No abstract

The main biotic factors determining the level of productivity potential of winter soft wheat in the Samara region are the amount of rainfalls before seeding and during the vegetation period, as well as the optimal temperature regime. The aim of the research was to evaluate winter soft wheat varieties at the final stage of the selection process (competitive variety testing) in different weather conditions. The research was conducted in Povolzhye SRISB-branch of SamRC RAS in 2016-2019. Winter soft wheat varieties were selected as research objects: Volga 86, Povolzhskaya Niva (included in the State register of selection achievements), Povolzhskaya Nadezhda (undergoing variety testing since 2019), as well as Erythrospermum 3730 and Erythrospermum 3765 varieties that have been distinguished over the years of research. Varieties were seeded on autumn fallow in four-fold repetition with a registered plot area of 25 m2. Meteorological conditions for 2016-2019 were analyzed, and their impact on the productivity and quality of grain of winter wheat varieties selected by Povolzhye SRISB was determined. Raindrop of the warm period (April-July)had a significant impact on the yield. The growth season of 2019 was characterized by less favorable weather conditions (the amount of raindrops to the norm – 65.3 %). The most adapted to the stress factors of the environment were varieties of local selection. In this regard, it is necessary to introduce varieties that are resistant to stress factors of the Middle Volga region, capable of producing stable grain yields with the use of mineral fertilizers.

The main task of selection programs in modern conditions of constantly changing climate is to obtain varieties that are resistant to abiotic and biotic factors, combining high potential of productivity and grain quality in the genotype. At the initial stage of the selection process, the use of varietal samples of various ecological and geographical origin remains relevant in order to create the source material. The research aim is to identify genetic sources of economically valuable traits for winter wheat breeding in the Middle Volga region. From 2016 to 2019, samples of national and foreign selection were screened. During the study of the collection material, contrasting meteorological conditions were observed. The most positive conditions for the assessment of varieties for winter hardiness and productivity were formed in 2017, and less favorable – in 2019. For all the years of research on winter hardiness and productivity, local varieties were distinguished: Povolzhskaya 86, Povolzhskaya Niva, Erythrospermum 3627, Erythrospermum 3730 (Povolzhsky NIISS). In 2016, the varieties of Don breeding center – Marathon and Severo-Donskaya-were distinguished. In 2017 the varieties showed high results showed Krasnodar research Institute of agriculture (Doca, Dmitry Viza, Zimtra), Samara ARI (Svetoch), ARI of the South-East (Kalach 60), Ukraine (Tsusperich, Manzhetiya). In 2018, the best studied indicators were varieties Moskovskaya 39 (ARI CRNZ) and varieties Zimnitsa, Yunona, Kristall (Krasnodar ARI), as well as the variety Kalach 60 selection niish South-East. In unfavorable 2019, the studied varieties included Doka (Krasnodar research Institute), Pearl of the Volga region and Victoria 95 (research Institute of the South-East). These samples were included in the laboratory's cross-breeding scheme.

Field studies were conducted in the forest-steppe zone of the Samara region on the experimental fields of the Volga Research Institute of Breeding and Seed Production in 2013 and 2015. The plots that were not littered (control) and were littered with weed hemp were compared. Due to its high plasticity to weather conditions and well-developed root system, weed hemp has a great competitiveness in relation to winter wheat. The spread of сannabis Ruderalis is focal in nature. Cannabis Ruderalis has contributed to the decrease in aboveground dry mass of wheat in 17-32 %, weight of ears per 13-18 %, the number of productive stems per 16-23 %, grain weight per spike on 4-51 %, mass of 1000 grains for 1-7 %, biological yield grain for 16-20% increase in the length of the ear by 7-10%, and the number of grains per spike by 3-8 %. The influence of weed hemp on the damage of grain by pests was ambiguous. The weather conditions of the spring–summer growing season of winter wheat have a great influence on the damage caused by wheat thrips. In the year with a dry and warm spring (2013), the number of grains damaged by wheat thrips was higher in the clogged areas than in the control. In the year with a wet and warm spring (2015), on the contrary, more wheat thrips-damaged grains were in control. During two years of research, an increase in grains damaged by bread bugs was observed in the clogged areas. Weed hemp has both a direct effect on winter wheat (a decrease in the elements of productivity) and an indirect effect (on the feeding process of wheat thrips and bread bugs).