Plant Growth and Development Test - 5

ABA stimulates the closure of stomata in the epidermis and increases the tolerance of plants to various kinds of stresses.Therefore, it is also called the stress hormone.

Gibberellins also promote bolting (internode elongation just prior to flowering) in beet, cabbages and many plants with rosette habit.

A unique role of cytokinins is to produce anti-aging effects on some plant parts. Cytokinins actually provide a younger, healthier look in plants. By adding this hormone to cut flowers, florists are able to slow down the aging process, providing us with prettier flowers for longer.

Apical dominance is the phenomenon whereby the main, central stem of the plant is dominant over (i.e., grows more strongly than) other side stems; on a branch the main stem of the branch is further dominant over its own side branchlets.

Ethylene is highly effective in fruit ripening. It enhances the respiration rate during ripening of the fruits.

GA3 is used to speed up the malting process in brewing industry.

2, 4 D (2,4-Dichlorophenoxyacetic acid)are widely used as herbicides. It is widely used to kill dicotyledonous weeds, does not affect mature monocotyledonous plants.

Auxins (IAA,IBA)also induce parthenocarpy,(Seed less fruits) e.g., in tomatoes.

Cytokinins help overcome the apical dominance. They promote nutrient mobilisation which helps in the delay of leaf senescence.