Introduction

In order to understand the performance of the NH-1 two experiments were conducted. The first of which was to show the range of conditions that the system can generate. This was a proof of principle experiment, which is meant to outline that a different conditions will generate different phenotypic responses in the plants. The second experiment was measuring the percentage germination from the optimal purple light conditions of the NH-1 against a simple windowsill (natural daylight) condition.

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-cuts of plywood and wrapping them in tinfoil to create a reflective surface, sourced from the architecture workshop. Figure 2.0 shows the dividers used. This allowed us to expose different areas of the hydroponics to different wavelengths of light by addressing different LED's.

Utilising the Arduinos' easy-to-adapt design we can manipulate this device to display the desired wavelengths at each individual LED. The first four LED’s emitted green light and the remainder emitted purple (separated by a divider), the intensities were measured to be 200, 1700 Lux respectively (code can be found here).Eruca sativa Seeds were then planted in two pipette-tip racks (96 in each), one green (A), one purple (B). They were then left to germinate for a week.

Results

After 1 week the seedlings were checked for germination (Figure 4) and had their height measured (Figure 5). The results show that a greater percentage germination was obtained from purple light (22/96) than green light (4/96). Out of the 4 that germinated in green light, the seedlings were much taller than those in the purple light, those grown in purple light were more uniform in their growth, showing the ability of the NH-1 to elicit a range of phenotypic responses and fulfilling its design purpose.

Figure 4. Graphical display of rocket germinations when exposed to green Vs purple light

Figure 5. Graphical display of rocket height when exposed to green vs purple light

Figure 6. Graphical display of rocket germinations when in the NH-1 or on the windowsill

For the second experiment the results are also clear (Figure 6). 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. Therefore 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 provided data that suggests our system is effective at creating a high throughput germinating environment. This system is also controllable and programmable if growing conditions need to be changed. Overall, 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.