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The below mentioned article will highlight the experiment done to compare the rate of photosynthesis by Wilmott’s Bubbler under different conditions.
Wilmott’s bubbler consists of a wide mouthed bottle fitted with a cork through which is inserted a glass tube. The lower end of this tube is fitted with a cork with hole through which a twig of Hydrilla plant is inserted; its other end terminates in a narrow bent nozzle.
The upper half of this tube is surrounded by another glass tube which acts as water reservoir. Whole of the apparatus is filled with water (preferably of the pond from where the Hydrilla plant has been collected). Care is taken so that the level of water in the reservoir remains above the bent nozzle (Fig. 11.35). The apparatus is placed in sun light.
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After sometimes as a result of the photosynthesis, O, bubbles come out from the cut end of the Hydrilla twig which gradually find their exit through the nozzle and can easily be counted. The rate of photosynthesis under different conditions can be studied by plotting the number of bubbles against specified period of time (e.g., 0.5 or 1 min.) or by noting the time in which a specified number or bubbles (e.g., 5 or 10) are released.
For comparing the effects of different wavelengths of light the bubbler is wrapped in cellophane papers of different colours. Effect of different intensities of light can be compared by placing the bubbler under shade, less intense and more intense light. The intensity of the light can be measured by a lux meter.
The effect of varying concentrations of CO, on the rate of photosynthesis can be observed by adding increasing quantities of sodium bicarbonate (50-100 mg at one time) in the bottle of the bubbler. Similarly, effect of temperature on the rate of photosynthesis may be compared by warming the apparatus at different temperatures.
