1. What is Relative Growth Rate?

Relative Growth Rate (RGR) measures the growth rate of plants or organisms relative to their size over time. It's a key metric in plant physiology and ecology that quantifies how efficiently plants convert resources into growth.

2. How Does the Calculator Work?

The calculator uses the RGR formula:

Where:

• \( W1 \) — Initial weight (g)
• \( W2 \) — Final weight (g)
• \( t1 \) — Initial time (days)
• \( t2 \) — Final time (days)
• \( \ln \) — Natural logarithm

Explanation: The formula calculates the exponential growth rate by comparing the natural logarithms of weights at two different time points.

3. Importance of RGR Calculation

Details: RGR is crucial for comparing growth performance across different species, genotypes, or environmental conditions. It helps researchers understand how plants allocate resources and respond to various growth factors.

4. Using the Calculator

Tips: Enter weights in grams and time in days. All values must be valid (weights > 0, t2 > t1). For accurate results, ensure consistent measurement conditions.

5. Frequently Asked Questions (FAQ)

Q1: Why use natural logarithm in RGR calculation?
A: Natural logarithm is used because plant growth typically follows an exponential pattern, and ln transformation linearizes this relationship for easier comparison.

Q2: What are typical RGR values for plants?
A: RGR values vary widely by species and conditions, but typically range from 0.01 to 0.3 g/g/day. Fast-growing annuals have higher RGR than slow-growing perennials.

Q3: Can RGR be negative?
A: Yes, RGR can be negative if the plant loses mass between measurements, indicating senescence, stress, or resource limitation.

Q4: How does RGR differ from absolute growth rate?
A: Absolute growth rate measures total size increase, while RGR measures growth relative to current size, providing a better comparison across different sized plants.

Q5: What time interval is best for RGR measurement?
A: The interval should be long enough to detect measurable growth but short enough to capture current growth rates. Typically 1-4 weeks for most plants.