Pollen Tube Growth: An Experiment With pH

Charles, Hannah, Rose, and Kathleen

Introduction

Our experiment focused on the pH of the solution in which the pollen was left in to grow the pollen tubes. In the experiment we used three different solutions. We used a control (a 10% sucrose solution), a basic solution (5:1 ratio of H20 and sodium hydroxide, respectively), and an acidic solution (5:1 ratio of H20 and lemon juice, respectively).

Introduction (Cont.)

This experiment was developed to test the effect of pH on the growth of pollen tubes. As a scale to determine the success of each solution, we used a micrometer, and a piece of string to guesstimate the lengths of the longest pollen tubes.

Method and MaterialsMaterials:• Three well plates• Three types of pollen

– Red bud– Blackberry– False Garlic

• Three solutions– 10% sucrose solution, 5 pH– 5ml H2O: 1ml lemon juice, 2-3 pH– 5ml H2O: 1ml 0.1M sodium hydroxide

• Three coffee filters• Three bendable straws• Three petri dishes

Method and Materials (Cont.)

Methods:We began by getting three well plates, cleaning them,

and then we put one type of pollen on each of the well plates. We put pollen on two adjacent wells on each row. After this, we put one solution in each pollen-containing well on each row. After this, we cut the bottom out of a coffee filter and put it in the bottom of a petri dish and wet it. We cut the straw and arranged the pieces in an arrow shape. We placed the well plates in the petri dishes, and then we put them aside for 24 hours. The next day we viewed them under the microscope and used a micrometer and string to measure the lengths of the pollen tubes.

Diagram of Solution Distribution in Well Plates

Control (10% sucrose mixture)

Basic solution (5mL H20: 1mL sodium hydroxide)

Acidic solution (5mL H20: 1mL lemon juice)

Data

• Data was taken in the form of pictures and then received by measuring the pollen tubes with a micrometer.

• Three photos were taken of each plant type (of which grew) as to ensure variety in the results.

• Measurements from each photo were then taken to ensure an even more precise average of pollen tube length.

Images of blackberry pollen tubes in sucrose solution from wells in the well plates.

Images of false garlic pollen tubes grown in sucrose solution taken from wells in well plates.

Images of red bud pollen tubes grown in sucrose solution taken from wells in well plates.

Results*Pollen Type Measure 1 Measure 2 Measure 3 Average

Blackberry 4.3 5.4 8.1 5.9

False Garlic 8.1 7.1 7.2 7.5

Red Bud 6.0 2.4 5.2 4.5

*All measurements were taken in micrometers (µm)

Conclusion

Various pollen grains in the surrounding areas have been determined to not germinate high or low pH conditions. There were no pollen grains that germinated from any of the pollen species that had a separate pH from the control sucrose solution. For the acidic solution there is the possibility that since lemon juice was used rather than a pure acid that another factor other that pH could have affected pollen tube formation.

Conclusion (Cont.)

This information could be important for control of reproduction in invasive flowering species. Lightly acidic or basic compounds (such as diluted citric acid or sodium bicarbonate) can be sprayed to coat stigmas of flowers to prevent pollen tube formation and reproduction. This can prevent invasive species from spreading without directly harming existing plant life.

Thanks for your attention!!!