Value of physiology for gardening. Reproduction of plants

you are: Value of physiology for gardening

Plants can breed in the sexual way by means of seeds or a sexless way (vegetativno), using a certain part of the body for reproduction of the whole plant. Almost all plants can breed vegetativno, and it they differ from animals from whom only most simply organised can increase the number, without passing through a stage of sexual cages. Every way reproduction has the advantages and lacks. formation of seeds allows to give a great number of potential new individuals which then are carried by a wind, water and animals on extensive territory. Besides, as at formation of seeds occurs usually genetic rekombinatsija, there are new variants which can appear better adapted to new and changing to the environment. On the other hand, vegetative reproduction, giving smaller number of individuals, provides ' parental ' support and a food for early growth; Sprouts unlike it have only minimum stock of nutrients in endosperme or cotyledons and should pass to own photosynthesis quickly. vegetative reproduction usually does not promote a kind wide circulation and as all individuals are genetically homogeneous, they have less than adaptation possibilities to changing conditions of environment. This way has the important economic value as allows to make multiple copies desirable grades.

Many plants have the natural ways of vegetative reproduction used by the person since prehistoric times. One of widespread methods - reproduction by means of reserving bodies (bulbs, rhizomes, tubers), capable to give new plants. steljushchiesja stalks, stolony and moustaches can take roots in some places, and each point of rooting is capable to give an independent plant.

Besides, gardeners have developed variety of artificial ways of vegetative reproduction. These ways connected with methods of culture of cages and fabrics will play, apparently, further an escalating role in commercial reproduction of plants. In this section we will consider some physiological principles on which reproduction of plants is based.

Germination of seeds. Many kinds of cultural plants at favorable temperature and humidity sprout without special processing. It is result of long selection by the person directed against rest of seeds or unusual requirements for germination. However light or a cold which reduces in them the maintenance ingibitorov is necessary for rest interruption for seeds of some ornamental plants or raises level of stimulators of germination. Other seeds have the impenetrable seed cover interfering receipt in water and oxygen. In the nature such strong seed covers collapse gradually bacteria. As it gives not levelled crops, such seeds can skarifitsirovat be (ground) mechanically or chemically for the purpose of cover destruction. if preliminary processing will allow water and oxygen to get in a seed, it will quickly sprout. Namachivanie seeds in water or their washing too it is possible to apply to a cover and removal softening ingibitorov. Seeds requiring in the light of, it is necessary to sow on a soil surface, and the seeds demanding holodovoj processing, humidify and place before crops in a refrigerator or out of a premise at temperature 2-7°С for 1-4 months. At holodovoj to processing oxygen and moisture access is important. It is usually reached by stratification - a premise of damp seeds between mix-sand and peat layers. Processing by hormones for a germination induction is used not so widely though for improvement of germination of the seeds requiring in the light of and a cold, it is possible to apply gibberellin.

Reproduction by shanks and an inoculation. At reproduction by shanks cut off a top of a stalk and its basis place century well aerated, damp environment - soil or sand.

To prevent zavjadanie these pieces without roots, often support their humidity by a premise in a polyethylene sack or creations water an aerosol. Formation kallusa and ksilemy, proliferatsija (kambija and a bookmark of roots occur in reply to concentration increase auksina as a result of it bazipetalnogo movings from a stalk top. Rooting can be improved small warming up of soil and processing of a surface of a cut synthetic auksinami, for example indolilmasljanoj or a-naftiluksusnoj acid (NUK) (fig. 14.15). On a cut surface usually develops kallus and roots start to grow about external edges of vascular bunches or - at wood plants - from young secondary floemy. Some shanks take roots without drawing auksinov is better, it is probable because already contain them in enough. The shanks synthesising few own auksina, require its addition.

At an inoculation a top of a stalk or a kidney from one plant (privoj) insert in rasshchep a stalk of other plant (stock), and they grow together, forming the uniform individual (fig. 14.16). This way apply when stock roots are more powerful or the plant roots which runaway wish to receive are steadier against illnesses, than. A junction tie and process wax or other protective material to prevent dehydration. In a case prizhivlenija a shank as a result of differentiation of fabrics of a stock in vascular elements vascular connection between privoem and a stock is formed. Differentiation of vessels partly causes auksin, synthesised by a top privoja and diffundirujushchy from its basis. In gardening were extended various types of inoculations. The choice of this or that type depends on a kind of plants.

Use of fabric cultures. Successful reception of cultures of vegetative fabrics in laboratory has naturally led to their use in gardening for reproduction of plants. A slice of the sterilised vegetative fabric place on an agar containing necessary nutrients, and also auksin and tsitokininy, a parity between which define experimentally. The fabric on such environment quickly expands, forming kallus. The growing fabric can be divided repeatedly and thus to receive it in a considerable quantity from initial tiny eksplantata. Changing hormonal balance, it is possible to cause formation of roots and runaways.

Received plants separate from parental kallusa and grow up separately on an agar until they do not become large enough for vysazhivanija in vessels with soil.

Faster way of vegetative reproduction by means of culture of fabrics consists in direct branch of tops of a stalk and their cultivation on an agar. In these conditions apeks forms kallus, and in an end result small runaways which can be grown up separately turn out many and to land in vessels.

The Main advantage of this method consists that it favours to fast clonal reproduction of the plants which seed posterity is split, and vegetative reproduction by usual ways occurs very slowly. This way used also for reception bezvirusnyh lines of plants as many system viruses moving on floeme, do not get in apikalnuju a point of growth which is not connected with floemoj.

These ways, now rather usual, used decades for reception of orchids. Apeks orchid runaway grow up for reception of weight of a fabric which it is possible then to divide into set of slices. These slices rotate in nutritious solutions to prevent development of polarity and differentiation.

Then they are replaced to a nutritious agar where they form runaways, by roots and develop in small rastenitsa which later land in vessels. Similar methods use now for carnations, chrysanthemums and some other plants. Possibly, soon in many large hothouses and nurseries will equip special premises for reception of plants from fabric cultures.

The Culture of fabrics almost for certain will appear useful at reproduction of wood kinds which not soon give seeds or do not transfer to seed posterity desirable signs. Recently it was possible to deduce a number of quickly growing lines of coniferous trees, but as they many years do not form seeds, their reproduction represents the big problem. The intensive researches directed on are now conducted achieving formation and growth of fabrics coniferous in culture with the subsequent regeneration of all plant. Last phase often appears a stumbling-block, and without it the culture of fabrics has only limited practical value. Some isolated bodies, such as roots, can synthesise the substances necessary to us, for example alkaloidy; the culture of such bodies can be economic.

Use of cultures of cages and fabrics in selection of plants. Besides that the culture of fabrics is used at vegetative reproduction of plants, it can serve also as means for realisation of an unusual way of their sexual reproduction. We will assume that we have the high-yielding cultural plant susceptible to certain illness, and related, but a kind not crossed to it. Steady against the given illness. If their normal crossing cannot be reached by means of pollination there is no other sexual way for introduction in a plant of a sign of stability to illness. However now there was possible a parasexual merge of cultivated somatic cages. Usual vegetative cages cannot merge in culture as their walls interfere with association of protolayers. However by means of a mix of the enzymes destroying cellular walls, they can be dissolved. In the beginning for branch of one cage from another it is used pektinaza. Then to destruction of walls of separate cages apply tselljulazu. It is possible then to collect protolayers (contents of live cages) in the form of a deposit by cautious tsentrifugirovanija, addressing with them as with svobodnozhivushchimi the microorganisms deprived of covers (fig. 14.20).

If destruction of walls make in a hypertensive solution to prevent rupture of protolayers isolated (' naked ') protolayers remain live. In corresponding conditions at them the wall can be formed again, they start to share and then recycle in the whole plant. If protolayers from two different kinds of plants to mix in the presence of agents inducing merge, such as polietilenglikol the small part of these protolayers will merge with each other, having formed geterokariony (fig. 14.21), i.e. The cages containing set of kernels from different sources (fig. 14.22). At merge of kernels the present parasexual hybrids can be formed.

After reception of products of merge it is necessary to have any selection method at the order, allowing to separate hybrids from products of self-cell fusion of each initial type. If the protolayer of one kind is steady against substance And, but is sensitive to substance the last can be used to kill this protolayer or products of its intraspecific merge. If the return picture of stability and sensitivity is found out in protolayers of other kind to the given substances it is possible to apply substance to their destruction And. In that case when stability to both these substances is transferred to all formed hybrid protolayers, they one appear steady both to that, and to other connection. Thus, only the hybrid (merged) protolayers will be capable to grow on the Wednesday containing both connections. And on the contrary, if, for example, a protolayer And avtotrofen in the relation auksina, but not tsitokinina, and a protolayer avtotrofen in the relation tsitokinina, but not auksina in the environment which is not containing both these hormones, products of their merge can grow only.

The Parasexual hybrid plants which have arisen from somatic cages, possibly, should be tetraploidnymi. Diploidnye hybrids are formed in the event that initial cages gaploidny. Such gaploidnye cages can be received, growing up in culture microdisputes or unripe pollen grains pylnikov.

The Given area of researches endures now rapid development thanks to constant introduction all new methods. Till now the full cycle from allocation of protolayers before regeneration of the whole plant has been carried out only on few plants (tobacco, a petunia, carrots, an asparagus, raps), and to parasex-alnoe merge to reception of hybrids is reached only at tobacco and a petunia, representatives of family Solanaceae. Yet it was not possible to achieve successful regeneration from representatives of families Gramineae and Leguminosae - two most important families of food plants. However it is quite probable that hybridization of somatic cages and regeneration of the whole plants will be carried out as well at representatives of these families that in the future will play the important role technologies of improvement of cultures.