Tag Archives: Jatropha breeding

Interspecific BC1 Jatropha hybrid

The Bionic Jatropha Breeding Platform in 2013

We have already passed the first half of February of this year, so this article is overdue, if we want to make this kind of posting a tradition. See last years version here: The Bionic Jatropha Breeding Program in 2012.

First of all let’s summarize some 2012 highlights one last time:

Interspecific BC1 Jatropha hybrid

Interspecific BC1 Jatropha hybrid

In December we have reached the BC2 stage following our interspecific breeding path. The first batch of BC2s are all descendants of an early and white flowering BC1, the female parent of which is in turn our non-toxic, male-sterile Jatropha plant from the wild in Guatemala. The pollen donor was an interspecific hybrid crossed from an elite toxic JcL cultivar and Jatropha integerrima. Many more genetically diverse BC2 hybrids will follow over the course of this year as our large population of different BC1s gradually start flowering. Some actually have done so by now.

Quite unexpectedly earlier in 2012 we observed enormous heterosis effects (hybrid vigor) in several different intraspecific hybrids we had kind of neglected. Some increasing seed weight compared to their parents by up to 100%. A finding which made us gravely rethink and adjust our breeding processes and objectives. Later we then saw heterosis again in another hybrid with fruit clusters consistently around 50 fruits and seed weight still significantly above the parental average. All three of those hybrids initiated flowering only 6 months after seed germination. These plants actually convinced us that consistent seed yields of 10 kg and more are within reach. We do expect to see a lot more of positive heterosis results as we only started to fully exploit our germplasm collection by crossing our genetically most distant accessions in the late months of 2012.

Two more areas are worth mentioning where we expanded our knowledge of Jatropha development significantly during 2012, possibly taking us to a global leadership position in Jatropha R&D: Grafting and multi species (more than 2) Jatropha hybridization. We have made great progress on both work streams and do expect major break-throughs to be reported by the end of this year.

BC1: 7.10xH1.1

Unusual Jatropha flowers on a hybrid BC1

The walk through of our 2012 results actually already covers most of the outlook for 2013: our interspecific hybrids will most likely reach BC4 stage moving closer to possible commercial exploitation through selection from a widening population and dedicated heterosis breeding will teach us all we need to know to develop a first line of F1 hybrids in 2014 from our germplasm range.

The first 6 weeks of 2013 gave us an extra boost in confidence looking at the great developments we saw in the usually not very eventful core dry season here in Ghana. This is symbolized by the beautiful flowers on the left, another BC1 which set flowers for the first time in January which were manually pollinated and emerged into 4 fast growing fruits by now.

Heterosis seed comparison

Jatropha hybrid heterosis: 50 fruits in a single cluster

Jatropha hybrid heterosis

50 fruits in one cluster

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.

CLO7.10xGHLT hybrid

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.

Heterosis seed comparison

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. 

Jatropha seed comparison

What makes an elite Jatropha cultivar

What exactly makes a certain Jatropha accession an elite cultivar? You can find the term everywhere but a clear definition is usually not given. Therefore I want to explore this subject today and attempt to demonstrate how an answer translates into  the daily work of a Jatropha breeder.

The term itself is simple: elite means something like “better than average” and cultivar is just an abbreviation of “cultivated variety”. But what does it really mean to us?

The most general and holistic objective when breeding for an improved commercial crop is of course always maximum profitability for the farmer. As this is self explanatory only a next level break down of objectives can offer some insight. In our program we use 4 groups of traits which in turn again break down into the real, identifiable traits when observing a selected plant.

The groups we use at Bionic Palm are:

  1. Seed Quality
  2. Seed Yield
  3. Agronomy
  4. Pest resistance.

We are looking for improved traits in all of the above groups. Let’s have a quick look at each group to see some of the aspects a breeder is really looking for every day.

Seed Quality
For us this includes several individual traits, all linking back to profitability of the crop of course.

  • Toxicity
  • Uniformity within the seeds
  • General healthiness of the seeds
  • Chemical composition of oil and cake.

No further explanations needed here I think.

Seed Yield
This is the most relevant for most people discussing Jatropha, but what are we really talking about, when we use the term? 

Many people would just want to count the seeds or go by tons per ha. An approach that would translate into something like number of seeds harvested per plant per year. This again translates into bottom line traits like branching (self or pruning induced), number of fruit clusters or fluorescences per branch, number of fruits per cluster (= number of total flowers in a fluorescence plus male:female flower ratio). Not too difficult to understand, once you know the Jatropha exclusively flowers at the top of a branch.

However, that’s not even half the truth. In our understanding the high level measurement must actually be average amount of crude oil obtained per ha (or acre) combined with average amount of cake per ha.

We have recently taken a closer look at seeds obtained from the various hybrids we produce. A comparison shows significant differences in seed weight and oil content which are actually quite stunning. And the spread is increasing the longer we breed…

Jatropha seed comparison

The typical measurement 100 seed weight varies from around 45g to 98g in our current accessions and oil content ranges from 25% to clearly over 50%. That means with an equal number of seeds per ha I can actually have up to 4 times the oil!

Agronomy

 Lets move on to traits important for agronomic reasons. Many of them are related to the cost involved in farming Jatropha and the most to the ease of harvesting.

There is the uniformity of fruit ripening which determines how many times a picker has to pass a plant per season, then there is canopy structure and size of fruit clusters which determine the ease and speed of harvesting. Other important agronomic traits are self branching (without the need of pruning). Also drought resistance or rather the reaction to water stress is an important trait. We find that there are tremendous differences between accessions. The difference is at what level of water stress a plant stops female flowers, no flowers at all, throws off developing fruits and more. We see a clear pattern of those reactions differing greatly among accessions. I also have to admit that so far the best performers are the weakest in terms of water stress resistance.

Pest Resistance

Many of the common publications about Jatropha suggest that their toxicity would protect them from pests. This is not the case! The most serious pest we are confronted with is the papaya mealy bug. It comes and goes with water stress. There is no correlation with toxicity at all, however a clear correlation with resistance against water stress. And it should be at least mentioned here that the available phosphorus in the soil plays a major role in any plants ability to handle water stress. Therefore the right soil amendments like mycorrhiza can make a huge difference in addition to the best suited accessions if you plan to plant Jatropha in the desert. :-)

I am aware that this review of relevant traits in Jatropha is anything but exhaustive, but I don’t want to bore my readers too much with the obvious. Therefore I tried to point out only a few of the less discussed but important aspects of this fundamental subject on the way to true Jatropha elite cultivars.