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Section 2. Geography
Abdullaev A'lo Kayumkhodjaevich, Professor, Doctor of Geographical Sciences, Scientific Research Hydrometeorological Institute (NIGMI)
E-mail: omakrae@mail.ru Sulaymonova Nigora Nozimjonovna, Senior Researcher, Scientific Research Hydrometeorological Institute, (NIGMI) E-mail: ufo789@mail.ru Ruzieva Malokhat Bakhtiyarovna, Senior Researcher, Scientific Research Hydrometeorological Institute, (NIGMI) E-mail: omakrae@mail.ru
CLIMATE CHANGE IMPACT TO THE BEGINNING OF VEGETATION CROPS IN THE CONDITIONS OF UZBEKISTAN
Abstract. The article discusses the impact of modern climate change on the beginning of the natural vegetative regeneration of desert-rangeland crops and the initial date of cotton planting, taking into account their demands for air temperature in the Republic of Uzbekistan.
Keywords: Agrometeorology, climate change, cotton, rangeland plants, Karakul sheep breeding, air temperature, transition date, trend line.
Introduction
The planet has experienced an increase in average air temperature, the winter has become milder, and the summer months - hotter and drier. The world ocean level is rising. Glaciers are melting in the mountains. Dangerous meteorological phenomena have become more frequent. According to media reports, it is noted that in different parts of the world, floods, typhoons, hurricanes, strong winds, droughts, etc. are often observed. Current global climate change is considered to be the cause of the events. Currently, one does not deny that climate change is occurring. Now there is no doubt about climate change. Exposure of the agriculture sector to climate extremes is threatening to reverse gains made in ending malnutrition. Climate events have the biggest impact on acute food insecurity and malnutrition of world population. In 2017, the number of undernourished people was estimated to have increased to 821 million [3].
The work does not attempt to identify the cause of the change or assess the opinions of scientists on climate warming. Our task is to consider, using the example of Uzbekistan, how much quantitative changes occurred at the beginning of
vegetation period of rangeland plants in the harsh agro-climatic conditions of the Kyzylkum desert and at the beginning of the sowing period of cotton crop. The results of this work are relevant and have practical importance, since desert pastures, which occupy more than 70% of the territory of Uzbekistan, produce such important products as karakul wool, meat and cotton growing yields valuable fiber for the textile industry, oilcake for livestock, oil for the food industry.
The aim of the work is to investigate the influence of modern climate change on the beginning of the natural vegetative regeneration of desert-rangeland plants and on the beginning of the cotton sowing period in Uzbekistan.
The discussion of the results. In Uzbekistan, quite large research work has been carried out on rangeland and cotton agrometeorology [1]. However, to date, less attention has been paid to the impact of climate change on the initial stage of the natural rangeland crops regeneration and on the cotton planting period, since these dates are closely related to the further occurrence of different interphase periods.
Agricultural organizations in their current activities need a constant assessment of past and expected meteorological
conditions in order to make an expedient choice of a solution that carries the least risk for crops and their yield.
For karakul sheep breeding, the main and important cheap fodder base is natural pastures, the productivity of which is closely related to climatic conditions. The yield of karakul pastures ranges from an average of 2 to 4.5 centner per hectare, and depends on the occurring weather changes.
In the spring, the mass development of the main pasture vegetation is closely related to air temperature. The lower limit for the natural regeneration of the growing season is considered to be above 5 °C.
Dates of a steady transition of air temperature through above 5 °C for particular years were found by climatic database materials of meteorological stations of Uzhydromet (Uzbeki-
From (table 1), it can be seen that the response to climate change for dates of the vegetative renewal desert-rangeland plant for different species manifests itself differently depending on the biological characteristics of the crops.
Analysis of these materials and table allows to note, that the beginning of the growing season is shifting to earlier terms, due to climate warming in Uzbekistan [2].
Further development of the pasture crops depends on the dates of the onset of their natural regeneration, including the dates of the onset of various interphase periods, which is clearly shown in figure 1 on the example of Haloxylon persicum (a) and Ferula assa-foetidaL (b). Mathematical-statistical processing of materials are carry out. The trends are calculated by linear approximation and the regression equations are obtained, which like this:
for Haloxylon persicum y = 0.99x +18.55 (l) for Ferula assa-foetida L. y = 1.12* + 9.58 (2) In these equations x, y is the date number starting March 1. For example, the number 1 corresponds to the date of March 1, 90 - corresponds to May 30. The strength of relationship between these parameters for Haloxylon persicum and Ferula assa-foetida L. (r = 0.87) showed that this is quite enough for practical use.
stan), which is located in the Kyzylkum desert, where the main base of karakul livestock feeding zone is concentrated.
Comparison of the dates of transition of air temperature in the karakul growing zone through above 5 °C for the current period of 1991-2018 with the base climate period of 1961-1990 showed a shift of dates towards earlier values, reaching 4 days in the northern areas (Akbaital), 5 days in the western (Buzaubai), 7 days in the central and western (Tamdy and Mashkuduk), 2 days in the southern (Ayakagitma). That is, on average, there is a shift of 5 days.
Along with the shift of the steady transition dates of the air temperature through above 5 °C, there is a shift in the beginning of the dates vegetative renewal of various pasture crops to earlier periods. This is clearly seen from (table 1).
In recent years in Uzbekistan, a number of research were conducted for agrometeorological support karakul sheep breeding. Among them developing of a method for calculating reserves of productive moisture under rangeland plants and preparation of a scientific applied reference book "Average Perennial Moisture Supply in the Desert Zone of the Kyzylkum". Additionally dependencies of rangeland vegetation yield on air temperature and moisture reserves in different layers of soil were found and used in operational practice.
Uzbekistan belongs to the cotton-growing countries, and cotton (Gossypium hirsutum) is a crop that is largely dependent on weather conditions, and also requires timely agrotech-nical measures. Therefore, it is of practical interest to study the influence of climate change on the date of sowing of cotton seeds in spring season.
Based on the materials of the meteorological stations of Uzbekistan located in the irrigated zone where cotton is cultivated, the dates of a steady transition of air temperature through above 10 °C, at which the germination of cotton seeds occurs, have been considered for more than 50 years. On the base of the materials the corresponding statistical processing was carried out. In the result diagrams on transition date change of temperature in spring through above 10 °C were plotted and the trend line equations were obtained.
Table 1.- The value of the shift of the beginning terms of natural rangeland regeneration to the earlier days in the Kyzylkum desert zone in Uzbekistan
Latin name of rangeland plants Shift to earlier terms (days)
Artemisia Krasch (sagebrush) 2
Salsola arbuscula Pall (saltwort 9
Сalligonum leucocladum Bge (juzgun) 4
Carex pachystylis Gay (Ilak) 2
Ferula assa-foetida L. (ferule) 6
Poa bulbosa L. var vivipara (bluegrass) 4
Bromus tectorum L. (campfire) 2
Figure 1. Relationship between the date of the beginning bud formation period Haloxylon persicum (y) and the onset of the growth shoots phase Ferula assa-foetida L. (y) from the date of the beginning vegetative renewal phase (x)
Comparison of the dates of transition of air temperature in the cotton growing zone of Uzbekistan through above 10 °C for the current period of 1991-2018 with the base climate period of 1961-1990 showed a shifts of dates to earlier values which were reaching 6-10 days in the northern regions, 2-4 days in the south, 1-6 days in the central, 2-5 days in the east.
Analysis of the materials allows us to state that climate warming is observed not only in the desert zone, but also in the irrigated regions of Uzbekistan.
In the cotton growing in Uzbekistan, an important role in increasing the yield plays the timely implementation of agro-technical measures, which include thinning, top removal, defoliation of plants, etc. These measures are dedicated to each interphase period of plant development.
Based on observations made under production conditions in the vicinity of meteorological stations, dependencies were obtained between different dates of occurrence of the phenological phases of cotton, which is necessary for agro-technical measures (thinning, watering, fertilizing, top removal, defoliation, etc.).
t has been found that in order to ensure optimal plant density in our conditions, cotton thinning is required during the onset of the first leaf deployment phase. To solve practical problems, it is important to have information about the date of the onset of the flowering phase and the opening of the first bolls in advance during the period of productivity formation, which are necessary for planning such important agrotechni-cal measures as top removal and defoliation. Removing of top foliage in cotton (the alienation of the upper part of the main stem) is carried out with the aim of directing nutrients to form
the productivity of the plant, and not on the growth of the main stem. Usually, top removal is carried out in 30 days after the onset of the flowering phase.
Defoliation is carried out to accelerate the disclosure of the formed boxes and create conditions for the timely harvest before the onset of inclement weather.
In (Figure 2) shows the relationship between the important dates of the onset of phenological phase development of cotton.
In practice you can use (Figure 2) to calculate the date of flowering and opening of the first boxes, respectively, if the dates of emergence of seadlings and flowering are known.
It is necessary to underline that adverse weather and agro-meteorological conditions may interfere with the implementation of agrotechnical measures in the required time frame. It has been scientifically proven that deviations from the dates of planned activities in the interphase periods lead to a decrease in cotton productivity and a deterioration in the quality of the fiber.
Summing up, generally, it should be noted that karakul and cotton growing is extremely important to the development of the agricultural sector of the country economy. But no matter how the food base grows in the desert and new agrotechnical measures are introduced in cotton growing, the role of meteorological factors will always play a major role. The developed methods for assessing the state, growth, development and forecast of phenological phases of both pasture vegetation and cotton, as well as assessments of the formation of the quality of cotton fiber based on agrometeo-
rological and agroclimatic indicators will always be a reliable In conclusion, we note that the topic concerned, of course,
means in the hands of agrometeorologists. is very complex, controversial, and requires continuation of
research in these fields.
a) b)
Figure 2. Relationship between the date of the onset of the flowering phase (y) from on the onset of the seadling phase (x) (fig. 2a) and the opening of the first bolls of the cotton (y) from the date of flowering (x) (fig. 2b)
References:
1. Abdullaev A. K. Proposals for a strategy for reorganizing cotton production due to possible climate change in Uzbekistan // Research papers of SANIGMI,-Vol. 160 (241).- Tashkent, 2000. - P. 121-130. (in Uzbek).
2. Sulaymonova N. N. Influence of climate change on the agroclimatic conditions of rangelands // Proceedings of the Geographical Society of Uzbekistan. - Vol. 49. - Tashkent, 2017. - P. 171-175. (in Uzbek).
3. URL: https://wmo//The state of the Global Climate in 2018.
