Transpiration effciency/transpiration ration is

Options

A. Water absorbed to water transpired
B. Unit weight of dry matter synthesised in relation to units of water transpired by the plant
C. Unit weight of dry matter in realtion to water consumed
D. Unit weight of water transpired to unit weight of dry matter synthesised

Answer

To determine the transpiration efficiency or transpiration ratio, we need to analyze the given options and understand the concept behind transpiration efficiency.

### Step-by-Step Solution:

1. **Understanding Transpiration Efficiency**:
- Transpiration efficiency refers to how effectively a plant uses water in relation to the amount of dry matter it produces. It is a measure of the water used for photosynthesis and growth.

2. **Analyzing the Options**:
- **Option 1**: Water absorbed to water transpired.
- This option is incorrect because transpiration efficiency does not consider the water absorbed; it focuses on the relationship between transpired water and dry matter produced.

- **Option 2**: Unit weight of dry matter synthesized in relation to units of water transpired by the plant.
- This option is also incorrect. The correct relationship should be the amount of water transpired in relation to the dry matter synthesized, not the other way around.

- **Option 3**: Unit weight of dry matter in relation to water consumed.
- This option is incorrect as it mentions water consumed instead of water transpired. Transpiration efficiency specifically looks at transpired water.

- **Option 4**: Weight of water transpired to unit weight of dry matter synthesized.
- This option is correct. It describes the ratio of the weight of water transpired to the weight of dry matter produced, which is the definition of transpiration efficiency.

3. **Conclusion**:
- After analyzing all the options, we find that the correct definition of transpiration efficiency is given by **Option 4**: weight of water transpired to unit weight of dry matter synthesized.

### Final Answer:
The transpiration efficiency/transpiration ratio is **Option 4**: weight of water transpired to unit weight of dry matter synthesized.

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