Selection of high-yielding, disease-resistant, promising, and export-oriented varieties of melons

. In the top melon-producing nations in the world, numerous scientific research are being carried out to develop types that are suited for growing melons at various times, particularly in isolated and protected places, and to advance cultivation techniques. The technology to grow melons in greenhouses throughout the winter and varieties appropriate for growth in greenhouses have been developed in a number of nations, and ultra-fast and exportable melon types are now being cultivated. Increasing the melon gene pool and its export potential by increasing the variety of exportable cultivars is one of the critical issues of the present. In this research paper, high-yielding, high-quality melon varieties are investigated by the means of selection of high-yielding, disease-resistant, promising and exportable melon varieties of the Khorezm oasis. For the investigation, 8 different melon varieties such as Ko’k Gulobi, Khan qizi, Non go’sht, To’yona, Bijir. Bashak, Qari qiz and L oybek are selected. In relation to standard melon variety, L Oybek melon variety showed higher field germination rate, tasting value, yield and percentage of commodity yield share in comparison with other selected melon varieties. The experimental variety test of melons of Khorezm oasis was conducted in 2018-2019. At the Khorezm Scientific Experimental Station of the Scientific Research Institute of Vegetables, Melons and Potatoes, varieties of melons with high-yielding, high-quality characteristics were studied..


Introduction
Many scientific studies are being conducted in the world's leading melon growing countries to create varieties suitable for growing melons in different periods [1][2][3][4], especially in remote and protected areas, and to improve cultivation technologies [5].
In a number of countries, the technology of growing melons in greenhouses in the winter season and varieties suitable for growing in greenhouses have been created [6,7], and ultrafast and exportable melon varieties are being grown. One of the urgent tasks of today is to further enrich the melon gene pool and increase the melon export potential on the basis of expanding its assortment of exportable varieties [8][9][10].
In recent years, special attention has been paid to the further development of the policing industry in Uzbekistan, in particular to the radical increase in the production of exportable melons. During the visit of the President of the Republic of Uzbekistan to the Khorezm province on November 29-30, 2018, "Organization of melon-growing farms in the Khorezm province, working in cooperation with scientific and research institutions, cultivation of melons in open fields and greenhouses based on innovative technologies, comprehensive development of its processing, development of the sector further increase of export potential" was specified separately [1].
Accordingly, it is important to study the rich collection of melon varieties under the conditions of the soil climate of the region, to further enrich its gene pool, to distinguish promising and exportable varieties, and to improve agro-technologies of varieties.

Materials and methods
In the experiment, Kok Gulobi variety was taken as the 1 st standard as a comparator of Khan qizi and Non gosht Khorezm varieties. Kechpishar Bijir, Beshak 9, Beshak 5 forms, Qari Qiz varieties and Toyona variety for L-Oybek line were studied as the 2 nd standard. The field experiment was conducted according to the methodology of the State Variety Testing Center.
Experiment took place 4 times, each plot length is 6 m. and there were 20 plants on each yard, the feeding area was 16.8 m 2 . The sowing time and sowing scheme of the seeds were carried out at the same time as the above Experiments.

Results and discussion
The experiment revealed seed germination, field germination, flowering of paternal and maternal flowers, and fruit ripening ( Table 1). As a result of phenological observations, the seeds of all cultivars germinated in the same period, i.e. 16 days. Field germination of seeds was 85-89% in standard varieties, with a relatively low rate of 76% in the Khan qizi variety and a relatively high rate of 92% in the L-Oybek line.
In the experiment, when the appearance of paternal and maternal flowers was observed, the appearance of paternal flowers in medium ripening varieties was 36-37 days, the appearance of maternal flowers was 52 days in the standard variety, Khan qizi and Non gosht Khorezm varieties were 42-43 days earlier. In late ripening varieties, the paternal flowers appeared in 35-44 days between varieties, in the standard Toyona variety in Beshak 9 f and L-Oybek varieties in 45 days, in Bijir and Qari qiz varieties in 48-54 days (Table 1). It was found that the ripening of fruits in medium-ripe varieties is 2 days later than in the standard variety of Khan qizi variety and 3 days in Non gosht Khorezm variety. In late ripening varieties, the standard Toyona variety matured in 104 days, while the L-Oybek line matured in 100 days, i.e. 4 days earlier than the standard. The remaining varieties were found to be 3-10 days later than the standard variety.
In the experimental varietal experiment of melons of Khorezm oasis, biometric measurements were carried out twice during the growing season on the growth and development of the aboveground part of plants. The length of the main stem of the plant, the number of side branches, the length of the side branches and the total length of the stalks were determined.
According to the results of the experiment, the results of the second measurement at the end of the growth period of the plant are given in Table 2. According to the results of the measurements, the length of the main stem was 138.0 cm in the standard Kok Gulobi variety from medium-ripe varieties, 206.0 cm in Khan qizi variety and 186.6 cm in Non gosht Khorezm variety. These figures showed a stronger growth of 47.4-68.0 cm compared to the standard variety (Table 2). In late ripening varieties, the length of the main stem ranged from 145.0 to 149.5 cm, and it was found that the main stem of all varieties grew less than the standard variety. In the experiment, the number of side branches in the melon plant was counted and according to this indicator, the lowest number of medium-sized varieties was 3.5 in the Khan qizi and Non Gosht Khorezm varieties and 1 less than the standard variety. In the late varieties it was 4.3-5.0 pieces, the highest was 5.0 in the L-Oybek line and the lowest was 4.0 in the Bijir, Beshak 9 f and Qari qiz varieties.
According to the results of biometric measurements, the length of the lateral branches of the plant was 430.5-600.6 cm between varieties. The total length of the main stem and lateral branches of the plant is 573.0 cm in the middle-aged standard Kok Gulobi variety, and we can see that the length of the stalks has grown strongly in both Khan qizi (806.6 cm) and Non gosht Khorezm (732.9 cm) varieties.
When measuring the total length of the main stem and side branches in the late-ripening varieties of melon, the standard Toyona variety was 610.5 cm, the lower value was 575.5 cm in the Bijir variety and the higher value was 747.0 cm in the L-Oybek line.
In the experimental samples, it was found that the total length of the above-ground part of the plant grew by 232.4 cm compared to the standard in the medium ripening varieties of Khan qizi, and 136.5 cm in the late L-Oybek line.
In order to determine the resistance of Khorezm melons to flour dew disease, 3 observations were made during the growing season of the plant. In this case, the degree of disease was determined before flowering, the first harvest and after the last harvest. In addition, the quality indicators of the yield of melon cultivars, i.e. fruit weight, flesh thickness and composition were determined (Table 3). In the experiment, the incidence of flour dew disease in medium-ripe varieties was less than 5 percent compared to the standard variety. Other medium-ripe varieties Khan qizi (15%) and Non Gosht Khorezm (20%) are strongly affected. Of the late ripe varieties, the standard Toyona variety was affected by 5 percent, the L-Oybek line by 8 percent and the remaining varieties by 17.5-20.0 percent with flour dew disease.
According to the results of measurements on the average weight of fruits, the largest fruiting L-Oybek line between varieties was identified. Its core weighed 7.2-8.1 kg. The Khan qizi variety with the lowest performance was that its core weighed 2.0-2.5 kg. In the remaining samples, it was 3.3-5.8 kg.
Pulp thickness of the tested cultivar samples was 3.0-6.0 cm. The highest figure was 6.0 cm in the Bijir variety and the lowest was 3.0 cm in the Khan qizi variety. In the remaining varieties it was observed in the range of 4.2-5.5 cm.
In the experiment, the amount of dry matter, sugar, vitamin C and nitrate in melons was determined. According to the results, one of the main indicators was the dry matter content of 18.5% in the standard Kok Gulobi variety from medium ripe varieties. The lowest rate was 13.5 percent in the Qari qiz variety. In other samples, the dry matter content was 14.6-15.5%.
In determining the tasting value, samples of each variety were evaluated on the shape, color, texture, taste, odor and other parameters of ripe fruit. At the same time, the mediumripe standard Kok Gulobi variety had a tasting score of 9.6 points, while the Khan qizi variety had a higher score of 9.8 points. Of the late ripe varieties, the standard Toyona variety scored 9.5 points, followed by the Bijir variety and the L-Oybek line (9.8 points). Beshak 9 f and Qari qiz varieties, which scored lower than the standard variety (9.2-9.4 points), were identified. In the experiment, Khan qizi, Bijir varieties and L-Oybek line, which had a high tasting value, were distinguished.
In order to determine the yield of Khorezm melons in the experimental variety test, the yield of each crop was weighed separately, focusing on commodity and non-commodity yields and their number (Table 4 and Figure 1). Yield, which is one of the main economic characteristics of melons, is important in the introduction of large areas in the production of melon varieties. Therefore, recommendations are made by evaluating the yield, quality and taste of Khorezm melons. In the experiment, when analyzing the average total yield in 2019-2020, it was found that among the middle-ripe melon varieties Non Gosht Khorezm variety yielded 5.0 tons/ha (27.1 tons/ha) higher than the standard Kok Gulobi variety. It turned out that the Khan qizi variety had the same total yield as the standard variety.
In late ripe varieties, the total yield of 2 standard Toyona varieties was 44.4 tons/ha, and the L-Oybek line collected about 45.2 tons/ha. The remaining varieties were lower than the standard variety, i.e. they had a total yield of 29.4-32.8 tons/ha.
The average yield of medium-ripe melons was 22.3 tons/ha in the 1 st standard Kok Gulobi variety, 20.1 tons/ha in the Khan qizi variety, and 27.1 tons/ha in the Non Gosht Khorezm variety. It can be seen that among the medium-ripe varieties, the Non Gosht Khorezm variety produced 21.5 percent more than the standard variety.
In the late ripe varieties, the L-Oybek line (41.5 tons/ha) was found to have a commodity yield close to 2 standard Toyona varieties (39.5 tons/ha), i.e. 5.0% higher. The remaining varieties yielded 10-13 tons less than the standard variety.
In the experiment, the share of commodity yield in the total yield was the lowest, i.e. 79.9% in the Khan qizi variety, and 91.8% in the L-Oybek line, which has a high commodity yield. In the remaining samples, this figure was 85.4-90.1%. The cost-effectiveness of the study was determined (Table 5). Based on the above data, in determining the cost-effectiveness of the experiment, varietal samples were compared with all types of costs incurred in growing the crop and the cost of the crop. Calculations showed that the total cost was relatively high in the cultivation of late ripe varieties of melons. The difference in costs in cultivation was due to the diversity of yields. The difference in labor costs was related to the cost of harvesting the additional crop.
Seeds, fertilizers, fuels, lubricants, maintenance and other costs amounted to 9,338,000 UZS. Harvesting and transportation costs amounted to 4,890,000 UZS from 2,817,000 UZS.
The higher the total expense of the product, the higher the cost of the product. The highest rate on the L-Oybek line was 20,321,000 UZS/ha, which is much higher than the control. The harvest price is set at 2,000 UZS per kilogram in 2020, based on the price of 1 kg of melons. At that time, the inter-variety amounted to 43,000 to 83,000 UZS.
In the experiment, the net income per hectare was 27,684,000 UZS in the 1 st standard variety and 60,913,000 UZS in the 2 nd standard variety. In the comparable varieties, i.e. Khorezm, the net profit was 34,033,000 UZS, the profitability was 169%, and the net profit and profitability of the L-Oybek line was 62,679,000 UZS (308%). The increase in production profitability and the decrease in the cost of production were due to the increase in the productivity of varieties and lines.