Aim of Experiment: Study pollen germination on a slide.
Specimen Required: Fresh seasonal flower
Apparatus Required: Slide, Needles, coverslips, microscope, beaker, dropper
Chemicals Required: Sucrose, boric acid, magnesium sulphate, Potassium nitrate.
Procedure:
1. Prepare a nutrient solution by dissolving 10g of sucrose, 10g boric acid, 30mg magnesium sulphate and 20mg Potassium nitrate in 100ml of water.
2. Take a few drops of this solution on a clean slide, and dust a few pollen grains from the stamen of a mature flower on it.
3. Observe the slide on the microscope after 5 minutes and then observe it regularly for about half an hour
Observations:
(1) Observe many
pollen grains germinating
over stigma. The growth of the pollen tube is stimulated by sugary substances secreted by the stigma.
(2) Pollen tube carrying with it
tube nucleus and the generative nucleus.
(3)
The generative nucleus divides forming two male gametes.
(4) Count the number of germinated
pollen grains.
Precautions:
There are precautions to be observed while performing this experiment:
- Dirty or previously used slides should not be used for dusting pollen grains. Slides should be clean and dry for use.
- Only a few drops of the nutrient medium is required for germination. 2-3 drops of the solution are enough, more than that may hinder the process of pollen germination.
- Only freshly plucked flowers should be used and the experiment should be conducted within sometime of plucking.
- The cavity slide used for observation should have depression at the center so that the solution can be held in that cavity and does not flow.
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