Sorghum bicolor L. Moench is a versatile crop, corn which is used for forage and fodder (for feeding agricultural animals, birds, fishes), as well as a source of raw materials for the food processing industry. Especially important is the cultivation of sorghum in the lower Volga region of Russia, characterized by frequent soil and air droughts. In "Rossorgo" scouting for earliness, high yield, improved grain quality, resistance to diseases and pests. The test sorghum genotypes were conducted at the experimental field of center "Rossorgo" in 2014-2016. All records of productivity elements of productivity and biochemical evaluation of grains are made according to standard techniques. The results of long-term work were identified and approved for use in the lower Volga region 12 varieties and 2 hybrids of sorghum. Varieties Pischevoe 35, Pischevoe 614, Кremovoe, Fakel can be used in the food industry. Grits from grain of sorghum has a higher ratio of the cooking property in comparison with cereals from other cultures. The early-maturing varieties Perspektivny 1 and Start, intended for planting with different width of spacing -15, 45 and 70 cm were bred. Varieties of Granat, Volzhskoe 44, Avans and hybrids Irgiz, Volgar, combine high yields (5.31-10.8 t/ha) and 11.32-12.56% of crude protein in grain. Heterotic hybrids of Irgiz and Volgar are by tall (149.6 of 175.9 cm) and highest grain yield (8.02-10.8 t/ha). As raw material for starch varieties recommended Avans, Volzhskoe 44, Sarmat, Perspektivny 1, Geliofor, Volzhskoe 4, Topaz and hybrid Volgar with content in grain starch 72.31-75.60%. New varieties (Azart, Geliofor, Magistr, Bogdan, Bakalavr, Granat) characterized by a high content of starch (71.47-74.50%) and medium protein (the 11.04-12.59%), pass state testing. Thus, "Rossorgo" offers a farmer a range of cultivars and hybrids of grain sorghum, allowing the obtaining stable yields of grain and extending the use of culture in the region.

Currently, the development of highly productive sorghum hybrids with a high content of the main nutritional components in grain is of great relevance. The current paper has presented the estimation results of the effects of true and hypothetical heterosis on percentage of protein, oil and starch in grain of the first-generation hybrids. There have been analyzed 54 combinations obtained on the basis of three CMS-lines and 18 pollinators. The components of the hybrids and their progeny were grown on the FSBSI RosNIISK “Rossorgo” experimental plots of 7.7 m2, in triple sequences with plant density of 100 thousand plants per ha. The biochemical composition of the grain was determined by the SpectraStarXT infrared analyzer. The parental components and their progeny differed in the biochemical composition of grain, which was confirmed by the analysis of variance. There was identified a slight variation of the ЗерновоехозяйствоРоссии № 2(68)’ 2020 50trait ‘starch content’ in maternal and paternal forms of the hybrids F1(V= 2.5–8.3%). There was identified an average variability of protein percentage in the initial forms (V= 7.9–14.6%) and a weak variability in hybrids (V= 9.1–10.8%). There were identified larger values of variation of oil content (9.0–17.2%). The manifestation frequency of true and hypothetical heterosis of protein percentage was identified in 31.5–62.9% and 44.4–79.6% of hybrids; of fat content was identified in 20.4–57.4% and 20.4–75.9% of hybrids; of starch content was identified in 16.6–33.3% and 16.6–44.4% of hybrids. A focused approach in breeding the varieties with the improved biochemical components of grain allowed us to identify 9 combinations characterized by the annual effect of heterosis in protein content (4 combinations), in raw oil accumulation (2 combinations) and in starch accumulation (3 combinations).

The ability of sugar sorghum plants to accumulate 18-24% of water-soluble sugars in the juice of stems expands the potential of the crop as a raw material for the production of not only feed (green feed, silage), but also in various areas of the processing industry for food (glucose-fructose syrup, sorghum honey) and technical purposes (bioethanol, biofuels). The brief review presents data on the origin; biological features of sorghum; on the fractional composition of water-soluble sugars; on global trends in the use of renewable energy sources. The advantage of growing Sorghum saccharatum as a sugar carrier in regions with insufficient moisture is reflected. Keywords: SUGAR SORGHUM, WATER-SOLUBLE SUGARS, FRUCTOSE, GLUCOSE, SUCROSE, SUGAR SYRUP, BIOETHANOL, BIOFUEL

Background. Global climate changes have recently led to a more frequent occurrence of adverse factors and a decrease in the productivity of major crops. Sorghum is a highly drought-resistant crop that can tolerate long-term soil and air droughts with much lower harvest losses than wheat or barley. It is important to understand physiological mechanisms affecting drought tolerance when breeding efforts are aimed at improving the adaptability to abiotic conditions and productivity of sorghum hybrids.Materials and methods. Twenty sterile lines of grain sorghum with 8 types of CMS were studied in 2019 and 2020 in the arid conditions of Saratov Province. Indicators of the leaf water regime were assessed according to VIR’s guidelines. Statistical processing of the research results was performed using the AGROS 2.09 software.Results. The indicators of the leaf water regime that reflected differentiated responses of the CMS-line plants to the prevailing water and temperature stressors during the critical flowering period for sorghum were analyzed. Four CMS lines were identified according to the chosen set of indicators: they manifested 71.13–72.02% of total water content, 5.26–9.08% of water deficit, and 57.40–83.17% of water retention capacity on average for the two years of research. For the first time, the effect of CMS in sorghum on the manifestation of water regime indicators was registered. In isonuclear CMS lines, the greatest effect on drought resistance was shown by cytoplasm A3 versus A4 (with the Zheltozernoe 10 genome), cytoplasm A5 versus A1 (with the Karlik 4v genome), and M35-1A versus the analog on cytoplasm 9E (with the Pischevoe 614 genome).Conclusion. It is shown that genetically different types of sterility can be used in breeding practice to increase the resistance to abiotic stressors in components of F1 crosses and hybrids.

Currently, breeders often use multidimensional statistics methods to process a large set of experimental data. To characterize the breeding value of 20 sorghum lines with cytoplasmic male sterility (CMS lines) under arid cultivation conditions, during the research there was applied a cluster analysis, allowing to group the lines into clusters according to similar indicators from 15 analyzed agronomic and physiological characteristics. The studies were carried out during 2019-2021, various in meteorological conditions: the hydrothermal coefficient was 0.59-0.84 during the vegetation period of plants. Cytoplasmic male sterility lines were sown at a density of 100 thousand plants per 1 hectare. Breeding and physiological traits were evaluated according to generally accepted methods. The assessment of agronomic and physiological characteristics was carried out according to generally accepted methods. For further practical work, based on the results of the conducted studies, four CMS lines of grain sorghum (clusters 2, 3, 5) were identified according to a complex of physiological and breeding characteristics. Sterile lines (A2 Vostorg, M35-1А Pischevoe 614, A3 Feterita 14 and A2 KVV 114) were distinguished by the highest seed yield of 3.02-3.50 t/ha, high water content (72.7-73.7 %) and water retention capacity of leaves (72.2-84.3 %), low water deficiency (6.5-8.7 %). The study of moisture loss during the natural wilting of leaves confirmed the high resistance to drought in the flowering phase of the sterile A2 KVV 114 line, in which the intensity of moisture loss after 1 hour was only 9.9 %, 1.5 h – 15.8 % and 24 h – 68.6 %. In breeding for increasing drought resistance the CMS-line A1 Efremovskoe 2 (the sixth cluster) should be noted, as it was inferior to the above-described lines only in terms of low water deficiency (16.5 %), indicating average drought resistance. The line is the tallest with large leaves (length – 46.7 cm, area – 163.8 cm2) and form 3.21 t/ha of seeds on average for the period presented. The use of the obtained data provides the increasing of the breeding process for the creation of productive drought-resistant F1 sorghum hybrids.