The Effect of Sunlight Exposure on Growth of Plants
...d flowers. These flowers are dicotyledons which then branch with two leaves and contain flowers that have four petals, four sepals and six stamens. The use of the RBBr in this study (compared to Brassica rapa) was preferred because it has a shorter life cycle. This makes it a good plant to use for a study in an introductory biology lab. The RBCr plants were derived by continuous genetic selection. When under 24 hours of light exposure and water supply, the plant is predicted to go through the entire life cycle within a few weeks. Within ten days, it is predicted that the seed will grow and leaves will emerge from the stem. The flower buds will appear and grow until day 13, when the flowers will be revealed. From the 18th to 22nd day, the pods will elongate and swell. The embryo development will begin. In the last few days of the life cycle, the embryo development will be completed and seeds are formed. There have been numerous research conducted in which the effect of duration of light exposed to plants was studied. In many of them, plants were exposed to 24-hour light using an incandescent lamp. These types of lamps have relatively low irradiances which is necessary for a photoperiodic response. (Shopshire and Mohr, 1983). Thus, in this study, the growth of two different plants was observed. One is exposed to artificial light for 24-hours a day using an incandescent lamp while the other was exposed to approximately 11 hours of natural sunlight. Materials and Methods For the control group, about 3-4 fertilizer pellets and 2-3 seeds of Brassica rapa were placed in soil in each of the 4 half-filled cells in the Styrofoam container. This was watered by a water spray initially and received an automatic 24 hour supply of water as needed. After being exposed to 24 hours of light from a lamp, observations were recorded every Tuesday and Friday for five weeks. For the experimental group, the below steps were followed, approximately four fertilizer and three seeds of Brassica rapa were placed in a black plastic container. The plant was placed near the window where it received sunlight from sunrise to sunset and received approximately half a cup of water everyday. Observations were recorded every Tuesday and Friday for five weeks. Results For observational purposes, the growth of the lab plant was recorded for each quadrant that were labeled as: Figure 1: Quadrants of Plant The results were recorded: Day 1 Plant in room: no visible growth Plant in lab: no visible growth Day 2 Plant in room: no visible growth Plant in lab: 1-1: no visible growth 1-2: no visible growth 2-1: germination visible; light green stem growing 2-2: no visible growth Day 4 Plant in room: no visible growth Plant in lab: 1-1: no visible growth 1-2: no visible growth 2-1: stem in ½ inch in length 2-2: germination visible; light green stem visible above soil Day 8 Plant in room: no visible growth Plant in lab: 1-1: small leaflet growing on corner of the container 1-2: small leaflet growing along left edge of container; ½ inch stem growing in center of quadrant; no leaves on stem 2-1: stem is 1-1/2 inch in length; growing straight up (not bending); 3 leaves on stem- 2 fully formed and one partially formed 2-2: 2 small leaflets formed on stem; stem is ¼ inch in length The plant was observed every few days until the 37th day where the following was observed: Day 12 Plant in room: no visible growth Plant in lab: 1-1: no visible growth 1-2: no visible growth 2-1: stem that is 1-1/2 inch in length diverts into 3 parts: a) 2.5 inch long stem with six flowers and 2 buds; b) 2 inch stem with three flowers and one leaf; and c) ½ inch stem with one leaf 2-2: 6.5 inch long straight stem with 4 leaves and 5 flower buds Figure 2: Graph comparing number of flowers grown under both conditions. Discussion The study displays that the plants in the lab that were exposed to light continuously grew and showed the characteristics of the life cycle. Meanwhile, the plant in the room didn’t grow at all. This shows that the amount of sunlight is extremely important for growth of RCBr plants. As can be seen by Figure 2, the lab plant grew an average of four flowers by Day 12...