Growth and formoobrazovanie at plants. The general review. Kinetika growth

you are: Growth and formoobrazovanie at plants. The general review

If height or weight of a plant to present as function of time which has passed from the moment of germination we will receive a curve similar to those what is represented on fig. 3.4. This S-shaped, or sigmoidnaja, a curve is characteristic for growth of all bodies, all plants, populations of plants or animals and even for human civilisations. The curve consists at least of four accurately differentiated pieces:) an initial log-phase on which extent there are the internal changes serving by preparation for growth; broad gulls-phases, or the period when dependence of the logarithm of growth rate on time is described by a straight line; phases of gradual decrease in growth rate and a phase during which the organism reaches a maturity, growth stops also the sizes are stabilised.

If to continue this curve in any.moment its course can change again, reflecting the period of ageing and death.

There are plants for which ageing and death are not an obligatory part of life cycle. In the western part of the North America grow an awned pine (Pinus aristata) and the sequoia, which age can exceed considerably 3000 years. These trees perish, apparently, from the casual reasons - from a lightning stroke, from an infection or that the tree basis at some instant appears insufficiently strong to sustain weight of a trunk. if it was possible to prevent somehow similar harmful influences, that, probably, growth of such tree would be potentially infinite. It is possible to show this potential immortality of vegetative cages a method of culture of fabrics from the whole plant separate its any parts and grow up them on artificial environments. The French researchers in 1937 Have shown, for example, that if slices of roots of carrots to separate in asepticheskih conditions and to place in the corresponding sterile chemical environment after a while in them cellular division will renew and there will be quickly growing weight of not differentiated cages, so-called kallus. If then slices of it kallusa often enough to transfer on the fresh environment it will continue to grow all with the same constant speed. To track such growth it was possible throughout forty with superfluous years. Carrots in norm - a biannual plant, and, mean, that copy from which there was no time the fabric is taken, should finish the cycle of development very long time ago. Naturally the conclusion arises that the usual termination of growth of any plant which ageing and death follow, is connected with any inhibition and that if this inhibition that or a different way to eliminate or bypass, we will receive a plant, capable to grow continuously, other words-potentially the immortal. Researches in this area proceed and, obviously, sooner or later will yield interesting and important results.

Growth Curves are valuable that they testify to existence of different types of physiological regulation of growth. On duration of a log-phase we can to judge character of those changes which should occur before growth will begin, for example. At many seeds the log-phase lasts no more than several hours, and it shows that here already there are available all systems necessary for growth, and water for activation is required only. Are known, however, and seeds at which the log-phase is measured by days, weeks and even months. At the such. Based seeds at fabrics usually are present any ingibitory growth and germination cannot begin until these substances will not be destroyed in the course of a metabolism or removed any mechanically - washing away, etc. Growth rate in a broad gull-phase is quite often defined by hormones about what we still will speak further. On a curve inclination it is possible to judge successfully often enough the genetic background defining rostovoj potential of the given plant, and also about that, how much well meet requirements of a plant of a condition in which it grows. The final height of a plant and terms of approach of a stationary phase often also happen are set genetically, but these characteristics can vary in some measure under the influence of Wednesday. Ageing and death of an organism are not necessarily rigidly defined by its genotype, their terms environment too can define.

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