Question:
The formulae for calculating heat unit (Degree days) is
The formulae for calculating heat unit (Degree days) is
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Remember heat unit calculation:
- GDD = (Tmax + Tmin)/2 - Tbase
- Monthly heat units = (Avg. temp - Base temp) × Days
- Base temperature varies by crop:
- Wheat: 5°C
- Maize: 10°C
- Tomato: 10°C
- Cotton: 15°C
Heat units are used to predict crop maturity and phenology.
- GDD = (Tmax + Tmin)/2 - Tbase
- Monthly heat units = (Avg. temp - Base temp) × Days
- Base temperature varies by crop:
- Wheat: 5°C
- Maize: 10°C
- Tomato: 10°C
- Cotton: 15°C
Heat units are used to predict crop maturity and phenology.
Updated On: Aug 19, 2026
- Av. monthly temperature \(\times\) No. of days
- Av. monthly temperature - Base line temperature \(\times\) No. of days in month
- Base line temperature + Av. monthly temperature \(\times\) No. of days in month
- No. of days in month + Base line temperature - Av. monthly temperature
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The Correct Option is B
Solution and Explanation
Step 1: Understanding the Concept:
This question tests knowledge of heat unit calculation in agriculture (Growing Degree Days).
Step 2: Key Formula or Approach:
Growing Degree Days (GDD) or heat units are calculated using the formula:
\[ \text{GDD} = \frac{T_{max} + T_{min}}{2} - T_{base} \] For monthly calculations:
\[ \text{Heat units} = (\text{Av. monthly temperature} - \text{Base temperature}) \times \text{No. of days in month} \]
Step 3: Detailed Explanation:
The formula for calculating heat units (degree days) is:
\[ \text{Heat units} = (\text{Average monthly temperature} - \text{Base temperature}) \times \text{Number of days in month} \] Where:
- Average monthly temperature is the mean temperature for that month.
- Base temperature is the minimum temperature below which crop growth stops (e.g., 10°C for many tropical crops).
- Number of days in the month gives the accumulated heat units.
Analyzing options:
- (A) Av. monthly temperature \(\times\) No. of days: Missing base temperature subtraction.
- (B) Av. monthly temperature - Base line temperature \(\times\) No. of days in month: Correct formula.
- (C) Base line temperature + Av. monthly temperature \(\times\) No. of days: Addition instead of subtraction.
- (D) No. of days in month + Base line temperature - Av. monthly temperature: Incorrect arrangement.
Thus, option (B) is the correct formula.
Step 4: Final Answer:
Thus, the correct formula for calculating heat units is (Av. monthly temperature - Base line temperature) \(\times\) No. of days in month, which corresponds to option (B).
[0.5cm]
This question tests knowledge of heat unit calculation in agriculture (Growing Degree Days).
Step 2: Key Formula or Approach:
Growing Degree Days (GDD) or heat units are calculated using the formula:
\[ \text{GDD} = \frac{T_{max} + T_{min}}{2} - T_{base} \] For monthly calculations:
\[ \text{Heat units} = (\text{Av. monthly temperature} - \text{Base temperature}) \times \text{No. of days in month} \]
Step 3: Detailed Explanation:
The formula for calculating heat units (degree days) is:
\[ \text{Heat units} = (\text{Average monthly temperature} - \text{Base temperature}) \times \text{Number of days in month} \] Where:
- Average monthly temperature is the mean temperature for that month.
- Base temperature is the minimum temperature below which crop growth stops (e.g., 10°C for many tropical crops).
- Number of days in the month gives the accumulated heat units.
Analyzing options:
- (A) Av. monthly temperature \(\times\) No. of days: Missing base temperature subtraction.
- (B) Av. monthly temperature - Base line temperature \(\times\) No. of days in month: Correct formula.
- (C) Base line temperature + Av. monthly temperature \(\times\) No. of days: Addition instead of subtraction.
- (D) No. of days in month + Base line temperature - Av. monthly temperature: Incorrect arrangement.
Thus, option (B) is the correct formula.
Step 4: Final Answer:
Thus, the correct formula for calculating heat units is (Av. monthly temperature - Base line temperature) \(\times\) No. of days in month, which corresponds to option (B).
[0.5cm]
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