.

4695

9.10

52.9

61.9

80.0

4.31

15 Ja

n (D

2)-3

4.3

0.90

311.

4670

8.60

55.0

63.6

79.2

4.36

30 Ja

n (D

3)-3

3.6

0.90

421.

4656

7.82

60.9

68.7

77.9

4.65

15 F

eb (D

4)-3

3.3

0.91

031.

4554

7.55

63.5

71.0

77.2

4.83

LSD

(p=0

.05)

NS

NS

NS

0.34

5.1

5.1

NS

NS

Mul

ch le

vel (

B)

No

mul

ch-3

5.2

0.90

211.

4652

8.45

54.6

63.1

79.4

4.65

Mul

ch (6

t/ha

)-3

3.8

0.90

451.

4636

8.09

61.5

69.6

77.8

4.42

LSD

(p=0

.05)

NS

NS

NS

0.24

3.6

3.6

NS

NS

Har

vest

ing

sche

dule

(C)

120

DA

P-3

5.3

0.89

961.

468

9.20

50.4

59.5

77.3

5.36

135

DA

P-3

4.8

0.90

421.

4643

8.14

58.0

66.2

78.6

4.48

150

DA

P-3

3.6

0.90

611.

4620

7.47

65.9

73.4

79.8

3.77

LSD

(p=0

.05)

NS

NS

NS

0.43

3.6

3.6

NS

0.32

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application of straw mulch. Our study revealedthat herbage and oil productivity of mint increasedlinearly and significantly with delay in plantingfrom Jan 1 to Jan 30 and thereafter resultsremained non significant. Higher fresh herb yieldin Jan 30 and Feb 15 planted crop resulted fromsignificantly higher stool count, plant height anddry matter accumulation because of betterestablishment of crop due to favourable tempera-ture as compared to Jan 1 and Jan 15 plantings.These facts are further get support from positiveand linear relation between delay in planting datesand increase in average soil temperature fromplanting to start and complete of emergence. Thedata manifested that days taken to start andcomplete of emergence also showed a negativebut linear relation with delay in planting.Secondly the curvilinear relation between daysto start and complete emergence and average soiltemperature also support the facts that soiltemperature was positively monitored with delayin planting. Thirdly, recent study conducted byAkhtar, et. al., 1 mentioned that mint plantproduced maximum dry matter under brightsunlight at 30°C day temperature regimes duringgrowing period. Our study also manifested thatcrop experienced more number of days with daytemperature of 30-35°C under later planting datesthan early and harvested more solar energy in 15days less field duration than early planting datesin first fortnight of January (Jan 1 and Jan15).

Application of straw mulch also had significanteffect on fresh herb yield, dry herb and oil yield

of M. arvensis and crop raised with surface strawmulch produced significantly higher yieldparameters. This might be resulted from efficientcontrol of weeds with better growth charactersviz. plant height, number of stools and dry matteraccumulation because of favourable microclimatic conditions in mulched plots. Though theweed dry matter increased significantly with delayin planting and had strong positive linear relationwith R2 value of 0.948 and 0.938 for with andwithout mulch, respectively however, applicationstraw mulch led to significant reduction in weeddry matter. These results prove the fact thatapplication of mulch buffer low temperature andsuppress weeds.

Fresh herb, dry herb, and oil yield increasedsignificantly and successively with delay inharvesting from 120 DAP to 150 DAP. This isdue to the fact that crop harvested at 150 DAPremained longer period in field than earlyharvesting at 120 and 135 DAP resulting in bettergrowth and development of plants with morenumber of stools having higher plant height.Sekhon 12 also manifested that crop harvested at150 DAP gave significantly higher fresh herbyield than those harvested at 105, 120 and 135DAP because of longer field duration and higherconsumption of heat units. However, there was adecreasing trend in oil content in fresh herbage,because under late harvesting, proportion ofleaves in total biomass decreased significantly andleaves are considered as the principle site forsynthesis of essential oil in mint 9. Our results

Table 4. Correlation among different growth and yield parameters of Japanesemint under different planting dates, mulch levels and harvesting schedules

Parameters PH SC LS FHY DHY OC

SC 0.998LS -0.920 -0.926FHY 0.983 0.986 -.873DHY 0.992 0.994 -.889 0.996OC -0.936 -0.943 0.799 -.973 -0.969OY 0.984 0.987 -0.867 0.998 0.993 -0.962

PH = Plant height: SC = Stool count:LS = Leaf : Stem: FHY = Fresh herb yield:DHY = Dry herb yield: OC = Oil content

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are further supported by the positive andsignificant correlation between oil content andleaf to stem ratio. Recent study conducted bySolomon and Beemnet 4 also reported adecreasing trend in leaf to stem ratio with delayin harvesting of Japanese mint. This mightpossibly be due to self shedding or senescence ofleaves during under delayed harvesting becausemint plant is of a bushy stature and at later stagesolar radiation are not reached to lower leaves.However, oil yield was significantly higher indelayed harvesting at 150 DAP because ofsignificantly higher total biomass productionwhich is evident from the strong positivecorrelation between oil yield and fresh herbageproduction. Interaction between planting datesand harvesting schedules revealed that maximumherb oil yield were obtained when crop wasplanted on Feb 15 and harvested at 150 DAPwhich was statistically at par with crop plantedon Jan 30 and harvested at 150 DAP but wassignificantly better than all other combination ofplanting dates and harvesting schedules. Datafurther manifested that crop planted on Jan 30and harvested at 135 DAP gave significantlyhigher fresh herb yield as compared to cropplanted on Jan 15 and harvested at 150 DAPdespite the 15 days less field duration. This mightbe because of significantly higher number ofstools per square meter and plant height resulted

from early and better establishment of the crop.The positive and strong correlation of plant heightand stool counts with oil and herb yield furthersupport above said facts. A slight increasing trendin menthol content and decrease in menthonecontent in mint herbage was observed with delayin harvesting from 120 to 150 DAP. These resultsare in line with those reported by Verma, et. al.,14 with the remarks that menthone contentdecreased under delayed harvesting because ofincrease in menthol levels because Clark andMenary 6 and Duhan, et. al., 7 reported thatmenthone content decreased because ofconversion into menthol through the terpenesbiosynthesis pathway.

ConclusionsDates of planting and harvesting schedules are

two important factors for increasing the herbageand oil productivity in spring planted Japanesemint. Application of straw mulch also provedbeneficial for increasing the oil and herb yieldthrough manipulation of micro climate of thecrop and suppressing the weed. Interactiveeffects of planting dates and harvesting schedulerevealed that Japanese mint should be plantedfrom Jan 30 to Feb 15 and harvested at 150 DAPfor realizing maximum herbage and oilproductivity without any impairment in thequality of essential oil.

References1. Akhtar, N., Sarker, M.A.M., Akhtar, H., Nada, M.K. (2009). Effect of planting time and

micronutrient as zinc chloride on the growth, yield and oil content of Mentha piperita. BangladeshJ. Sci. Ind. Res. 44: 125-130.

2. Anonymous. (2012). Package of Practices for Kharif crops. pp 120. Punjab Agricultural Univer-sity, Ludhiana, Punjab.

3. Anwar, M., Chand, S., Patra, D.D. (2010). Effect of graded levels of NPK on fresh herb yield,oil yield and oil composition of six cultivars of menthol mint (Mentha arvensis L.) Indian J. Nat.Pdt. Res. 1: 74-79.

4. Beemnet, M.K., Jaime, T.D.S., Solomon, A.M. (2011). Agronomic characters, leaf and essentialoil yield of peppermint (Mentha piperita L.) as influenced by harvesting time and row spacing.Medicinal Aromatic Plant Sci. Biotech. 5: 49-53.

5. Chand, S., Patra, N.K., Anwar, M., Patra, D.D. (2004). Agronomy and uses of menthol mint(Mentha arvensis) – Indian perspective. Proc. Indian Nat. Sci. Acad. B70: 269-297.

6. Clark, R.J., Menary, R.C. (1979). The importance of harvest date and plant density on the yieldand quality of Tasmanian peppermint oil. J. Am. Soc. Hort. Sci. 104: 702-706.

7. Duhan, S.P.S., Garg, S.N., Roy, S.K. (1975). Effect of age of plant on the quality of essential oil

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of peppermint (Mentha piperita L.). Indian J. Pharm. 37: 41-42.8. Ellis, N.K., Gaylard, F.C. (1944). Relationship of yield of oil from peppermint (M. piperita L.)

and menthol content of oil. Proc. Am. Soc. Hort. Sci. 45: 451-500.9. Guenther, E. (1949). The essential Oils. Ed. Ist Vol. III. D. Van Nostrand Co. Inc., New York,

pp. 685.10. Lawrence, B.M. (1981). Progress in essential oils. Perfumes and flavourist 6: 73-75.11. Ram, M., Singh, R., Ram, D., Roy, S.K. (2003). Essential oil yield of menthol mint (M. arvensis)

varieties as influenced by time of transplanting in the North Indian plains. Indian Perfum. 46:353-360.

12. Sekhon, K.S. (1995). Harvesting schedules/ management in bergamot mint (Mentha citrataEhrh). M Sc Thesis, Punjab Agricultural University, Ludhiana, India.

13. Solomon, A.M., Beemnet A.M. (2011). Effect of inter row spacing and harvesting time ongrowth and essential oil yield of spearmint (Mentha spicata L.) Int. J. Sus. Agri. 2: 39-43.

14. Verma, R.S., Rahman, L., Verma, R.K., Chauhan, A., Yadav, A.K., Singh, A. (2010). Essentialoil composition of menthol mint (Mentha arvensis) and peppermint (Mentha piperita) cultivarsat different stages of plant growth from Kumaon region of Western Himalaya. OAJMAP 1: 13-18.

15. Yadav, R.L., Prasad, S.R., Singh, R., Srivastava, V.K. (1994). Recycling sugarcane trash toconserve soil organic carbon for sustaining yield of successive ratoon crops in sugarcane.Bioresource Tech. 49: 231-235.

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