Plant Growth & Development

       

I. Plant Hormones

        A. Auxins

                1. Basic effects: regulates lateral buds & stem                                                   elongation

                2. Discovery:   Darwin, Went

                3. Chemical nature: IAA

                4. Mechanisms: plasticity, suppresses bud growth

                5. Synthetic auxin

        B. Cytokinins

                1. Basic effect: Differentiation

                2. Mechanism: cell division

        C. Gibberelin

                1. Mechanism: elongation

                2. Commercial applications

        D. Ethylene

                1. Mechanism: suppresses bud formation w/ auxin,                                           suppresses stem & root elongation, hastens ripening

                2. Commercial applications: Hasten drops, stimulate                                         germination, kill weeds

        E. Abscisic acid

                1. Actions: leaf drop, dormancy, stomata

II. Tropisms

        A. Phototropism

        B. Gravitropism

        C. Thigmotropism

III. Turgor movements

        A. Touch sensitive plants: Mimosa

        B. Carnivorous plants: Venus flytrap

IV. Photoperiodism

        A. Short-day/ Long-day/ Day-neutral

        B. Phytochrome

V. Dormancy

        A. Temperate, seasonally dry, seasonal drought climates