Plant Growth Rate

Increase in growth per unit time is called growth rate or efficiency index.

• The ratio of change in the cell number (dn) over the time interval (dt) is called Absolute growth rate (AGR).
• Absolute growth rate is the measurement of total growth per unit time.

• Relative growth rate is the growth per unit initial parameter.
• RGR refers to the growth of a particular system per unit time, expressed on a common basis or it is the ratio of growth in the given time over initial growth.

\[\mathrm{AGR}=\frac{\mathrm{dn}}{\mathrm{dt}}\]

\[\mathrm{RGR}=\frac{\mathrm{AGR}}{\mathrm{n}}\]

• Growth Rate - Increase in growth per unit time; also called efficiency index. Measured by increase in size, length, volume, or dry weight.
• Absolute Growth Rate (AGR) - Total growth per unit time; ratio of change in cell number over a given time interval.
• Relative Growth Rate (RGR) - Growth per unit initial parameter; obtained by dividing AGR by the total number of cells.
• Measurement of Growth - Measured by increase in cell number, leaf area, length, volume, or dry weight. (e.g. Watermelon ovary increases 3,50,000 times after fertilisation.)
• Instruments - Direct method (scale), Horizontal microscope (field), Auxanometer (linear shoot growth), Crescograph (by Sir J.C. Bose; magnifies up to 10,000 times).