Cultivation Methods and Management Techniques for Thai Mesona

Organic Cultivation and Management of Thai Mesona

Plant Characteristics

    Mesona (Mesona procumbens Hemsl.) is an annual or biennial often cross-pollinated crop of the mint family (Labiatae). Plant types include erect, semi-erect and prostrate forms; leaves are ovate, elliptical or oblong, with toothed margins; leaf color ranges from yellow-green to light green to dark green; stems are square and green, light purplish-red or deep purplish-red, with colorless hairs covering the whole plant. Stems and vines can reach about 2 m in length, and the vegetative growth period is about 140 to 180 days. Flower spikes are white or light purplish-red, with four didynamous stamens; the chromosome number is 2n=32. Flowering occurs from September each year to February of the following year.

Climate and Soil Requirements

    Mesona is a long-day crop; growth is poor when sunlight is insufficient, leaves become thinner and the content of important components is low. However, in the later growth stage it prefers a mild climate, and generally grows well at a suitable temperature of about 20-25 °C. It is not demanding about soil texture; sandy loam or humus loam with good drainage and convenient irrigation is most suitable.

Distribution of Production Areas

    Native mesona in Taiwan is distributed in the foothills throughout Taiwan. In earlier times, ancestors used its stems and leaves to boil a tea drink as a summer refreshment. In recent years, merchants and the food industry have used it to develop a variety of health beverages and foods that are well liked by consumers, so farmers have begun cultivating it on a large scale. Cultivation areas extend widely to Guanxi Township in Hsinchu County; Sanyi, Sanwan, Shitan and Tongluo Townships in Miaoli County; Zhongzhuang and Niuchoupu in Shuishang Township, Fanlu Township, Zhuqi Township and Zhongpu Township in Chiayi County; Jiji Township in Nantou County in central Taiwan; and Taitung County, Jian Township in Hualien County and Luodong in eastern Taiwan, among other places. According to a survey report on major agricultural and livestock production areas in Taiwan, the planted area was 185 hectares in 1997 and 155 hectares in 1998.

Characteristics of Major Varieties

    The mesona varieties planted by local people in the early days were all collected from native species near the foothills and domesticated over many years, so the varieties grown in each region have characteristics adapted to the local environment. In the northern Guanxi area, vegetative propagation is used for raising seedlings to grow the deeply prostrate variety (73-K-4); harvesting is labor-intensive, and it is better suited to cultivation in the mild climate of the north. When grown in the hotter areas of the south, its late-stage growth is poor and the leaves tend to turn brown-yellow and drop. The average dry plant yield is about 6,000 kg per hectare. In the southern Shuishang Township area, the erect type (83-S-7) is commonly cultivated; seedlings are raised by sowing seeds and then transplanting. However, due to long-term natural cross-pollination, the germplasm is highly mixed and variable, resulting in unstable yield and quality, and the vegetative growth period is short (about 140 days); the harvest period often coincides with the rainy season, making harvesting and drying operations very difficult. The characteristics of the varieties cultivated in each region are briefly summarized in the following table:

 The new variety TARI No. 1 was named in the 88th year of the Republic of China (1999). It has many excellent characteristics: 1. Dry plant yield and dry leaf yield reach 9,000 kg and more than 3,000 kg per hectare; 2. Moderately prostrate, saving labor at harvest; 3. High leaf gel strength; 4. Can be grown as a ratoon crop and has strong regeneration ability; 5. High survival rate of cuttings; 6. The harvest period runs from the end of September to mid-October, a period that happens to avoid the rainy season, making harvesting and drying operations convenient.

Content of Major Components in Mesona

    Regarding the mineral element content of the mesona plant, potassium is the most abundant in both stems and leaves. Per 100 grams of dry matter, leaves average 3,805 mg and stems average 2,571 mg; next is calcium, with leaves averaging 794 mg and stems averaging 594 mg; phosphorus averages 554 mg in leaves and 252 mg in stems; magnesium averages 255 mg in leaves and 136 mg in stems. It also contains manganese and iron.

     In the analysis of general component content, crude protein content is 3.87 % in stems and 13.85 % in leaves; crude fat content is 2.26 % in stems and 9.32 % in leaves; crude fiber content is 41.95 % in stems and 15.73 % in leaves; nitrogen-free extract (NFE) content is 43.66 % in stems and 43.95 % in leaves; ash content is 8.27 % in stems and 17.15 % in leaves. The nitrogen-free extract contains a large amount of polysaccharides, which are related to the level of gel strength and serve as an indicator for processors in making mesona jelly. However, the composition of the nitrogen-free extract in stems appears to differ in ratio from that in leaves; therefore, the gel strength of stems is very low. According to a report by Lu Zheng-yi and others, the main body of the mesona gel network is the Fraction C component of the polysaccharides, while the aroma of mesona is mainly contained in the stems.

       The nitrogen-free extract obtained from general component analysis includes free sugars such as monosaccharides, disaccharides and oligosaccharides (oligo-saccharide); polysaccharides (polysaccharide) such as starch, fructosan, xylan and mannan; and also pectin, plant gum, pigments, mucilaginous substances, acids, glycosides and many other components of differing properties. The most important of these is of course carbohydrates, commonly known as saccharides, which include free sugars, sugar alcohols and glycans. The polysaccharide content of TARI No. 1, for example, was analyzed at 17.7 %.

Functions of Mesona Juice

    According to Volume 4 of Gangmu Shiyi, mesona jelly, also called liangfen cao, can treat nephritis, high blood pressure and venereal disease, though this has not yet been confirmed by scientific data. Professor Yan Guo-qin of Chung Hsing University has given a more detailed report on the functions of mesona. He pointed out that the human body produces reactive oxygen species and free radicals during normal metabolism, and that free radicals play a rather important role in the development of many human diseases. In other words, the oxidative damage caused by free radicals has a considerable impact on human health.

       The human body has an innate defense mechanism for scavenging reactive oxygen species or free radicals, but among the external foods people eat daily, some foods often reduce or destroy the function of these defense mechanisms. Therefore, trying to take some water-phase solutions and fat-soluble antioxidants is currently the most popular health care method. Mesona tea is unique in having a superoxide anion scavenging effect; in particular, the new variety TARI No. 1 reaches a scavenging effect of 91.5 %, higher than other local varieties (as shown in Table 2).

Current Problems in Production and Marketing

    Because of inappropriate cultivation methods, domestic mesona in Taiwan mostly relies on large amounts of chemical fertilizers to obtain high yields. However, affected by the high-nitrogen effect, the leaf gel strength of mesona cannot be raised, product prices are low, and farmers' income decreases. As a result, farmers' willingness to cultivate declines, leading to a year-by-year reduction in planted area. After the domestic industry began developing diversified products, these became popular with a broad range of consumers, and demand for dried mesona increased daily, causing an imbalance between supply and demand in the market. To meet their own needs, merchants imported large quantities from the mainland and Indonesia, which inadvertently dealt a blow to the domestic mesona industry.

Organic farming is a cultivation method that uses no or little chemically synthesized fertilizer and chemical fertilizer for crop production. Mesona has the characteristic of resisting pest and disease attack, making it relatively easy to adopt organic cultivation, and the mesona products produced, such as organic tea or organic mesona jelly, can also offer consumers another choice. For cultivation, it also appears to be another agricultural product with business potential. Past trial results from the Taiwan Agricultural Research Institute show that using organic cultivation for mesona, with chicken manure compost completely replacing chemical fertilizer application, has the effect of increasing mesona gel strength. Trial results from the Chiayi Shuishang trial site show that the average dry plant yield of mesona in the organic plot still reached 8,726 kg per hectare, and the gel strength was more than 2 times that of the chemical fertilizer plot (108.3 g/cm2 : 49.4 g/cm2).

Cultivation and Management Methods

1.

 Seedling raising:

Propagation is by cuttings. For propagation material, select relatively robust mesona stems in the field in August and plant them in a previously prepared nursery. In November-December, cut off the flower spikes, carry out intertillage with an appropriate amount of organic fertilizer and moderate irrigation, and wait until new branches sprout again in February-March of the following year, then dig them up for use as seedlings and transplant them directly into the field. Alternatively, when directly taking ratoon seedlings from the field, the soil beside the mother plants should be loosened in January-February, with appropriate application of organic fertilizer and irrigation, so that the ratoon mother plants sprout robust branches for use as cuttings. The planting period should preferably be after mid-February. When cutting, use hole-planting pots for planting, and transplant to the field after roots have formed and the plants have survived. This method can ensure the excellent germplasm of the variety and is less prone to variation.

2.

Site selection:

Mesona should not be grown continuously on the same land. The planting site should preferably be land following organic rice, or land that has been fallow for more than half a year and has been flooded for more than six months. If long-term dryland crop land is used for planting, mesona is prone to a suspected wilt disease, and plants that do not develop the disease usually also grow poorly. Therefore, planting in land under continuous dryland cultivation should be avoided as much as possible.

3.

Land preparation:

This is divided into rough land preparation and fine land preparation. The purpose of the former is to deeply plow and bury the residues of the previous crop and loosen the soil; at this time, chicken manure compost can be broadcast and mixed in, or applied in the furrow when making beds, at a rate of 9,000 kg per hectare; this can be moderately increased or decreased according to the soil fertility of the cultivated field. The nitrogen requirement of mesona is 130-180 kg per hectare, which can be converted into the actual application rate by multiplying the nitrogen content of the chicken manure compost by 1.5 times (taking into account the mineralization rate of organic fertilizer). The latter operation is to finely break up the soil to facilitate bed making and planting. Rough land preparation should be carried out one month before field planting, while fine land preparation is carried out 7 days before planting. Immediately after land preparation, make beds and irrigate to moisten the soil, and drain away any excess water.

4.

Row and plant spacing:

The row spacing is 1.4 m, and the plant spacing can be 60 or 90 cm, that is, the bed width is 1.4 m, then holes are dug on the bed according to the selected plant spacing for planting, with 8,000-11,900 plants per hectare.

5.

Planting period:

According to the results of cutting-period trials, the survival rate of mesona seedlings in this province is relatively high from mid-February to mid-March. Therefore, the most suitable planting period for mesona can be chosen between mid-March and mid-April, and when planted at this time, the vegetative growth period until harvest is about 180 days, enough for mesona to realize its high-yield potential.

6.

Intertillage, weeding and earthing up:

From 30 to 90 days after planting, intertillage should be carried out between the furrows, on the one hand to weed and on the other to loosen the soil and place soil on the beds to raise them, so as to facilitate irrigation and drainage and promote the development of mesona roots.

7.

Irrigation:

Taiwan is in the dry season from April to June. During this period, mesona is in the early growth stage when the plant form is being established, and an appropriate amount of water is needed to help survival and growth. Therefore, in addition to irrigating immediately after transplanting, timely irrigation should be carried out during the growth period. July to August is usually the rainy season, and heavy rain will cause water to accumulate in the furrows; at this time, attention should be paid to drainage to prevent mesona leaves from rotting due to soaking in water. However, after September there is less rain, so irrigation should be carried out 1-2 times.

8.

.Occurrence of pests and diseases:

There are very few diseases and insect pests during the whole growth period of mesona, so farmers generally do not spray pesticides. However, when the planting site is selected as land under many years of dryland cropping, wilt often occurs in the mid-growth stage of mesona; after isolating diseased plants, no pathogenic bacteria were found. As for the insect fauna, surveys show that crickets cause damage in the early growth stage, and leaf beetles and leafhoppers cause damage in the mid-to-late growth stage, but none are serious.

9.

Harvest:

The suitable harvest time is when flower buds emerge from the terminal and axillary buds of the plants. Harvest time in Taiwan varies: in the south it is generally from the end of August to early September (erect type), and in the north before mid-October (prostrate type). When the new variety is planted, it is always harvested from the end of September to early October. At harvest, use a sickle to cut the adventitious roots separately, then turn the whole plant over and place it on the bed to sun-dry. After it is 70-80 % dry (so it breaks less easily), tie it into small bundles and pile them in a storage room.

10.

 Storage:

Dried mesona usually can increase in gel strength and aroma after a period of storage, so ordinary traders prefer to buy mesona that has been stored, but no mold should occur. The storage site should be a dry, ventilated place, and the floor should be raised and the dried mesona covered with black plastic sheeting to prevent moisture and deterioration.

Conclusion

Mesona is commonly known as liangcao or tiancao. When made into a beverage or mesona jelly, it is what is generally sold as herb tea or tiancao ice. It has accompanied the growth of rural areas and brought joy to farmers. In recent years, driven by product diversification in the food industry, the instant mesona powder developed by adding hot boiled water with some peanuts, rice cakes and red beans, under the trade name shao xiancao (hot mesona), has become even more popular with young consumers. Therefore, mesona products are no longer limited to summer demand; it can be said that consumers need them all year round.

     Domestic mesona in Taiwan has ample aroma that imported products cannot match. Among traditional localized crops at present, it is a special crop with strong competitiveness and development potential. After diversified products have been developed and launched, domestic demand is increasing day by day. In addition, mesona cultivation and management are extensive, and no pesticide spraying is needed to control pests and diseases during the growth period. If it can be rotated with organic rice, it will not only help increase the yield and quality of mesona itself, but also improve the physical and chemical properties of the soil and reduce pollution in terms of soil management.