Asexual Propagation

Two Types of Reproduction in Plants Sexual Reproduction development of new plants by the process of meiosis and fertilization in the flower to produce a viable embryo in a seed Asexual Reproduction The production of new plants by any vegetative means not involving meiosis and the union of gametes

Advantages of Asexual (Vegetative) Reproduction Maintain clone Uniform results Faster (cut production time) May be cheaper “Custom Design” a plant Can use it for experimental purposes Virus Indexing -Bud and graft to diagnose plant diseases

Disadvantages of Vegetative Reproduction Diseases Propagate disease with plant (seeds occasionally spread disease also, cruciferous seeds are dropped in boiling water to stop disease) Certified plants – use virus indexing or tissue culture to get disease free plants Costly Sometimes more expensive vegetatively e.g. tomatoes – easy by cuttings, cheaper buy seed

Disadvantages of Vegetative reproduction No Variation – no rearranging genetics, no new cultivars Couldn’t breed.. Disease resistant plants Plants that use less fertilizer Insect resistance No genetic variation Plants with higher yields

Types of Vegetative Reproduction Apomixis Layering Cuttings Grafting Tissue Culture Specialized stems and structures

Types of Vegetative Reproduction Apomixis Vegetative seed Bluegrass Citrus onions Gen nuclei causes mitosis of cell membrane Clone of female Ovary wall Chalaza Anitpodal cells Stigma surface Embryo sac Two polar nuclei Pollen tube Nucellus Egg Synergid cells Generative nuclei Integuments Tube nucleus Micropyle Funiculus

Types of Vegetative Reproduction Layering

Types of Vegetative Reproduction Layering

Air- Layering

Types of Vegetative Reproduction Cuttings Stem cuttings Herbaceous Softwood Deciduous hardwood Narrow-leaved evergreen hardwood Semi hardwood Whole leaf Leaf sections Leaf bud cuttings Cane cuttings Tip cuttings Bulb leaf cuttings Root cuttings

Grafting Tools and Terms Stock Scion Interstock Hand pruners Grafting knife Grafting wax Budding rubbers

Grafting “Rules” Close taxonomic relationship (family) 2 parts secure Dif Genera only a few Species (Plums onto Peaches) Cultivars of species (almost always will work) Puzzles of incompatibility Pear on quince (sometimes) Quince on pear never 2 parts secure Protect from dessication Polarity

Types of Grafting Grafting – joining parts of plants together to unite and grow as one Budding – scion of one bud T-bud Patch bud Grafting – scion of two or more buds Side or stub graft Side bark graft Whip and tongue Cleft graft Approach graft Bridge graft Inarching Top-working (changing cultivars)

Patch budding

Banana graft Apple whip tongue grafting

Approach Graft – 2 methods

Whip and Tongue Graft

Types of Vegetative Propagation Tissue Culture Specialized Stems and Structures Divisions Stolons Rhizomes Suckers Crowns Corms Bulbs Tubers Tuberous roots

Tissue Culture/Micropopagation Tissue culture is a process where tiny plantlets are maintained on sterile artificial media containing nutrients. Totipotency describes the capacity of certain cells to regenerate a whole plant. Meristems are considered to be totipotent.

Tissue Culture/Micropopagation Advantages Takes less room quicker Method Undifferentiated cells (explants) placed on agar with nutrients and hormones under sterile conditions Callus tissue generates cells in globs like jello dividing callus tissue is influenced with growth hormones Can get millions from a single plant

Stem structure

Other forms of Stems Chief characteristics are nodes and internodes The following structures also have nodes and internodes and are therefore stems Rhizome Stolon Corms Bulb tuber

Node Internode

Corm

Cormels

Bulbs

Bulbils

Tuber

Sweet potato - Yam Stem or Root?

Root Types Fibrous Tap roots Adventitious roots Secondary roots Aerial roots

Root Functions Absorb water and nutrients Anchorage Storage autotrophic Anchorage Storage Propagation Photosynthesis Aerial roots help plant cling or climb