Which of the following is a non-symbiotic biofertiliser ?

Options

A. VAM
B. Azotobacter
C. Anabaena
D. Rhizobium

Explanation

To determine which of the following is a non-symbiotic biofertilizer, we will analyze each option provided:

1. **VAM (Vesicular Arbuscular Mycorrhizae)**:
- VAM refers to a symbiotic relationship between fungi and the roots of higher plants. This means that VAM is not a non-symbiotic biofertilizer, as it involves a mutualistic association.

2. **Azotobacter**:
- Azotobacter is a genus of free-living bacteria that can fix atmospheric nitrogen. It does not require a host plant for its survival and growth, making it a non-symbiotic biofertilizer. Therefore, this option is a candidate for the answer.

3. **Anabaena**:
- Anabaena is a cyanobacterium that forms a symbiotic relationship with the aquatic fern Azolla. This association helps in nitrogen fixation, indicating that Anabaena is also not a non-symbiotic biofertilizer.

4. **Rhizobium**:
- Rhizobium is a genus of bacteria that forms symbiotic relationships with leguminous plants, aiding in nitrogen fixation. This means that Rhizobium is not a non-symbiotic biofertilizer.

After analyzing all options, we conclude that the correct answer is:

**Answer: Azotobacter (Option B)**