I am a latecomer to this blog, however i would like to answer some of your points one by one:
1. Allelopathy: We have tried various intercrops with Jatropha with economic yield. Even after harvest of Jatropha if the soil is well ploughed these effects do not appear, as is the case tried by us. However, if mild effects exists , it vanishes in a few weeks.
2. I agree with you here. Because on marginal soils without inputs these crops can grow but not yield economically. Also note that water also is an equally important input.
3. It is observed that if the plants are propogated by seeds such differences are observed. However, if they are vegetatively propogated these differences minimises. The only other way is development of good plant types, which i think most of the reserach institutions are into.
4. Again this is a factor due to the varietal influence and can be solved only after release of a consistent and high yielding variety, which will take some more time as per the public info
5. Jatropha is poisonous and cannot be used as feed.
6. The invasive potential of Jatropha cannot be agreed to as hundred's of researchers are working on the field and have found no such property of the plant.
Hi Carol,I would like to emphasize some of your points of view:
Poor yield on poor soil is evident,based on our reseachs about the suitability of the plant throught out the country,It has been observed to grow and develop well on fertile and watered soils while development and growth on acidic and infertile soil of the western province of the country(Rwanda) is very week, diseases and insects'attack are more frequent,thus jatropha need to be fertilized and management practices respected. The crop do not thrive on marginal soils
It is a good coohabitant to traditional food crops like maize,as it has been observed on our field trial,maize has not encountered any problem in grow and even yields the same as those from maize grown alone.