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Revision as of 15:02, 17 October 2018
Alternative Roots
Results
LUX Levels
First measurements taken from the LED's was when they had the 'rainbow' function loaded. Meaning the lights cycled through the colours of a rainbow. We applied this test so we could determine which colour gave the highest Lux. Which established that purple 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 1300 lux. Leading us to believe we could tweak this light level even more. therefor we tried different preset colours; Blue, Green, Red, White, Blue proved to be the highest. Realising that the LED's 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 preset Blue. Which meant 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. Giving white light which performed worse than the preset Blue and white. Therefor we created purple via Blue, Red: 265. Which also proved to be less than the preset blue. Figure 1.0 show the results from these measurements.
Therefor thinking that the preset 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 peak Lux peak when the Red is at a light level of 129. Next we tried Blue:265, Red:129 and varied green from 0-265. Which appeared to have a detrimental effect on the light intensity. Figure 1.1 shows the relationship between these colours
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
There was 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).
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.
It was expected that there would be more germinations from rack B, and 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 that for germinating a higher number of plants to be tested in a lab the purple light performs better. 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 quite clear. The percentage of germinations for NH-1 after 4 days was significantly over 50%, compared to the windowsill which was 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.
