Plant Growth Regulators • Control the growth and development of trees • Act on plant process at very low concentration • Often they are produced at one location and

transported to another where they exert their influence ; they may also act on the same tissue in which they are produced

• What is definition of the term growth and development ?

• So, plant growth regulators = plant hormones influence both growth and development

• root initiation on cutting : soaking or diping • Prevention of absciscion : spraying or

applying + lanolin • Bud inhibition : spraying or using volatile

compounds - thiourea • Bending effects : young fruit trees –

hormones are applied to unilaterally to growing stems or leaf petiole – more lateral shoot -

Senyawa retardanyang menghambat sistesis GA

• In plant propagation, cuttings are dipped in a rooting hormone to stimulate root development.

• In greenhouse production, many potted flowering plants (like poinsettias and Easter lilies) may be treated with plant growth regulators to keep them short.

• Seedless grapes are treated with plant growth regulators to increase the size of the fruit.

• In special situations, turf may be treated to slow growth and mitigate the need for mowing.

• Plant growth regulators are effective in parts per million or parts per billion