Reproduction:

Process of producing offspring and a mean of self-perpetuation.

Asexual reproduction (vegetative reproduction or vegetative propagation): Plant reproduces without fusion of gametes.

Apomixis:

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Formation of new individuals through asexual reproduction without involving the formation and fusion of gametes.

1. Amphimixis:

Formation of new individuals through the normal process of sexual reproduction by meiotic formation of gametes and their subsequent fusion during fertilization.

Apomixis takes place by three methods:

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1. Agamospermy

2. Spore formation

3. Vegetative propagation

Parthenospore or azygospore:

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A spore formed directly from a gamete.

Parthenoapogamy:

Fusion of vegetative nuclei.

Apospory:

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Involves development of gametophyte from sporophyte directly may be somatic apospory (embryo sac from somatic cell) or generative apos­pory (embryosac from archesporium).

Apogamy:

Development of sporophyte from gametophyte without the fusion of gametes.

Diplospory:

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Diploid embryosac can develop directly from diploid megaspore mother cell.

Parthenogenesis:

Development of seed/embryo from a female gamete without fertilization.

2. Spore formation:

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Spores which take part in asexual reproduction are called accessory spores or mitospores (produced by mitotic division of a parent cell) e.g., conidia, sporangiospores, aplanospores, akinetes, zoospores etc. They are quite common in algae, fungi, bacteria and protistans.

3. Vegetative reproduction:

Occurs naturally in a number of wild and domesticated plants. Two types:

(A) Natural, and (B) Artificial methods.

(A) Natural methods

(a) By stems:

Runners (Cynodon, Oxalis), stolons (Vallisneria), offsets (Pistia), bulbs (Onion, Garlic), corms (Colocasia, Banana), rhizomes (Typha, Ginger), suckers (Mint, Chrysanthemum), tubers (Potato) etc.

(b) By roots:

Adventitious buds (Dalbergia, Guava), tuberous roots (Topoioca, Dahlia) etc.

(c) By leaves:

Adventitious buds (Bryophyllum, Begonia), buds on the tip of leaves (Adiantum).

(d) By bulbils: e.g., Oxalis, Agave, Allium etc.

(e) By turions: e.g., aquatic plants (Utricularia, Potamogeton) etc.

(B) Artificial methods:

(a) Cutting e.g., Sugarcane, rose, cocoa, bougainvillea etc.

(b) Layering: May be mound layering (e.g., Grape vine, strawberry etc.) or air layering or gootee (e.g., Litchi, orange etc.).

(c) Grafting: Especially in dicotyledonous plants having vascular cambia e.g., mango, rose, apple, peach, Citrus, etc.

(d) Bud grafting or Budding e.g., Rose, Apple, Peach etc.

(e) Micropropagation (Propagation by plant tissue culture) e.g., Chrysanthemum, gladiolus, orchids, carnation, ornamental plants etc.

Significance:

Quicker, easier, cheaper method of multiplying the plants which have either poor viability or prolonged seed dormancy.

i. Helps is removing common infections from the parent plant.

ii. Grafting helps in getting an economically important plant having useful characters of two different individuals in a short time.