Growth regulators :

Growth regulators are of two types :

1. Growth promoting substances and
2. Growth inhibiting substances

• The imbalance in growth promoting and growth inhibiting substances causes hypertrophy (excessive increase in cell size) and atrophy (decrease in cell size).
• Symptoms may appear as tumors, galls, knots, witches broom, stunting, excessive root branching, defoliation and suppression of bud growth.