PL SC 324 Lecture 5: Growth & Plant Measurement

Growth

Is the increment in dry mass, volume, length, or area, and it mostly involves the division,

expansion and differentiation of cells.

Can tubers increase in mass without increasing size?

yes

Why can leaves expand an roots elongate at night while the total plant biomass decreases?

Due to respiration

If division doesn’t lead to increase in plant volume, what does?

The daughter cells elongating after cell division

4 Ways to measure plant growth

1. Simple rates of change: single variable over time, ex: dry weight measured at different times of year

2. Simple ratios between two variables: ex leaf dry weight/ total plant dry weight, r:s

3. Compounded rates of change: rates involving more than one variable, ex: dry weight increase per unit leaf area.

4. Integral durations: estimates of the areas beneath plots or primary or derived quantities and time, ex: leaf area duration (leaf area x time).

What does “A” stand for and what is it’s units

Rate of CO2 assimilation umol CO2/m2/s

[C]

Carbon concentration , nmol C/ g

LAR

Leaf area ratio (whole plant) m2/ kg

LMA

Leaf mass per unit leaf area, kg/m2

LMR

Leaf mass ratio (whole plant) g/g

LRm

Rate of respiration, umol CO2/ m2 (Leaf area or mass)/s

NAR

Net assimilation rate, g/m2/day

NP

Nutrient productivity/ efficiency, g(plant mass)/ mol (plant nutrient) day

PNC

Plant nutrient concentration, mol (nutrient)/ g (plant mass)

RGR

Relative Growth Rate, mg/g/day

RMR

Root mass ratio, g/g

RR

Rate of root respiration, nmol CO2/g (root mass)/s

SLA

Specific Leaf Area, m2/kg

SR

Rate of stem respiration, nmol CO2/ g (stem mass)/ s

SRL

Specific root length, m/g

SMR

Stem mass ratio, g/g

Word definition for RGR

rate of increase in plant mass per unit of plant mass already present

Word definition of NAR

net assimilation rate which is the rate of increase in plant mass per unit leaf area

LAR word definition

the leaf area ratio: amount of leaf unit area per total plant mass

SLA

is the specific leaf area: amount of leaf area per unit leaf mass

LMR word definition

is the leaf mass ratio: fraction of total biomass allocated to leaves

Besides Respiration, how else is Carbon lost from plants?

Volatization (Trees releasing volatile compounds), Exudation (plants oozing out sap)

RGR when it comes to nutrient

RGR = NP x PNC

Plants from —— environments tend to have higher RGR

favorable

High SLA leaves are

large and thin

Leaves with low SLA are

Small and thick

Species with low RGR have — SLA

low

Does NAR have a relationship with RGR

NO.

Slow growing species respire — Carbon

more

Fast growing species invest in —

new growth

RGR is negatively correlated with — and is positively correlated with —

Root respiration and leaf mass density, SLA