Which of the following promotes pollen germination and tube growth

Options

A. Starch
B. Boron
C. Calcium
D. Potassium

Answer

**Step-by-Step Solution:**

1. **Understanding Pollination**: Pollination occurs when pollen grains land on the stigma of a flower. This is the first step in the fertilization process.

2. **Pollen Germination**: Upon landing on the stigma, the pollen grain does not enter the stigma entirely. Instead, it germinates and forms a pollen tube through a structure called the pollen germ pore.

3. **Pollen Tube Growth**: The pollen tube grows through the stigma and style by secreting specific enzymes, such as pectinases and hydrolytic enzymes. These enzymes help in breaking down the tissues, allowing the pollen tube to penetrate through.

4. **Mechanism of Growth**: The growth of the pollen tube is influenced by two main factors: intercellular movement and chemotropic movement. Chemotropic movement means that the pollen tube is attracted to certain chemicals present in the style.

5. **Chemical Attractants**: The primary chemical that promotes pollen tube growth is a calcium boron inositol complex. This complex plays a crucial role in guiding the pollen tube towards the ovule.

6. **Role of Boron**: Among the components of the calcium boron inositol complex, boron is particularly significant as it stimulates the growth of the pollen tube.

7. **Conclusion**: Based on the information gathered, the substance that promotes pollen germination and tube growth is boron. Therefore, the correct answer to the question is option number 2: Boron.

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