Vegeative propagation and sexual repro. in flowers
VEGETAIVE PROPAGATION TYPES OF VEGETATIVE ROPAGATION NATURAL VEGETATIVE PROPAGATION ARTIFICIAL VEGEATIVE PROPAGATION PARTS OF FLOWER FERTILISATION POLLINATION SEEDS AND FRUITS
Vegetative propagation is a form of asexualreproduction of a plant. Only one plant isinvolved and the offspring is the result of oneparent. The new plant is genetically identical tothe parent. It can occur naturally or be inducedby horticulturists . Plants raised by this methodcan bear flowers and fruits earlier than thoseproduced from seeds.
Natural vegetative reproduction is mostly a process foundin herbaceous and woody perennial plants .It typicallyinvolves structural modifications of the stem , root and leafbut underground part of a plant can contribute to vegetativereproduction .EXAMPLE- In Bryophyllum leaves small buds are formed,which are at dormant state. During favorable condition,these buds activates and detaches from its parent. Each budthen grow into complete new organisms.
In grafting 2 plants are used todevelop a new plant withcombined traits from the 2 parentplants. In grafting the scion is theabove ground part of one plant.The scion is attached tothe stock which is the rootedpart of the second plant. In layering a shoot of a parent plant is bent until it can be covered by soil. The tip of the shoot remains above ground. New roots and eventually a new plant will grow. These plants can then be separated.
In this technique a small piece oftissue of a desired plant is cut. This isplaced with a suitable nutrientmedium under proper conditions.The tissue grows into an unorganizedmass, known as callus. Small part ofthis tissue is put in anothermedium, which induces theformation of plantlets. The plantletscan be transplanted in soil or pots foedeveloping to maturity. Thistechnique is also called micropropagation. This method is used inpropagating plants likeAsparagus, orchids, Chrysanthemum.This method allows us to grow wholeplant from cells taken from variousparts of the plant body.
•In flowering plants, fertilization is unlike that of any other livingorganism. Pollen of a flowering plant contains two sperm nuclei. Bothsperm nuclei from the pollen grain are involved in fertilization. Thisfertilization process is actually a double fertilization.•The first fertilization occurs when one of the sperm fuses with theegg. The resulting zygote contains genetic material from both the maleand female parts of a flower . Through cellular division, the zygotebecomes the embryo, or immature plant.•In the second fertilization, the other sperm nucleus fuses with twopolar nuclei in the ovule. It eventually develops into the endosperm.The endosperm is food storage tissue in the seed, which is used by theembryo. Following fertilization, the ovule develops into a seed. Theseed contains the embryo plant and stored food. The ovary ripens andbecomes the fruit. Fruit serves the purpose of protecting seeds fromdrying. It also aids in the dispersal of seeds .
The reproductive process begins with pollination. Pollination is thetransfer of the male sperm carried in the pollen to the female part ofa flower, the stigma. Plants rely on wind and water to transfer thepollen. In addition, plants depend on animals to help withpollination. Birds, insects, bats, and other animals are attracted toscented or brightly colored flowers. These animals transfer pollenfrom the anthers of the flowers they visit to the stigmas of otherflowers. When the pollen of a plant pollinates a flower on the sameplant, the process is called self-pollination. Many plants can self-pollinate. A plant with genetic mechanisms that prevent its pollenfrom growing a pollen tube on a style of the same plant has acondition called incompatibility. When the pollen of a plantpollinates the flower on another plant of the same species, theprocess is called cross-pollination. Most floral crops today are theresult of cross-pollination by plant breeders. Once the pollen lands onthe stigma, it grows a thin pollen tube down the style to the ovary.The cell within the grain of pollen divides to form two sperm nuclei.The sperm cells, or male gametes, travel down the pollen tube to anovule that holds the egg. The female sex cell (the egg) is also a gamete.
A seed is a living entity that serves as a bridge between generationsof a plant. The seed is formed in the pistil of the flower and developsfrom the ovule following fertilization. It consists of anembryo, stored food, and a seed coat. As the fertilized egg, orzygote, grows and develops, it becomes the embryo of the seed. Theembryo is an immature plant held in a dormant, or resting, phaseinside the seed. It has a stem, a root, and one or two seed leavescalled cotyledons . Dicot plants, such as soybean, pea, and oak, havetwo cotyledons, or seed leaves, in their seed. Monocot plants, such ascorn , Kentucky bluegrass, and lilies, have one cotyledon in their seed
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