`star` Measurable Growth
`star` Phases of Growth


● `color{Brown}"Growth"`, at a `color{violet}"cellular level,"` is principally a consequence of `color{violet}"increase"` in the `color{violet}"amount of protoplasm"`.

● Since `color{violet}"increase in protoplasm"` is difficult to measure directly, one generally `color{violet}"measures some quantity"` which is more or less `color{violet}"proportional to it"`.

● `color{violet}"Growth"` is, therefore, measured by a `color{violet}"variety of parameters"` some of which are:

`star` Increase in `color{violet}"fresh weight"`, `color{violet}"dry weight"`, `color{violet}"length, area, volume"` and `color{violet}"cell number"`.

● It is amazing to know that `color{violet}"one single maize"` `color{violet}"root apical mersitem"` can give rise to more than `color{violet}"17,500 new cells"` per hour, whereas cells in a watermelon may increase in size by upto `color{violet}"3,50,000 times"`.

● In the former, `color{violet}"growth"` is expressed as `color{Brown}"increase in cell number"`; the `color{violet}"latter expresses"` growth as `color{Brown}"increase in size"` of the cell.

● While the `color{violet}"growth of a pollen tube"` is measured in terms of its `color{violet}"length,"` an `color{violet}"increase in surface area"`.


● The `color{Brown}"period of growth"` is generally divided into three phases, namely, `color{violet}"meristematic, elongation"` and `color{violet}"maturation"`.

● The `color{violet}"constantly dividing cells,"` both at the `color{violet}"root apex"` and the `color{violet}"shoot apex"`, represent the `color{Brown}"meristematic phase"` of growth.

● The `color{violet}"cells in this region"` are rich in `color{violet}"protoplasm"`, possess `color{violet}"large conspicuous nuclei"`.

● Their cell walls are `color{violet}"primary in nature,"` `color{violet}"thin and cellulosic"` with abundant `color{violet}"plasmodesmatal connections."`

● The `color{violet}"cells proximal"` (just next, away from the tip) to the `color{violet}"meristematic zone"` represent the `color{Brown}"phase of elongation"`.

● `color{violet}"Increased vacuolation"`, `color{violet}"cell enlargement"` and `color{violet}"new cell wall depositio"`n are the characteristics of the cells in this phase.

● Further `color{violet}"away from the apex,"` i.e., more proximal to the phase of elongation, lies the `color{violet}"portion of axis"` which is undergoing the `color{Brown}"phase of maturation"`.

● The `color{violet}"cells of this zone"`, attain their `color{violet}"maximal size"` in terms of `color{violet}"wall thickening"` and `color{violet}"protoplasmic modifications."`