Growth phases of autumn rapeseed effect of seedling thickness

. Rapeseed is a highly valuable livestock feed as its seeds contain a higher percentage of oil and protein compared to other agricultural crops such as pea, wheat, and barley flour. Rapeseed seeds are rich in protein and oil, with percentages ranging from 21% to 33% and 42% to 48%, respectively. Rapeseed flour now has a protein content that is 1.9 to 4.0 times higher than that of wheat, barley, and pea flour. Rapeseed also produces 1 ton of seeds per hectare along with 0.41 to 0.44 tons of oil and roughly 0.2 tons of protein. With the introduction of contemporary cultivars that contain low amounts of erucic acid and glucosinolates in both the oil and seed tissues, the importance of rapeseed as a livestock feed has been further increased. Its seed yield is also high, with one hectare producing one ton of seeds, 0.41-0.44 tons of oil, and 0.2 tons of protein. In this research, scientific research experiments were carried out in the fields of experimental scientific research and educational experimental farm of Tashkent State Agrarian University during 2020-2021. The results showed that during the flowering phase, the development of the Yasna control variety slowed down and was delayed by 1-3 days compared to the Sarmat and Loris varieties. In the flowering phase, differences in varieties of rape began to be noticed.


Introduction
Rapeseed is an excellent source of livestock feed and surpasses many agricultural crops in terms of nutritional content. The seeds of rapeseed contain high levels of oil and protein, ranging from 42% to 48% and 21% to 33%, respectively. This makes rapeseed flour 1.9 to 4.0 times more protein-rich than wheat, barley, and pea flour. Additionally, rapeseed has a seed yield of 1 ton per hectare, with an oil yield of 0.41 to 0.44 tons and protein yield of about 0.2 tons. The significance of rapeseed as a livestock feed has been further enhanced with the development of modern varieties that have low levels of erucic acid and glucosinolates in both the oil and seed tissues [1][2][3][4].
Modern varieties of rape have both positive and negative characteristics, which are manifested differently depending on the year. For example, only in favorable meteorological and agrotechnical conditions, they can produce a high yield and sharply reduce it when it deteriorates [5,6]. Currently, the role of rap in the world is increasing. The rapidly growing demand for oilseeds in the world market leads to an increase in the volume of seed cultivation and processing in our country [7].
To increase the planting area of winter rapeseed hybrids in Belarus, it is necessary to understand the best methods for their cultivation. One crucial factor for obtaining high yields from autumn rape seeds is achieving an optimal seedling thickness of plants, which is influenced by the seeding rate. Plant density significantly affects crop formation, and either excessive or insufficient seed planting reduces the yield compared to the ideal seedling thickness. The optimal seedling thickness is determined by the seeding rate and decreases as the plants grow, accounting for germination, wintering, and harvest in the field [8,9]. In different regions of Belarus, scientific studies were conducted to determine the optimal planting rate of seeds of autumn rape varieties [10].
With the introduction of winter rapeseed hybrids, which differ from varieties in terms of development characteristics, the requirements for planting standards have changed. Thus, due to the effect of heterosis and the ability of hybrid plants to produce a large number of side branches, a high yield compared to varieties can be achieved even with the sparseness of seedlings.

Materials and methods
In this research, scientific research experiments were carried out in the fields of experimental scientific research and educational experimental farm of Tashkent State Agrarian University during 2020-2021. In the field experiment, varieties of winter rapeseed Yasna, Sarmat and Loris were planted in 12 variants, four repetitions. The area occupied by each variant is 28 m 2 , of which 14 m 2 is taken into account , and the total area occupied by the experiment is 0.13 ha. Based on the goals and tasks of the experiments, phenological observations and calculations were carried out in Yasna (control), Sarmat and Loris varieties of autumn rapeseed [5][6][7][8].
The Yasna variety is a Serbian autumn plant that was added to the state register in 2019. It belongs to the "00" group and has been specially selected for its low levels of erucic acid and glucosinolate. The seeds used in the state test were provided by "SP URUG' INVEST" company. Sarmat variety is another autumn plant that was created at the RFIM "Russian Federal Scientific Center "V.S. Pustovoit Institute of Oilseeds". It was included in the State Register of the Russian Federation in 2018 [1][2][3][4][5]. The Sarmat variety was developed using the "Sylvia variety x No. 23627" hybrid combination and is also a "00" type plant with very low levels of erucic acid (less than 2.0%) and glucosinolate (up to 35 μmol/g seed). Loris variety is also a "00" type plant that was created at the RFIM "Russian Federal Scientific Center "V.S. Pustovoit Institute of Oilseeds". Like Yasna and Sarmat, it has low levels of erucic acid and glucosinolate [7][8][9][10].
The same amount of mineral fertilizers (N150 kg/ha, R300 kg/ha, K40-60 kg/ha) was applied annually before and during the growth season. The seeds were planted at a depth of 2-3 cm, according to the experimental standards. Prior to planting, the seeds were treated for diseases and pests, and aphids were treated with "Alfa Yuca" and "Urell-D" insecticides. Additionally, in the stem phase, 500 grams of carbamide-urea fertilizer was mixed with 45 liters of water and applied to an area of 0.13 ha as a foliar feed [1][2][3][4][6][7][8][9].
varieties mature 2-4 days later than the control Yasna variety may be due to the fact that they have not yet adapted to the conditions of the typical gray soils of the Tashkent region, because these varieties are created in the fertile black soils of the Russian state.
It was observed that Yasna control variety fully enters the ball formation phase 46 days after seeding, while it was observed in 64 and 69 days in foreign varieties. Yasna was found to be 20-25 days late compared to the control variety. So, the Russian varieties develop very slowly in the initial development phase and form a ball leaf. The ball leaf formation phase occurred in the last days of November in the Yasna control variety, while in the Russian varieties it occurred after the middle of December. In Uzbekistan, the cooling of the day in autumn is observed early in some years, and later in some years. In 2022, the cooling of the day was observed at the end of November, and it did not harm the formation of leaves of Loris and Sarmat varieties. No difference was observed between variants.
As a result of observing the phase of leaf formation, we have come to the conclusion that the Loris and Sarmat varieties, which are Russian varieties, develop slowly in the initial development phase, so it is appropriate to plant them after the middle of September, and at the end of November, the level of full leaf formation and wintering was high (Table  1). On the other hand, because the Yasna control variety has developed rapidly in the initial development phase , it is optimal to plant this variety in the first ten days of October, and we intend to conduct a scientific experiment on the planting dates of autumn rapeseed varieties in the future. In the spring, as the days warmed, the canola varieties continued to develop a ball of leaves, during which the overwintered canola varieties began to develop. Along with the phase of stem formation, side branches were also formed in the plant. In the Yasna (control) variety of rapeseed, it was observed that the stem and side branches were fully formed on March 18-19, or 157-158 days after planting, but in Russian varieties, this phase was found to be delayed by March 23, that is, 4 days later than in the control variety . Loris and Sarmat cultivars were found to have formed main stems and branches after 162 days of planting. No difference was observed between variants of cultivars in the experiment (Table  1).
It was reported that during the flowering phase, the development of the Yasna control variety slowed down and was delayed by 1-3 days compared to the Sarmat and Loris varieties. In the flowering phase, differences in varieties of rape began to be noticed. Yasna (control) variety, full flowering was observed on April 9 in variants planted with 0.8 and 1.0 million seeds per hectare, on April 11 when 1.2 million seeds were planted per hectare, and on April 12 when 1.4 million seeds were planted per hectare. -3 days late.
The Sarmat variety was planted on April 7 at a rate of one hectare, using one million seeds in the second option, and on April 8 in the third and fourth options, with an increased sowing rate of 1.2 and 1.4 million seeds per hectare. During the flowering phase, it was observed that the variants with increased planting rates had an earlier flowering time of 3-4 days compared to the Yasna control variety. To put it simply, planting the Sarmat variety with a higher sowing rate led to earlier flowering compared to the Yasna control variety.
It was found that the flowering phase of the Loris variety was delayed by 1 day compared to the Sarmat variety, but Yasna flowered 2-3 days earlier than the control variety. The regularity observed in the above Yasna and Sarmat varieties regarding the consumption of planting standards of the flowering phase was also observed in the Loris variety. It was found that the variants with low planting standards entered the flowering phase on April 7-8, while the variants with increased planting standards were delayed by 1-2 days (Table 2).
At the beginning of the tillering phase, a delay in tillering formation was detected in the Yasna control variety, which was developing ahead of Loris and Sarmat varieties in all growth phases , that is, when this variety reached the tillering phase, its development slowed down. It was found that this variety entered the full budding phase in 200 days or 22 days after the flowering phase in the case of 0.8 million seeds planted per hectare. According to foreign scientists, rapeseed flowers bloom for 2-3 days, one plant blooms for 20-30 days.
Flowering of rapeseed starts from the main stem, then with an interval of 1-2 days, the flowers of the side branches of the first order begin to bloom [7]. I.I. According to Kuznets, the maximum number of flowering flowers in a plant is observed on 8-9 days after the beginning of flowering [8]. During the experiment, as shown in the scientific literature, the formation of tubers was observed 20 days after the full flowering phase. In Yasna control and Loris cultivars, in the options with 1.2 million and 1.4 million seeds planted per hectare, the full tillering phase is 1-2 times longer than in the options with 0.8 and 1.0 million seeds planted per hectare. The Sarmat variety ripened earlier than the Yasna and Loris varieties, with a difference of 3-7 days. The Sarmat variety was planted at rates of 0.8 and 1.0 million seeds per hectare in the first and second options, while in the third and fourth options, 1.2 and 1.4 million seeds were used, respectively. The tillering phase occurred on May 3, 200 days after seeding, in the first and second options, whereas it was delayed by 4 days in the third and fourth options ( Table 2). The ripening period of autumn rape occurred from the end of May to the beginning of June. The first and second variants of the Sarmat variety ripened on May 29 in 230 days, while the third and fourth variants ripened three days later on July 1 in 233 days. The Loris variety ripened slightly later than the Sarmat variety, while the Yasna control variety ripened later than both Sarmat and Loris varieties.