What is transpiration? Features of the consumption of moisture in plants

The process of water consumption in a plant organism is based on evaporation. However, it is complicated by some of the anatomical and physiological characteristics of cultures.

What is transpiration?

The volume of water that is evaporated by the plant, inmany times higher than the amount contained in the culture. In modern agricultural practice, the issue of economical use of moisture is one of the most urgent. According to KA Timiryazev, the process of transpiration in its usual volume is a physiological evil. In fact, it is not considered necessary for a plant. For example, if you grow crops in low and high humidity conditions, in the first case, transpiration (evaporation) will be more intense. In this case, the growth of plants will be the same or even better in the second case.

Transpiration: value

To some extent, it is useful to the plant. Explaining what transpiration means, it is necessary first of all to note its protective function. Evaporation helps protect the plant from overheating under the influence of direct sun rays. For example, the difference in the temperature of the leaves giving and not giving up moisture, can fluctuate within 7 degrees. This is of particular importance for the process of photosynthesis. The fact is that when overheating begins the destruction of chloroplasts. This, in turn, significantly slows down photosynthesis. The optimum temperature for it is in the range of 30-33 degrees. So, what is transpiration? This is a plant protection product that allows them to tolerate high temperatures well.

Continuity of water movement

Clarifying what transpiration is, one shouldpay attention to one more positive property. It promotes the continuous movement of water from the root system to the leaves. This connects all the elements of the plant into one whole. Together with moisture, mineral compounds and some organic substances move through the organs of culture. The more intensive the process of transpiration, the faster will be their movement. Some compounds can enter cells passively. Transpiration, in short, is the accelerator of the delivery of substances.

Classification

Having understood what transpiration is, you can go toconsideration of its species. In science, two types are distinguished. Transpiration can be stomatal and cuticular. In the first case, evaporation is carried out through the stomata, in the second - from the entire surface of the leaf. This distinction was first made in 1877. To make sure that transpiration goes not only through stomata, it is possible quite simply. For example, you can take the apple tree leaves. In them, the stomata are found only from the lower part. This surface should be smeared with petroleum jelly. Evaporation will continue through the cuticle, but in a smaller volume.

Stomach Evaporation Structure

Transpiration includes:

1. The movement of water from the vessels of xylem along the cell walls and the symplast.
2. Evaporation into the podostic cavities and intercellular spaces with further diffusion into the surrounding air through stomatal gaps.

The lower the relative humidity, the lowerwater potential of the surrounding atmosphere. If it is less than in the podostichnyh cavities, evaporation will occur outside. The regulation of transpiration can be stomatal and extra-cardiac. The first is carried out by opening and closing the pores. With full cover, transpiration is reduced by approximately 90%.

Intensity

The periodicity of diurnal transpiration is noted inmany plants. However, in different types of cultures the functioning of stomata occurs unequally. In shade-tolerant plants, trees, many species of cereals and other hydrostable plantations, which are characterized by perfect regulation of stomatal transpiration, it begins at dawn. Its maximum reaches evaporation in the morning. By noon, the intensity of transpiration decreases. Its increase is again observed in the evening with a drop in air temperature. This intensity of evaporation causes slight diurnal changes in the osmotic pressure and volume of water in the leaves. In hydrolytic (having the ability to withstand sharp fluctuations in the moisture content during the day), single-peak evaporation occurs at a maximum at noon time. And in either case, transpiration at night will be minimal or completely absent.