Kurbonali

The Republic of Tajikistan is a mountainous country, 93% of whose territory is occupied by mountain ecosystems. The vertical zonation where it is possible to grow crops extends at altitudes from 350 to 4000 m above sea level. Tajikistan is rich in such important natural resources as water energy, the number of sunny days throughout the year (more than 300 sunny warm days a year), biodiversity (more than 23 thousand species of flora and fauna), etc. The rarest species of animals and birds live here, listed in the Red Book: mountain goats, snow leopards, storks, hawks and others. The largest nature reserves in the country: Tigrovaya Balka, Ramit, Dashtidzhumsky and Sarikhosorsky reserves.

An important energy-intensive sector in the republic is the agricultural sector, which annually provides about 24% of the GDP (Gross Domestic Product) in the republic. The length of the territory of the republic from west to east is 700 km, from north to south 350 km. Tajikistan is a mountainous republic. The absolute altitude above sea level ranges from 300 to 7495 meters. The total area of the republic's land fund is 14.3 thousand hectares. Of these, about 4.58 million hectares are in economic use (including 3.3 million hectares of pasture land).

The soil cover of the republic consists of:

• Plain-low mountain, with gray soils;
• Mid-mountain, with mountain browns;
• Alpine, with high-mountain meadow-steppe, steppe, desert-steppe, zang, desert soils;
• Nival, unformed skeletal soils in cracks of high-mountain rocks, hollows, etc.

Main types of soil in Tajikistan:

• clayey;
• loamy;
• limestone;
• sandy;
• sandy loam;
• swampy.

Tajikistan's position in the desert zone, arid climate and mountainous terrain determined the characteristics of its soil cover. It is dominated by gray soils - the main zonal type.

Taking into account the growing population of the republic, scientists are faced with the task of finding and implementing innovative ways and methods of obtaining the maximum volume of necessary products and biological mass per unit area while maintaining and increasing the fertility and quality of land and soil resources. In the republic, the total land fund or total land area is 14255.4 thousand hectares, of which 3746.0 thousand hectares are farmland, 673.1 thousand hectares are arable lands, 2909.8 thousand hectares are pastures, etc. Over the past 30 years, the state of land resources in the Republic of Tajikistan has deteriorated. The share of irrigated land in relation to the area of agricultural land/arable land decreased from 14.8% to 14.4%; area of arable land per capita – from 0.16 to 0.12 ha/person. The share of agricultural land in relation to the total territory decreased by 1%. (http://www.cawater-info.net/ecoindicators/pdf/land-tj.pdf

At the same time, there are natural limitations on the area of land resources of 3746.0 thousand hectares of farmland. This actualizes the need for their effective and rational use. 90% of the area of rain-fed arable land shows signs of degradation, of which 40% are highly degraded. Of the irrigated arable lands, 22% of the area is highly degraded, 38% shows signs of low and moderate degradation, and 40% shows no signs of degradation. Degradation of forest plantations affects about 70% of the land area, of which 22% are classified as highly degraded, 30% of the area is classified as low and moderate, 48% do not show signs of degradation.

Available estimates indicate the dependence of the agricultural sector on the state of land and soils and the need for special attention to the choice of approaches to the use of agroclimatic resources and crops (https://www.unpei.org/files/pdf/the_economic_cost_of_agricultural_and_land_degration_in_tajikistan_in_russian.pdf). Intensive agricultural activities on mountain slopes inevitably lead to soil erosion. They are eroded, which, as the gorges grow, leads to a reduction in the area of arable soil. Slopes up to 250 m high are widely cultivated without anti-corrosion measures.

Jerusalem artichoke plant (Helianthus tuberosus L.).

The article reports that in various agro-ecological conditions of Tajikistan, collection material of Jerusalem artichoke (more than 25 varieties) was studied in order to determine its production potential and further introduction in various ecological zones of the republic.

Jerusalem artichoke plantings were carried out in the Southern (Vaseisky, Vakhsh and Muminabad districts, located respectively at an altitude of 460, 600 and 1200 m above sea level), Central (Dushanbe, Kanask zone, at an altitude of 840 and 2560 m, respectively) and Eastern (Rasht and Lyakhsh areas located respectively at an altitude of 1800 and 2000 above sea level) in Tajikistan.

In the conditions of Tajikistan, the soils mainly belong to the following types: light gray soils, typical gray soils and mountain carbonate soils. It has been established that the productivity of Jerusalem artichoke varieties varies significantly depending on vertical zonation and this is mainly due to the influence of air temperature.

The yield of Jerusalem artichoke largely depends on the altitude above sea level and the sum of effective temperatures. The yield of Jerusalem artichoke tubers in various agro-ecological growing conditions ranges from 10 to 63 t/ha, and the total biological mass from 30.8 to 175.7 t/ha.

A relatively high yield in our experiments was obtained in the conditions of the south of Tajikistan (at an altitude of 460 m above sea level). Here, the yield of Jerusalem artichoke tubers was 63 t/ha, and the total biological mass was 175.7 t/ha. Depending on the zone of Jerusalem artichoke cultivation, the correlation coefficient between such characteristics as the mass of tubers and the total plant biomass, between the mass of stems, leaves and roots and the total plant biomass is quite high (r = 0.982 and 0.953, respectively). The correlation between the sum of effective temperatures and total plant biomass was r = 0.970.

Key words: Jerusalem artichoke, variety samples, variety, biological mass, productivity, yield, tuber, correlation coefficient, agroecology, altitude above sea level, precipitation, sum of effective temperatures, soil type, light sierozem, typical sierozem, mountain carbonate soils, mountainous areas, climate change, gross domestic product (GDP), Tajikistan.