Jatropha breeding

8 Breeding
Breeding objectives
Breeding objectives will depend on use. Oil yield will, in most cases, be the most important
part of physic nut cultivation. Components that contribute to physic nut oil yield
per hectare are: number of pistillate flowers per inflorescence and subsequent number
of capsules per shrub, number of seeds per capsule, 1000-seed weight, oil content of
seeds (%) and plants per hectare. As the maximum number of seeds per capsule is
limited and the agronomic factor of planting density does not offer much flexibility for
increasing yields, selection should focus on the other yield components.
Ferrao and Ferrao (1984), and later Heller (1992), found highly significant correlations
in different seed samples between the 1000-seed weight and percent of crude fat
content. This might be interesting from the breeders’ point of view, as simple selection
for high 1000-seed weight could imply increased crude fat contents. From this, it cannot
be concluded that shrubs which produce seeds of a high 1000-seed weight, and consequently
a higher crude fat content, will yield more oil per hectare. A high 1000-seed
weight can also be the consequence of a low seed yield per shrub. Further research on
this is required.
Other important objectives are reduced plant height to facilitate harvesting of capsules
and development of non toxic cultivars, where the seed cake could be used as
fodder.