Forms of vegetative propagation of cultivated plants. Vegetative propagation of flower crops. Reproduction using layering
The ability to reproduce is an important property of all living organisms. Every plant reproduces at a certain time in its life.
Reproduction, that is, an increase in the number of plants, by vegetative organs - roots, stems, leaves - is calledvegetative propagation.Vegetative propagation in wild plants is widespread. Some of them rarely reproduce by seeds. Such plants include, for example, lily of the valley, many types of bulbous plants and others.
You recently learned about underground escapes. Reproduction by underground shoots occurs in many plants. A supply of organic nutrients is stored in underground shoots for the winter. So, in the tuber - the underground shoot of the potato - starch reserves accumulate. A lot of sugar is deposited in the bulbs and rhizomes. In spring, above-ground shoots grow from buds located on underground shoots. Many of these above-ground shoots, separated from the mother plant, develop into independent plants. For example, wheatgrass reproduces by rhizomes.
A single wheatgrass plant will settle somewhere in a garden bed. Soon you see: behind the thick, branched shoots of the weed, the plants planted in the garden bed are no longer visible. It is very difficult to get rid of wheatgrass. You start weeding it, and strong white rhizomes penetrate the soil, intertwined with the roots of cultivated plants. You will pull out the wheatgrass rhizome and along with it the roots of cultivated plants. Several days will pass after weeding, and again young shoots of weed stick out thickly in the garden bed. It was from the lateral buds on pieces of wheatgrass rhizomes that new stems began to grow. To destroy wheatgrass on a school site, you need to carefully select all its rhizomes from the soil.
Some plants reproduce by bulbs. One bulb, for example, onion, tulip or daffodil, by autumn forms several small baby bulbs.
Reproduction by aboveground shoots is very diverse. For example, wild strawberries reproduce by runners. Several creeping shoots grow from one mother plant in the summer - mustache At the nodes of such stems roots and adventitious buds are formed, from which young plants develop. They quickly take root and in the spring, after the shoot has rotted, they begin an independent life.
Trees such as poplar and willow can reproduce in nature by rooting pieces of above-ground stems. The wind breaks a small twig, carries it to the damp soil and presses it to the ground with something - and now it has already taken root, a tree has begun to grow.
Observing the rooting of shoots and stems in nature, man began to propagate many plants with pieces of shoots -stem cuttings and layering.
There are many known methods for vegetative propagation of cultivated plants. Here are the main ones: propagation by stem cuttings, layering, rooting, tubers, bulbs and dividing rhizomes.
Reproduction cuttingswidely used in gardening and floriculture. Many indoor plants are propagated by cuttings of stems with leaves: ficus, tradescantia, begonia, agave, roses, geranium, balsam and others.
Take stem cuttings of these plants with 3-4 leaves. Cut off the bottom two leaves. Plant the cuttings obliquely in moistened coarse sand, under which good nutritious soil is poured. To reduce water evaporation from the leaves, cover the cuttings with a glass jar.
After 2-3 weeks, adventitious roots form on the lower part of the cuttings, immersed in the ground.
Rice. 86. Wheatgrass with rhizome.
Stem cuttingscurrants, poplars, willows and some other trees and shrubs are propagated. Annual lignified cuttings 25-30 cm long in the spring, before buds open, are planted in well-prepared soil.
By autumn, adventitious roots form on the cuttings. Then the cuttings are dug up and planted in a permanent place.
Perennial phlox, dahlias and some other ornamental plants are also propagated by stem cuttings.
By layering Plants reproduce in different ways. The easiest way is to tilt the young shoot towards the ground in the spring so that its middle touches the ground. On the lower part of the shoot under the bud, cut the bark. At the place of the cut, pin the shoot to the soil and cover it with damp soil. Tie the end to a stick stuck in the ground. By autumn, adventitious roots form at the site of the cut. Then the shoot must be cut off from the bush and planted in a permanent place. Currants, gooseberries and other plants are propagated by layering.
Plants reproduce quickly and tubers. In the spring, potato tubers are planted in the soil, and in the fall, dozens of new ones are harvested from each plant that grows from a tuber. Usually, medium-sized whole tubers weighing about 80 g are selected for planting.
When there are not enough tubers, valuable potato varieties can be propagated bud eyes , sprouts And tops- This is also vegetative propagation by shoots.
When propagating potatoes with eyes, you need to cut out the buds with small pieces of tuber pulp and plant them in a box with fertile soil or in a greenhouse. From the planted buds sprouts will develop, in the lower part of which adventitious roots will grow. The resulting seedlings can be planted in the field.
To propagate by sprouts, the tubers are first germinated in the light. The resulting sprouts must be broken off. Cut the long ones into several parts - cuttings - so that each of them has a bud, and then plant them in boxes or greenhouses. When the cuttings take root, they can be planted in a permanent place.
Sometimes potatoes are propagated by the tops, that is, the upper parts of the tubers where the buds are located.
Fruit trees are usually propagated vaccination. To do this, an eye bud or cuttings of a cultivated plant are spliced with the stem of a wild plant. This is done in order to use the wild root system, which has great power, unpretentiousness to the soil, frost resistance and other qualities that the grafted plant does not have. Dichok is a young plant grown from the seeds of a fruit tree. The eye or cutting of a cultivated plant taken for grafting is called scion, and the wild one to which they are grafted - rootstock.
To graft a bud, a one-year-old shoot is cut from a cultivated fruit tree, from which the leaf blades are then removed, leaving only the petioles. At the base of the stem of the wild rootstock, use a sharp knife to make a cut in the bark in the shape of the letter T, as shown in Figure 90, and by turning the knife blade in the cut, separate the bark of the wild rootstock from the wood. Then a well-developed bud with a thin layer of wood 2-2.5 cm long is cut from a shoot of a cultivated variety and inserted under the bark into a cut. The grafting site is tightly tied with a washcloth so that the kidney itself remains free from the binding.
Vegetative propagation is of great practical importance, as it guarantees the production of offspring that fully retain the properties and characteristics of the mother plant; Flowering in a number of species occurs earlier than during seed propagation; Some plants here do not produce seeds (Japanese anemone, etc.).
Methods of vegetative propagation .
1) Reproduction by rhizomes. This method is used to propagate rhizomatous plants - irises, larkspur, chrysanthemums, lilies of the valley, goldenrod, etc. The rhizome is an underground stem; it has dormant buds that give rise to new shoots. Rhizomatous plants therefore grow very quickly, take root well after transplantation and develop well. The dug up bush is cut into pieces with a shovel or knife, or you can break it with your hands, trying to cause as little injury to the plant as possible. Each part of the bush should have 3-4 buds and its own roots. Plants that bloom in spring are best divided in autumn, those that bloom in summer and those that bloom in autumn are best divided into spring.
2) Reproduction by tubers. Tubers are of stem origin (modified stems) and root origin - modified roots. A distinctive feature of stem tubers from root ones is the presence of dormant buds on them, which allows them to be propagated by division (artichoke - tubers die off after a year; tuberous begonia, cyclamen - tubers live for several years). Root tubers that do not bear buds are separated from the part of the root collar where dormant buds (dahlias) are located.
3) Reproduction by bulbs and corms. Bulb plants are divided into 2 groups based on the structure of the bulbs: the first has scaly bulbs (lilies), the second has filmy bulbs (tulips, daffodils, hyacinths, etc.). In filmy and scaly bulbs, baby bulbs are formed from the axillary buds, with which plants reproduce. Lilies can also be propagated by bulb scales, and some species form aerial bulbs in the leaf axils.
Gladioli and crocuses reproduce by corms; they can be divided into parts, each of which should have 1-2 buds.
4) Reproduction by mustache(stem shoots growing horizontally and forming new rooting plants at the nodes) is typical for Indian strawberry, periwinkle, tenacious, fragrant violet, etc. Rooted specimens in spring or autumn are separated from the mother ones and planted in a new place.
5) Root suckers propagated by plants on the roots of which there are adventitious buds capable of developing into above-ground shoots (bindweed, dracaena, hops, etc.). The offspring are separated from the mother plant and planted.
6)Cuttings- one of the most common methods of plant propagation. Any part separated from a plant intended for vegetative propagation is called a cutting. Cuttings are divided into stem, root and leaf. Stem cuttings, in turn, are: green, harvested with immature wood and unformed leaves, intended for propagation of biennials, perennials, potted crops and certain types of shrubs; semi-lignified, characterized by formed leaves and incompletely ripened wood (roses, lilacs, indoor jasmine, fuchsia, etc.); lignified, characterized by durable, well-formed wood without leaves (willow, jasmine, spirea, etc.).
Most rhizomatous plants (peonies, phlox, irises, oriental poppy, etc.) are propagated by root and rhizomatous cuttings. In most cases, greenhouse plants (Rex begonia, gloxinia, sanseveria, echeveria, etc.) are propagated by leaf cuttings.
It is better to carry out cuttings in greenhouses, greenhouses or in a specially protected area with well-fertilized and treated soil. Planting is carried out in autumn or spring. The cuttings are covered for the winter. In the first year of plant life, flowers and inflorescences are plucked out, giving the opportunity to better develop vegetative organs.
7) Reproduction by grafting– transplanting a cutting or eye from one plant (scion) to another (rootstock). This method is used to propagate roses, azaleas, lemons, cacti, etc. For grafting to be successful, it is necessary to combine living cells capable of dividing, i.e. at least in some areas, the cambium (tissue between the phloem and the wood) of the scion should coincide with the cambium of the rootstock.
Vaccination should be carried out during the period when the scion buds are dormant. There are several methods of vaccination. They are quite widely described in the horticultural literature. The most commonly used method is budding (by eye). It is performed in the spring (with the germinating eye) and in the summer (July - August) with the dormant eye.
Lecture 6. Plant propagation
Reproduction is an integral property of living organisms to reproduce their own kind. Reproduction ensures continuity and continuity of life. There are two main forms of reproduction: asexual and sexual.
Asexual reproduction. Reproduction in which one organism takes part, there is no formation and fusion of gametes, there is no fusion of genetic material in any form. This is the most ancient form of reproduction, widespread in all groups of plants, occurs by mitotic division or with the help of spores, a special form of asexual reproduction is vegetative reproduction.
Division . Reproduction by fission is characteristic of unicellular algae. Division occurs by mitosis, resulting in the formation of individuals that are genetically identical to each other and the maternal organism.
Reproduction by spores . Plant spores are reproductive, single-celled formations that serve to form new individuals.. Most algae living in water have motile spores because they have flagella. Such disputes are called zoospores. In terrestrial plants and fungi, they do not have special adaptations for active movement. Spores are formed in the organs of asexual reproduction - sporangia or zoosporangia. In algae, almost any cell can become a sporangium; in higher plants, sporangia can become a multicellular organ. In plants, spores are always haploid. If they arise on a diploid plant, then their formation is preceded by meiosis, if on a haploid plant, by mitosis. The spores formed as a result of meiosis are genetically unequal, and the organisms that develop from them are genetically unequal.
The plant on which spores are formed is called a sporophyte. If the spores are morphologically indistinguishable, then the plants that form them are called homosporous; heterosporous plants are plants that form spores, always differing in size and physiological characteristics. Microspores are smaller spores that form in microsporangia, from which they grow male gametophytes (plants that produce male gametes ). Megaspores are larger spores formed in megasporangia, from which they grow female gametophytes . Heterosporousness is more common among higher plants (some mosses, ferns, all gymnosperms and angiosperms).
Reproduction by spores is of great biological importance - as a result of meiosis, recombination of genetic material occurs, in spores new combinations of gene alleles arise that come under the control of selection; Typically, plants produce spores in huge quantities, which ensures high reproduction rates. Due to their small size and lightness, spores are carried over long distances, ensuring the dispersal of plants; The dense spore shell serves as reliable protection from unfavorable environmental conditions.
Vegetative propagation of plants - this is an increase in the number of individuals due to the separation of viable parts of the vegetative body and their subsequent regeneration (restoration to a whole organism). This method of reproduction is widespread in nature. Both algae and higher plants reproduce vegetatively.
Vegetative propagation occurs natural and artificial . Thanks to natural vegetative reproduction in nature, there is a rapid increase in the number of individuals of the species, their settlement and, as a result, success in the struggle for existence. Natural vegetative propagation occurs in several ways: fragmentation of the mother into two or more daughters; destruction of areas of ground-creeping and lodging shoots (moss mosses, gymnosperms, flowering plants); using special structures specifically designed for vegetative propagation (tubers, bulbs, rhizomes, corms, axillary buds, adventitious buds on leaves or roots, brood baskets of bryophytes, etc.).
Artificial vegetative propagation is carried out with human participation when growing cultivated plants. Artificial vegetative propagation has a number of advantages over seed propagation: it ensures the production of offspring that retain the characteristics of the parent organism, speeds up the production of offspring, and allows one to obtain a large number of offspring. In addition, using vegetative propagation, it is possible to reproduce clones of those plants that produce non-viable seeds or do not produce them at all.
Methods of vegetative propagation. Plants can be propagated by vegetative organs - dividing the whole plant into parts, aboveground and underground shoots, leaves, roots.
Fragmentation called the division of an individual into two or several parts, each of which regenerates into a new individual (Fig. 34). Such reproduction is typical for filamentous and lamellar algae (scraps of filaments or parts of the thallus), and some flowering plants (for example, Elodea canadensis). Only female specimens of Elodea came to Europe; they were unable to produce seeds due to the lack of male plants, and fragmentation turned out to be the only method of reproduction.Dividing bushes. Currants, gooseberries, primroses, and rhubarb reproduce well from parts of bushes. The plant is dug up, divided into parts and planted separately from each other. Bushes are usually divided in spring or in the second half of summer.
Reproduction by aboveground shoots.
Mustache . In agricultural practice, strawberries and wild strawberries are propagated with mustaches. At the nodes of the mustache, lateral buds and adventitious roots are formed. After the internodes dry out, the plants become isolated. In nature, plants such as creeping buttercup and saxifrage reproduce with tendrils.
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Stem cuttings. A stem cutting is a section of an above-ground shoot. Grapes, currants, gooseberries, ornamental types of spirea, red peppers, eggplants and others are propagated by stem cuttings. For propagation, cuttings are taken from 2-3 to 6-8 cm long, consisting of one internode and two nodes. The leaves are left on the top node (if the leaf blades are large, then they are cut in half). The cuttings are planted in special greenhouses, and after rooting - in open ground.
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a piece of bark and wood (eye) grafted onto another plant is called scion. Rootstock– the plant or part thereof on which the grafting was carried out. Grafting allows you to use the root system of the rootstock to preserve or propagate a certain variety, replace a variety, obtain new varieties, accelerate fruiting, obtain frost-resistant plants, repair or rejuvenate old mature trees.
There are many methods of grafting, but they can all be reduced to two main types: grafting by proximity, when the scion and rootstock remain on their roots, grafting by separated scion, when only the rootstock has roots.
The most common grafting methods are the following (Fig. 38). Grafting into cleft or half-split. Used if the scion is thinner than the rootstock. The cross section of the rootstock is completely or partially divided and a scion, obliquely cut on both sides, is inserted into it.
Bark grafting. The scion is also thinner than the rootstock. A horizontal cut is made on the rootstock under the stem node, the bark is cut vertically and its edges are carefully turned away. A half-cone-shaped cut is made on the scion, inserted under the bark, clamped with bark flaps and tied.
Copulation. It is used if the scion and rootstock have the same thickness. Oblique cuts are made on the scion and rootstock and combined, ensuring a tight connection.
Budding. Kidney-eye grafting. A T-shaped cut is made on the rootstock, the edges of the bark are folded back, and a bud with a small piece of wood is inserted behind the bark and bandaged tightly.
Reproduction by underground shoots.
Tuber . Of the agricultural plants that reproduce by tubers, the most famous are potatoes and Jerusalem artichokes. They can be propagated by planting whole tubers or parts of them with buds and eyes. Tubers, as a storehouse of nutrients, are formed in such wild plants as syt, sedmichnik.
Rhizome . In agriculture, rhizomes are used to propagate rhubarb, mint, asparagus, bamboo, and in ornamental gardening - lily of the valley, iris and others. They easily reproduce by dividing the rhizome into parts, each of which must contain a vegetative bud.
Forests, steppes, and meadows are home to a large number of rhizomatous plants, primarily cereals. Rhizomatous plants include wheatgrass, timothy, white grass, rosemary, wood sorrel, horsetail and other wild plants. Many rhizomes branch, and when the old parts die off, new plants separate.
Bulb . In agricultural practice, bulbs are used to propagate onions, garlic, and ornamental plants: tulips, daffodils, hyacinths and others. In nature, many plants reproduce by bulbs: tulips, goose onions, scilla, snowdrops, etc. Vegetative propagation of bulbous plants is carried out by overgrown adult bulbs, children, and individual scales.
Corm . The corm's reserve nutrients are used up for flowering, but by the end of the season a new corm is formed. In addition, one or more corms may form - fleshy buds that develop between the old and new corms. Corm plants include gladiolus and crocus.
Root tubers . They are thickenings of lateral roots. In ornamental gardening, dahlias and sweet potatoes are propagated from root tubers. When propagating dahlias, it is necessary to take root tubers with the base of the stem bearing buds, since root tubers do not form buds. Spring grass and Lyubka bifolia reproduce by root tubers.Reproduction by root suckers. Root shoots are shoots arising from adventitious buds on the roots (Fig. 36). Plants that easily form adventitious buds on the roots are propagated by root suckers: cherry, plum, raspberry, lilac, aspen, sow thistle, thistle, etc.
Root cuttings. A root cutting is a part of a root. They propagate species whose roots easily develop adventitious buds: horseradish, raspberries, cherries, roses. Root cuttings are harvested in the fall, less often in the spring. To do this, use lateral roots of the first order at the age of 2-3 years. The length of the cutting is up to 10-15 cm, the diameter is 0.6-1.5 cm. The cuttings are planted in the soil to a depth of 2-3 cm. Many wild plants are also propagated by cuttings: willow, poplar, aspen, dandelion
Reproduction by leaves.
Whole leaves. Many flowering plants are propagated by leaves, such as Saintpaulias and begonias. It is enough to put the leaf in water, adventitious roots and adventitious buds appear, after some time the plant is transplanted into the soil.
Leaf cuttings. Sometimes even part of a leaf is enough for vegetative propagation. In a royal begonia, a part of a leaf with a large vein is cut out; a sansevieria leaf can be cut into several leaf cuttings and placed in water.
Adventitious buds on leaves, children . Bryophyllum produces adventitious buds on its leaves that look like small plants. When they fall, they become independent plants.
Tissue culture. Tissue culture is the growth of plant cells in artificial media. Plant cells have the property totipotency– a single cell can develop into a normal plant using certain phytohormones. The tissue culture method makes it possible to obtain clones some higher plants. Cloning– obtaining a set of individuals from one mother by vegetative means. Cloning is used to propagate valuable plant varieties and to improve the health of planting material.
Sexual reproduction. Sexual reproduction is associated with the formation of a special type of cell by plants - gametes. The plant on which gametes are formed is called gametophyte. The process of gamete formation is called gametogenesis. It occurs in special organs - gametangia. In homosporous plants, the gametophyte is usually bisexual: it bears both female and male gametangia. In heterosporous plants, a gametophyte with male gametangia develops from microspores, and a gametophyte with female gametangia from megaspores. Plant gametes are formed mitotically, meiosis occurs after the formation of the zygote ( zygotic reduction) – many algae, or when spores form ( sporic reduction) – in diploid algae and higher plants. In animals, meiosis occurs during the formation of gametes ( gametic reduction).
Sexual reproduction has a number of advantages over asexual reproduction. Firstly, when gametes merge, an organism is formed with a unique double set of gene alleles received from parents with different genotypes, an organism with a unique genotype is formed. As a result of selection, individuals will survive whose genotype allows them to adapt to given environmental conditions, even if these conditions change.
Secondly, mutations that change genes are often recessive and harmful under given environmental conditions. The diploid set of genes allows the survival of emerging recessive alleles due to the presence of dominant alleles of these genes. Each diploid organism contains hundreds, thousands of genes in a recessive state, just as a sponge is saturated with water, so the genotype is saturated with them, they are passed on to the next generation and gradually spread throughout the population. A mutation will appear if both gametes carry a given recessive allele of a gene, and by this time the environment may have changed and the mutation may be beneficial. This is how mutations accumulate and spread.
Gametes are always haploid. When male and female gametes fuse, a diploid zygote is formed, from which a new organism develops. The process of gamete fusion is called fertilization. The essence of the sexual process is the same for all living organisms, and its forms are varied. The following types of sexual process are distinguished: hologamy, conjugation, isogamy, heterogamy and oogamy (Fig. 39).
Hologamy . Hologamy is the fusion of haploid single-celled, outwardly indistinguishable organisms with each other. This type of sexual process is characteristic of some unicellular algae. In this case, it is not gametes that fuse, but entire organisms that act as gametes. The resulting diploid zygote usually immediately divides meiotically ( zygotic reduction) and 4 daughter haploid unicellular organisms are formed.
Conjugation. A special form of the sexual process is conjugation, characteristic of some filamentous algae. Individual haploid cells of filamentous thalli located close to each other begin to form outgrowths. They grow towards each other, connect, the partitions at the junction dissolve, and the contents of one cell (male) pass into another (female). As a result of conjugation, a diploid zygote is formed.
Isogamy. With isogamy, gametes are morphologically similar to each other, that is, identical in shape and size, but physiologically they are of different quality. This sexual process is characteristic of many algae and some fungi. Isogamy occurs only in water, in which gametes are equipped with flagella for movement. They are very similar to zoospores, but are smaller in size.
Heterogamy. With heterogamy, the fusion of motile germ cells occurs, similar in shape, but differing in size. The female gamete is several times larger than the male one and less mobile. Heterogamy is characteristic of the same groups of organisms as isogamy, and also occurs in water.Oogamy. Characteristic of some algae and all higher plants. The female gamete - the egg - is large and immobile. In lower plants it is formed in unicellular gametangia - oogonia, in higher plants (excluding angiosperms) - in multicellular archegonia. The male gamete (sperm) is small and mobile, formed in fungi and algae in unicellular gametangia, and in higher plants (excluding angiosperms) - in multicellular gametangia - antheridia. Sperm can only move in water. Therefore, the presence of water is a prerequisite for fertilization in all plants, with the exception of seed ones. In most seed plants, male gametes have lost their flagella and are called sperm.
Key terms and concepts
1. Asexual reproduction. 2. Plant spores. 3. Zoospores. 4. Sporophyte. 5. Male and female gametophytes. 6. Microspores and megaspores. 7. Vegetative propagation. 8. Scion. 9. Rootstock. 10. Gametangia. 11. Zygotic reduction. 12. Sporic reduction. 13. Gametic reduction. 14. Hologamy. 15. Isogamy. 16. Heterogamy. 17. Oogamy. 18. Conjugation. 19. Oogonia. 20. Archegonia. 21. Antheridia. 22. Totipotency.
Basic review questions
1. Plant propagation by division.
2. Reproduction by spores.
3. Natural vegetative propagation.
4. Reproduction by fragmentation and division of bushes.
5. Reproduction by above-ground shoots (tendrils, layering, stem cuttings).
6. Basic methods and features of propagation by grafting.
7. Basic methods of propagation by underground shoots.
8. Basic methods of propagation by roots.
9. The main methods of plant propagation by leaves.
10. Reproduction by tissue culture.
11. Advantages of sexual reproduction.
12. Characteristics of the main types of sexual processes (chologamy, conjugation, isogamy, heterogamy, oogamy).
15. Seed and vegetative methods of propagation. The value of each method for growing ornamental plants.
Arboriculture. When growing ornamental tree species, seed and vegetative propagation methods are used. Seed propagation of most ornamental trees and shrubs remains the main method due to technological simplicity, the possibility of mechanization and overall cost-effectiveness. In addition, the seed propagation method is the only way of plant introduction, which has received the greatest development in green construction. The use of vegetative propagation methods in ornamental tree growing is due to the following:
the decorative features of a large number of ornamental and garden forms and varieties (roses, lilacs, clematis, rhododendrons, thujas, etc.) are not reproduced at all or are reproduced in a very small number of plants when propagated by seed;
the presence of species that are difficult to propagate by seed under production conditions due to the fact that their seeds quickly lose their viability (poplar, willow seeds) or are often of poor quality (seeds of mock orange, actinidia, grapes, some spirea and honeysuckle);
propagation of introduced species that do not set seeds at all;
to speed up the introduction into culture of plants that have not yet entered the fruiting season;
to extend the propagation period (terms) when using both seed and vegetative propagation methods for a specific species or variety.
The main and most valuable property of seed propagation is the ability to obtain plants based on individual variability that are more adapted to certain environmental conditions. This valuable property of seed progeny is also important during the introduction of plants. It should be noted that with prolonged vegetative propagation, degeneration of plants is possible. This happens if the material is taken from old mother plants. In plants from cuttings and grafts, long-term preservation of the age characteristics or developmental pattern of the mother plant is often observed. During generative reproduction, complete rejuvenation of the body occurs. The same phenomenon is observed when plants propagate by pieces of meristem tissue. On the contrary, when branches from old trees are used for propagation, a certain stage of development and aging continues without rejuvenation. However, plants, having plasticity and the ability to rejuvenate organs and tissues, can restore their vital functions to some extent. This is especially evident in the rejuvenation of plants by cutting branches to the basal part and subsequent propagation by cuttings or layering. It is this phenomenon that can explain that aspen plants obtained from leaf cuttings do not differ from seed plants.
Seed propagation. We should strictly avoid collecting seeds from random trees and shrubs that are not typical in terms of the clearly expressed qualities that interest us. Plants that are damaged as a result of diseases and adverse effects of the urban environment and are not resistant to pests should not be used for collecting seeds. Particular attention should be paid to the need to prohibit the use of seeds from trees with signs of degeneration and old age. The offspring obtained from them are characterized by fragility, poor growth, and poor resistance to pests and diseases.
During seed propagation of decorative forms, the heritability of individual traits depends on the meteorological conditions of the year and pollination conditions. With free pollination, the characteristic features of purple-leaved forms appear in 60% of plants, variegated - in 20% and dissected-leaved - in 30%. Therefore, a preliminary test for the transmission of certain characteristics to offspring can be established for individual species and forms only experimentally. Propagation of forms and species by seeds should be considered justified if the trait of interest appears in 40% of the plants.
Vegetative propagation. Vegetative propagation in ornamental plant growing primarily pursues the goal of obtaining plants with certain qualities: crown shape, color and shape of leaves, doubleness of flowers, etc., which are not transmitted to offspring during seed propagation or are transmitted to a very small number of specimens.
The yield of decorative forms can be increased if pollination is allowed only between plants of a given form, and in no case with plants of the main species. But when propagating varieties, this way is also ineffective: the diversity of offspring is very great. Therefore, in practice, only vegetative propagation methods are used to propagate forms and varieties.
The basis of vegetative propagation of plants is the natural ability to regenerate that part of the mother (uterine) plant that is used for vegetative propagation. Vegetative propagation - grafting and cuttings.
The essence of vegetative propagation is to obtain from individual vegetative organs of plants - roots, stems, leaves - or from their parts independent new plants with the characteristics and properties of the mother plant. The basis is the ability of living tissues to regenerate the whole plant, that is, to restore lost parts.
You can get new plants without separating parts (shoots, roots) from the mother plant before they take root and from separated small parts; Recently, plant propagation by culture of meristem tissue has become widespread.
Reproduction by unseparated parts : layering, root suckers, stolon suckers (rhizomatous, dividing bushes
Reproduction by parts separated from the plant: The separated parts of plants from which new independent plants must develop are called cuttings. Propagation by separated parts is carried out by root, lignified stem, semi-lignified (green) stem, and leaf cuttings. In ornamental tree growing, stem cuttings are used mainly, root cuttings are used less, and leaf cuttings are not used at all. New plants from stem cuttings are obtained by rooting them or grafting them onto other plants (rootstock).
Floriculture. One of the mandatory properties of a living organism is reproduction of offspring, reproduction. In nature, there are two ways of plant reproduction: sexual and asexual.
Sexual reproduction of plants is reproduction by seeds formed during the fusion of specialized cells - gametes. As a result, new individuals with richer hereditary capabilities appear. For many plants, seed propagation is the only method of propagation. This applies primarily to annual plants. But in the practice of growing flower products, many perennial plants grown as annuals are also obtained from seeds - ageratum, verbena, lobelia, petunia, etc. Many greenhouse and industrial crops are also propagated by seeds - cyclamen, cineraria, gloxinia, calceolaria, as well as open ground perennials - aquilegia, multileaf lupine, alyssum, lilies, primroses, etc. Modern heterotic F 1 hybrids are also propagated by seeds. The main disadvantage of seed propagation is that with it only self-pollinating plants retain their varietal qualities. In cross-pollinating varieties (zinnia, tagetes), the characteristics of the variety are not always preserved without special selection. The latter is also typical for hybrid plants, the same F 1 hybrids. At the same time, seed propagation makes it possible to obtain new valuable plants that differ in quality from the parent ones.
Asexual reproduction in botany is divided into two main forms: vegetative and actually asexual. An example of asexual reproduction itself is reproduction by spores in ferns. Vegetative propagation is very widespread in ornamental herbaceous plants in nature and in cultivated plants. In flower crops, vegetative propagation is carried out by parts of vegetative organs - roots, stems, leaves and metamorphosed organs (bulbs, rhizomes), as well as groups of cells (microclonal propagation, meristem culture). All these methods are specifically discussed for individual crops in the relevant sections. The advantage of vegetative propagation is that it allows you to recreate and preserve plants with certain decorative qualities inherent in the original maternal individual.
In higher plants, which include flower crops, the forms of vegetative propagation are most diverse: by dividing the bush, tubers, bulbs, corms, rhizomes, cuttings. Reproduction by layering, offspring and grafting is less commonly used. The latter method is used for tree crops of roses, which, as beautifully flowering plants, are used in flower decoration (parterres, mixborders, borders). Vaccinations are also used in cactus culture. Vegetative propagation is used for perennial plants.
1.4. Where is the vaccine used?
Introduction
Goal: find out what vegetative propagation is and study it.
1. Consider the basis of vegetative propagation.
2. Consider how vegetative propagation is carried out.
3. Study methods of artificial vegetative propagation.
4. Find out where vegetative propagation is used.
What is the basis of vegetative propagation?
Vegetative propagation - This is a property that distinguishes plant organisms from animals. The basis of vegetative propagation is the ability of plants to regenerate. Regeneration- This is the renewal of the whole organism from its parts due to cell division. As a result of vegetative propagation, a large number of identical descendants appear, which are a copy of the parent plant. All together they form clone - offspring that arises from one individual through vegetative propagation. Cloning allows a person to preserve the varietal characteristics of many cultivated plants. Today, a method of cell and tissue culture has been developed, thanks to which plant clones are obtained by growing them on a nutrient medium from a single cell or group of cells. Cloning allows you to grow valuable or rare plants from individual cells (for example, growing ginseng), quickly obtaining a large plant mass to extract certain useful substances from it. So, the basis of vegetative propagation is regeneration.
1.2. How is natural vegetative propagation carried out?
As you already know, plants have modified organs - bulb., rhizome, tuber etc., by which vegetative propagation is carried out. Bulbs lilies, daffodils, tulips, etc. multiply. And plants such as wheatgrass, lily of the valley, sow thistle can quickly cover a large area with the help rhizomes The division and transformation of parts of the rhizome into independent plants can be facilitated by animals living in the soil (for example, moles, mice, beetles), etc. Some plants reproduce tubers(potatoes, corydalis, Jerusalem artichoke). Plants often reproduce by above-ground shoots. Thus, wild strawberries grow several creeping shoots during the summer - mustache, on the tops of which young shoots and adventitious roots develop. Over time, the tendrils dry out and die, and new plants begin to live on their own. Poplar, willow, and aspen can reproduce by rooting branches. The wind breaks the branch, carries it to damp soil - and now it has already taken root and given rise to a new plant. In many woody plants (for example, cherry, raspberry, lilac) reproduction is common root suckers. So, natural vegetative propagation occurs with the help of parts of vegetative organs and their modifications.
What are the methods for artificial vegetative propagation of cultivated plants?
For vegetative propagation of plants, people often choose the same methods by which wild species propagate: strawberries are propagated with a mustache, potatoes are propagated with tubers, etc. Lilacs and raspberries are propagated by root suckers, and berry crops are propagated by dividing a bush. In plant growing, special methods of vegetative propagation are also used - cuttings And vaccination.Cuttings -This is reproduction by parts of a shoot or root separated from the body. Handle called a part of a shoot or root with several buds. Stem cuttings, that is, by parts of a shoot with several buds, tradescantia, grapes, etc. are propagated. By parts of roots with several adventitious buds - root cuttings - Raspberries and plums are propagated. Plants such as begonia, lemon, propagate leaf cuttings - separate leaves on which there are adventitious buds that give rise to adventitious roots and shoots. Graft- Thisthe fusion of a cutting from one plant (scion) with another rooted plant (rootstock). There are about 100 different vaccination methods, which are divided into three types: inoculation(budding) - scion grafting, having only one bud, taken with a thin layer of bark (for example, roses); grafting by cuttings(copulation) - grafting obliquely a cut scion cutting with several buds (for fruit trees, etc.); grafting by proximity(ablation) - grafting in which the scion is not separated from the parent plant until it has completely fused with the rootstock (for example, in grapes). So, artificial vegetative propagation is carried out using parts of vegetative organs or their modifications, using special propagation methods- cuttings and grafting.
1.4 .Where is the vaccine used?
Fruit plants - apple trees, citrus fruits, grapes and many others - reproduce mainly vegetatively - by grafting. Plantations of such industrial crops: aromatic (mint), cinchona, are created thanks to the ability of these plants to reproduce vegetatively.
Forestry has also long used this feature of the propagation of woody plants. In place of felling of oak, birch, ash, maple, shoots appear the very next year, and after two or three years a young low-trunk forest is already growing.
Aspen conquers large territories, often displacing species such as oak, spruce, pine, etc., due to its ability to quickly reproduce with the help of root shoots. Species such as willows and poplars are propagated on large plantations exclusively by cuttings.
Conclusion
As a result of the work done, we learned what vegetative propagation is, learned methods of vegetative propagation and learned where it is used.
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