The intensity of light radiating from a point source that reaches a surface is inversely proportional to the square of the surface’s distance from the source - Inverse square law. This simply means that if an object is twice as far away it receives only a quarter of the light.
This is the basis of this experiment. For a long time we have relied on the sun as the source of food, but with recent scientific studies, man has stared to grow plants indoors with the help of artificial light from bulbs. Artificial light from florescent lamps has proved to be able to support photosynthesis though it lacks some components of the radiation that plants require hence a low output.
Photosynthesis is the process by which plants, some bacteria and some protistans use the energy from sunlight to produce glucose from carbon dioxide and water. This glucose can be converted into pyruvate which releases adenosine triphosphate (ATP) by cellular respiration. Oxygen is also formed. In simpler terms, photosynthesis is the process by which plants make their food. Carbon Dioxide + water in the presence of sunlight and Chlorophyll will produce Glucose and Oxygen. Thats why plants use up Carbon Dioxide and Release Oxygen.
This project is also available on my Instructables Page Instructables Page
Artificial light is light radiation that comes from lamps which are used to provide light. Its light that does not come from the sun.This is the light that am going to use in this experiment. More productive experiment shave used LED(Light Emitting Diode) which have proved by far to produce more healthy plants.In this experiment I will use CFL(Compact Florescent Lamps) which are in the class of fluorescent lamps. CFL’s work on the same principle of fluorescent lamps through their design is more compact making them easy to use in confined spaces.
CFL’s can run for upto 10,000hrs and have a 44-80 Lumens/Watt light output. They come in 125,200,250 and 300W Power ranges. The following list shows the amount of light in Kelvin required by plants when growing. CGL’s produce Red and Blue Spectra which combine to make white light that we can see.
2700K - Warm/Red - Flowering 5000K - Full Spectrum/Daylight 6500K - Cool/Blue - Vegetative/Growth Different grow lamp types emit light in different ways. The light spectrum in grow lights is expressed in degrees Kelvin (K), a number that indicates a visual “temperature.” Grow lights with higher color temperatures (5000-6500K) provide the full light spectrum and promote all stages of vegetative growth. They emit light with a bluish tinge. Grow lights with lower color temperatures (2500-3000K) are known to encourage flowering and are often used when the plant develops fruit. They put off a reddish or even yellow glow. The best artificial light source for tomatoes imitates the light in their natural environment. Natural daylight has a high color temperature (about 6000 K). Select your grow lights accordingly
|1700 K||Match flame, low pressure sodium lamps (LPS/SOX)|
|1850 K||Candle flame, sunset/sunrise|
|2400 K||Standard incandescent lamps|
|2550 K||Soft white incandescent lamps|
|2700 K||"Soft white" compact fluorescent and LED lamps|
|3000 K||Warm white compact fluorescent and LED lamps|
|3200 K||Studio lamps, photofloods, etc.|
|3350 K||Studio "CP" light|
|5000 K||Horizon daylight|
|5000 K|| Tubular fluorescent lamps or cool white daylight
compact fluorescent lamps (CFL)
|5500–6000 K||Vertical daylight, electronic flash|
|6200 K||Xenon arc lamp|
|6500 K||Daylight, overcast|
|6500–9500 K||LCD or CRT screen|
|15,000–27,000 K||Clear blue poleward sky|
| These temperatures are merely characteristic;|
considerable variation may be present.
Temperature Source 1700 K Match flame, low pressure sodium lamps (LPS/SOX) 1850 K Candle flame, sunset/sunrise 2400 K Standard incandescent lamps 2550 K Soft white incandescent lamps 2700 K “Soft white” compact fluorescent and LED lamps 3000 K Warm white compact fluorescent and LED lamps 3200 K Studio lamps, photofloods, etc. 3350 K Studio “CP” light 4100-4150 K Moonlight 5000 K Horizon daylight 5000 K Tubular fluorescent lamps or cool white daylight compact fluorescent lamps (CFL)
5500–6000 K Vertical daylight, electronic flash 6200 K Xenon arc lamp 6500 K Daylight, overcast 6500–9500 K LCD or CRT screen 15,000–27,000 K Clear blue poleward sky These temperatures are merely characteristic; considerable variation may be present. Light radiation which our eyes see is normally in the range of 390 - 700nm. This light in respect to growing plants is produced by various types of lamps:
Incandescent - Least efficient and doesn’t produce wavelengths appropriate for growing plants. High Pressure Sodium LED Technology Plants produce energy by photosynthesis using two units, Chlorophyll A and Chlorophyll B. Chlorophyll A uses light in the deep red spectra (600 - 700 nm), while B uses light in the deep blue spectra (435 - 450 nm)
H1 Notes on Purchasing CFL’s Correct wavelengths are measured on Kelvins Higher wattage lamps are good Lamps with 6500K and 2100K lamps are the best since thats where the Red and Blue spectra falls Lumens are amount of Visible Light falling on a square area. Visible light does not hit the Red and Blue Spectra thus not good for growing plants.
Germination Information of Seeds
H2 Peas Peas will sprout in 21 to 30 days if the soil temperature is 38 degrees Fahrenheit and the germination rate, or number of seeds that do sprout, will be low. At temperatures of 65 to 70 F the seeds will sprout within 7 to 14 days and the germination percentage will be in the high 90s for fresh seed. Above 75 F the germination percentage goes down quickly even though the seeds sprout quickly. Remember, these are soil temperatures, not air temperatures.
Most green beans should be planted after the soil warms and the danger of frost is gone, and need to be planted about an inch deep (and as deep as two inches, especially in arid climates). As a rule of thumb for planting, plan for about 10 to 15 green bean plants for each person in your household. Once planted, the beds should be watered to stay evenly moist until all of the seedlings emerge from the ground, at which point the surface of the soil can be allowed to dry out between watering. Green beans will do best in fertile soil that is rich in organic matter, and digging some finished compost into the garden beds will help them thrive. Once the green bean seedlings have several true leaves, cover the garden beds with several inches of mulch to conserve moisture, keep soil temperatures cooler, and keep weed seeds from germinating.
|Friday 26 August 2016 (14:00)||Idea conceptualized|
|Sunday 28th August 2016 (14:50)||Foil added to the compartment for growing the plants|
|Friday 9th September 2016 (18:50)||First weeds break the surface|
|Saturday 10th September 2016 (08:56)||First bean seedlings break the surface|
|Sunday 25th September 2016 (14:50)||Plants removed from incubator and growing with desk-lamp|
|Tuesday 6th October 2016 (07:05)||Experiment Ended|
The following are daily observational notes:
|Date/Time||Tray A - 2 Green Gram Seeds & 1 Bean Seed||Tray B - 6 Bean Seeds|
|Thursday 8th September 2016 (07:00)||Soil moist and small weeds shots can be observed to be growing. Leaves are yellow in color, a possible indication of poor or NO light. Air temp warm||Soil moist and small weeds observed to be shooting. Yellow also yellow due to poor light received.Air temp warm|
|Thursday 8th September 2016 (18:50)||Soil moist before watering and small weeds growing well. Leaves are green but still no sign of green grams seedlings or bean seedlings||Soil moist before watering and small weeds growing well. Leaves are green but still no sign of green grams seedlings or bean seedlings|
|Friday 9th September 2016 (06:36)||Soil moist before watering. More green leaved weeding are growing. 2 bean like seeding can be seen growing. Been seeds are shooting much faster. No sign of green grams yet. Air temp cool||Just like in Tray A more green leaved weed-lings are growing but no sign of bean seedling. Soil is damp before weeding.|
|Friday 9th September 2016 (19:03)||Many weed-lings have grown to 1cm in height all having green leaves. They all seem to face the source of light and heat. Bean seedlings can be seen germinating.||Many weed-lings have grown to 1cm in height all having green leaves. They all seem to face the source of light and heat. Bean seedlings still not visible.|
|Saturday 10th September 2016 (08:06)||Many weed-lings have filled the surface of the tray with green leaves. 2 bean seeds have cracked the surface and are shooting but no leaves visible yet. A seedling that looks like a green gram seedling can be seen shooting to ground level.||Many weed-lings have filled the surface of the tray with green leaves. All have green leaves. One bean seedling has cracked the ground level while the others haven’t|
|Saturday 10th September 2016 (21:53)||Two bean seedlings and a green gram seedling have made it above ground. In-fact one bean seedling has already reached the bulb height and almost touching the lamp.||No bean seedling can be seen so far, a condition that is to worry. Weedlings are germinating so far.|
|Sunday 11th September 2016 (09:00)||2 bean seedlings have shot to the ground level. A green seeding that appears to be a green gram has also appeared. All plants have green leaves.||A couple of been seeds are breaking the surface and can be seen germinating. However, an unidentified plant has almost emerged but I think its a weed despite the large green leaves.|
|Sunday 11th September 2016 (18:30)||2 Green gram seedlings have shot well. The taller one is 135mm while the smaller one is 35mm. The taller one has charred leaves due to having come into contact with the bulb. As for the shorter one, it has brown spots on its leaves. The bean seeding has also experienced exponential growth to 140mm and appears healthy. It also has charred leaves due to coming into contact with the bulb.||5 been seedlings have made it to the surface and look very healthy. They seem to be growing much slower that their counterparts in Tray A. Leaves are green.|
|Monday 12th September 2016 (10:00)||2 green grams are germinating well. The lone bean seed is also growing well. I rotated the tray to solve the problem of seedlings touching the lamp. Cut the weeds to save nutrients, Not watered.||All 6 bean seedlings have germinated and are looking healthy. Tray has also been rotated Not watered.|
|Monday 12th September 2016 (22:30)||Room was very moist due to prolonged exposure to light. Trays were rotated so the plants have slowly changed their direction of growth. All the plants are germinating well. Weeds to be cut||2 bean plant leaves have charred and almost dried up due to coming into contact with the bulb. All other seedlings are doing well, cut the weeds|
|Tuesday 13th September 2016 (06:32)||Another tray rotation to solve burning of the leaves. All plants are doing well||Another tray rotation to solve burning of the leaves. All plants are doing well.|
|Tuesday 13th September 2016 (19:00)||Power was not available from 2pm so plants received half a day’s light, 2 green grams are growing tall while the bean seed has bigger leaves. Leaves of the green grams appear to have dried on the edges.||The charred leaves on the bean plant do not seem to be doing well. All leaves are brown watching for outcome. Another bean’s seedling leaf that I cut off might not make it too. All the rest are doing fine.|
|Wednesday 14th September 2016 (07:56)||Added bulb insulation cover to stop charring of leaves. Green grams don’t seem to be doing well.||All plants are doing well except the one bean plant whose leaves were charred. Cut weeds but still growing exponentially|
|Wednesday 14th September 2016 (18:00)||All green grams have been lost and have dried up. Seems conditions were but favorable for them, Single bean seed is doing well.||The non-leaved bean plant seems to be drying up, A bean plant has a dark spot in its leaves. The others are doing fine. Weeds are surprisingly back.|
|Thursday 15th September 2016 (08:00)||It’s been a week so far of running the experiment, 1 bean plant and some weeds are present in this tray||5 bean seedlings doing well and 1 that has no leaves, A few weeds that seem not to go|
|Thursday 15th September 2016 (18:30)||The leaves are becoming bigger and the plant is bending towards the lamp. To get more light||All plants are doing well and have large leaves also hanging toward the lamp. Another lamp to be added tomorrow|
|Friday 16th September 2016 (07:56)||Plants are doing well, Weeds still growing||Plants are doing well. Weak bean has been uprooted which had lost two leaves|
|Friday 16th September 2016 (18:00)||The bean plant is growing well but the leaves are getting charred on one end. Soil surface has some white color||Plants are doing well and have very broad leaves as compared to tray A. This might be due to the capture of more light.|
- Voltage: 240V
- 3X 15W CFL Compact Florescent Lamps
- 1X Foil Paper
Observations, Conclusions and The Future
I brought the experiment to an end on 6th October 2016 after it was clear that the plants were not doing well under the light of the desktop lamp. Also being outside meant that my feline predator occasionally feasted on the tender leaves of the plants which greatly contributed to the slow growth and drying up of some plants. However despite these problems I have collected and learnt allot of information about pants and that why I will build a bigger set up in Growing With Plants 2 where I will monitor the growth more carefully with upto date data and good instrumentation.
This experiment was a good learning curve. You can find the data in the above table. I will create a Images section to hold the many project images.