Team:Newcastle/Results
Alternative Roots
Results
LUX Levels
Introduction
After creating our system we needed to measure the light intensity that the LED’s output. This will give us a bearing on the probability of a successful germination. For example, an over cast day in Lux is between; 1,000 - 30,000 [1]. Therefor a simple Lux sensor will give us a starting point. From this we can then begin to experiment with different colours of light. Through our Human Practices we expected that purple light would give us the most Lux since this is the most commonly used in the industry.
Results
Our initial tests were to run the pre-programmed colours i.e. Blue, Green, Purple, Red, White and a rainbow function which cycles through the spectrum.
Firstly we decided to measure the 'rainbow' function. We applied this test so we could determine a range which may give us the highest Lux. We established that purple/blue is the 'optimal' colour to use peaking at 1100 lux, confirming what our Human Practices has revealed when visiting various hydroponic facilities.
Next we loaded the Arduino with a programmed in 'purple' colour. This measurement stabilised at roughly 1000 lux. Leading us to believe we could tweak this light level. Therefor we tried different pre-set colours; Blue, Green, Red, White, giving roughly; 1375, 300, 525, 1360 Lux respectively. Realising that the LEDs manage colours by producing different quantities of Blue, Green and Red light, we figured we may be able to create an optimum between these colours hopefully improving on the pre-set Blue. Which means we couldn't use a preset library and would have to define the light levels of the primary colours manually.
Before starting we defined the brightness of each colour as an 8 bit integer (265 light levels). The most obvious place to start was to turn all the primary colours up to 265. Producing altered white light which performed worse than the pre-set Blue and white at roughly 1300 Lux. Therefor we created purple via Blue and Red at 265 (altered purple). Which also proved to be less than the pre-set blue but slightly higher that ‘altered white’.
Therefor thinking that the pre-set Blue was actually our maximum we attempted one more test. Holding Blue at a constant 265 but varying Red from 0-265 and plotting the results. We discovered that there is a Lux peak when the Red is at a light level of 129. Next we tried Blue:265, Red:129 with a varied green from 0-265. This appeared to have a detrimental effect on the light intensity. Figure 1.1 shows the relationship between these colours.
Conclusion
From these measurement we can determine that the Lux level should be adequate to germinate Arabidopsis, Rocket and various other plants. Heating control does not need to be built as this system will be held inside a room with a constant temperature. Also water and air flow are not a pressing issue since the water needs to be changed once a week. Therefor the next experiment will involve real plants.
UP TO
SEEDS CAN BE GROWN
IN HYDROPONICS
APPROXIMATELY
KWH OF POWER ANNUALLY
USED TO POWER SYSTEM
PROVIDES UP TO
LUX OF LIGHT
TO GROW SEEDS
CONTAINS
INDIVIDUALLY ADDRESSABLE
LOW-POWER LED'S
Stage Two
Green light & windowsill experiment
Introduction
There were two separate experiments we ran in order to understand the performance of our NH-1. The first of which was to confirm that our rendition of purple light was significantly better than an alternative green light. This was a proof of principle, which is meant to outline that a higher Lux reading will result in more germinations. The second experiment was measuring the germinations from the optimal purple light against a simple windowsill (natural daylight).
Method
For the first experiment we had to make a rudimentary barrier to place inside the NH-1 in order to block light effectively. We did this by using off cut plywood and wrapping them in tinfoil to create a reflective surface, sourced from the architecture workshop. Figure 2.0 shows the dividers used. This allows us to expose different areas of the hydroponics to different wavelengths of light.
Utilising the Arduinos easy to adapt design we can manipulate this device to display the desired wavelengths down to an individual LED. The first four LED’s emitted green light and the remainder emitted purple, the intensities were measure to be 200, 1700 Lux respectively (code can be found
here). Seeds were then placed in two 96 well racks, one green (A), one purple (B). They were then left to germinate for a week.
Results
It was expected that there would be more germinations from rack B, figure 2.1 displays the data collected. The germintations for racks A and B were; 6, 22 respectively. However the shoots in A are significantly taller as they are straining for light. Whereas the Rocket in rack B is more uniform. Indicating Purple light is more effective for germinating a higher number of plants. Which at least indicates that the higher the Lux the greater the superior the yield. Confirming why Purple light is used more frequently.
Figure 2.1; Graphical display of rocket germinations when exposed to green Vs purple light
Figure 2.2: Graphical display of rocket germinations when in the NH-1 or on the windowsill
For the second experiment the results are also clear. The percentage of germinations for NH-1 after 4 days were significantly over 50%, compared to the windowsill which were around 25%. The gap slightly closed after 8 days, however the NH-1 was still roughly 25% more efficient. Therefor we can conclude that our system works, it provides a more efficient germination period than a natural counter part (Newcastle daylight). Whilst also allowing us greater control over the day and night cycles, if we need to starve the plants of sunlight we can quite easily adjust the settings.
Conclusion
Both of the experiments ran, provided data that suggests our system is effective at creating a high throughput germinating environment. Which is controllable if growing conditions need to be changed. Overall, I believe this system is a success and we have met of our aims which were to provide a guide for a system that is controllable but more importantly worked, and was a suitable substitute for a windowsill.
References & Attributions
1. Pattern Guide; 17 Apr 2011, https://patternguide.advancedbuildings.net/using-this-guide/analysis-methods/lux-overcast-sky
Attributions: Luke Waller, Umar Farooq