Relative growth rate (RGR) is a measure used in plant physiology to quantify the speed of plant growth. It is measured as the mass increase per aboveground biomass per day, for example as g g-1 d-1. It is considered to be the most widely used way of estimating plant growth, but has been criticised as calculations typically involve the destructive harvest of plants.[1]
RGR is calculated using the following equation:[1]
RGR = (ln W2 - ln W1)/(t2-t1)
Where:
ln = natural logarithm
t1 = time one (in days)
t2 = time two (in days)
W1 = Dry weight of plant at time one (in grams)
W2 = Dry weight of plant at time two (in grams)