Differentiation of sunflower lines by cold tolerance

Abstract

Purpose. The study purpose was to differentiate sunflower lines by cold tolerance and economically valuable traits for breeding hybrids with an increased adaptability to environmental stressors at the initial ontogenetic stages.Material and methods. Lines from a working collection of the Laboratory of Sunflower Breeding and Genetics of Plant Production Institute Industry named after V.Ya. Yuriev of NAAS (sterility fixers and fertility restorers) were taken as the test material. The field experiments were carried out in the scientific crop rotation fields of the Institute (township Elitne, Kharkivska Oblast, Kharkivskyi Raion). The field experiments were planned and conducted in accordance with conventional methods, with due account for the zonal features of sunflower cultivation.In the laboratory, the breeding material was assessed for tolerance to low temperatures by cold germination of sunflower seeds, with due account for the temperature mode peculiarities (5°C) and the germination length of sunflower line and hybrid seeds in a refrigerated thermostat (10 days). Cold tolerance was determined by germinability of sunflower seeds at 5оС related to the control (25оС). The resistance of breeding material to the causative agent of downy mildew was assessed in the laboratory by the method developed by YeM Dolgova et al. The oil content in seeds was determined by nuclear magnetic resonance. Data were statistically processed using Excel software.Results and discussion. Using cold germination of seeds harvested in 2016-2018, we differentiated sunflower lines by tolerance to low temperatures at the initial ontogenetic stages.The low temperature tolerance of lines – sterility fixers (sterile analogues) was found to range 4.7% to 88.8%. A high cold tolerance was noted in lines Skh 93 A (88.8%), Skh 1006 A (79.3%), and Skh 777 A (76.4%). The cold tolerance of sunflower lines – fertility restorers was revealed to vary in the range of 11.3–93.6%. A high tolerance to low temperatures was noted in lines Kh 720 V (93.6%), Kh 4913 V (77.9%), and Kh 15146 V (62.0%).The field results characterized the lines - sterility fixers (sterile analogues) and fertility restorers by breeding characteristics and their year-to-year variability. The valuable economic features, morphological traits and resistance to the downy mildew pathogen are described for lines – sources of cold tolerance.Conclusions. By the laboratory method of cold germination, the sunflower lines were differentiated by tolerance to low temperatures at the initial ontogenetic stages. Five lines with a high cold tolerance - Skh 93 A (88.8%), Skh 1006 A (79.3%), Skh 777 A (76.4%), Kh 720 V (93.6%), and Kh 4913 V (77.9%) - were identified as sources of this trait. The genotypic diversity of the sunflower lines was evaluated by breeding characteristics and their year-to-year variability. The lines – sources of cold tolerance were characterized by valuable economic features, morphological traits and resistance to the causative agent of downy mildew