Plant Growth and Development – Solutions

1. List the five main groups of natural plant growth regulators. Write a note on discovery, physiological functions and agricultural/horticultural applications of any one of them.

Solution:

The five main plant growth regulators are as follows:-

(i) Auxins (ii) Gibberellic acid (iii) Cytokinins (iv) Ethylene (v) Abscisic acid

(i) Auxins

Discovery:

Auxins were the first plant hormones to be discovered. Charles Darwin, through his experiment, suggested that the tip of the coleptile is responsible for perceiving light and producing some growth factors.

In 1928, “Went” developed through his avena curvature test, established the nature of growth hormone and named it auxin. Later, Kogl isolated auxin from human urine.