Transcript chapter 10
Growing Plants Vegetative Propagation Propagation Process of increasing the supply of a type of plant Can be done sexually (using seeds) - plants developed are non-identical Can also be done asexually - plants that develop are identical - can be done naturally – using natural structures (e.g. bulbs) - or artificially – e.g cuttings Natural propagation structures Bulbs - made of many leaf bases attached to a stem - swollen with stored food - side buds found in between the leaf bases - these develop into daughter bulbs - spring flowering bulbs can be re-planted in autumn - many bulbs (e.g. daffodil) make daughter bulbs naturally Tubers - swollen part of the stem or root – for food storage - each tuber can grow into a new plant if re-planted -e.g. potato plants form tubers on underground stems - ‘eyes’ form new shoots - use food stored inside the tuber to help grow - tubers kept in a cool room (6 weeks) before re-planting - this is sprouting or chitting Use of attached offspring Plantlet - tiny plant still attached to parent - often develop at the leaves - e.g. Mexican Hat plant, Piggy Back plant Runner - plantlets at end of ‘horizontal’ stems - e.g. spider plant, strawberry plant Offsets - plantlet that develops at the base of the parent - these can be cut away from parent & replanted E.g mother-in-laws tongue Artificial Propagation Increasing plant supply, using non-natural methods Plant growth takes place at growth points e.g root tips, buds Also at nodes – part of stem where side branches grow If plant is wounded, it can regrow and replace missing parts Parts of plants can be cut off and re-planted Cuttings Piece of plant cut, and re-planted Roots grow from cut surface Cut end needs planting in moist soil or in water Rooting powder can help root growth Cuttings can lose water through their leaves Water loss can be reduced by - trimming off lower leaves on cutting - placing cutting in a propagator/plastic bag Heat during propagation Heating systems/propagators keep constant temperatures Encourages cuttings to root Useful in colder months of the year, BUT - too high a temperature will cause water loss - too moist (humid) an atmosphere helps spread disease - heating costs can be high A thermostat controlled system is best Layering A stem is made to root whilst attached to parent A cut is made into stem, just below a node Rooting powder applied to this ‘wound’ Rest of plant pegged in place until new roots grow Then new plant is cut away from parent Effective for plants that don’t grow well with cuttings