Basics of Plant Growth and Development

 

We observe that the tree attains growth in its height and girth regularly at regular time intervals. The leaves, flowers and fruits of plants fall off and originate periodically. All organs of plants are made up of tissues and tissues are made up of cells.All cells of plants are descendants of zygote. Zygote gives rise to a mature plants through the process of development.

👌👌Remember development is sum of growth and differentiation

Growth is the most fundamental and conspicuous character of living organism.The permanent increase in a cell or part or organ is called growth. Growth occurs due to metabolic processes with the expenditure of energy.

Plants are capable of attaining unlimited growth throughout their life. This capability of plants is due to the presence of meristem. Meristems are present at specific locations in plants and cells of meristem are capable of cell division.The organs or tissue that are derived from meristem, lost the property of cell division and remain present as permanent tissue in plants body.

Root apical meristem and shoot apical meristem are responsible for the primary growth of plants and these meristems help in elongation of plants. Besides this, lateral meristems like vascular cambium and cork cambium are responsible for secondary  growth  in Dicotyledonous plants and gymnosperm.

At cellular level, when the amount of protoplasm is increased then it is said to be growth. To measure the amount of protoplasm is very difficult therefore we adopt different parameters like length, area, dry weight,volume, and cell number to calculate the growth of the protoplasm.

For Example - Root apical meristem in Maize plants may form more than seventeen thousands cells per hour. It is an example of an increase in cell number. Similarly in Watermelon the size of the cell may increase upto 35000 times. It is an example of cell growth in size of cell. The growth of the pollen tube may be measured in length and growth of dorsiventral leaf may be measured in terms of surface area.

The growth period may divide into three phases - meristematic ,elongation and  maturation. 

Meistmatic  phase represents the cells of the meristematic zone  that are capable of cell division continuously. These cells are rich in protoplasm with large conspicuous nuclei. Near the meristematic zone, the cells represent the elongation phase. These cells undergo cell enlargements and cell wall deposition. Maturation phase is located near the phase of elongation. The cells of this zone attain maximum size in the form of protoplasm modification and wall thickening.