We are currently observing another impressive result of hybrid vigor in our Jatropha Breeding Program: a six months old hybrid exhibits the first fruit cluster with exactly 50 healthy fruits. The seedling germinated on March 17 (my birthday :-)) and has reached a height of more than 2.5 meters by now. Manual pollination has been conducted 10 days ago.
Among other this hybrid also shows a distinctively superior tolerance to drought stress than both parents. As usual drought tolerance goes together with relative (horizontal) pest resistance.
2 sister plants of the identical hybrid which had germinated in the same week are showing similar impressive fruit counts for their first clusters: 35 and 42 respectively.
Hybrid fruit cluster
Update: the same fruit bunch 10 days later…
Update 2: On November 23 we harvested the first fruits from this bunch. Obviously, we were very curious to find out about a possible heterosis effect on seed size and weight. Well, what can I say? It’s another breakthrough really that would deserve its own separate article on this site:
We weighed 15 freshly harvested seeds at a total of 18 grams. This converts into a 100-seed weight of 120g. That’s a new record in our breeding program.
Seed comparison with parental accessions
As a matter of completion, the 100-seed weights of the parents:
female parent (top left): 90g
male parent (top right): 45g.
It will be interesting what we are going to see in the next generations of hybrid crosses. The plant has already been crossed with most of our high quality accessions and also back crossing with both parents has begun. We will definitely report again in the future.
We have harvested a first batch of Jatropha seeds from the intraspecific hybrid exhibiting by far the strongest heterosis effects in leave size and height. And we were up for a real surprise.
We had recently seen 2 scientific reports on heterosis trials with Jatropha in South East Asia describing maximum positive heterosis in seed weight of up to 25%. We therefore never expected to see our highest 100-seed weight increasing so much. Extrapolated from 20 harvested seeds it slightly exceeds 110g. Size can be compared well in the picture above with control being a typical average size seed at a 100-seed weight of 56g.
Our own findings are completely in line with the above mentioned reports, while showing even further potential. We still have to cross those parental lines in our possession with the greatest distance according to our genetic map. As all available results point to the very strong positive correlation between heterozygosity and heterosis in intraspecific Jatropha hybrids we expect that our latest findings can easily be exceeded once all our planned hybrid crosses have fruited.
This latest success supports our ongoing planning for a dedicated heterosis breeding sub-program which could allow for stable, highly superior F1 hybrids within less than 2 years.