Purpose. To evaluate the stability and plasticity of new varieties of grain sorghum in ecological conditions of the Fores-Steppe and Steppe zone of Ukraine.Methods. Field study, statistical evaluation.Results. It was found that in Ukraine the average yield of grain sorghum in 2015 was 3.72 t/ha and in 2016 – 3.36 t/ha. In field experiments during 2009–2016, ‘Praim’ and ‘Sprynt 2’ hybrids appeared to be significantly better as compared to averaged yields of 3.9 t/ha. Evaluation of yield plasticity in environmental conditions of the Forest-Steppe and Steppe zones showed that the hybrid ‘Praim’ did not differ from the group standard and its index is no more than one. At the same time, the ‘Sprynt 2’ is highly-plastic hybrid and ‘Dniprovskyi 39’ belongs to relatively low-plastic varieties.Conclusions. It was established that, as an average of an experiment, hyb­rids of grain sorghum ‘Praim’ and ‘Sprynt 2’ had a yield of 4,2–4,3 t/ha. According to the analysis of ecological plasticity, ‘Sprynt 2’ can be included with the intensive type and ‘Dniprovskyi 39’ – with relatively low-plastic varieties. It was found that proper selection of varieties and far­ming practices of cultivation is one of the main factors that favors high yields and respectively determine 37% and 34% of the level of grain sorghum productivity.

Purpose. Reveal varietal features of formation grain sorghum yield structure elements depending on inter-row spacing and fertilizing doses of nitrogen fertilizers. Methods. Laboratory, field, statistical. Results. Data on features of structural elements formation and productivity of grain sorghum in dependence on varietal characteristics, inter-row spacing and level of mineral nutrition are presen­ted. An important indicator for plant productivity formation is productive tillering, since grain sorghum, like most cereals, has the ability to tiller, which under favourable conditions allows forming up to 25–45% of yield on the side shoots. In our case, sowing of grain sorghum with sowing rate 190 thousand pcs./ha and inter-row spacing 35, 50 and 70 cm, respectively, we got the same plant nutrition area – 526 cm2; the distance between plants in the row is 15, 10.5 and 7.5 cm, respectively. The average number of grains per panicle in the sorghum hybrid ‘Lan 59’ according to the experiment was 866.9 grains, but the maximum values were observed with inter-row spacing 70 cm and fertilizers N60P60K60 + N40 – 1035.1 pcs. In hybrid ‘Brigga F1’, on the average in the experiment was 554.3 pcs. grains/panicle, and with inter-row spacing 70 cm and fertilizing by nitrogen fertilizers N20–60, respectively 595.7 – 602.4 pcs. We obtained similar indicators in hybrid ‘Burggo F1’ and fertilizing rate N60P60K60 + N40 – 961.7, but on average, in the experiment, the hybrid formed 858.6 pcs. grains/panicle. Mass of grain from one plant allows fully evaluate individual productivity of plants of studied hybrids. The best indicators of grain mass per plant were obtained with inter-row spacing 50 cm and fertilizing rates N60P60K60 + N60. So, on average, in the experiment in hybrid ‘Lan 59’, 41.2 g of seeds were formed per one plant, in the hybrid ‘Brigga F1’ – 63.4 g, in the hybrid ‘Burggo F1’ – 64.0 g. The best weight parameters of 1000 seeds were obtained with the inter-row spacing 50 cm and fertilizing rates N60P60K60 + N60, that is, ‘Lan 59’ – 37.3 g, ‘Brigga F1’ – 37.4 g, ‘Burggo F1’ – 30.2 g. Conclusions. Changes in inter-row spacing and level of mine­ral nutrition cause variability in formation of yield structural components of grain sorghum hybrids – productive tillering, number of panicles per hectare, number of grains per panicle, mass of grain per plant, mass of grain per panicle and mass of 1000 seeds, which determine individual productivity of plants.

Purpose. To evaluate the stability and plasticity of new varieties of grain sorghum in ecological conditions of the Fores-Steppe and Steppe zone of Ukraine. Methods. Field study, statistical evaluation. Results. It was found that in Ukraine the average yield of grain sorghum in 2015 was 3.72 t/ha and in 2016 – 3.36 t/ha. In field experiments during 2009–2016, ‘Praim’ and ‘Sprynt 2’ hybrids appeared to be significantly better as compared to averaged yields of 3.9 t/ha. Evaluation of yield plasticity in environmental conditions of the Forest-Steppe and Steppe zones showed that the hybrid ‘Praim’ did not differ from the group standard and its index is no more than one. At the same time, the ‘Sprynt 2’ is highly-plastic hybrid and ‘Dniprovskyi 39’ belongs to relatively low-plastic varieties. Conclusions. It was established that, as an average of an experiment, hyb­rids of grain sorghum ‘Praim’ and ‘Sprynt 2’ had a yield of 4,2–4,3 t/ha. According to the analysis of ecological plasticity, ‘Sprynt 2’ can be included with the intensive type and ‘Dniprovskyi 39’ – with relatively low-plastic varieties. It was found that proper selection of varieties and far­ming practices of cultivation is one of the main factors that favors high yields and respectively determine 37% and 34% of the level of grain sorghum productivity.

Purpose. To establish the optimal seeding time and depth of ‘Dniprovskyi 39’ and ‘Vinets’ sorghum varieties, to prove their effect on the crop photosynthetic capacity in the Right-Bank Forest-Steppe of Ukraine. Methods. Field, laboratory, comparative, analytical, generalizing, mathematical and statistical. Results. It was proved that the best results of crop photosynthetic capacity of sorghum were obtained by sowing in the first decade of May (the second sowing period) at a seeding depth of 4–6 cm. Accordingly, the leaf surface area in these variants reached its maximum during the “panicle-blooming” period and equated 36.13–38.81 thousand m2/ha for the ‘Dniprovskyi 39’ variety and 34.23–36.91 thousand m2/ha for the ‘Vinets’ variety. By sowing seeds in the third decade of April (the first sowing period) at the seedining depth values described above the leaf surface area of the varieties was slightly smaller and amounted to 29.56–31.20 thousand m2/ha for the ‘Dniprovskyi 39’ variety and 27.76–29.40 thousand m2/ha for the ‘Vinets’ variety. By sowing seeds in the second decade of May (the third sowing period), the leaf surface area was 30.68–32.92 thousand m2/ha for the ‘Dniprovskyi 39’ variety and 29.08–31.32 thousand m2/ha for the ‘Vinets’ variety. The highest photosynthetic potential was obtained for sorghum plants in the second sowing period at the seeding depth of 4–6 cm and was 1.27 and 1.34 million m2/ha for the ‘Dniprovskyi 39’ variety and 1.16 and 1.22 million m2/ha for the variety ‘Vinets’. In the first sowing period, this indicator was slightly lower and amounted to 1.18 and 1.23 million m2/ha for the ‘Dniprovskyi 39’ variety and 0.98 and 1.02 million m2/ha for the ‘Vinets’ variety respectively. In the third sowing period, it was the smallest one and equated 1.09 and 1.13 million m2/ha for the ‘Dniprovskyi 39’ variety, and 0.88 and 0.93 million m2/ha for the ‘Vinets’ variety at the optimal seeding depth. The photosynthetic potential was lower at the seeding depth of 2 and 8 cm, which is explained by the different soil and climatic parameters during a certain period of sorghum plant vegetation. The highest value of the photosynthetic capacity net indicator was obtained by sowing seeds at the optimal time and the optimal seeding depth and it equated 3.84–4.02 g/m2 per day for the ‘Dniprovskyi 39’ variety and 3.79 – 3.98 g/m2 per day for the ‘Vinets’ variety. Conclusions. It has been established that the sorghum plants had better vegetation and formed photosynthetic capacity by sowing seeds in the first decade of May at the planting depth of 4–6 cm, which we recommend for growing this crop in the Right-Bank Forest-Steppe of Ukraine.