## Parameters arrived through growth analysis

 Parameters arrived through growth analysis
1) Leaf Area (LA)
• It is the surface area of leaf, which aids in photosynthesis.
• Total leaf area per plant is often a useful measurement in bio-productivity studies.
• Area can be measured by graphic methods, weight method, by using Leaf Area Meter and by measuring length and breadth of the leaf.
A) Weight method
X
LA = ---------- x B
A
Where
X = known area of leaves
A = dry weight of known area of leaf
B = dry weight of unknown area of all leaves
The leaf area of standard leaves, usually 3rd leaf from the top is measured and dried.

B) Linear measurement method
LA = LBK (cm2 or m2)
Where
L=maximum length, B=maximum breadth, K=constant (can be worked out by regression analysis)
K value may not be the same for different varieties in the same species.
2) Leaf Area Index (LAI)
• Watson (1947) proposed the term leaf area index which is the ratio of the leaf area of a plant to the ground area occupied by the plant.

Total leaf area of the plant
Leaf area index = -----------------------------------------------------
Ground area occupied by the plant (spacing)

3) Leaf Area Ratio (LAR)
• The term leaf area ratio was suggested by Redford (1967).
• It is defined as the ratio of area of the leaf to the total plant biomass per plant.
• It is expressed in terms of cm2g-1.
Leaf area per plant
LAR = -----------------------------
Total plant dry weight

• It is ability of the plant to maintain the green leaves per unit area of the land over a period of time.
• It reflects the vitality of leaves and an opportunity for assimilation.
• It also measures the persistence of the assimilating surface.
• This factor was suggested by Power et al.(1967) and expressed in days.

L1 + L2
LAD = ----------------- x (t2 – t1)
2
Where
LAI (i) – Leaf area index at first stage
LAI (ii) - Leaf area index at second stage
t2 –t1 – Time interval between the two consequent stages and expressed in days.

5) Leaf Area Ratio (LAR)
• In order to estimate the carbon assimilatory efficiency of leaves or to estimate the leafiness of plants, Radfort (1967) suggested leaf area ratio as a measure of leaf area to the weight of the whole plant. It is expressed as cm2 g-1.

L1 + L2
LAD = ----------------- x (t2 – t1)
2
• In broad sense, LAR represents the ratio of photosynthesizing to respiratory material within the plant.
6) Specific Leaf Area (SLA)
• It is the ratio of assimilating area to its dry weight.
• Following formula was proposed by Kvet et al. (1971) to arrive SLA and expressed as cm2 g-1.

Leaf area
SLA = --------------------------
Leaf dry weight

7) Specific Leaf Weight (SLW)

• Using the leaf dry weight and leaf area, SLW is calculated.
• It is the ratio of leaf dry weight to its area of assimilating surface.
• The formula was suggested by Pearce et al. (1968) and expressed as mg cm-2.

Leaf weight
SLW = -----------------
Leaf area

8) Leaf Weight Ratio (LWR)
• It is the ratio of total leaf dry weight to the whole plant dry weight.
• It is the measure of leafiness of the plant on a weight basis.
• It is expressed in g kg-1.
Leaf dry weight
LWR = ----------------------------------------
Total plant dry weight

9) Net Assimilation Rate (NAR)
• It is the rate of increase of leaf by dry weight per unit area of leaf per unit time.
• Williams (1946) employed the formula and expressed as mg cm-2 day -1

Where

Log e L2 = Natural log of leaf area at stage 2.
Log e L1 = Natural log of leaf area at stage 1.
L2 & L1 = Leaf area at stage 2 & 1 respectively
W2 & W1 = Dry weight of the whole plant at stage 2 & 1 respectively
t2-t1 = Time interval between the two stages
NAR is expressed as mg cm-2 day -1

10) Relative Growth Rate (RGR)
• It is the rate of increase of dry weight per unit weight already present per unit time.
• Williams (1946) suggested the formula.

Loge W2 – loge W1
RGR = -----------------------
t2 – t1
Where
W2 & W1 = Whole plant dry weight at t2 & t1 respectively and expressed as g g-1 day-1
11) Crop Growth Rate (CGR)
• CGR is a simple and important aid of agriculture productivity.
• It is the rate of increase of dry weight per unit land area per unit time.
• Watson (1958) suggested the following formula to arrive Crop Growth Rate

Where,
W2 and W1 are total plant dry weight at time t2 and t1 and P is plant population per unit area.
CGR is also the product of leaf area index and net assimilation rate.
CGR = LAI X NAR
CGR increases as LAI increases to an optimum because of greater light interception.
CGR is expressed as mg m-2 day -1.

12) Harvest Index (HI)
• It reflects the proportion of assimilate distribution between economic yield and total biomass yield (Donald and Hamblin, 1976).