Agronomy And Uses Of Menthol Mint

 INTRODUCTION

Japenese mint, an essential oil-bearing crop is cultivated for natural menthol, which is widely used in pharmaceutical, cosmetic and flavouring industries. Although there are many species and varieties of mints grown in different parts of the world, only four species are reported to be cultivated commercially in India and other countries. These include menthol mint (Mentha arvensis L. ), peppermint (Mentha piperita L.), bergamot mint (Mentha cirata L.) and spear mint (Mentha spicata L.). Besides China and the United States of America, India is a major producer of mint with annual productions of about 15,000 to 20,000 tonnes of essential oil per year. Natural Mint Products supplier In USA presents in this article the agronomy and uses of Menthol mint from an Indian perspective.

AGRONOMY AND NUTRITION

Fertilizer Application and crop management

The essential oil, a product obtained from the plant is located in the leaves of the mint plant. The vegetative growth for the higher production of leaves can be stimulated by the application of essential plant nutrients to the soil or the plant directly. Some of the work carried out on agronomy and nutrition of M. arvensis is presented below.

In a study, Rao et. Al (1963) observed that top dressing Mentha arvensis at the rates of 25 kg urea ha^-1 rapidly improved plant growth one month after planting. Moderate nitrogen nutrition during the budding and flowering stages has been reported to increase the content of essential oil in the mint leaves as compared with the pre-planning addition of nitrogen. Rajendra Bahadur and Gupta( 1964) found that amongst organic manures, the application of FYM, before the planting of suckers, produced a beneficial effect on crop growth. It has also been observed that green manuring followed by ammonium sulphate had positive effects on plant growth and productivity. Experimental results suggested that an application of 30 kg of inorganic nitrogen ha^-1in two equal doses at an interval of 3 weeks as a top dressing for each flush of the crop is profitable (Gupta 1965). The time of fertilizer application is of paramount importance. The fertilizer should be applied preferably in split doses; the first dose 35-40 days after transplantation and the second and the third doses a week or ten days after each harvest (Chopra &Kapoor 1967). Singh and Singh (1971) observed that phosphorus deficiency reduced the rate of dry matter accumulation and the final dry weight of Japanese mint (Mentha arvensis) plants. It also reduced the rates of P and total uptake of N, K, Ca and Mg while reducing that of K. Plants receiving ammonium contained a higher percentage of essential oil in their leaves, but on a single plant basis the essential oil was higher in plants receiving nitrate N due to the production of more foliage.

Propagation of mint is generally done through suckers as well as through pre-raised plants in nurseries. In both cases, time of planting played a key role in crop establishment and productivity. Balyan and Singh (1975) reported that the time from the end of December to the end of January was a suitable time to plant Japanese mint, (Mentha arvensis). In later plantings, herb and essential oil yield declined markedly without decreases in oil content. Summer grown plants bore a maximum number of inflorescence/plants. Similarly, leaf N content was higher in winter plantings, but leaf essential oil content was higher in summer grown plants, attaining a maximum, at 65 days.

Among the various factors affecting plant growth, planting geometry, soil fertility in general and nitrogen supply, in particular, are the most important. Yadav et al. (1983) found that Mentha arvensis grown at 30, 45 or 60 cm spacing between rows and at N rates of 80-200 kg ha^-1, produced maximum herbage yield (10.4t ha^-1) and the highest totalmenthol yield(66.4kg ha^-1) was achieved with 45 cm spacing and 160 kg N ha^-1. Oil content was not affected by planting materials or row spacing.

Since mints are mostly grown in light-textured soils to promote sucker development and crop growth, the efficiency of applied N is sometimes very low. Several modified urea coating and slow release urea formulation are reported for higher N utilization in mint. Ram et. al (1987) observed that essential oil accumulation in Japanese mint (Mentha arvensis ) increased with neem coated urea(NCU), urea super granule(USG)  and lac coated urea over prilled urea and with crop age. During the main accumulation period (60-120 days after planting), USG and NCU increased the menthol content of the essential oil by 13.6 and 6.4 %, respectively, over that obtained with prilled urea(PU). Application of nitrification inhibitors with prilled urea significantly increased herb and oil yields in menthol mint.

 

 

Integrated nutrient management

In a mint cropping system, the joint application of inorganic fertilizers and organic manure plays a significant role in sustaining crop productivity and restoring soil fertility. (Patra et al. 1997, Chand et al.2001a , Chand et al. 2001d). Because of their availability and capacity to supply macro as well as micronutrients, the farmyard manure, farm residues and other organic materials can supplement the nutritional requirement of the crop(s). Although mint responds very favourably to high doses of inorganic fertilizers; best results are obtained after green manuring the field with a leguminous plant such as ‘senji’ ( Melilotus parviflora ), ‘ dhaincha’ (Sesbania cannobina sp, Sesbania aculeate) or alternatively a basal dose of 28 tonnes of farm yard manure per hectare.

Mentha distillation waste, which retains its plant nutritional values even after steam distillation for oil extraction has been reported to have great promise as an organic source of plant nutrients(Chattopadhyay et al. 1993, Patra and Singh, 1993, Patra et al. 1997, Chan et al. 2001b). Availability of N, P, K, and Zn was maintained at significantly higher levels in all mint residue fertilizers alone. The addition of mint residue fertilizer also ensured the recycling of other secondary and micronutrients along with organic carbon for the maintenance of soil fertility. The fertilizer requirement of mint can be supplemented by manure at 30-50% of total requirements. This is possible due to the sustained availability of macro as well as micronutrient through well-decomposed organic manure. The supply of organic manure significantly improved the physio-chemical characteristics of the soil and carries the beneficial effect to succeeding crops in a mint-mustard cropping sequence.

Cropping System:

The present agriculture scenario in India and elsewhere, because of much pressure on land for the production of food crops, perhaps does not permit increasing acreage of any marginal crop, other than principal food crops and thus monocropping of mint has not been recognized as a viable proposition. The strategies are, therefore to grow mint as a summer crop component after harvest of traditional winter wheat, Brassica, lentil, chickpea or potato or as an intercrop in the traditional cropping systems and agroforestry.

 

Disease, Insect, and Pests of Mint Crops and their control

Like other crops, mints, especially Mentha Arvensis, are infected by a number of pests and diseases. Major diseases reported in mentha crops are stolon rot, rust, powdery mildew, leaf blight and wilt, viral disease and verticillium wilt.

The incidence of insect pests in Mentha is not as severe as in common agricultural crops. However, a number of insects and pests have been observed to damage crop growth to varying degrees depending on crop management and climatic conditions. Sandhu et al. identified 23 different pests that caused damage to mint. Some of the major insects are termites, cutworm, Bihar hairy- caterpillar, semiloopers, red pumpkin beetle, menthe leaf roller, white fly, Aphids.

Weeds and their control

A variety of weeds infest mint fields. The weed flora between the fields can vary widely. Some of the weeds if not removed on a timely basis can lead to major oil yield losses. The weed infestation like in other crops depends on the past history of the field. The weeds are best managed by combining manual, mechanical and chemical control methods. The best procedure is to first apply the herbicide followed by manual or mechanical weeding at 8 to 10 weeks when mulching should be applied.

Constituents and Quality of essential oil of Japanese Mint

Menthol mint oil has many technical applications in a variety of commercial products. Besides being the natural source of natural menthol, a number of terpenoides of economic importance are fractionated from menthol mint oil. After fractionation of menthol, the de-mentholated oil is also used as a substitute for Mentha piperita oil for a variety of applications. The major constituents generally identified in menthol mint oil are: menthol, p-menthone, L-menthol, (+)-isomenthol,neomenthol, menthyl acetate, o-mentha-1(7)-8-dien-3-ol, 3-menthyl cyclo-hexane, 3-octanol, pulegone,limonene and a series of other trace compounds. However, the percentage proportions of various constituents vary considerably according to genetic make-up, geographical and ecological conditions and stages of growth.

 

CHEMISTRY AND USES

Menthol mint essential oil is the main source of natural menthol. The decentralised oil (DMO) is reconstituted to produce an oil similar to Mentha piperita oil. Several of the many dozens of terpenes present in the essential oil are valuable compounds like menthone, isomenthone, methyl acetate, neomenthol, menthol, isomenthol, piperitane and pulgeone. Menthol is used as a flavouring agent in toothpastes, candies, chewing gums and mouthwashes etc.

Menthol mint oil because of its antimicrobial properties enhances the shelf life of edible products and grains. Menthol mint oil is an essential ingredient of ointments, pain balms, lozenges and syrups. It is also used in cosmetic preparations, colognes, deodorants, cosmetics, etc.ON going research in recent years has added to the list of products in which menthol mint is used. A large number of patents of such products are taken each year. In India, menthol and mint oil are extensively used in betel (pan) related industries.