Post authored by Dr Michelle Eckert
When you think of planting seeds, the traditional way is to place the seeds directly into the soil. But with seeds of some species that germination process is not as successful as you want it to be.
That is why at EucXylo we use alternative methods to germinate our Eucalyptus seeds.
First, capsules are harvested from mature trees (Figure 1A), in this case, focusing on Eucalyptus cladocalyx (common name “sugar gum”). After leaving the capsules in paper bags for a few weeks to dry out, they are coarsely sieved (Figure 1B), resulting in a mixture of materials (Figure 1C). Then to extract most of the seeds from the mixture, a fine sieve is used (Figure 1D) to remove any unwanted materials.
Figure 1. (A) Tertius Venter (left) and Deon Malherbe (right) harvesting capsules from mature Eucalyptus cladocalyx trees, (B) the capsules after the drying process, (C) materials collected from coarse sieving the capsules, and (D) seeds collected after another process of fine sieving.
Once the seeds have been obtained (Figure 2A), they are sowed in Petri-dishes containing water agar, and kept in our growth chamber at 26°C. Germination is then continuously monitored over two weeks to determine germination success (Figure 2B-C).
Figure 2. (A) An example of a Eucalyptus cladocalyx seed, (B) seed showing germination on Day 4, (C) a seed that has successfully germinated and has started to root by Day 4.
After sowing 400 Eucalyptus cladocalyx seeds using this method, we (myself and Dr. Leandra Moller) already had a 65% germination by the seventh day; a number that we consider quite successful for a tree species known to be recalcitrant.
We are excited to see how many more seeds will germinate over the remaining few days!