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

    4) Leaf Area Duration (LAD)
    • 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

    NAR


    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
    CGR



    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).

Last modified: Wednesday, 13 June 2012, 6:34 AM