Successful seeding starts with good seed quality
Seed selection and storage
If you do not want to go into the process of breeding “improved” Jatropha material (It takes many years and lots of money and some big players are already doing it so the seeds will become available anyhow), you could at least start to make your own selections. You can select from local seeds or/and seeds acquired from other destinations. It takes about three years to set up proper selection trials and to get an idea about yield potentials. Selecting good Jatropha seeds is necessary to overcome the natural variability in yield. From a given population of Jatropha plants only 20 % will give satisfactory yields as was shown in this trial in Madagascar.
Seed viability and germination rate.
Healthy Jatropha seeds should germinate within 10 days!! Find the complete research here.
Germination of seeds is positively affected by a combination of water, good drainage and high temperature.
Pre-soaking or other seed treatments does not automatically improve germination and can even create adverse effects. Manure or other additives do affect the germination rate negatively but stimulate growth after germination positively.
a. Direct seeding in the field (Picture AvP Tanzania ) is the cheapest and easiest method. However……… although direct planting and direct seeding are methods to minimize planting costs, these methods are quite risky.
During a period of six weeks to three months, enough water should be available to initiate rooting and to support the establishment of the young seedlings.
During the first year, weed- or intercrop control is crucial, otherwise the young Jatropha plants will be overgrown.
Although cattle will not eat Jatropha, they can step on it and destroy the young saplings.
Apart from the fact that direct seeding is cheap, it also produces plants with a taproot, which might be an advantage in dry periods. This statement however still has to be proven. Although it sounds logical, there is hardly any scientific evidence or otherwise documented information that plants from direct seeding are superior to transplanted seedlings. (See planting methods)
In fact, there is no research showing the influence of different root systems on plant yield and condition. The only difference on the short term is that transplanted poly bag seedlings lack behind in absolute growth due to a transplaqnting shock. After they pick up growth again, there is hardly in growth rate between direct seeding and poly bag transplants.
b. Seeding in seedbeds is cheap and easy and successful, provided that the seedbeds are prepared properly. (pictures by the author)
Seedbeds should be prepared with ample sandy soil.
The soil should be worked on till a depth of at least 30 cm.
There should be proper drainage.
Seedbeds can be covered with straw (to protect against rain!!), have natural shade from existing trees or remain uncovered. Jatropha seedlings love sunlight, provided there is enough water. The more light, the stronger the seedlings.
These seedlings could be transplanted in poly bags after 2-3 weeks or later on (6-10 weeks) directly into the field.
c. Seeding in polybags. (Pictures D1 Malaysia) is an excellent way to produce good Jatropha seedlings. However, it is more expensive than the methods shown in a and b, because of polybags, extra soil and transport costs to the planting area.
Seeding in polybags should therefore be located as close as possible to the planting area.!
Special attention has to be paid to the soil mixture. Soil in the bags should be light and good draining. To many nutrients is not necessary and in fact will negatively influence germination. Different local mixtures can be used to fill the bags. Cocopeat turns out to be an excellent rooting medium, but might be to expensive. Mixtures of soil and sand and compost (1-1-1) are doing quit well. Make sure water and soil do not content to much salts. Farm yard manure can be very salty. Do a small trial with different mixes from local available material before you start a big nursery. The trial takes you only 4 weeks. Materials that can be used: sand, soil, compost, rice husk, peat, coco-peat, charcoal, saw dust.
Poly bags should not be to big. Volume of about 3/4 ltr is enough to allow the roots to develop a root ball. Smaller bags will cause poor root systems. Bigger bags will cause problems at transplanting, because the root ball will break.
In case the mixture in the pots is hampering drainage, germination rate will be low.
Plants can stay in the bags from 6 weeks to 3 months before they become root bound.