Second important reason is that transpiration process helps to ‘cool’ the plants. Transpiration rate depends on 2 issues, first is the gradient in humidity trot the leaps internal air spaces to the outside air and the diffusion resistance provided by the stomata pores. One way to measure the rate of transpiration in plants is by using a photometer. In this practical photometer will be used as device to measure the rate at which water enters a leaf shoot.
The rate at which water enters a plant depends on he rate at which it evaporates from the leaves, for instance transpired into surrounding atmosphere. Also, in the shoot, the water could stay in the cells, or be used in photosynthesis and assimilated into carbohydrate, or it could be passed on up the xylem to the leaf tissue. Any external conditions which affect the rate Of transportation Will be expected to effect on the rate Of water uptake. In this practical different effects of external conditions on rate of water uptake of plant.
Factors affecting transpiration: * High light intensity (bright sunlight) * Increased/decreased temperatures (hot/ cold weather) Wind * Low humidity (dry conditions) Aim: The aim of this practical is to assess the effect of different environmental conditions (e. G. Temperature, wind speed, light intensity ) on transpiration rate tot water uptake, by a shoot from a woody plant and using a photometer, Safety Some people find sap trot plants irritating to the skin, monitor your tutor if you have something * Take care when cutting the plant shoot. k Take care when assembling and handling the glass photometer: it is easy to break the long Blabs tubes and cut or stab yourself with the broken ends. Be repaper with first aid for cuts from broken glass, and brief students how to deal with breakages Methods and materials: 1. Apparatus was set up as in the diagram B in lab manual. 2. U- tube was placed on flat level surface, and water was added until it get meniscus on the top of both sides. Attention was pay that bubbles should not be inside the photometer 3.
The stem Of the leafy shoot was cut under water and then fit into the hole bung The stem was tested to make sure the leafy twig will fit snug tightly into the top of the bung because it may affect on results. Some amount of Baseline as used to create a seal. 4. Second bung was place on the second tube of the photometer and inside the hole of this bung graduated pipette was placed. Excess water was released. 5. The photometer was put on the flat surface, by being not disturbed and moved. 6.
The time was started to note and labeled by the meniscus tot water in the scale, when different factors affected to transpiration of water such as temperature, wind and light. From 2 ways one was chosen to take measurements. 7, The stop clock was stopped after fixed minutes and the distance of water absorbed was noticed. 8. Light intensity. A lamp was used in this part to make different light conditions and try to lighten the plant shoot from different distances. 9. Wind speed. A fan was used to make a different wind conditions and try to blow from different distances.
The wind speed was measure by anemometer. 10. Temperature. Water absorption was measured at different temperatures. The temperature was measured by thermometer. II. Results were recorded in tables and graphs were plotted according to results. Results: Table I Water absorption Of plant in standard conditions. Time (min) I Pipette reading(Pl) . 5 1-1. 1 3 | -0. 2 4 10. 11 0. 25 0. 65 101091 Table 2. The effect of light intensity on avatar absorption of plant. Pipette reading(ICP) Time (min) 11201 2. 0 | | 2. 15 2. 2 2. 35 2. 40 9 2. 2 1012451 Rate of transpiration : (distance=volume of water absorbed)/ time of water absorbed Table 3. The effect of wind speed on water absorption of plant Time (min) I Pipette 101271 2. 50 | 2. 65 2. 71 2,71 Table 4. The effect of temperature on the water absorption of plant Time (min) Pipette Temperature (CO) I 2. 91 25 1 271 2 12. 91 28 | 2. 9129 | 2. 95 30 | 2,95 30 | 2. 95 36 | 2,97 36 | 2. 7 37 | 37 | 101 2. 8138 | Rate of transpiration: of water absorbed)/ time of avatar Discussion: Transpiration is essential process for plants, where water evaporate into the atmosphere from the leaves and Stems Of plants.
Plants absorb water from soil through their roots and this avatar can originate from deep in the soil. Plants pump the water up from the soil to deliver nutrients to their leaves. This pumping is driven by the evaporation of water through small pores called “stomata”, Which are found on the undersides Of leaves, where the water is transported from the root to the leaves. The xylem is the vessel. In the stem, through which water go up. Generally, the process is required in order to supply the plant with water and necessary minerals and ions.
During the practical transpiration was studied by 3 different factors that affect transpiration: wind speed, light intensity and temperature. Additionally, the photometer was used to calculate the amount of water uptake of plant. The first environmental factor is light intensity. The amount of absorbed water measured during 10 minutes. The first graph shows that in both cases the rate tot transpiration increase steadily. The reason of such difference is light intensity is that plants transpire more rapidly in the light than in the dark.
This is largely because light stimulates the opening of the stomata. Light also speeds up transpiration by warming the leaf, The second environmental factor is wind speed. The amount of absorbed water measured during 10 minutes in two wind speeds: 38,km/h and 26. 1 km/h_ The second graph shows that in both cases the rate of transpiration increase gradually, in comparison with graph of effect of wind speed . When there is no mind, the air surrounding a leaf becomes increasingly humid, it reduces the rate of transpiration.
When a wind is present, the humid air is carried away and replaced by drier air. So a steep diffusion gradient is maintained. The third environmental factor is change of temperature. The amount of absorbed water measured during 10 minutes in temperatures from ICC to ICC. In general, plants transpire more rapidly at higher temperatures because water evaporates more rapidly as the temperature rises due to the increased kinetic energy of the water molecules. At 30;C, a leaf may transpire three times as fast as t does at ICC.
However in this lab practical was no mechanism to measure the water uptake during the different temperatures, so it was measured from the heat from fan. So following this further, results are valid, because of the errors during the lab practical. Nevertheless, there could he different errors during the practical work, for instance some mistakes could be in calculations, careless work was done, bubbles that are left inside the photometer or any other causes of the interrupting the transpiration and the number of the other factors. All of these could lead to unexpected or wrong results.
Additionally, to improve this procedure some more practice should be done, because it is quite a tricky set of apparatus to handle. Setting up a controllable chamber -? with consistent air currents and variably humidity/ temperature would make results more accurate. Conclusion: In conclusion, during the practical favor the transpiration was observed by providing the process in the 3 different conditions for 30 minutes, whereas the amount of the taken water Vass measured for each I C minutes interval. The rates were calculated in each of the conditions and the graph was plotted.
According to all Of the collected data, it was investigated, that the most effective transpiration with the most water taking was in the light conditions, where the plant was kept under the light source, lamp. The Wind effected less significantly, and during different conditions have the lowest water uptake. Finally, it is clear, that all Of the observed conditions have own effect on the transpiration in the plant. However, because the combination of the factors happened, the results could be different. Nevertheless, the mistakes could be obtained during the laboratory work because of the lack of the experience.