Proc. Indian Acad. Sci., Vol. 87 B (Plant Sciences-2), No. 5, May 1978, pp. 157-160, �9 printed in India.

Cultivation of Mentha citrata Ehrh in Burdwan District, West Bengal

M L GHOSH* and S K CHATTERJEE** Department of Botany, Burdwan University, Burdwan 713 101, West Bengal Present address: *Department of Botany, B N Mahavidyalaya, P O Itachuna 712 147, Dist. Hooghly

**Cinchona and Other Medicinal Plants, Government of West Bengal, 10/1A, Indian Mirror Street, Calcutta 700 013

MS received 4 February 1977

Abstract. The effects of variation in planting times and spacings on the growth behaviour, yield of green herbage and essential oil formation in Mentha citrata in the Burdwan District of West Bengal is reported,

Keywords. Mentha citrata; oil content.

Introduction

Mentha citrata Ehrh (family Labiatae) generally known as Bergamot mint is a hybrid between M. aquatica L. and M. spicata L. which originated in Europe, but is also cultivated in USA. Its cultivation in India was first introduced in 1972 in the Tarai region of Kumaon Hills (UP) and in the Jammu-Kashmir (Kapil et al 1974). As the Bergamot mint oil is rich in linalool and linalyl acetate it has a great commercial importance. In West Bengal, no systematic approach had been made in the cultiva- tion of this plant and the present paper seeks to report on some of the important features regarding plantation time, seed spacing, growth behaviour and yield in M. citrata in the Burdwan District of West Bengal.

2. Materials and methods

The stolons of Bergamot mint were collected from Indian Agricultural Research Institute, New Delhi. The experiments were conducted on soils wihch were loamy and rich in organic matters and which had the following compositional characteristics - -pH --6, N~ -- 0"4 Yo, P (as P~ 06) -- 0"03 ~o, Ca (as CaO) -- 0"01 ~o and K -- 0"04 ~o. The soil was worked out to a depth of 30 cm. and the fields were prepared without adding any chemical fertilizers. The plot size was 10 sq m and the experiments were laid out in a randomized block--design with 3 replications. 4 planting times were followed viz. mid-December, early January, mid-January and early February. Each planting was followed by two spacings viz. 30 • 45 cm and 30 • 60 em (i.e.,

157

158 M L Ghosh and S K Chatterjee

45 and 60 cm between the rows and 30 can between the plants). After each planting and harvest, the plots were liberally watered. During summer, the plants were irrigated every 3 days and during winter, every 5-7 days. No irrigation was made during the rainy season. Totally, 5 weedings were made to keep the plots weed-free.

Growth behaviour of the plants was followed by a study of the total extension growth, branch formation, leaf formation and formation of buds and flowers. Total herbage and essential oil yield/hectare]year were recorded from 3 harvests (April, July and October) and the harvest timing was determined on the basis of sufficient leafy growth and optimum oil content. The essential oil content was also recorded at an interval of 15 days to determine the period of active oil synthesis. Essential oil was extracted by the method of steam distillation of Von-Rechenberg modified by Guenther (1948a). The linalool content (calculated as total alcohol) of the oil was determined following the method described by Guenther (1948b). The results were based on observation and statistical analysis for 2 years (Panse and Sukhatme 1967).

3. Results and discussion

The plants of Bergamot mint planted during the middle of/anuary revealed maximum extension growth (52 cm), branch formation (22 branches) and leaf formation (310 leaves) as compared with other planting dates. Plants had a luxuriant growth at a spacing distance of 60 can between the rows than the 45 can spacing (table 1). Dura- tions of total and active growth periods of the plants were higher when planted during mid-lanuary (table 1).

Dutta (1971) found that in the case of M. arvensis, a spacing of 45 crn was ideal and that it should be guided by soil fertility and transportation of farm implements. The work carried out at Central Indian Medicinal Plants Organization which also agrees with our findings had shown that planting Mentha before February in rows at a distance of 60 cm and using stolons, gives a good growth and yield. Ghosh and

Table 1. Effect of planting time and spacing on growth performance of Mentha citrata Ehrh.

Planting time Spacing (cm) Growth data/plant Duration (days)

Total ex- Total hum- Total hum- Totalgrowth Activegrowth sion growth ber of bcr of period period

(cm) branches leaves

Mid-December 30 x 45 30x60

Early January 30 x 45 30•

Mid-January 30 • 45 30 • 60

Early February 30 x 45 30x60

36 10 140 225 195 38 14 190 228 210

42 15 265 235 220 48 18 290 240 230 46 17 275 240 230 52 22 310 255 250 44 14 270 230 225 48 19 305 235 230

CD values at 30x45 1.30 2.24 7.52 5 % level in betwe, n the planting times 30 • 60 2.92 1.11 5.96

Cultivation of M. citrata 159

Chatterjee (1976a) also reported that planting in January with 60 cm spacing between rows exhibited better growth in M. spicata L. in Burdwan soil. However, Virmani and Datta f1974) showed that planting at 45 cm spacing also gives a good growth.

It is seen from table 2 that plants grown during mid-January at 30 x 60 cm spacing showed a maximum yield of green herbage (200 q/ha/yr) and essential oil (104 kg/ha/ yr). The plants grown in mid-December with a spacing of 30 x 45 crn revealed minimum yield of herbage production (118 q/ha/yr) and essential oil (35.76 kg/ha/yr). Maximum linalool content (84 %) was also recorded when the plants were grown at 30 x 60 cm spacing during mid-January (table 2).

Table 2. Effect of planting time and spacing on herbage yield, essential oil content and linalool content of Mentha citrata Ehrh.

Total yield of Total yield of Period of Linalool* Planting time Spacing (cm) green herbage oil (kg/ha/yr) active oil content (%)

(g/ha/yr) synthesis (days)

Mid-December 30• 118 35"76 180-185 75"25 30 x 60 119 40.46 180-185 75.25

Early January 30 • 45 160 60-00 195-200 76"80 30 X 60 161 72.45 195-200 77.10

Mid-January 30 x 45 180 90.00 210-215 83" 80 30 • 60 200 104.00 210-215 84.00

Early February 30x45 164.50 65.80 200-205 79.00 30 • 60 171.50 82.32 200-205 79.00

CD values at 30 x 45 1.20 2.60 5 % level in between the planting time 30 x 60 3.16 2.24

*Mean percentage of 3 harvests

Table 3. Effect of planting time and spacing on the patterns of essential oil forma. tion in Mentha citrata Ehrh.

Planting Spacing % Essential oil content after days time (cm) 60 75 90 105 120 135 150 165 180 a 195 B 210 c 225 D

XMid- December 30x45 0.05 0.12 0.18 0.20 0-22 0.27 0.30 0.30 0,32 0.29 0.28 0.25

30• 0.07 0.14 0 .21 0.24 0.25 0.30 0 .31 0.33 0.34 0.30 0.30 0.26

Early January 30x45 0.05 0.15 0.22 0.25 0.27 0.33 0.34 0.34 0.35 0.38 0.35 0.34

30x60 0-08 0.17 0.24 0.28 0.30 0.36 0.37 0.40 0.43 0.45 0.42 0.40

Mid- January 30• 0.06 0.20 0.28 0 .31 0.35 0.37 0.40 0.43 0.47 0.49 0.50 0.46

30• 0.09 0.22 0 .31 0.33 0.37 0.40 0.42 0.45 0.48 0 .51 0.52 0.48

Early February 30x45 0.08 0.19 0.24 0.25 0.28 0.32 0.32 0-34 0.37 0-40 0.40 0.37

30• 0.08 0.20 0.26 0.32 0.34 0.35 0.39 0 .41 0.45 0 .48 0.48 0.42

l = N o floral initiation in the plants; A=Time of floral initiation; B----Half bloom stage; C=Ful l bloom stage; D=End of bloom

160 M L Ghosh and S K Chatterjee

Virmani and Datta (1974) also found that January planting gives a higher yield of oil in M. citrata. This result and our previous report (Ghosh and Chatterjee 1976a) on M. spicata confirmed the present findings. The results from table 2 also reveal that increase in herbage yield was due to the increased yield o f essential oil. Upadh- yaya et a l (1974) had shown that differences in the yield of oil/ha due to various spacings also causes yield differences in the herb. According to them, different plant populations/unit area due to various spacings and differential growth of the plants were responsible for the differences in the yield of green herb. The earlier findings of Ghosh and Chatterjee (1976b) on M . piperita and M . spicata also established that increased green herbage yield was accompanied with an augmentation of essential oil formation.

The analysis of essential oil formation at 15 days interval clearly revealed a gradual increase of essential oil content up to a certain period (180-185 days for mid-Decem- ber planting, 195-200 days for early January planting, 210-215 days for mid-January planting and 200-205 days for early February planting). In general, essential oil content steadily increased up to the flowering stage (half bloom to full bloom stage) of the plants, then declined later (table 3) which confirmed the earlier results of Grahle (1955), Ellis (1960), Burbott and Loomis (1969) and Ghosh et al (1976).

Acknowledgements

Our thanks are due to Dr R Gupta o f IARI, New Delhi for supplying the planting materials. Research grant of CSIR, New Delhi is also gratefully acknowledged.

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