Rocket: a Mediterranean crop for the world - Bioversity International

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ROCKET GENETIC RESOURCES NETWORK
material that is not yet fully mature. This means that the maturation will
occur after collecting. One system that has been tried at IdG is collecting a lot
of stalks and putting them into big paper bags to allow natural desiccation.
After a few days, mature silique will open and the seeds will accumulate in
the bag. One can get a high seed yield in this way, and even though the
germination is lower, the numbers compensate for this deficiency.
• Oily seeds. There are reports in the literature that oily seeds are less easily
stored and much care has to be taken with their desiccation and storage. At
IdG, we have little experience on this subject and therefore more information
from seed physiologists should be sought on how to best preserve them.
• Capsules opening at maturity. The influence of this point on seed
germination has been discussed earlier. It is important to stress now that for
multiplication purposes the dehiscence of fruits poses another question: the
material near maturity needs daily inspection and careful collecting in order
to minimize seed loss. In insulated conditions this implies a lot of labour
with an increased cost. This point is of some importance, especially for
genebanks which plan large-scale multiplications and have allocated few
funds to rocket and other underutilized species.
• Possibility of contamination with local pollen. As just stated, the necessity
to open the isolation cages for plant care may allow the entrance of foreign
pollen into the isolation space, especially in those areas where rocket grows
spontaneously near the multiplication field. This implies that the allocation
of the multiplication facility has to be chosen very carefully, possibly
exploring in previous years those areas less infested by wild rocket. The
irony is that, in this case, germplasmists always looking for rocket need to
find ways in which to get rid of it!
• Possibility of increasing self-incompatibility. During multiplication in
insulation it has been noticed that the level of self-compatibility of these
species reported as strictly allogamous is rather high. Nevertheless, in the
next generations problems might arise owing to inbreeding depression or to
the build-up of an incompatibility system. Many allogamous species have
internal genetic mechanisms limiting their possibility of selfing over a long
period. Unfortunately, both Eruca and Diplotaxis have not been sufficiently
studied from this point of view. The issue is, however, not a minor one since
it has importance when one needs to select commercial varieties of rocket. In
this case the possibility of breeding a true variety is linked with the
possibility of maintaining the stocks in purity throughout selfing. Otherwise
one needs to choose alternative strategies such as maintenance of artificial
populations through appropriate mixtures of genotypes. It seems to me that
this point should receive much more attention by geneticists and plant
breeders.
Questions for the future
The last 2 years have been very productive for the Rocket Network, and this success
allows some optimism for the future. Nevertheless some points have to be brought
to the attention of the participants of this workshop. The first is the minor funding
of this activity. It is essential that all Network participants be proactive in finding
some ad hoc financial support for the Network; otherwise, the risk is that after a first
phase of voluntary enthusiasm, this activity will cease. Even a little funding could
increase the commitment of Network members.