The article presents the results of studying potato accessions according to the accumulation and morphological properties of starch in tubers in the nursery of dynamic testing in agroecological conditions of the Kirov region (Volga-Vyatka region) in 2022. The objects of the research were 11 new hybrids bred by the Falenki Breeding Station – branch of the Federal Agricultural Research Center of the North-East named N.V. Rudnitsky. The early-maturing variety Udacha, the middle-early variety Nevsky, and the mid-season variety Chaika were used as standards. There have been identified hybrids with increased starch content (19 % and higher) on the 80th day of vegetation: early-maturing 172-13, medium-early – 165-00, 27-07, 13-18, mid-season – 182-13, 580-13, 252-18. The hybrids of the middle early group had the largest average size of starch grains: 165-00 (34.3±2.6 microns), 132-18 (36.0±3.0 microns), 233-12 (39.2±3.3 microns). Most of the hybrids had starch grains of regular rounded shape, accessions 233-12 and 232-12 – mostly irregular (angular) shape. In the course of the research, it was found that storing potatoes at the temperature of 3...4 ° C led to a decrease in the fraction of starch grains of very large size: in early-maturing varieties from 9.2 to 2.7 %, in middle early – from 13.5 to 5.0 %, in mid-season – from 9.6 to 3.2 %, which was due to starch resynthesis. As a result of the breeding work, promising potato hybrids of various maturation periods have been identified for transfer to state variety testing with improved agronomic traits, including high potential productivity: early-maturing 172-13, middle-early 233-12, mid-season 182-13 and 580-13.

The article provides the results of studying the accessions of potato in the nursery of dynamic test for 2019-2021 in agro-ecological conditions of the Volga-Vyatka region (Kirov region) by the yield and starch content in tubers. The objects of the study were 10 hybrids bred by Falenki Breeding Station - branch of Federal Agricultural Research Center of the NorthEast named N. V. Rudnitsky (FARC North-East). Early variety Udacha (Russian Potato Research Centre), middle-early variety Nevsky (North-West Research Institute of Agriculture), mid-season variety Chaika (FARC North-East) were taken as standard. Promising potato hybrids of different maturity groups with high potential yield have been selected: early variety 172- 13 (24.1 t/ha), middle-early varieties 27-07 (22.7 t/ha), 179-10 (22.9 t/ha), 233-12 (24.0 t/ha), mid-season 232-12 (22.4 t/ha). By favorable agro-weather conditions (2019) the highest yield (more than 28.0 % t/ha) was developed by hybrids: early 172-13, middle-early 27-07 and 179-10, mid-season 580-13. In the unstable environment of 2020 and 2021 the following hybrids were noted: middle-early 233-12 (19.6 and 27.7 t/ha) and mid-season 232-12 (19.2 and 24.0 t/ha). In the group of middle-early varieties with high starch content (15 % and more) during the years of study there were selected the hybrids 27-07, 179-10, 72-13, 182-13. The maximum accumulation of starch (18-21 %) was noted in mid-season hybrid 580-13. Significantly high inter-seasonal correlations by yield on the 60th day from the planting have been established, that characterized all the varieties as the most stable. On the 80th day there were noted weak inter-seasonal correlations that proved the instability of this parameter during the years which differed in weather conditions (strong interaction “genotype-environment”, that is the yield of variety samples during this period depended on the effect of environment factors). High inter-seasonal correlations by the parameter “starch content” on the 80th day have been revealed. The varieties and hybrids by the time of complete ripeness preserved the stability by this indicator unlike early harvesting periods when they were more dependable on the fluctuations of environmental factors.