13.5 Plant Growth and Development

Pages 605-612

Walking palm

• The adventitious roots in the shade die and new roots in the direction of the sun form.

Growth

• Increase in size

Differentiation

• A cell becomes specialized to perform a particular function.

Apical meristem

• found at the tips of plant’s buds, stems and roots.• primary growth occurs here• plant height increases

Lateral meristem

• found at the sides of plant’s buds, stems and roots.

• causes secondary growth • increases the width of the plant

Primary Growth

• Apical meristem cells divide and elongate• Differentiation into epidermal, parenchyma or

vascular cell types.

• Shoot apical meristem becomes stems, leaves and reproductive organs

• Root apical meristem has three zones:– Zone of maturation– Zone of elongation– Zone of cell division

Secondary growth

• Only in woody species after first year.• Example: vascular cambium and cork

cambium

Light

• Photoreceptor- a molecule that reacts when struck by light of a certain intensity and/or wavelength.

• Some seeds need light to germinate Example: lettuce• Some seeds need darkness to germinateExample: lilly

Photoperiod

• Plants respond to daylength• Timing of flowersExample: Spinach- long daylengthExample: Tulip-short daylength

Macronutrients

• Large quantities (more than 1g/kg of dry mass)

Examples: N, P, K

Carbon

• From carbon dioxide in the air• Carbon backbone of organic molecules

Hydrogen

• From water

Oxygen

• From the air

Nitrogen

• Nitrates and ammonia• Proteins, DNA, RNA, chlorophyll

chlorosis

Phosphorus

• From hydrogen phosphite ion• For DNA, RNA, membranes

Potassium

• From K+ ions• For activation of enzymes and cellular

transport

Calcium

• From calcium ion• For cell walls, membrane transport

Sulfur

• From sulfate ion• For proteins

Magnesium

• From magnesium ion• For chlorophyll, enzyme activation

Micronutrients

• Nutrients needed less than 100 mg/kg of dry mass.

• B, Cl, Cu, Fe, Mn, Mo, Ni, Zn• Used for Chlorophyll synthesis, cell division,

enzyme production

Temperature

• Opening and closing stomata• Timing of seed germination• Timing of flowering

Soil

• Medium to anchor roots• Retains water and nutrients• Air• pH