Vegetative Reproduction

VEGetAtivE REPROducTIon

Vegetative reproduction is a type of asexual reproduction

found in plants, and is also called vegetative propagation or vegetative multiplication. It is a process by which new plant "individuals" arise or are obtained without production of seeds or spores. It is both a natural process in many plant species (as well as non-plant organisms such as bacteria and fungi) and one used or encouraged by horticulturists to obtain quantities of economically valuable plants. Natural vegetative reproduction is mostly a process found in herbaceous and woody perennial plants, and typically involves structural modifications of the stem, although any horizontal, underground part of a plant (whether stem or a root) can contribute to vegetative reproduction of a plant. And, in a few species (such as Kalanchoë shown at right), leaves are involved in vegetative reproduction. Most plant species that survive and significantly expand by vegetative reproduction would be perennial almost by definition, since specialized organs of vegetative reproduction, like seeds of annuals, serve to survive seasonally harsh conditions. A plant that persists in a location through vegetative reproduction of individuals over a long period of time constitutes a clonal colony. In a sense, this process is not one of "reproduction" but one of survival and expansion of biomass of the individual. When an individual organism increases in size via cell multiplication and remains intact, the process is called "vegetative growth". However, in vegetative reproduction, the new plants that result are new individuals in almost every respect except genetic. And of considerable interest is how this process appears to reset the aging clock.

Vegetative Structures

Asexual reproduction, the vegetative reproduction, is forming a new individual plant from a single parent plant. Many parts of plant are used for the asexual reproduction, but a stem is a common organ for the asexual reproduction. [2]

Stems The stems are the most common organ for the vegetative reproduction. Corms, tubers, bulbs, runners or stolons, and rhizomes are underground stems.

Leaves While some plants use the stems for the vegetative reproduction, some are using the leaves for it. When leaf margins produce plantlets, the plantlet will fall off from a plant. And then, the leaf can live as an independent existence. [3]

Roots Along the stems and leaves, the roots are another organ for the vegetative reproduction.

Types of Vegetative Reproduction Corms and Tubers and Bulbs Corms are vertical underground stem, and they grow thicker as they continue growing. Plants can regenerate the corms. Gladioluses and crocuses reproduced by a method of corms. Tubers are thickened rhizomes, and they grow vertically underground as the corms do. Potatoes and dahlia are reproduced by a method of tubers. Bulbs are special buds, and they are thick and fleshy. The bulbs function as food storage, because they contain lots of nutrients. Onion, hyacinth, narcissus, and tulips are reproduced by a method of bulbs. [4]

Grafting

Watermelon grafted onto Cucurbita rootstock. Grafting is a cloning method, but it is not using a complete cloning method. It is widely used for the vegetative reproduction of trees or shrubs. Mostly apples use grafting. reproduction Definition of grafting is attaching a shoot from individual to root stock of tree. It is only work from old trees, but most old trees can be used for grafting. A dormant

scion (shoot cutting with terminal bud) is cut from upper part of tree, and it will attach to another top of tree, which has similar diameter of the scion. Contacting xylem, phloem, and cambium of the root stock is important thing to do for the grafting. If they are not contact well, water and nutrients cannot pass through. Finally, the grafting plant will die. Grafting is used for horticultural purpose. [5] T Budding or Shield Budding T budding (or shield budding) is one of grafting methods. Scion is a shoot cutting with terminal bud. Shoot cutting is grafted on rootstock (stock). Bud stick is a branch with many buds on it, and it is suitable for T budding. To success on T budding, there are three things are required. First thing is that the scion needs to be mature. Second thing is that vascular cambium in the rootstock should actively grow. The last thing is that plant bark should peel off easily to less damage on the plant. Usually T budding is used in late July or early August. There are 8 steps for T budding: 1. Cut bud stick from branch. Take out all leaf blades, but leave petiole on the bud stick. (The leaf blades are useful source for holding the bud.) 2. Cut the bud from the bud stick with a sharp budding knife. When cut the bud, use upward slicing motion from 0.5 inch below from the bud. (Using sharp budding knife reduces damage to the bud.) 3. Do same thing as step 2. (Cut the bud with downward splicing motion from 0.5 inch above from the bud.) 4. Cut the rootstock vertically deep enough to put the bud. 5. Cut perpendicular cut right above the vertical cut. 6. Peel the bark gently to place the bud. (If the bark does not peel well, it means that the plant is not in active growth. This plant is not suitable for T budding, so do T budding later.) 7. Place the bud carefully between bark flaps and close the them tightly. 8. When the flaps are closed tightly, wrap the bud and rootstock together with grafting tape. Sometimes the tape is break down by weather or a grafter should take it off within 2 to 3 weeks. [6]

Layering Layering can happen naturally. When lower branch or fallen part of trees is contacting with soil, adventitious roots will form at the point that the branch and the soil are contacting. With the adventitious roots, an individual plant will grow. Because the individual tree is fallen from original tree, they are genetically identical.

Air layering happens artificially. When a gardener covers a wounded tree with wrap, moist will form around the wrap. Because of the moist, new adventitious roots will grow near by the wounded place. [7]

Rhizomes Rhizomes are horizontal modification of the stems. Irises and day lilies are examples of rhizomes. They spread rapidly by growth of the rhizomes. [8]

Rooted Cuttings Rooted cutting does not happen naturally. It is an artificial method for the vegetative reproduction. Use auxin hormone to help development of adventitious root at the cut end. Because auxin is a hormone which controls growth of plant, it will help rooting with any species. Usually the rooted cuttings use young plants, because younger plants will grow better than older ones. (Younger plants, which are used for the cutting stems, can stand better with diseases. Also, they will not require much tape.) [9]

Runners and Stolons Runners or stolons is used for natural vegetative reproduction. Strawberries, grasses and some ferns are examples of runners or stolons. The strawberries and the grasses spread stem stems horizontally everywhere. Only first leaf node on the strawberries runners will produce leaves. Second leaf node will produce adventitious roots instead of producing the leaves. [10]

Suckering Suckering is one of the reproductions that a plant grows stem from root system. It happens from a root and makes a plant as an individual plant. Auxin and cytokinin are important hormones for the suckering. Low ratio of auxin and cytokinin will encourage the plant to grow.

Tissue Culture

Potato plants grow from tissue culture. Tissue culture occurs placing explant (piece of leaf, or cotyledon, or embryo) on hormones, sugars, amino acids, and micronutrients. After tissue culture, adventitious buds are produced. When it is growing well, it will grow as an individual plant. Taking out cells from a plant and growing the cells in nutrient liquid are another form of tissue culture. This method is used for genetic engineering. Tissue culture is useful method for horticulture, but it is hard method to use.

Advantages and Disadvantages Advantage The vegetative reproduction is a good way of producing large quantities of offspring rapidly and easily. That is why the vegetative reproduction is used for economical reason. When seeds are expensive or the seed production is low, gardeners can allow propagation of plants by using the vegetative reproduction. The vegetative reproduction allows cloning of plants, so the gardeners can produce combination of traits. (Use desirable root and desirable stem to produce a “new desirable” plant.) Therefore, the gardeners can create better plants in their favors. A daughter plant might flower at younger age by a mature parent plant.

Disadvantage Because the vegetative reproduction happen rapidly with large quantities, it seems to be a good method of surviving their kind. However there are disadvantages because the parent plant and the daughter will grow to close to eachother, forcing competition amongst the gathering of nutrients from soil and sunlight. One will inevitably start to lack the necessary nutrients and will become unhealthy, thus unable to survive. For vegetative reproduction, the plants might be broken into two or more pieces.