This tube was the first to achieve root nodules, the event happening on Day 14. On day 55 – the end of our trial, we counted a total of 20 nodules and observed that the average height of a plant was 13.3 cm. Moreover, 2 of the plants were in third trefoil growth stage, whereas the other one had achieved just the second trefoil. (see chapter White vs Magenta Comparison for more information)
The biggest advantage for the plants that had Magenta Light was the very large size of the nodules (see sections Individual Seedling Nodules Analysis – Images through Magnifying Glass & Microscopic Analysis below for detailed images).
As for the overall health, during the 7 weeks and a few days of growth, we saw no signs of contamination, such as extreme change of colour, mold, or withering.
In conclusion, we stand that Tube #1 was our most successful experiment and could therefore be a top candidate for future ISS missions.
Individual Seedling Nodules Analysis – Images Through Magnifying Glass:
Seedling
L1
L2
L3
Number of nodules
9
9
2
Measurements:
Microscopic Analysis:
Tube #2: White Light
Overall Analysis:
This tube closely followed the Magenta Light one in terms of achieving root nodules, the event happening during Week 3 in this case. On day 55 – the end of our trial, we counted a total of 25 nodules and observed that the average height of a plant was 16.5 cm. Moreover, we ended the experiment with one plant in third trefoil stage and another one with only one trefoil. (see chapter White vs Magenta Comparison for more information)
Even though the nodules were smaller in size compared to those in the Magenta Light (see sections Individual Seedling Nodules Analysis – Images through Magnifying Glass & Microscopic Analysis below for detailed images), the height of the plants inside the White Light tube was a record among our five experiments).
As for the overall height, we need to mention that one plant withered due to contamination as it touched the wet wall of the tube during Week 2. However, except for that, no other unfortunate events occurred.
In conclusion, we stand that Tube #2 has indeed proven meaningful results (two records: the biggest number of nodules & tallest plants), even though we might have had lower expectations in comparison to the Magenta Light at the start of the experiment.
Individual Seedling Nodules Analysis – Images Through Magnifying Glass:
Seedling
R1
R2
Number of nodules
9
16
Measurements:
Microscopic Analysis:
White vs Magenta Comparison
Nodules & Height Comparison:
Tube #1: Magenta Light
Tube #2: White Light
Total Number of Nodules
20 (from 3 alive plants)
25 (from 2 alive plants)
Nodule Size
verylarge
medium
Average Plant Height
13.3 cm
16.5 cm
Growth Stage
L1 & L3-third trefoil ; L2-second trefoil
R1-third trefoil ; R2-first trefoil
Key events in plant development:
The growth pattern was quite similar for Tubes #1 & #2, the following events occurring only a couple of days apart in the two tubes of the ExoLab.
1. GERMINATION: The plants at school germinated during the 48-hour dark period, but I closely analysed my plants at home and came to the conclusion that the first sign of germination was the change of appearance of the seedlings and also the occurrence of a tiny white “stem”.
2. RADICLE: The radicle emerged during the 48-hour dark period.
3. COTYLEDONS: The cotyledons appeared approximately 5 days after planting.
4. ROOT NODULATION: The first complex root branches with nodulation appeared on Day 14 inside the Magenta Light tube, and during Week 3 inside the White Light tube.
5. SINGLET LEAVES: The singlet leaves emerged during March 5 and March 7, depending on the plant, which means 8-10 days after planting.
6. FIRST TREFOIL: The first trefoil appeared between March 12 and March 16 (15-19 days after planting).
Chlorophyll analysis:
Our analysis was extended by using a Raspberry Pi for taking pictures of our plants and further processing with the help of the infragram.org platform (an online tool for analyzing plant health with near-infrared imagery). Regard below some detailed images showing the level of chlorophyll of the plants that had Magenta and White Light respectively.
Our conclusion on this topic is that the chlorophyll is very similar in both situations, maybe just a bit better for the Magenta Light.
Tube #3: Double Magnetic Field
In the tube with a larger magnetic field B, one of the plants has not grown vertically upwards, the stem actually made a loop.
Another interesting aspect is that one of the seeds germinated only around week 6, but, unfortunately, remained at that germination stage up to the end of the project.
When looking carefully at our plants through the magnifying glass we saw that there were actually a lot of small points protruding from the root. We might have missed these in our weekly reports due to their tiny size, but you can observe these when zooming in the last picture below.
These points protruding from the root could have turned into real-size nodules if they would have been allowed to grow for a bit more and that’s an observation that really mystified us. As we try to be very rigorous, we stopped the experiment very close to the ISS mission end-date. However, in our future projects, we will give this hypothesis one more chance as we believe it is bound to give meaningful data if we leave the experiment on for a longer time period.
Please see chapter Double Magnetic Field vs Double Rhizobia Comparison below for a more detailed analysis.
Tube #4: Double Rhizobia
Although we initially thought that a double content of Rhizobia would lead to the appearance of several nodules, still the plants with this double amount have had the roots on the air-agar separation surface, not inside the growth medium, during the whole period of our ground trial.
That is probably why the plants did not achieve serious root nodules like those inside the ExoLab device. Also, another possible factor could have been the dimmer light.
Similar to the double magnetic field tube, here, in comparison to the pictures of the plants that we took weekly, a surprise we had when looking at our plants through the magnifying glass was that there were actually a lot of small points protruding from the root. We might have missed these in our weekly reports due to their tiny size, but we now believe they represent an important finding.
That’s because these points protruding from the root could have turned into real-size nodules if they would have been allowed to grow for a bit more. Therefore, in our future projects, we will give this hypothesis one more chance as well and we hope the scientific results both for the Double Rhizobia and Double Magnetic Field case will be worth sharing. (see chapter Double Magnetic Field vs Double Rhizobia Comparison below)
Double Magnetic Field vs Double Rhizobia Comparison
Tube #3: Double Magnetic Field
Tube #4: Double Rhizobia
Average Plant Height
6.5 cm (3 plants, out of which one has just germinated)
10 cm (3 plants)
Maximum Plant Height
12.5 cm
10.5 cm
Growth Stage
1 x second trefoil, 1 x first trefoil, 1 x germination
1 x third trefoil, 2 x second trefoil
Total Number of Protruding Points
12
26
Tube #5: No Rhizobia
This final hypothesis fully lived to our expectations. By starting it, we wanted to prove that Rhizobia directly impacts the appearance of root nodules and therefore did not add Rhizobia to these plants. As a results, none of the seedlings has achieved root nodulation.
This tube was kept inside my at-home student lab and therefore was stopped on a different day compared to the others. So, it’s important to note that these plants had a growth duration of 53 days (including the 48-hour dark period at the beginning).
As for the overall health, the plants did not have any problem, but mold was formed on the opposite side of the jar.
The height difference between the plants and the fact that plant #1 is the only one in all experiments to be close to a fourth trefoil really drew our attention, but the most unusual aspect is that the plant that has only 5 cm has formed 3 trefoils. See the whole distribution below:
Seedling No.
#1
#2
#3
Height
10.2 cm
9.7 cm
5 cm
Growth Stage
almost fourth trefoil
first trefoil
third trefoil
Home Plants Gallery
Even though our main subjects for detailed observation were the plants inside our school lab, still each member of our team (a collaboration between 3 classrooms) improvised an at-home lab where all of us studied multiple work hypotheses which turned out to produce significant results. If you want to see whose red clover seedlings achieved root nodules, see the gallery below!
Gallery: Taking Pictures with the Raspberry Pi Camera
*Notes:
This analysis shows the results of our ground trial 55 days after planting (including the 48-hour dark period at the beginning). *except for Tube #5 which was held at home for 53 days including the 48-hour dark period.
Tubes #3 (Double Magnetic Field), #4 (Double Rhizobia) & #5 (No Rhizobia) were exposed to natural & light bulb light exclusively, only Tubes #1 (Magenta Light) and #2 (White Light) were kept in ExoLab device conditions. On the other hand, Tube #5 benefited from an improvised dimmer Magenta light inside my at-home student lab.
In the Munsell colour system, magenta is called red–purple. The additive secondary colour magenta, as noted before, is made by combining violet and red light at equal intensity; it is not present in the spectrum itself.
