Geographical distribution and botanical characteristics
Jatropha curcas (physic nut, purging nut) is a shrub or a small tree belonging to the family Euphorbiaceae. It is widely distributed in almost all countries in the tropical regions of Africa, Asia and Latin America and has several local names, showing that it has become almost indigenised in most of these countries.
It is considered to have existed for a long time (over 70 million years) and shows considerable variability as it adapted to various climatic and soil conditions (Münch and Kiefer, 1986; Münch, E., Kiefer, J., 1986. Die Pugiernuß (Jatrophacurcas L.): Mehrzweckpflanze als Kraftstoffquelle der Zukunft. Gesellschaft für Technische Zusammenarbeit (GTZ), TZ Verlagsgesellschaft mbH, Roßdorf, Germany; article in German). Jatropha plants with yellow, greenish or rose-colored flower bunches, with red or green leaves, with dark coloured or paler seeds and with mostly toxic, but sometimes edible seeds (in Mexico) have been recorded.
Jatropha grows to about 5-6 m height. It is a monoecious plant, meaning that the same plant bears both male and female flowers in the same cluster. They mature at different times so that self fertilisation is usually avoided. However, observations that we made indicate that also a considerable self fertilisation can occur in Jatropha. Recent publications (http://link.springer.com/article/10.1007%2Fs11295-013-0623-y) also indicate high incidence of apomixis (development of seeds without fertilisation) in Jatropha curcas. Pollination is by insects, usually honey bees. Jatropha fruits usually contain three oval seeds though sometimes there may be four, two or only one. The dry fruits weigh about 2.5 g per whole fruit. The seeds have a hard, black, lignified seed coat that protects the soft, white or cream, oil-rich kernel inside.
Jatropha produces seeds from the very first year onwards when conditions are favourable. The speed of maturation and seed production after plantation depends on levels of inputs and local climatic and soil conditions.
The plant is usually non-edible, as it produces phorbol esters as its natural protection against pests and pathogens (for a review on phorbol esters please see Goel, G., Makkar, H.P.S., Francis, G. and Becker, K., 2007, Phorbol Esters: Structure, Biological Activity, and Toxicity in Animals. International Journal of Toxicology, 26, pp. 279-288). The phorbol esters produced by jatropha are unstable and loose their toxicity quickly if taken out of the plant or its parts. The phorbol esters do not accumulate in the soil as they are broken down by soil micro-organisms. The following pictures show jatropha flowers (left) and fruits (right).
Non-toxic Jatropha varieties exist naturally in Mexico
Non-toxic Jatropha plants occur naturally in Mexico and are eaten by locals after roasting. The difference between the toxic and non-toxic Jatropha is the presence of plant secondary compounds called phorbolesters in the seeds and other plant parts of the former.
JATROPOWER has identified the potential of non-toxic Jatropha early and has researched it extensively on its biochemical and genetic aspects. The focus of this research has been:
- Studying the performance of non-toxic plants in comparison with the conventional toxic Jatropha.
- The inheritance pattern of the non-toxic character from generation to generation in the event of cross fertilisation with toxic Jatropha varieties.
- Identification of high yielding non-toxic Jatropha genotypes and their further improvement through conventional breeding.
First results indicate that also non-toxic Jatropha can reach yields similar to those of conventional elite Jatropha seeds, which is several times higher than the average yield of wild plants under semi-arid climate and on degraded soil, read more.
JATROPOWER will have the first selected elite seeds of non-toxic Jatropha for sale to plantation developers in 2015.