(31 Dec 1997) The major classes are absicisic acid, auxin, cytokinin, ethylene and gibberellin, others include steroid and phenol derivatives. Plant Growth Regulators are defined as small, simple chemicals produced naturally by plants to regulate their growth and development. plant growth substances (Science: plant biology) substances that, at low concentration, influence plant growth and differentiation.

They can accelerate as well as retard the rate of growth in plants. Reapplication is required. Plant growth substance definition is - a growth regulator for plants. They are also described as phytohormones, plant growth substances, or plant growth hormones.

These are simple organic molecules having several chemical compositions. Plant Growth Regulators are formulated by humans. Hence, the effects are temporary.

Hence, the effect is long lasting. Characteristics Plant Growth Regulators can be of a diverse chemical composition such as gases (ethylene), terpenes (gibberellic acid) or carotenoid derivates (abscisic acid). The major classes are absicisic acid, auxin, cytokinin, ethylene and gibberellin, others include steroid and phenol derivatives.

Extraction of Descriptive hormones and growth-regulating substances from plants 118 iv Page Supplementary techniques—Continued Observing and measuring plants—Continued Formative effects of regulating chemicals 119 Interferometer method of detecting minute growth movements 120 Freehand sections for studying cell responses to 120 Measurement of root response 121 Radioautographs of … Plant growth substances are well known to enhance the source-sink relationship and stimulate the translocation of photo-assimilates to sink, thereby helping in effective flower formation, fruit and seed development and ultimately enhancing the productivity of crops (Ammanullah et al., 2010).

Plant growth substances The growth of a plant is regulated through gene action and environmental conditions. Hence, they are natural substances. Hence, they are artificially synthesized substances. Formerly referred to as plant hormones or phytohormones, these terms are now suspect because some aspects of the hormone concept, notably action at a distance from the site of synthesis, do not necessarily apply in plants. Plant Growth Regulators are exogenous.

Effect: Plant Hormones are long-lived chemicals.

Plant Growth Regulators are short lived.

These chemicals substances are called Plant Growth Regulators and are produced naturally by the plants itself. Origin: Plant Hormones are endogenous.

There are substances, which are produced by plants themselves, which regulate their growth and many physiological and biochemical activities.

Also called plant growth regulators.