Growth Conditions for ''Arabidopsis thaliana''

Temperature and Humidity

Updated: grow chamber temperatures are kept at 18°C at night and 22°C during the day.

The cold room should be maintained at 18°C while during the day the LED lights and reflective material will raise the temperature to 22°C.

The boxes will maintain the humidity between 60 and 70 % humidity.

Lighting

Version 1 Lighting should be around 100-200 umol/m2/s during the 16 hour photoperiod.

Note: Our grow chamber is equipped with sets of 4 fluorescent bulbs per shelf - each bulb is 2650 Lumen, and so 4 of them in conjunction equals 10600 lumen. Based on the size of our shelves, that is roughly equivalent to 10600 lux (as each of our shelves are around 1 square meter). A conversion website [1] shows that 100-200 umol/m2/s is equivalent to 7,400 and 14,800 lux, respectively. Thus, our approx. 10,600 Lux light source falls within the necessary range of lighting.

Note: After recognizing that many of the lights mentioned above were defective (owing to the fact that the fixtures themselves were purchased in 1994), we purchased 6 new fluorescent grow lights that would be smaller and more efficient. These lights are 6500K and feature a 5,000 Lumen output. As stated above, lumens are approximately equivalent to lux in this experiment given that our shelves are around 1 square meter. Given that 3 of these lights would add to approximately 15,000 Lux, we would only slightly overshoot the 14,800 lux bar that corresponds to 200 umol/m2/s. [2]

Lighting levels and the photoperiod in the greenhouse is based on whatever light comes in through the windows from the outside.

Note for future research: We determined that 4 grow-lights for each shelf in the grow-tent is sufficient to grow healthy A. thaliana. However, given the inaccuracy of the HOBO data loggers regarding light intensity measurements, it would be beneficial to borrow a multi-directional light sensor to measure the light levels inside the grow-tent.

Version 2

Updated due to the experimental tests of the new lighting conditions. The shelves are covered with silver Mylar reflective material, in both the back and the front. The front sheet should be removable and attached to the shelving unit by velcro. The shelves are placed 24" apart from one another. Three LED lights are placed at the edges of the shelves and the center of the length of the shelf. They can be hung by zip-ties and attached to the bottom of the above shelf by reusable zip-ties. The boxes should be arranged according to the evenness of the light according to the Hobo light tests.

Irrigation

Irrigation is only needed for Arabidopsis thaliana plants grown in non-sterile conditions. Once seed flats have been transferred to the greenhouse, keep soil well watered until true leaves have appeared on seedlings - at this point, "reduce the watering frequency to as low as once or twice per week as needed" [3]. Watering can be conducted by misting the plants for 30 seconds with a hose mister. Over the course of the experiment, plants also responded well to growing in seed flats placed in trays of water.