Influence of planting period on the growth, development and productivity indicators of durum wheat

. It is known that two varieties of wheat are grown in Uzbekistan. Common wheat ( Triticum aestivum L.) and durum wheat ( Triticum durum L.) are cultivated in the main part of wheat fields. Durum wheat varieties included in the State Register in Uzbekistan are mainly spring and duvarak. Considering this feature and the high quality of the grain, the purchase price is 30-50% more expensive than that of common wheat, they fully meet the needs of the ever-growing macaroni-confectionery industry. Durum wheat grain is the main raw material used in the preparation of pasta and pasta products, as well as in the confectionery industry. In this case, high technological quality of durum wheat grain is required. In the next two years, the purchase price of durum and common wheat grain in the world increased significantly. Therefore, expansion of durum wheat cultivation areas in different soil and climate conditions, improvement of agrotechnology of care, obtaining high and quality grain harvest are urgent issues.


Introduction
Durum wheat is of great economic importance in the national economy [1]. Durum wheat grain has a number of technological properties, the products made from it are nutritious and very fragrant. is a commodity [2]. The large amount of protein in the grain and the excellent quality of gluten ensure that pasta products made from durum wheat flour are yellowgolden or lemon-colored and do not crumble when cooked [3]. To date, the demand for high-quality durum wheat grain in the international market is not fully satisfied, which leads to an increase in their price [4].
For example, 1 ton of quality durum wheat grain is equivalent to 4 tons of corn grain. In Uzbekistan, durum wheat grain is considered unique, and the demand for it has not been met for many years. In recent years, considerable success has been achieved in wheat cultivation in Uzbekistan, but it cannot be said that the quality of all wheat grain grown meets state standards. The creation of durum wheat varieties resistant to drought, diseases and pests, resistant to dormancy and severe cold, high-quality grain, high-yielding varieties, care in different soil and climate conditions have been studied in a few scientific research works by agrotechnology [5][6][7]. It is considered appropriate to carry out scientific research in order to achieve high-quality grain yield from the created durum wheat varieties [8].
A number of scientific studies were conducted on the development of agrotechnics for growing winter wheat with high productivity and quality of grain from winter wheat varieties [9][10][11]. Also, some elements of winter wheat cultivation in the conditions of different regions of Uzbekistan were studied. At the same time, in order to increase the productivity and grain quality of winter durum wheat varieties in different soil and climate conditions, it is necessary to choose the optimal varieties for the regions, determine the optimal planting dates, ensure economic efficiency, and correctly take into account the grain harvest period. insufficient scientific studies have been carried out on productivity, technological and seed quality effects when mowed.
The purpose of this article is to study the impact of planting dates on the growth, development, biometric indicators and grain yield of durum wheat variety "Javoxir".

Materials and methods
The scientific novelty of the research is that in the conditions of typical gray soils of Tashkent province of Uzbekistan, when durum wheat varieties are planted in three planting periods in the autumn season, the optimal planting period has been determined, which has a positive effect on plant germination, development phases, biometric indicators and productivity.
Research was carried out in 2020-2021 at the agricultural scientific research and educational experimental farm of Tashkent State Agrarian University (Tashkent, Uzbekistan). The experimental farm is located in the upper reaches of the Chirchik River, at an altitude of 481 m above sea level, at 41 0 11 '' N and 38 0 31 '' E, in Kibray district of Tashkent province. The experimental farm is 1500 meters away from the yard of the university, it is bordered by the Salar stream on the east side, the Buz water channel on the west side, the hospital of Tashkent PTI on the south side, and the residential area on the north side.
The soil of the experimental farm is a typical gray soil that has been irrigated since ancient times. This soil contains 0.8 -1.0% humus, about 0.058 -0.089% nitrogen, about 0.141 -0.184% phosphorus, and about 0.154 -0.148% potassium, which is very little of the nutrients used by plants during growth. The soil is not saline. This soil differs in water permeability and the complexity of softening.
Groundwater is located in a layer deeper than 3 m. The experimental field is insufficiently supplied with nitrogen and phosphorus. If mineral and organic fertilizers are used, it is possible to grow a high yield of field crops. For irrigation, water from the Buz canal flowing from the northern part of the experimental farm was used. Scientific research work was carried out in the central region. The central region unites the regions of Tashkent, Syrdarya, Samarkand and the mountains located at the foot of the Tyan-Shan, Pamir-Oloy mountains, and the region is distinguished by its high thermal resources.
The temperature of the winter months in the plains and hilly regions is unstable and varies from year to year. The coldest month in the region is January, when the air temperature ranges from 0 0 C to -19 0 C. The amount of precipitation in the region is also different. During a year, there will be 261 -316 mm of atmospheric precipitation in the plains, 366 -435 mm in the foothills, and 700 -895 mm in the mountain regions. Data on air temperature and average precipitation for the "Tashkent" weather station are presented in Table 1.
The main part of atmospheric precipitation occurs in the form of snow in the mountain region, and in the form of rain in the hilly and plain regions. Most of the precipitation falls in the winter and spring months, and a small part falls in the autumn months. There is almost no rain in the summer months. In autumn, the warm days last much longer, the air temperature slowly decreases. At the end of October or at the beginning of November, frost comes and the period of field crops stops. During this period, the amount of precipitation increases. In the years of the experiment, it was observed that the air temperature was different compared to the average of the long-term data. In the first year of our scientific research, i.e., in 2009-2010, it was observed that the air temperature was 0.7 0 C higher than the longterm data.
In the research work, "Qahrabo" was studied as a control variety. Due to the small grain size of local durum wheat varieties, each variety is divided into 4 rows (randomly placed) 0.7 x 4 = 2.8 m wide and 3 replicates of 18 m long each (2.8 x 18 = 50 m 2 -this is the area of option 1. In total, 6 options were carried out in 3 repetitions, totaling 900 m 2 ). Ammonium nitrate (34% N) was used as a nitrogen fertilizer, ammophos (12% -N; 46% -P2O5) as a phosphorus fertilizer, potassium salt (54% -K2O) as a potassium fertilizer. Table 2 lists the norms and terms of using mineral fertilizers in winter wheat.

Results and discussion
Complete germination of wheat planted in the fall depends on many factors, mainly the biological characteristics of the variety, planting time, planting standards, soil moisture, feeding with mineral fertilizers, temperature and others are considered. For example, in order for the grain of winter wheat to germinate, it is necessary to absorb 45-47% of water in relation to its weight. This process is especially important for autumn-sown wheat. Because in the fall, as a result of rapid changes in air temperature, moisture in the soil can affect the germinating seeds [4].
The creation of favorable conditions for plant nutrition in the fall creates the ground for a good wintering of winter wheat. The period between the emergence of winter wheat and the end of the growing season is the viability of the plant.
The viability of irrigated winter wheat in the Zarafshan Valley varied from 52.6 to 70%, depending on the various agrotechnical measures used. The above-mentioned laws were also confirmed in the data obtained from the research on the dependence of the important economic characteristics of durum wheat varieties on the planting dates in the conditions of the typical gray soils of the Tashkent region.
In general, wheat should be planted in autumn in all regions of Uzbekistan. Because they make full use of autumn, winter and spring rainfall. It begins to grow early in the spring, it ripens 10-12 days earlier than the spring crops, and the flowering period of the autumn wheat does not suffer from hot summer winds, and it gives a higher (25-30%) and quality harvest compared to the spring wheat.
After the seed is planted, it starts trying to break the shell and come out to the surface of the soil. The coleoptile stops growing, cracks, and the 1st leaf appears outside. Germination period begins. When the temperature is 14-16 °C and humidity is sufficient, it starts to germinate 7-9 days after planting. This period is reduced to 1.5 -2 days in optimal planting periods. In addition, winter wheat differs from spring wheat in its resistance to cold. Wheat can withstand 12-13 0 C frost, it dies at 16-18 0 C frost.
Cold resistance of winter wheat depends first of all on the biological characteristics of each variety, and then on its growing conditions and agrotechnics. The frost resistance of the first sprouted lawns varies depending on the time of planting and the depth of seed burial. When planted in early periods (September, early October), the grasses germinate and bloom until late autumn, i.e. until frost, and the plants overwinter in this phase.
The budding phase is a favorable period for plants to winter, and they are resistant to cold during this period. When winter wheat is planted late, the seeds may not produce grass until after frost, or they may not establish when they produce grass. So, when the seeds are sown late, they overwinter in a state where they germinate and form a sod or in the beginning of a stand. During these periods, plants are resistant to cold. As a result, plants die in winter, and the yield decreases. The depth of seed planting is also very important. If the seeds are buried to a normal depth at the time of planting, the joint will be located deeper in the soil and will be resistant to frost.
Based on the recommendations for the cultivation of winter wheat developed by our scientists above, durum wheat varieties were planted on October 15 at a depth of 3-4 cm, at the rate of 5.0 million pcs/ha, in the first planting period of our scientific research work. Since there was not enough moisture in the soil, the seeds were watered. The fact that the weather and air temperature was warm created favorable conditions for the uniform horizontal germination of the winter wheat varieties planted in the experiment.
After planting the seeds of the "Qahrabo" variety studied in the control option in the first planting period on October 15, as a result of watering for the purpose of obtaining full seedlings in a short period of time, 6 days later, i.e. 21 105 m 2 /pcs in October, 154 m 2 /pcs after 8 days; 257 m 2 /pcs after 10 days; 345 m 2 /pcs after 12 days; and after 14 days, it was found that 413 m 2 /pcs of seeds germinated (Table 3). According to the data obtained during the month of October 2020, on October 15, when durum wheat varieties were planted, due to the low amount of precipitation, the same amount of seed water was given, and the air temperature was hot, since the day of planting wheat seedlings. It was observed that after 6 -7 days it starts to appear, and after 12 -14 days, grass sprouts.
After planting the seeds of the "Qahrabo" variety studied in the control option in the first planting period on October 15, as a result of watering for the purpose of obtaining full seedlings in a short period of time, 6 days later, i.e. 21 21.0% of seeds sown in October, 30.8% after 8 days; 51.4% after 10 days; 69.0% after 12 days; after 14 days, it was observed that 82.6% of the seeds germinated (Table 4). In the options where the second sowing period was carried out on October 25, the information obtained on the determination of seed germination in field conditions is recorded in Tables 5 and 6.
The second planting period was carried out on October 25, as a result of irrigation work in order to obtain full seedlings from the seeds of the "Qahrabo" variety selected as a control variety in a short period of time, 6 days later, i.e. on November 2, 88 m 2 /pcs, after 8 days 143 m 2 /pcs; 231 m 2 /pcs after 10 days; 327 m 2 /pcs after 12 days; after 14 days, it was found that 394 m 2 /pcs of seeds germinated.
As a result of irrigation in the researched "Javoxir" variety, 6 days later, on November 2, 97 m 2 /pcs, 8 days later 152 m 2 /pcs; 244 m 2 /pcs after 10 days; 341 m 2 /pcs after 12 days; after 14 days, it was found that 404 m 2 /pcs of seeds germinated. The obtained data is reflected in Table 5. In the second planting period, after the seeds of the "Qahrabo" variety studied in the control option were sown on October 25, as a result of irrigation for the purpose of obtaining full seedlings in a short period of time, 6 days later, i.e. 1 17.6% of seeds sown in November, 28.6% after 8 days; 46.2% after 10 days; 65.4% after 12 days; after 14 days, it was observed that 78.8% of the seeds germinated (Table 6). In total, 19.4% of the seeds sown in the second period after 6 days, i.e. on November 1, and 30.4% after 8 days; 48.8% after 10 days; 68.8% after 12 days; after 14 days, 80.8% of the seeds germinated.

Conclusions
The following conclusion was reached in the scientific research conducted in order to study the influence of planting dates on the growth, development, biometric indicators and grain yield of durum wheat variety "Javoxir".
Durum wheat varieties are sown for the first time in October, and taking into account that the provision of seed water creates favorable conditions for the plant stem number to go into the budding phase until the winter dormancy period, durum wheat variety "Javoxir" in the 2nd option planted in the autumn season, the plant stem number it was found that it germinated in a higher amount (average 421 pcs/m 2 -84.2%) than in other planting periods.