The concentration of a macroelement per gm of dry matter in plants is at least

Options

A. (a) 1000 `mu g`/gm of dry matter
B. (b) 100 `mu g`/gm of dry matter
C. (c) 50 `mu g`/gm of dry matter
D. (d) 995 `mu g`/gm of dry matter.

Answer

To solve the question regarding the concentration of a macroelement per gram of dry matter in plants, we can follow these steps:

### Step-by-Step Solution:

1. **Identify Macroelements**: Understand that macroelements (or macronutrients) are essential nutrients required by plants in larger quantities. Common macroelements include carbon, hydrogen, oxygen, nitrogen, phosphorus, and potassium.

2. **Determine the Required Range**: The concentration of these macroelements in plants typically ranges from 1 to 10 milligrams per gram of dry matter.

3. **Convert Units**: Since the question asks for the concentration in micrograms, we need to convert the lower limit of the range from milligrams to micrograms.
- 1 milligram (mg) = 1000 micrograms (µg).

4. **Calculate the Minimum Concentration**: The minimum concentration of macroelements in plants is 1 mg, which converts to:
- 1 mg = 1000 µg.

5. **Evaluate the Options**: The options provided in the question will likely include various concentrations in micrograms. We need to identify which option matches our calculated minimum concentration of 1000 µg.

6. **Select the Correct Answer**: Based on the evaluation:
- If option A states 1000 µg per gram of dry matter, this is the correct answer.
- Other options like 100 µg, 50 µg, or 995 µg are less than 1000 µg and therefore incorrect.

### Final Answer:
The concentration of a macroelement per gram of dry matter in plants is at least **1000 micrograms**.

---