Plant Growth One of the characteristics of plant life is that the plant undergoes a growth process. Growis an irreversible increase in volume. The amount of growth per unit time is calledgrowth rate. The growth rate of a plant or its parts changes over time. Therefore, if the growth rate is depicted by a graph, with the growth rate on the ordinate and time on the abscess, then the graph is an S-shaped curve or sigmoid curve. This sigmoid growth curve applies to the complete plant, its parts or cells. The sigmoid curve is useful for experts in conducting further research about the growth and development of plants, because it shows the stages of development. In experiments using live plants, the plant development phase needs to be taken into account to be able to analyze a phenomenon correctly. Biologists and mathematicians have attempted to formulate a mathematical equation for the growth curve. It is hoped that with such an equation we can accurately estimate growth from sprouting to harvest, only by using growth data in the early phases. This is very important both for theoretical development purposes and for practical purposes. This growing process is a complex or very difficult process, both regarding plant characteristics and environmental factors. The greatest growth is growth that consists of the enlarging and elongating phases of the cells. Because it is difficult to measure this growth phase, for example measuring volume, in this experiment we will measure the growth and elongation of roots, stems and leaves. Experiment a. Sigmoid Curve of Leaf Growth Objective: Examining the rate of leaf growth from the embryo in the seed until the leaf reaches a fixed size. Materials and tools: Plant material : Seeds of legume plants Tools : Millimeter paper, razor blade, pot filled with sand mixture and soil in a ratio of 1: 1 Ways of working: 1. Soak the seeds for 2 to 3 hours in a glass beaker, select 30 seeds for the experiment. 2. Peel 3 seeds and open the cotyledons, measure the length of the leaves in the embryo with millimeter paper, then calculate the average value. 3. Plant 25 seeds in a pot, water them with water, keep them in the laboratory for 2 weeks. 4. Make the following observations: a. Measure the length of the leaves and petioles (the first leaf which is a single pair of leaves) at the age of 3, 5, 7, 10 and 14 days. b. Leaf measurements at the age of 3 and 5 days were carried out by digging up the seeds. Each measurement was carried out on 3 plants. Don't use seeds that don't appear to have germinated. c. Subsequent measurements are carried out without cutting the sprouts/plants. Always use the same 3 plants for these follow-up measurements. d. Determine the average leaf length from each series of measurements. 5. Make a graph with the average length of the leaves (including the petioles) as the ordinate and the measurement time (plant age) as the abscissa. Experiment b. Root and Stem Growing Area Objective: Observe the growing areas on the roots and stems. Materials and tools: Plant material : Bean sprouts,Chinese ink Tools : Glass tube, glass plate, ruler. and filter paper Ways of working: A. Growth area on the root 1. Take 10 sprouts with straight roots and a length of more than 2 cm. Starting from the tip, 10 lines are marked with Chinese ink at 1 mm intervals. 2. Using a rubber band, the sprouts are placed in an upright position on a glass plate that has been wrapped with filter paper. 3. Take another 10 sprouts and mark them with a line 10 mm from the root tip as a control and place them as in number two. 4. The glass plates to which the sprouts have been attached are placed in a glass tube containing a little water and then covered so that the space in the tube remains moist. 5. The tube is placed in a dark room. 6. After 24 hours, the distance between each interval on each sprout is measured. 7. Compare with the control, then make a graph of the increase in length for each interval. B. Growing areas on the stem 1. Choose 20 plants with straight stems. The epicotyl of the plant is marked with 10 lines from the tip at 2 mm intervals. Treat the 10 selected plants and label the plants number 1 to 10. 2. As a control, the other 10 plants were marked 20 mm from the tip and labeled with plant numbers 1 to 10. 3. Place the pots with the plants in a dark place. 4. After 48 hours, the distance of each interval is measured then the increase in the average length of each interval is plotted on a graph.