In recent years, there has been a growing interest in the problem of asymmetry of bilateral traits in plants. Three types of bilateral asymmetry are found in the leaf blade, of interest to ecologists and evolutionists. A brief review of the methods used in testing bilateral asymmetry and developmental stability discusses their role in the development of homeostasis and ontogenesis. Intra-and interspecific differences are considered on the example of woody plants under the influence of factors influencing the expression of bilaterally symmetry. The influence of stress on the manifestation of asymmetric traits is considered. Apparently, the climate and topography of the area play a more important role, determining the plastic and fluctuating variability. The relationship of plasticity, evolutionary canalization, and development stability is considered on the example of woody and cultivated plants. Plasticity and fluctuation variability are in a relationship coordinated by climatic conditions, primarily lighting and temperature. This, in turn, determines the mechanisms of gene regulatory networks. Thus, phenogenetics, which studies the patterns and mechanisms of gene expression and ontogenesis, is based on the data from field botanical studies of plant shape and asymmetry. Epigenetic and population studies of phenotypic variations play a role in standardizing and finding suitable plant species and varieties.
The aim of the study was to find differences in the shape and asymmetry of the leaf blade of spring wheat grown at different dose of fertilizer. 52 landmarks were applied to the digitized images of the leaf blade and using the methods of geometric morphometrics the shape configuration was aligned. The components of the shape and asymmetry were estimated using Procrustes distances. Two types of asymmetry – fluctuating and directional were evaluated in Procrustes analysis of variance. The Procrustes distance showed a difference in the shape of the leaves of plants grown on mineral fertilizers in compare to the control (0.003; p <0.001). Visually, the width of the leaf blade of the plants formed with fertilization was bigger than in the control leaves. With an increase in the fertilizer dose, the Goodall criterion value increased from 30.0 to 46.2 (directional asymmetry; p <0.0001) and from 3.8 to 23.02 (fluctuating asymmetry; p <0.0001). There was no change in overall asymmetry of the experimental leaves, as Procrustean distance showed no difference between the centers of the sets in experimental variables (p ≥0.05). Thus, an increase in the dose of mineral-organic fertilizer influenced both the shape and the asymmetry including the structure of the bilateral asymmetry of spring wheat leaf blades, influencing the homeostasis of plant development.
The plastic variability, shape and asymmetry of the leaf plates of meadow clover (Trifolium pratense L) depending on various doses of fertilizer and soil cultivation methods were studied. A correlation between the index of plastic variability and the value fluctuating asymmetry was obtained (r = 0.23-0.63; p <0.05). Using the geometric morphometrics, the presence of directional asymmetry was confirmed, and a highly statistically significant variation in the shape of the sheet plate was obtained. In only one sample, a pure fluctuating asymmetry was obtained; in remain cases – a mixture of two types of asymmetry. The authors explain the effect of the declining developmental stability by a low dose of fertilizer, as well as a crop rotation scheme with a relatively low content of trace elements in the soil. A high dole of directional asymmetry verified the influence of genotypic variation on the asymmetry and shape of leaf blade and, therefore, a high dependence of phenotypic variation on the genotype.
Fluctuating asymmetry (FA) is a kind of asymmetry used to assess the stability of development, as the body’s ability to regulate its development on the phylogenetic level. Phenotypic plasticity helps plants to overcome negative effects of temperature variability, and allow to adjusting traits to adverse conditions. The aim of the study is to evaluate the level of plasticity and fluctuating asymmetry in leaf blade under influence of environmental factors. The leaf blades from urban population linden, Tilia spp. located in Moscow region, Russia were used. Fluctuating asymmetry was measured as FA = L – R / (L + R) in absolute value (L and R – left and right value of bilaterally symmetrical metric trait. Plastic variability was measured as PL = 1 – x/X (x and X – smallest and largest value of trait size). When some traits of a leaf blade had a high plasticity, other ones exposed instability of development with an increased FA value. The correlation PL - FA was changeable. In one site correlation r was – 0.69 (p<0.05; 2014; high temperature in May, up to 60% higher norm). The cold and humid vegetative season in 2017 revealed an increase in the plastic dimensions of leaf blades of the broad-leaved linden (Tilia platyphyllos Scop.) with increasing plastic variability of bilateral traits. We attribute results to the phenotypic deviation caused by low temperatures. The predominance of one type of variability was compensating by the weakness of other type variability most likely due to genetic epistasis.
Fluctuating asymmetry as an indirect deviation in the difference between the right and the left bilaterally symmetrical traits is considered an indicative symptom of stress. The results of urban populations studying Betula pendula, Tilia cordata, Quercus robur and Acer platanoides using the conventional normalizing method and the geometric morphometrics are presented. The relationship between the environmental stress of an urbanized area and asymmetry values was analyzed. 8-10% of the samples | R – L | / (R + L) had a normal distribution (K-S test, p <0.01). Only one trait in birch and one in linden significantly (p <10−4) reflected the stress effect in a direct relationship. Q. robur and A. platanoides had a wider range of FA, and the traits reflecting stress were different. No correlation was found between the FA and GMFA integral indices. High heterogeneity of values (R – L) was accompanied by the significance of directional asymmetry. The GM method extinguished the kurtosis in trait and showed a significant value of GMFA at kurtosis values γ < 2.5. The high heterogeneity (γ >2.5) accompanied by insignificant fluctuating asymmetry in Procrustes ANOVA. The authors emphasize that the toxic effect of pollutants can be associated with the relief and protection from winds in urbanized areas. The heterogeneity of the genotype of plantings from different nurseries increases the factor diversity, which makes the results of the analysis of developmental stability much more critical.
Introduction. Issues of formation of maximum expenses and their forecast, risk extreme flow rates on the rivers of Armenia represents a significant interest for consumers of water resources. The works of scientists of the Republic of Armenia are devoted to the solution of this problem: (Vardanyan T. G., Muradyan Z. Z., 2014), forecasting the maximum water flow for the Jermuk hydrological station on the Arpa River (Misakyan A. E., Azizyan L. V., Azizyan A. O., 2014), assessment of long-term fluctuations of the maximum runoff of rivers in the mountainous territories of Armenia in the context of global changes climate (Margaryan V. G., Ovcharuk V. A., Goptsy M. V. Borovskaya G. A., 2020). This paper analyzes the risks of extreme spring runoff river flood Arpa (Republic of Armenia) related to degree assessment the danger of flood waves. Problem solving can help prevent economic damage and loss of life, and raise issue of extreme runoff risk management. Unlike listed works, this study uses longer series of actual observations and a certain section of the river. Purpose of research. Assessment and management of hydrological risks during the period spring flood in the river basin Arpa. Methods. The work used the methods: of mathematical-statistical, extrapolation, analysis, analogy, correlation. Results. Correlations between the values of the modulus of extreme costs 1 and 10 % security and weighted average height drainage basin, as well as the relatively close relationship between the average values of extreme costs for the periods 2001–2020 and 1981–2000 biennium, integral curve of extreme flow rates of floods in the section Yeghegnadzor of the Arpa River. These dependencies can be used to preliminary estimates of the maximum runoff of the spring flood unexplored rivers of the considered territory. To manage and planning of extreme water resources, multifactorial dependencies that can be applied when making forecasts. The rate of extreme flow rates of the spring flood has been calculated, coefficients of variability (Cv) and skewness (Cs), absolute maximum costs of various security. Conclusion. Average values of extreme water flow rates of the river. Arpa for the period 2001–2020 mostly inferior or slightly higher than average values for the period 1981–2000. In the Arpa river basin from 1981 to 2020 year mainly there is a tendency of decreasing extreme river flow, that is, the degree of risk of extreme expenses.
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