Dependence of pigment content in meadow clover leaves on soil phosphorus level

In 2018-2019, the effect of different levels of soil phosphorus on the pigment complex of the clover (Trifolium pratense L.) leaves was assessed. Total chlorophyll content was 15.34-19.05 and 11.47-14.10 mg g- 1 dry matter, of which Chl a accounted for 9.64-11.36 and 6.67-7.98 mg g-1 (2018 and 2019 respectively). Carotenoids content varied within 2.69-3.12 and 1.52-1.88 mg g-1 in 2018 and 2019 respectively. Weight ratio of total chlorophyll/carotinoids (5.7-6.7 in 2018 and 6.8-9.6 in 2019) gives the grounds to consider that there was not disorders in structure of the pigment complexes of leaves in both year. There were statistically significant linkage of level of soil phosphorus with Chl a (r = 0.536-0.743) and Chl b (r = 0.725-0.748) in cooler conditions of 2019. In wormer 2018, these links were insignificant (Chl a = -0.146 to -0.286 and Chl b = -0.257 to -0.275). Correlation between phosphorus content in soil and carotenoids content in leaves was insignificant in all cases. Chl pigments showed a polynomial second order relationship with level of soil phosphorus. In 2019, these relations was statistically significant at p ≤ 0.05 (R2 = 0.68-0.76) for both chlorophylls. Under conditions of 2018 these relations was insignificant (R2 = 0.10-0.43)

Genotypic differences in reaction of barley root system on Mn and Fe toxicity

The study was performed to determine genotypic differences in spring barley cultivars on resistance to 1.1 mM manganese and 1.2 mM iron at early stage of growth. Resistance level was estimated by morphologic (root length) and physiological (level of antioxidant activity, accumulation coefficient) parameters. Morphologic trait was less sensitive for cultivar differentiation in compare with physiological one. Based on relative root length index all cultivars were classified as resistant having resistance index about 80-94% for Mn and 67-76% for Fe. Reaction to Mn by change in antioxidant activity was uniform: it was increased from 4% in cv. Bionic up to 28% in cv. Farmer. According to reactions to Fe, studied cultivars were divided into three groups: high resistant (cv. Belgorodsky 100 and Farmer; increase in antioxidant activity 2 and 18% accordingly), weak resistant (cv. Forward, Bionic, and 29-11; changes were insignificant) and sensitive one (cv. 346-09; 8%-decrease in activity). For manganese accumulation coefficient is higher than for iron. The maximum accumulation coefficient for manganese was characteristic of cv. 29-11 (190), for iron - cv. Bionic (120). The genotypic specificity for root antioxidant activity can be used as a rapid test of resistance to manganese or iron in initial breeding material