Leaf pigment complex of spring soft wheat cultivars of different maturity groups under different moisture regimes

Creation of new higher productive cultivars of cereal crops is often linked with straightening of degree of resistance to abiotic environmental factors. Indirectly this degree of resistance could be estimated on quantitative change in leaf pigment composition. There is practical interest to compare the activity of pigment complex of flag leaves of wheat cultivars belonging to different maturity groups that could give information on direction of breeding improvement of plant physiological-and-genetic traits under different ecological conditions. Plants of nine breeding lines and two standard cultivars grew in 2016–2018 at the experimental field of FARC of North-East (Kirov) under continental climate conditions with moderately cold winter and warm summer. The study of flag leaves pigment complex allows to discover differences between early and middle-ripening cultivars on investigated parameters in different hydrothermal conditions. During the study years, middle-ripening cultivars accumulated more chlorophyll a than the early ones. On average this excess was about 10%. The studied cultivars were differed on distribution of pigment between structural parts of photosystems: middle-ripening cultivars had more chlorophyll a in reaction centers whereas the amount of the pigment in light-harvesting complexes was not differed. Hydrothermal conditions significantly influenced the differences between cultivar groups. Thus, under dry conditions the content of chlorophyll b and carotenoids in flag leaves of cultivars belonging to both group of maturity had no significant differences. Under normal or moist conditions middle-ripening cultivars contained 11,0–12,6% more chlorophyll b and 7,6–23,1% more carotenoids than the early cultivars. Under dry conditions the two groups of cultivars significantly differed on mass ratio chlorophyll a/b: in the middle-ripening cultivars it was 5,0% higher than in the early ones. Based on chlorophyll a and b content at flowering stage breeding lines С-64, С-65, С-103, and С-129 were selected. The amount of chlorophyll in these genotypes was significantly higher than in Margarita standard cultivar. Within the group of early cultivars, no one exceeded Bazhenka standard by the pigment content. The cultivars of this group reacted on abiotic growing conditions change very much (the amount of precipitations and air temperature): the coefficients of chlorophyll a content variation were 6,5–16,3%, of chlorophyll b content – 26,9–29,7%, of carotenoids content – 4,1–17,2%.