3. Maca Origin, Distribution and Ecology

Origin: South American plant, native to the Peruvian Central Andes (Cerro de Pasco, Junín, Tarma, Jauja, Concepción and Huancayo).
The Lepidium species cultivated by indigenous people of central Peru is a domesticated species that was probably cultivated for the first time in San Blas, Junín, between 1,300 and 2,000 years ago, but little is known about its origin (Matos 1978; Rea 1992).

Distribution: Lepidium meyenii Walp. is an Andean crop that occupies a very restricted area. Today, it is found only on the central sierra of Peru, in the suni and puna ecosystems (Bonnier 1986) of the departments of Junín and Cerro de Pasco, principally, at elevations above 3,500 m and often reaching 4,450 m in the central Andes of Peru (Leon 1964; Tello et al. 1992). The largest cultivated area is found around lake Junín at Huayre, Carhuamayo, Uco, Ondores, Junín, Ninacana and Vicco. There are a few reports of its cultivation in the department of Huancavelica.

In the past, it is believed that it was cultivated much more widely, covering from Junin to Puno. Out of Peruvian Central Andes, cultivation of Lepidium meyenii Walp. is very scarce. Although production of Lepidium meyenii Walp. is restricted primarily to the central Andes of Peru, it can be grown successfully in other parts of the world. Field experiments in Davis, California indicate that this crop can be grown during the winter in this area as an annual crop if irrigation is available throughout its whole life cycle. Some short-scale experimental cultivation has also been done in Japan and Germany.

It is believed that in the 16th and 17th centuries Lepidium meyenii Walp. had a wider range of cultivation than today. In addition to Junín and Cerro de Pasco, presumably, it also was grown in Cusco and in the Lake Titicaca watershed. Although it is believed that in Inca times Lepidium meyenii Walp. was cultivated in Puno, there is no evidence of this crop being cultivated there at the present time.

In 1994, less than 50 hectares were being dedicated to the production of Lepidium meyenii Walp. in Peru and presumably in the world (Tello et al 1992). However, the popularity of this crop is steadily increasing, not only in its area of production but also in large cities because of its putative medicinal properties. Hence, by 1999 over 1,200 hectares were under production due to rising demand in the U.S. and abroad.

There exist some Lepidium accessions collected out of the traditional area of cultivation, namely Bolivia and Argentina, and have also been classified as Lepidium meyenii Walp. After superficial morphological inspection, however, no resemblance to cultivated Lepidium can be seen in these early herbarium specimens, which in many cases are not in optimal shape. Therefore the species name change to Lepidium peruvianum Chacón sp. nov. seems justifiable, although further taxonomic research is required to solve this problem.

At least seven wild species of Lepidium, including the cultivated one, have been reported in Peru by Brako and Zarucchi (1993) from the departments of Ancash to Puno. In addition, other Andean species have been collected in Ecuador, Bolivia and Argentina. Practically nothing is known about the origin of these species and even less about their possible relationship to Lepidium meyenii Walp. Although Lepidium meyenii Walp. is an octoploid, the Andean wild species of Lepidium surveyed so far include both tetraploid and octoploids.

In the departments of Cusco and Apurimac at 3,600 m to 3,950 m asl Lepidium bipinnatifidum, Lepidium chichicara and Lepidium kalenbornii have been found, but no cultivated Lepidium was detected in these regions.

Ecology: Lepidium meyenii Walp. is a biennial plant that propagates by sexual seeds —unlike many other tuberous plants— and develops in an inhospitable region of intense sunlight, violent winds, and below-freezing and dry weather in the puna agro-ecological zone or cold steppe between 4,000 m and 4,500 m above sea level, in poor and rocky sedimentary soils of limestone and dark clay, where low temperatures and strong winds limit other crops.

These specific environmental conditions limits its cultivation mostly to the puna agro-ecological zone of the central region of the Peruvian Andes, at altitudes between 4,000 m and 4,500 m.

Lepidium meyenii Walp. is a very resistant plant. It tolerates frosts —that is, lowering of temperature under 0º C— fairly well. Low temperature is a condition that characterizes the puna weather. In other latitudes, such as in Berlin, Germany, (lat. 52°N), where it was sown in 1990, Lepidium meyenii Walp. has failed to form hypocotyls/roots. This result appears to support the idea that Lepidium meyenii Walp. is a short-day plant.

The Lepidium meyenii Walp. is sown at the beginning of the rainy period (September-November), usually in the morning to avoid winds, as the sole crop or combined with strips of bitter potato. According to the peasants in the area, this combination protects the potato from insect attack, since Lepidium meyenii Walp. contains repellent volatile substances.

It can be sown on freshly ploughed pasture land that has lain fallow (purun), or on ground under an annual rotation with another crop (kallpar) such as the bitter potato. Generally speaking, soil preparation is deficient and broadcast sowing is carried out without any fertilization or, at best, only a sheep manure dressing. The seeds are buried using branches or are left to be trod on by sheep.

Tillage is not usually carried out, except to make sure that the small plants are not trampled by animals. Often the plants are thinned out 2 months after sowing to obtain uniform and larger hypocotyls. The pastures lie fallow for as many as 10 years before Lepidium meyenii Walp. is again planted in the same plot. This is because Lepidium meyenii Walp. seems to exhaust the soil by extracting nitrogen and other nutrients (Tello et al. 1992). This probably occurs when the nutrients removed are not sufficiently replenished. Weeds, if present in the field, are removed by hand.

One kilogram of seed with 15 kg of soil is used for high-density planting or 1 kg of seed and 25 kg of soil for low density. Then sheep are released to the field to trample the seed. This will result in 700,000-400,000 plants/ha depending on the sowing density used.

Crop duration is 8 to 9 months. Harvesting begins in May or June. The yield is very variable: in fields where little care has been devoted to managing the crop, about 2 to 3 tons per hectare of edible fresh matter are obtained while, with appropriate row cultivation practices, fertilization and the prevention of pest attacks, it is possible to produce up to 15 to 16 tons of fresh edible matter per hectare (approximately 5 t/ha of dried hypocotyl/root).

The main pests and diseases, which are just a few, include a root borer called ‘gorgojo de los Andes’ (Premotrypes spp.) and a leaf fungus causing mildew (Peronospora parasitica). Other fungal pathogens causing diseases present in the area are Fusarium graminium and Rhizoctonia solani (Tello et al. 1992; Aliaga-Cárdenas 1995).

The hypocotyls/roots are harvested from May to July when they are at their maximum size, about 5 cm in diameter (Leon 1964; Tello et al. 1992). At this time, most of the leaves in the plants are still growing, without showing signs of senescence. A local hand hoe called a cashu is used for digging the plants one by one. The curved blade of this tool avoids damage to the roots.

After harvesting, the whole plants are dried during the day under the sun for 10-15 days, and covered during the night to avoid rain and frost damage. The leaves are left on the plant during drying because the local farmers believe that this will result in sweeter roots. After drying, the leaves are removed and the hypocotyls/roots are taken to the market or stored in a cool, dark place until they are eaten.

Plants which produce the hypocotyl/root in the first year do not produce seed. The following practices are carried out to obtain seed: after selecting the biggest, soundly formed and suitably ripened hypocotyls, between 30 and 50 are placed in a hole which is 50 cm to 60 cm deep and of the same radius and which is covered with damp earth. The plantlets take 25 to 30 days to grow. To transfer them, a seed bed is prepared with soft earth and fertilized with farmyard manure. Care must be taken to ensure that there is adequate humidity for the vigorous development of the plants, which will produce seeds within six to seven months after transplanting.

Lepidium meyenii Walp. has one of the highest frost tolerances among other native cultivated plants, since it is able to grow in the puna where only alpine grasses and bitter potatoes thrive (Bonnier 1986). The natural habitat of highland Peru where Lepidium meyenii Walp. is grown has an average minimum temperature of -1.5o C and an average maximum of 12°C (Tello et al. 1992). Frost is frequent and temperatures can get as low as -10°C. The relative humidity is high, with an average of 70%. The natural soil in the Lepidium meyenii Walp. production area is acidic, having a pH of 5 or less (Tello et al. 1992).

Lepidium meyenii Walp. has also been cultivated in other climates and therefore its range of adaptation is not as narrow as previously believed (Tello et al. 1992). At Davis, California, a short-scale experimental cultivation has been done. Four to six-week-old seedlings of that experiment that were transplanted in the field at the middle of September initiated hypocotyl development in 6-8 weeks. At this time of the year daylength is approximately 10 hours and mean soil temperature approximately 12°C. The hypocotyls/roots reached a maximum size of 35-50 mm in diameter 7 months after transplanting, when daylength was over 13 hours and mean soil temperature was approximately 20°C. By the middle of March, at the end of the rainy season, irrigation water was supplied as needed. Floral stems developed at this stage at the base of the stem, reaching anthesis and fruit-setting 8-9 months after sowing the seed. Therefore, most of the plants completed their seed-to-seed cycle in 10-11 months.

Experiments on photoperiod response in growth chambers demonstrate that Lepidium meyenii Walp. does not require short days for general development, hypocotyl enlargement or flowering. Hypocotyl enlargement takes place at similar rates under either short (12 hours) or long days (14 hours). Similarly, flowering takes place independently of daylength and without need of a vernalization period (Quirós et al. 1996). It is unknown, however, whether vernalization will promote more profuse and coordinated flowering in this species.

According to the results of these experiments, Lepidium meyenii Walp. can be considered photoperiod-neutral and can be grown as an annual or biennial species, depending of water availability and optimal temperatures. Low temperatures and water availability during the growing season seem to be more important than daylength in the development of the Lepidium meyenii Walp. plant.