BOTANICAL CHARACTERISTICS OF THE TEA BUSH
BOTANICAL CHARACTERISTICS OF THE TEA BUSH
The tea plant, cultivated for the purpose of producing tea, belongs to the Tea family, genus Tea, Chinese tea species (Thea chinensis L.). This name was given to the plant by the famous botanist C. Linnaeus in honor of the Greek goddess Thea. Tea grows in tropical and subtropical regions of the globe. Biologically and morphologically, the tea bush is very similar to the group of camellia plants, therefore some authors attribute it to the genus Camellia. However, the similarity is only external, since the tender shoots of camellia contain neither caffeine nor tannin - substances for which tea is so valued. The tea bush is native to the tropical and subtropical regions of China and India. Research in recent years, based on the quality indicators of finished tea, suggests that the birthplace of tea could also be the countries of Indochina. In the tropics, the tea plant reaches a height of 15-18 m. In the subtropics, it is a shrub no more than 3-4 m high. The tea bush is one of the evergreen plants. It has leathery, elongated or elliptical (sometimes almost round) leaves with a strongly serrated blade and a short petiole. Their size, depending on the variety and variety, ranges from 2-3 to 35-40 cm. The flowers of tea are white, with a delicate pleasant aroma and bright yellow anthers; There are up to five flowers on the false raceme. The corolla consists of 5-9 petals. Large flowers reach 40-50 mm in diameter. The stamens (from 100 to 200) are placed around the pistil in several rows. The calyx is formed from 5-7 leathery sepals. In the conditions of the Krasnodar subtropics, budding of the tea plant begins in July, and flowering begins at the end of September and continues throughout the fall until frost, from which the flowers quickly die. Flower buds are formed at the end of June - beginning of July in the axils of the leaves. The period from the moment of their establishment to the collection of seeds is 16 months. Of the total number of flower buds, no more than 2% form ovaries and produce seeds. On the island of Java, according to Stuart (1920), the useful percentage of ovary is much higher - up to 20-30. Such a high fruit set is explained by the optimal soil and climatic conditions of these areas. The fruit of the tea is a three-, four-, less often five-leaf capsule, dark green, and brown when ripe. The seeds are round in shape, from 10 to 20 mm in diameter, dark brown with a matte coating. The kernels contain about 30-35% tea oil, so if stored improperly, the oil in them oxidizes and the seeds quickly lose their viability. The fruit box contains from 2 to 5 seeds. Full ripening of the fruit occurs in late October - mid-November. It has been established that the productivity of the tea bush is to a certain extent related to the habit of the plant. The wider the crown of the bush, the larger its leaf-collecting area. Large-leaved plants usually have strong shoots with a large number of growing buds. The anatomical characteristics of the tea leaf vary greatly depending on the place of growth, variety, variety, and soil conditions. The size of stomata, cells, and tissue thickness are indicators of the vitality of the plant. For example, Chinese tea has a two-layer palisade fabric, Indian tea has a single layer, and Japanese tea, which is relatively frost-resistant, has a three-layer fabric. Thus, frost- and drought-resistant tea varieties are characterized by a thin, but very dense, multi-layered epidermis with a relatively large number of small stomata on the underside of the leaf. In the process of phylogenesis, along with the age periods of the life cycle, tea plants have developed a peculiar rhythm of growth and development throughout the year, which gives them the opportunity to go through one or another phase under the most favorable climatic conditions. During the growing season, the tea bush experiences increased growth of shoots and leaves, the formation and development of generative organs, flowering and fruiting occur. During the dormant period, the growth of the vegetative mass stops, assimilation, respiration, and metabolism slow down. At all stages of development, the tea plant requires certain conditions, the presence of which largely ensures the normal passage of the phases, and therefore provides the necessary economic effect. Taking into account the biological characteristics of a particular crop, as well as the purposes of its cultivation, a person can purposefully change the nature of the plant, enhancing useful and weakening or eliminating its undesirable characteristics. By applying one or another influence on the environment and the plant, you can get dwarf and giant forms of plants, turn annuals into perennials, change the aroma, taste and color of fruits.
Tea, as you know, is cultivated to obtain the largest possible amount of leaves, which is why it is formed in the form of a bush or trellis, which is given a wide hemispherical surface. The pattern of shoot formation also changes accordingly - instead of the usual five or six orders of branching, 12-14 orders are formed on the trellis. When harvesting tea leaves, a significant portion of the growing shoots from the bush is systematically removed. Such annual pruning significantly enhances the vegetative activity of the plant. In an effort to restore the disturbed balance, the tea bush expels more and more new shoots, developing its shoot-forming ability to the maximum. As a result, the plant moves from the monopodial branching characteristic of tea to sympodial branching. The rate of photosynthesis in pruned bushes is significantly higher than in unpruned ones. This is explained by the plant’s desire to produce the greatest possible amount of plastic substances to create a new crown to replace the removed one. Being the oldest plant on earth, tea, as already noted, developed in the process of phylogenetic development a peculiar rhythm of growth and dormancy, corresponding to certain environmental conditions. In the subtropical regions of the Krasnodar Territory, the growing season begins in late February - early March with an average daily air temperature above 9-10°C. The first manifestation of the growing season is the swelling of growth buds. The further development of plants and the rhythm of shoot formation depend not only on environmental conditions, but also on the methods of cultivating the crop and the age of the plantings. In young plants in the first years of life, increased shoot growth is observed throughout the entire growing season with a short (25-30 days) growth pause in June. In July, a second wave of growth begins, subsiding only with the onset of low temperatures in late October or early November. With optimal plant care, especially with irrigation, the summer dormancy phase in young plants is noticeably reduced. Removing a significant mass of leaves during their collection causes a disruption in the correlation between the above-ground and underground systems, which also determines changes in the physiological functions of plants - photosynthesis, transpiration. The desire of plants to restore the cut growth leads to a reduction in their life expectancy. Therefore, high productivity and longevity of leaf plantations are possible with an optimal set of agrotechnical measures, which would ensure an increase in the leaf surface of the tea bush and at the same time extend its lifespan. The alienation of leaves is associated not only with harvesting, some of them are lost during natural leaf fall. The average lifespan of leaves is no more than two to four years. The most active in terms of assimilation are young annual leaves, which accumulate the maximum amount of plastic substances by winter. Older leaves, along with assimilation products, accumulate waste products and, gradually losing vital activity, fall off at the age of two to three years. In the annual cycle, the tea plant has several active periods of shedding leaves, although a small amount of leaf shedding occurs throughout the year. The root system of the tea bush, like its above-ground mass, is characterized by the cyclical nature of its development. Active roots have three periods of growth and two periods of dormancy in the annual cycle. The spring growth period covers the end of February, March and April. At this time, there is a massive growth of new suction roots and at the same time, intensive growth of the roots of last year, which were in a state of winter dormancy, continues. The beginning of root activity is noted at a soil temperature in the upper horizons of 7-9°C. In the above-ground part of the plant, this period corresponds to swelling, and then massive blooming of leaf buds. The second period of root growth - summer - occurs in July and August, and the third - autumn - begins in September and continues until mid-December. These periods of root growth correspond to increased growth of shoots of the first to fourth orders, budding, flowering and seed setting. Dormant periods occur at the end of May–June and at the end of December–beginning of February. At this time, root growth is not observed even under the most favorable conditions. The summer period of root dormancy usually lasts about 30-40 days. The winter dormant period, unlike all previous periods, is characterized by an almost complete cessation of vegetation of the above-ground and root parts of the plant. In accordance with the above-mentioned periods of growth and dormancy, all technology for caring for tea plants should be carried out - fertilization, summer fertilizing, autumn-winter and summer tillage.
Studying the mechanism of water and nutrient solutions entering the plant is of not only theoretical, but also practical interest. In the annual life cycle of the tea bush, there is a phase of partial death of active roots, which is especially clearly visible in winter. Such a death of suction roots was called root fall by Professor P. G. Schitt (1940), by analogy with the annual fall of leaves. The phenomenon of root fall is described in the works of V. A. Kolesnikov (1962), I. A. Muromtsev (1940) and other researchers. Root dying has been observed in many heat-loving evergreen plants, in particular tea, bay laurel, hazelnut, etc. It has been established that in adult plants the process of root dying is much more intense than in young ones. In early spring, there is an increased growth of new roots, the number of which significantly exceeds the mass of roots that die during root fall. At the site of the alienation of the dead corpuscle, a thin cork tissue is formed, protecting its living part from mechanical damage and infection. Simultaneously with the biological death of the root system, its partial destruction occurs during various agrotechnical practices (plowing, cultivation, digging). The results of observations showed that during the annual winter digging of the soil on tea plantations, a significant mass of both active and conducting roots is destroyed. Roots are also damaged during summer cultivation. According to A.D. Kalichava (1950), the yield of tea plantations left without winter digging increased by 8% on average over 6 years. In our experiments, on an annually dug plantation, in the upper (up to 10 cm) layer of soil there were 2.4% of suction roots, while in the uncultivated zone at the same depth their number was 8.1% of the total mass of all roots. Therefore, tea cultivation technology eliminates frequent soil cultivation. Root hairs and mycorrhiza of the tea bush. There are different opinions regarding the mechanism of absorption of nutrient solutions and water by tea roots. Some researchers believe that this process occurs with the help of root hairs, others believe that the tea bush is a mycotrophic plant.
We have found that there are very few root hairs on the surface of the suction roots of a tea bush, and sometimes they are completely absent, for example, in the root cap area. On average, there are no more than 90 root hairs per 1 cm of suction root, while an apple tree has about 2-3 thousand of them in the same area. Moreover, their length in tea plants is extremely small - only a few tens of micrometers. The absence of root hairs at the root tips of tea plants is apparently compensated to some extent by the presence of a large number of hyphae (there are up to 20 of them per 1 mm of root). The mycelium is homogeneous with a small number of partitions; the color of the hyphae varies from light to dark yellow. The hyphae of the fungus spread through the intercellular spaces and penetrate individual cells of the crustal layer; Vesicles are clearly visible - spherical formations with a diameter of 20 to 40 microns. The presence of mycelium in the root tissues, as well as on their tender ends, allowed us to establish in the tea bush the presence of ectoendotrophic mycorrhiza, which is in symbiosis with the host plant and supplies it with water and nutrients. The relationship of the tea plant to growing conditions. To form high and sustainable yields, plants need certain environmental conditions that correspond to their nature. The discrepancy between these elements leads, as is known, to the suppression or death of plants. To a large extent, the creation of optimal conditions is facilitated by agrotechnical measures, the correct choice and timely implementation of which guarantees the normal functioning of plants. Requirements for heat and light. The factor limiting the development of tea in the subtropical regions of the Krasnodar Territory is, first of all, low temperature. Its influence in different phases of the growing season is different. Here, the preparation of plants for winter is of great, if not decisive, importance. Early autumn frosts, even of relatively small severity, can cause the death of a significant part of the leaves and young non-lignified shoots. The cause of severe damage to tea bushes can be heavy snowfalls, accompanied by breakages of skeletal branches and twigs. Deep snow cover leads to damping off of leaves and their death. A condition for successful overwintering of tea is the passage of appropriate hardening in the autumn-winter period, which allows plants in the dormant growth phase to withstand drops in temperature relatively easily. To a large extent, the favorable condition of plants in winter is due to the timely ripening of wood, a sufficient amount of reserve plastic substances, primarily sugars and fats, the concentration of cell sap, as well as the terrain, altitude, soil types, and optimal timing of agrotechnical measures. As plantations move north, tea plants, under the influence of low temperatures, experience a shortening of the growing season, a decrease in the size of the crown and a decrease in the yield of green leaves. The resting phase of tea is clearly expressed even at high winter temperatures. The beginning of the dormant period is usually associated with the end of vegetative growth of shoots, ripening of wood and a decrease in average daily temperatures to 7-9°C. However, a complete suspension of all life processes in tea plants does not occur at this time; they continue to assimilate, breathe and even bloom. The most active physiological activity of the tea bush was observed at an air temperature of 19-27°C. In hot weather, tea leaves are actively assimilated only in the early morning hours; During the day, during periods of particularly strong insolation, the outflow of nutrients exceeds assimilation. In spring, high physiological activity occurs with an increase in air and soil temperatures. A. R. Romanova (1956) found that in the conditions of the Krasnodar Territory, with an increase in soil temperature by 4-4.5 ° C, the energy of photosynthesis increases by more than 2.5 times. The heat requirements of tea during budding and flowering are relatively low in comparison with other subtropical crops. If lemon blooms in May at an average monthly temperature of 17-19°C, then intensive flowering of tea is observed in November - January at an average temperature of 6-9°C.
The formation of flower buds in tea occurs in late June - early July, when the air temperature reaches 18-20°C. During this period, plants especially need sufficient nutrition and water supply. Tea is most demanding of heat during the growing season. Maximum shoot regrowth is observed at a temperature of 20-25°C. Its growing season is approximately 220-230 days. The sum of active temperatures in areas where industrial tea plantings are cultivated should be at least 3000-4000°. Despite the fact that tea is an undergrowth plant and is a shade-tolerant plant, in the conditions of the Black Sea coast it is not afraid of direct solar radiation and does not need shading, as is practiced in hot tropical countries, where to obtain high yields of tea leaves, plantings are shaded by planting on plantations of tall leguminous plants It has been established that at night the tea plant requires less light for its life activity than during the day. However, in low light conditions, especially in cloudy weather, the photosynthesis reaction, and with it the flow of plastic substances into the plant, sharply weaken.
Recently, due to air pollution in areas adjacent to large cities, clean air has become important for the normal functioning of plants, including tea. The most dangerous for plants are car exhaust gases, as well as compounds of sulfur, fluorine, ethylene, chlorine and nitrogen that enter the atmosphere as waste from industrial enterprises. Relation to soils. Extensive experience of tea farms in Western Georgia and the Black Sea coast of the Krasnodar Territory indicates the relatively low demands of tea plants on soil. Meanwhile, it is possible to obtain a high yield per leaf only on deep, well-aerated acidic soils (pH sol 4.5-6.5), which have a good structure and do not experience excess moisture. If there is more than 2.5-3% lime in a meter layer of soil, tea plants die. The mechanical composition of the soil, the size of soil particles and their quantity in soil lumps are often the determining factors when choosing tea areas. The best soils for tea in the subtropical regions of the Krasnodar Territory are brown forest soils rich in humus and nutrients, developed on red-brown clays. They are formed on the eluvium of clay shales, underlain by gray and greenish-gray dense rocks, which, when reaching the surface, are easily destroyed, forming thick sediments. Brown forest soils with high moisture capacity developed on yellow-brown clays are also suitable for tea. They are located on the border with a strip of yellow earth soils and are characterized by less favorable physical properties and contain less humus and mineral elements. These soils are formed on calcareous clay shales and sandstones, so only those varieties can be used in which horizons boiling from hydrochloric acid are located at a depth of at least 70-80 cm. The heavy mechanical composition and less durable structure of these soils require significant material resources for their development. costs. Yellow earth varieties, located mainly in the coastal zone, are used for tea only in small areas, as they are poor in humus and nutrients. Due to frequent waterlogging and strong gleyization in the lower part of the profile, the development of these soils involves extensive reclamation work, deep loosening and killing, as well as enriching them with organic matter. These soils, usually emerging from beech-hornbeam-liana forests, have an acidic reaction and a dusty structure. Most often they are found on plains or on gentle slopes of the coastal strip, as well as on the upper floodplain accumulative terraces. A characteristic feature of the soil is the low thickness of the arable horizon. Often, at a depth of 40–50 cm, ortstein grains and ortstein layers up to 20–40 cm thick are found. In some cases, the thickness of ortstein horizons reaches 1.5–2 m. Table 18 shows a morphological description of the soil according to genetic horizons using the example of yellow soils of the Adler tea state farm . As can be seen from the table, already at a depth of 12–15 cm, ortstein grains are found on these soils, and from a depth of 15–20 cm, gleyed horizons with a pronounced bluish-gray tint appear. According to V.S. Lavriychuk (1953) and P.M. Bushin (1975), the predominance (up to 70%) in the surface layer of deeply leached fine earth podzols (silt particles less than 0.25 mm) determines their poor water permeability. As a result of the weak percolation of the lower horizons during the period of autumn-winter precipitation, even on the slopes there is surface stagnation of water (overwater), which during heavy rains merges with nearby groundwater, forming long-term swamping in the zone of activity of the root system.
Prolonged exposure of the root system of tea plants to water without access to oxygen causes rotting and death of a large mass of active roots. The observed gradual movement of the bulk of the root system from the lower soil horizons to the upper ones negatively affects the growth of bushes and their productivity, because the surface root system does not provide plants with water and mineral nutrition during dry periods. During periods of severe drought, vegetation on such soils completely stops, the bushes shed their leaves, and in some years their complete death occurs. The topography of the area also has a certain influence on the distribution of active roots along soil horizons. For example, on light slopes the mass of active roots in the upper 50-centimeter layer was significantly greater (166.7 g) than in the same layer on the plain (total 110.5 g). The roots were also distributed differently among individual horizons, as evidenced by the following data: the mass of active roots on young tea plantations in soil layers of 0–10, 10–20, 20–30, 30–40 and 40–50 cm on a light slope was respectively 31.6; 59.8; 40.6; 27.5 and 1.8 g, on the plain - 25.9; 39.6; 30.7; 14.3 and 0. Tea plants planted on yellow earth soils without long-term preliminary cultivation and reclamation measures, even under relatively favorable conditions of the growing season, grow poorly and give a very low yield not only in size but also in quality (leaves are small, with yellowish tint). In the Adler tea state farm, for example, tea bushes growing on uncultivated soils had a height of only 40 cm and a width of 45 cm at the age of 10. Observations showed that the groundwater level on such plantations 2 days after heavy rain fell (80 mm) rose significantly, lying at a depth of 25-35 cm from the soil surface. The yield of these plantings was extremely low - only 100-150 kg of green leaves per 1 hectare. After a few years on such plantations, plants show signs of aging and the need for rejuvenating pruning arises. Their frequent implementation, however, leads to significant weakening and often death of plants. Thus, the development of yellow earth soils for any subtropical plantings, especially for tea crops, requires their careful cultivation and, above all, the implementation of reclamation measures. The most effective ways to combat excessive soil moisture are the following: deep (at least 40-45 cm) loosening of row spacing to create favorable water-physical properties of the soil with the obligatory destruction of tightly compacted gleyed layers and breaking of the nozzle. This work is performed by a ripper-killer pulled by powerful tractors; applying organic fertilizers (peat, compost, organic residues) simultaneously with loosening the soil with their further embedding to the greatest possible depth; discharge of excess water is a mandatory method when developing yellow earth soils after their cultivation; cultivation of the soil for two to three years by sowing annual cereals and legumes and planting them annually to a depth of 20-30 cm. In the valleys of mountain rivers, alluvial soils formed on acidic sediments and to varying degrees affected by meadow processes can be used for tea. With a medium clayey mechanical composition, these soils are often characterized by unsatisfactory physical properties and require a number of reclamation works.
Tea, as you know, is cultivated to obtain the largest possible amount of leaves, which is why it is formed in the form of a bush or trellis, which is given a wide hemispherical surface. The pattern of shoot formation also changes accordingly - instead of the usual five or six orders of branching, 12-14 orders are formed on the trellis. When harvesting tea leaves, a significant portion of the growing shoots from the bush is systematically removed. Such annual pruning significantly enhances the vegetative activity of the plant. In an effort to restore the disturbed balance, the tea bush expels more and more new shoots, developing its shoot-forming ability to the maximum. As a result, the plant moves from the monopodial branching characteristic of tea to sympodial branching. The rate of photosynthesis in pruned bushes is significantly higher than in unpruned ones. This is explained by the plant’s desire to produce the greatest possible amount of plastic substances to create a new crown to replace the removed one. Being the oldest plant on earth, tea, as already noted, developed in the process of phylogenetic development a peculiar rhythm of growth and dormancy, corresponding to certain environmental conditions. In the subtropical regions of the Krasnodar Territory, the growing season begins in late February - early March with an average daily air temperature above 9-10°C. The first manifestation of the growing season is the swelling of growth buds. The further development of plants and the rhythm of shoot formation depend not only on environmental conditions, but also on the methods of cultivating the crop and the age of the plantings. In young plants in the first years of life, increased shoot growth is observed throughout the entire growing season with a short (25-30 days) growth pause in June. In July, a second wave of growth begins, subsiding only with the onset of low temperatures in late October or early November. With optimal plant care, especially with irrigation, the summer dormancy phase in young plants is noticeably reduced. Removing a significant mass of leaves during their collection causes a disruption in the correlation between the above-ground and underground systems, which also determines changes in the physiological functions of plants - photosynthesis, transpiration. The desire of plants to restore the cut growth leads to a reduction in their life expectancy. Therefore, high productivity and longevity of leaf plantations are possible with an optimal set of agrotechnical measures, which would ensure an increase in the leaf surface of the tea bush and at the same time extend its lifespan. The alienation of leaves is associated not only with harvesting, some of them are lost during natural leaf fall. The average lifespan of leaves is no more than two to four years. The most active in terms of assimilation are young annual leaves, which accumulate the maximum amount of plastic substances by winter. Older leaves, along with assimilation products, accumulate waste products and, gradually losing vital activity, fall off at the age of two to three years. In the annual cycle, the tea plant has several active periods of shedding leaves, although a small amount of leaf shedding occurs throughout the year. The root system of the tea bush, like its above-ground mass, is characterized by the cyclical nature of its development. Active roots have three periods of growth and two periods of dormancy in the annual cycle. The spring growth period covers the end of February, March and April. At this time, there is a massive growth of new suction roots and at the same time, intensive growth of the roots of last year, which were in a state of winter dormancy, continues. The beginning of root activity is noted at a soil temperature in the upper horizons of 7-9°C. In the above-ground part of the plant, this period corresponds to swelling, and then massive blooming of leaf buds. The second period of root growth - summer - occurs in July and August, and the third - autumn - begins in September and continues until mid-December. These periods of root growth correspond to increased growth of shoots of the first to fourth orders, budding, flowering and seed setting. Dormant periods occur at the end of May–June and at the end of December–beginning of February. At this time, root growth is not observed even under the most favorable conditions. The summer period of root dormancy usually lasts about 30-40 days. The winter dormant period, unlike all previous periods, is characterized by an almost complete cessation of vegetation of the above-ground and root parts of the plant. In accordance with the above-mentioned periods of growth and dormancy, all technology for caring for tea plants should be carried out - fertilization, summer fertilizing, autumn-winter and summer tillage.
Studying the mechanism of water and nutrient solutions entering the plant is of not only theoretical, but also practical interest. In the annual life cycle of the tea bush, there is a phase of partial death of active roots, which is especially clearly visible in winter. Such a death of suction roots was called root fall by Professor P. G. Schitt (1940), by analogy with the annual fall of leaves. The phenomenon of root fall is described in the works of V. A. Kolesnikov (1962), I. A. Muromtsev (1940) and other researchers. Root dying has been observed in many heat-loving evergreen plants, in particular tea, bay laurel, hazelnut, etc. It has been established that in adult plants the process of root dying is much more intense than in young ones. In early spring, there is an increased growth of new roots, the number of which significantly exceeds the mass of roots that die during root fall. At the site of the alienation of the dead corpuscle, a thin cork tissue is formed, protecting its living part from mechanical damage and infection. Simultaneously with the biological death of the root system, its partial destruction occurs during various agrotechnical practices (plowing, cultivation, digging). The results of observations showed that during the annual winter digging of the soil on tea plantations, a significant mass of both active and conducting roots is destroyed. Roots are also damaged during summer cultivation. According to A.D. Kalichava (1950), the yield of tea plantations left without winter digging increased by 8% on average over 6 years. In our experiments, on an annually dug plantation, in the upper (up to 10 cm) layer of soil there were 2.4% of suction roots, while in the uncultivated zone at the same depth their number was 8.1% of the total mass of all roots. Therefore, tea cultivation technology eliminates frequent soil cultivation. Root hairs and mycorrhiza of the tea bush. There are different opinions regarding the mechanism of absorption of nutrient solutions and water by tea roots. Some researchers believe that this process occurs with the help of root hairs, others believe that the tea bush is a mycotrophic plant.
We have found that there are very few root hairs on the surface of the suction roots of a tea bush, and sometimes they are completely absent, for example, in the root cap area. On average, there are no more than 90 root hairs per 1 cm of suction root, while an apple tree has about 2-3 thousand of them in the same area. Moreover, their length in tea plants is extremely small - only a few tens of micrometers. The absence of root hairs at the root tips of tea plants is apparently compensated to some extent by the presence of a large number of hyphae (there are up to 20 of them per 1 mm of root). The mycelium is homogeneous with a small number of partitions; the color of the hyphae varies from light to dark yellow. The hyphae of the fungus spread through the intercellular spaces and penetrate individual cells of the crustal layer; Vesicles are clearly visible - spherical formations with a diameter of 20 to 40 microns. The presence of mycelium in the root tissues, as well as on their tender ends, allowed us to establish in the tea bush the presence of ectoendotrophic mycorrhiza, which is in symbiosis with the host plant and supplies it with water and nutrients. The relationship of the tea plant to growing conditions. To form high and sustainable yields, plants need certain environmental conditions that correspond to their nature. The discrepancy between these elements leads, as is known, to the suppression or death of plants. To a large extent, the creation of optimal conditions is facilitated by agrotechnical measures, the correct choice and timely implementation of which guarantees the normal functioning of plants. Requirements for heat and light. The factor limiting the development of tea in the subtropical regions of the Krasnodar Territory is, first of all, low temperature. Its influence in different phases of the growing season is different. Here, the preparation of plants for winter is of great, if not decisive, importance. Early autumn frosts, even of relatively small severity, can cause the death of a significant part of the leaves and young non-lignified shoots. The cause of severe damage to tea bushes can be heavy snowfalls, accompanied by breakages of skeletal branches and twigs. Deep snow cover leads to damping off of leaves and their death. A condition for successful overwintering of tea is the passage of appropriate hardening in the autumn-winter period, which allows plants in the dormant growth phase to withstand drops in temperature relatively easily. To a large extent, the favorable condition of plants in winter is due to the timely ripening of wood, a sufficient amount of reserve plastic substances, primarily sugars and fats, the concentration of cell sap, as well as the terrain, altitude, soil types, and optimal timing of agrotechnical measures. As plantations move north, tea plants, under the influence of low temperatures, experience a shortening of the growing season, a decrease in the size of the crown and a decrease in the yield of green leaves. The resting phase of tea is clearly expressed even at high winter temperatures. The beginning of the dormant period is usually associated with the end of vegetative growth of shoots, ripening of wood and a decrease in average daily temperatures to 7-9°C. However, a complete suspension of all life processes in tea plants does not occur at this time; they continue to assimilate, breathe and even bloom. The most active physiological activity of the tea bush was observed at an air temperature of 19-27°C. In hot weather, tea leaves are actively assimilated only in the early morning hours; During the day, during periods of particularly strong insolation, the outflow of nutrients exceeds assimilation. In spring, high physiological activity occurs with an increase in air and soil temperatures. A. R. Romanova (1956) found that in the conditions of the Krasnodar Territory, with an increase in soil temperature by 4-4.5 ° C, the energy of photosynthesis increases by more than 2.5 times. The heat requirements of tea during budding and flowering are relatively low in comparison with other subtropical crops. If lemon blooms in May at an average monthly temperature of 17-19°C, then intensive flowering of tea is observed in November - January at an average temperature of 6-9°C.
The formation of flower buds in tea occurs in late June - early July, when the air temperature reaches 18-20°C. During this period, plants especially need sufficient nutrition and water supply. Tea is most demanding of heat during the growing season. Maximum shoot regrowth is observed at a temperature of 20-25°C. Its growing season is approximately 220-230 days. The sum of active temperatures in areas where industrial tea plantings are cultivated should be at least 3000-4000°. Despite the fact that tea is an undergrowth plant and is a shade-tolerant plant, in the conditions of the Black Sea coast it is not afraid of direct solar radiation and does not need shading, as is practiced in hot tropical countries, where to obtain high yields of tea leaves, plantings are shaded by planting on plantations of tall leguminous plants It has been established that at night the tea plant requires less light for its life activity than during the day. However, in low light conditions, especially in cloudy weather, the photosynthesis reaction, and with it the flow of plastic substances into the plant, sharply weaken.
Recently, due to air pollution in areas adjacent to large cities, clean air has become important for the normal functioning of plants, including tea. The most dangerous for plants are car exhaust gases, as well as compounds of sulfur, fluorine, ethylene, chlorine and nitrogen that enter the atmosphere as waste from industrial enterprises. Relation to soils. Extensive experience of tea farms in Western Georgia and the Black Sea coast of the Krasnodar Territory indicates the relatively low demands of tea plants on soil. Meanwhile, it is possible to obtain a high yield per leaf only on deep, well-aerated acidic soils (pH sol 4.5-6.5), which have a good structure and do not experience excess moisture. If there is more than 2.5-3% lime in a meter layer of soil, tea plants die. The mechanical composition of the soil, the size of soil particles and their quantity in soil lumps are often the determining factors when choosing tea areas. The best soils for tea in the subtropical regions of the Krasnodar Territory are brown forest soils rich in humus and nutrients, developed on red-brown clays. They are formed on the eluvium of clay shales, underlain by gray and greenish-gray dense rocks, which, when reaching the surface, are easily destroyed, forming thick sediments. Brown forest soils with high moisture capacity developed on yellow-brown clays are also suitable for tea. They are located on the border with a strip of yellow earth soils and are characterized by less favorable physical properties and contain less humus and mineral elements. These soils are formed on calcareous clay shales and sandstones, so only those varieties can be used in which horizons boiling from hydrochloric acid are located at a depth of at least 70-80 cm. The heavy mechanical composition and less durable structure of these soils require significant material resources for their development. costs. Yellow earth varieties, located mainly in the coastal zone, are used for tea only in small areas, as they are poor in humus and nutrients. Due to frequent waterlogging and strong gleyization in the lower part of the profile, the development of these soils involves extensive reclamation work, deep loosening and killing, as well as enriching them with organic matter. These soils, usually emerging from beech-hornbeam-liana forests, have an acidic reaction and a dusty structure. Most often they are found on plains or on gentle slopes of the coastal strip, as well as on the upper floodplain accumulative terraces. A characteristic feature of the soil is the low thickness of the arable horizon. Often, at a depth of 40–50 cm, ortstein grains and ortstein layers up to 20–40 cm thick are found. In some cases, the thickness of ortstein horizons reaches 1.5–2 m. Table 18 shows a morphological description of the soil according to genetic horizons using the example of yellow soils of the Adler tea state farm . As can be seen from the table, already at a depth of 12–15 cm, ortstein grains are found on these soils, and from a depth of 15–20 cm, gleyed horizons with a pronounced bluish-gray tint appear. According to V.S. Lavriychuk (1953) and P.M. Bushin (1975), the predominance (up to 70%) in the surface layer of deeply leached fine earth podzols (silt particles less than 0.25 mm) determines their poor water permeability. As a result of the weak percolation of the lower horizons during the period of autumn-winter precipitation, even on the slopes there is surface stagnation of water (overwater), which during heavy rains merges with nearby groundwater, forming long-term swamping in the zone of activity of the root system.
Prolonged exposure of the root system of tea plants to water without access to oxygen causes rotting and death of a large mass of active roots. The observed gradual movement of the bulk of the root system from the lower soil horizons to the upper ones negatively affects the growth of bushes and their productivity, because the surface root system does not provide plants with water and mineral nutrition during dry periods. During periods of severe drought, vegetation on such soils completely stops, the bushes shed their leaves, and in some years their complete death occurs. The topography of the area also has a certain influence on the distribution of active roots along soil horizons. For example, on light slopes the mass of active roots in the upper 50-centimeter layer was significantly greater (166.7 g) than in the same layer on the plain (total 110.5 g). The roots were also distributed differently among individual horizons, as evidenced by the following data: the mass of active roots on young tea plantations in soil layers of 0–10, 10–20, 20–30, 30–40 and 40–50 cm on a light slope was respectively 31.6; 59.8; 40.6; 27.5 and 1.8 g, on the plain - 25.9; 39.6; 30.7; 14.3 and 0. Tea plants planted on yellow earth soils without long-term preliminary cultivation and reclamation measures, even under relatively favorable conditions of the growing season, grow poorly and give a very low yield not only in size but also in quality (leaves are small, with yellowish tint). In the Adler tea state farm, for example, tea bushes growing on uncultivated soils had a height of only 40 cm and a width of 45 cm at the age of 10. Observations showed that the groundwater level on such plantations 2 days after heavy rain fell (80 mm) rose significantly, lying at a depth of 25-35 cm from the soil surface. The yield of these plantings was extremely low - only 100-150 kg of green leaves per 1 hectare. After a few years on such plantations, plants show signs of aging and the need for rejuvenating pruning arises. Their frequent implementation, however, leads to significant weakening and often death of plants. Thus, the development of yellow earth soils for any subtropical plantings, especially for tea crops, requires their careful cultivation and, above all, the implementation of reclamation measures. The most effective ways to combat excessive soil moisture are the following: deep (at least 40-45 cm) loosening of row spacing to create favorable water-physical properties of the soil with the obligatory destruction of tightly compacted gleyed layers and breaking of the nozzle. This work is performed by a ripper-killer pulled by powerful tractors; applying organic fertilizers (peat, compost, organic residues) simultaneously with loosening the soil with their further embedding to the greatest possible depth; discharge of excess water is a mandatory method when developing yellow earth soils after their cultivation; cultivation of the soil for two to three years by sowing annual cereals and legumes and planting them annually to a depth of 20-30 cm. In the valleys of mountain rivers, alluvial soils formed on acidic sediments and to varying degrees affected by meadow processes can be used for tea. With a medium clayey mechanical composition, these soils are often characterized by unsatisfactory physical properties and require a number of reclamation works.