Question

Select the correct statements among the following
I. The use of biofertilizers reduce the use of chemical fertilizers.
II. Mycorrhizae enhances phosphorous content in the soil.
III. An important biofertilizer in legume crops is Rhizobium.
IV. Glomus forms mycorrhizal association with plants.

• A. I, II, III
• B. II, III
• C. III, IV
• D. I, III, IV

Hint:

Biofertilizers enhance nutrient availability (e.g., nitrogen fixation by Rhizobium, phosphorus solubilization by mycorrhizae) rather than adding nutrients to the soil. Mycorrhizae (like Glomus) are crucial for phosphorus uptake, and their benefits include increasing the efficiency of nutrient acquisition.

Answer 1

The Correct Option is D

Step 1: Understand the question.
The question asks to identify the correct statements regarding biofertilizers and microbial associations in plants. Step 2: Evaluate each statement. \begin{itemize} \item Statement I: The use of biofertilizers reduce the use of chemical fertilizers.
Biofertilizers are living microorganisms that improve soil fertility and plant growth by enhancing nutrient availability through processes like nitrogen fixation, phosphorus solubilization, and potassium mobilization. By doing so, they can effectively reduce the reliance on synthetic chemical fertilizers. This statement is Correct. \item Statement II: Mycorrhizae enhances phosphorous content in the soil.
Mycorrhizal fungi form a symbiotic relationship with plant roots. They extend their hyphae into the soil, greatly increasing the root's surface area for absorption. Their primary role concerning phosphorus is to solubilize insoluble forms of phosphorus in the soil, making it available for plant uptake, thereby enhancing phosphorus availability or uptake by the plant. They do not typically increase the total content of phosphorus in the soil, but rather make existing phosphorus more accessible. Due to the precise wording "enhances phosphorous content in the soil" (implying increasing the total amount), this statement is often considered Incorrect in a strict sense, as they facilitate uptake rather than directly adding content. \item Statement III: An important biofertilizer in legume crops is Rhizobium.
Rhizobium is a genus of bacteria that forms a symbiotic association with the roots of leguminous plants, leading to the formation of root nodules. Within these nodules, Rhizobium bacteria fix atmospheric nitrogen into ammonia, a form usable by plants. This process significantly contributes to the nitrogen nutrition of legume crops, making Rhizobium an important biofertilizer. This statement is Correct. \item Statement IV: Glomus forms mycorrhizal association with plants.
Glomus is a well-known genus of arbuscular mycorrhizal (AM) fungi. These fungi form endomycorrhizal associations with the roots of about 80% of terrestrial plant species, playing a crucial role in enhancing nutrient (especially phosphorus) uptake by the plants. This statement is Correct. \end{itemize} Step 3: Identify the correct option based on the evaluation.
Statements I, III, and IV are correct. Statement II is generally considered incorrect due to its precise wording. Therefore, the combination of correct statements is I, III, and IV. This matches option (4). The final answer is $\boxed{\text{I, III, IV}}$.