GRU Information Resource 1: Guide to how to cross peas.wmv

Introduction

This tutorial provides a comprehensive guide on how to perform successful crosses in peas. By following this step-by-step process, you will learn how to select the right flower buds, emasculate them, and apply pollen, ultimately allowing you to combine different traits from various pea lines. This process not only highlights the practicality of pea genetics but also demonstrates the ease of controlled pollination established by Mendel in his studies.

Step 1: Select Flower Buds at the Right Developmental Stage

• Choose flower buds that are in an early developmental stage.
• Early-stage buds are preferred because they have not yet released pollen.
• Look for buds that are still tightly closed to ensure they are suitable for emasculation.

Step 2: Emasculate the Selected Flower Buds

• Carefully remove the petals from the selected flower buds. This will expose the inner parts of the flower.
• Next, remove the stamens, ensuring to take out the intact anthers, which contain the pollen. This process is crucial for preventing self-pollination.
• After emasculation, the rudimentary carpel and style will remain, along with the stigmatic surface, which is now ready to receive pollen.

Step 3: Prepare Male Flowers for Pollen Transfer

• Collect male flowers from another pea plant that you wish to use for crossing.
• Ensure that the pollen is in good condition—look for bright yellow and clumpy pollen.
• Gently tap or shake the anthers to release the pollen for application.

Step 4: Apply Pollen to the Stigmatic Surface

• Immediately after emasculation, apply the collected pollen to the stigmatic surface of the emasculated flower.
• Use a small brush or your finger to transfer the pollen, making sure it makes good contact with the stigma for effective pollination.

Step 5: Monitor the Success of Pollination

• After pollination, observe the carpel over the next few days.
• At approximately 15°C, you should see signs of success as the carpel begins to extend within three days.
• In about two weeks, the young pod will reach its full length, and you can check for developing ovules by holding the pod up to the light.

Tips and Considerations

• Under normal weather conditions, expect a high success rate (up to 100%).
• In hotter weather, the process speeds up, but flower size may be smaller and pollen production lower. Still, you can anticipate about a 60% success rate.
• Always ensure that your working environment is clean to prevent contamination.

Conclusion

Crossing peas is a straightforward process that allows for the combination of traits from different pea lines. By selecting the right flower buds, carefully emasculating them, and applying fresh pollen, you can achieve successful pollinations. Experimenting with this technique not only deepens your understanding of plant genetics but also enhances your gardening skills. Start your journey in genetics by trying out these steps, and enjoy the results of your efforts in breeding new pea varieties.