The structure of variability of traits of seed productivity of Allium charadzeae Tschlok in the mountainous conditions of Dagestan

As a result of the experimental studies, results were obtained on the variability of the traits of seed productivity of the narrow-local endemic of Dagestan – Allium charadzeae under various conditions along the altitude gradient. Analysis of the data obtained revealed significant differences in the indicators of seed productivity of individuals. The actual seed productivity is significantly inferior to the potential, which indicates a low degree of realization of the potential for seed formation in mountainous conditions. With an increase in the height above sea level of the experimental plots, the absolute indicators of traits of seed productivity decrease (the number of fruits in the umbrella from 14.9 to 8.5, the number of flowers in the inflorescence from 24.7 to 12.1, the number of seeds in the umbrella from 26.6 up to 19). At the same time, the relative indicators, the percentage of fruit blossoming from 60.5 to 71.2 and the coefficient of seed production from 0.17 to 0.27 increases. As a result of the analysis of variance, a significant influence of the conditions of the year and altitude above sea level on the studied characteristics was revealed.


Introduction
The study and conservation of biological diversity, the identification of species adaptations in the process of evolution, as well as adaptive traits and reactions, methods of survival are among the most important scientific tasks in modern biology. Various natural and climatic conditions of Dagestan, in particular the strong dissection of the relief and the presence of geographical barriers, are the reasons for the great floristic diversity and endemism, which are most characteristic of the communities of upland xerophytes. In this regard, the question of studying endemic, rare and endangered plant species becomes relevant, since only a comprehensive study of the biology of species, intra-and inter-population variability, tactics and strategies of survival can provide an objective assessment of the state of cenopopulations of endemic, rare species and organize their effective protection. Some endemic species with reduced adaptive capabilities disappear, being unable to adapt to changing environmental conditions, unable to withstand competition from other species. Due to their extreme ecological specialization, they are easily vulnerable and therefore require special attention [1].
In the study of the taxonomy of this genus, the method of molecular genetic analyzes has been widely used in recent years, including the use of some local endemics of the Caucasian flora for this purpose [3][4][5][6].
Particular attention should be paid to the study of seeds and seed productivity as the basis for the reproduction and introduction of endemic species. The seeds of blossoming plants are the main elements of a system of adaptive or reproductive strategies. Among the characteristics of seeds closely related to the reproductive strategy, their size and weight are important. The quantitative characteristics of seeds are also of interest in the development of seed science of introduced species. Qualitative characteristics of seeds (shape, surface traits) are also used in the taxonomy of the genus Allium [7].
Seed productivity is one of the most important indicators of the adaptation of a species to specific habitat conditions. Determination of the potential seed productivity and the degree of its realization makes it possible to characterize the reproductive capabilities of the species, its ability to reproduce itself in cenopopulations. The ratio between the indicators of seed productivity, or the coefficient of seed production, is considered a reliable indicator of the adaptation of a species to certain environmental conditions and a criterion for successful seed reproduction and the well-being of the population [8][9][10]. Experimental studies allow a deeper study of the features of the formation of the population structure of species, to reveal the patterns of micro-evolutionary processes in a changing environment along the altitude gradient, depending on the combination of environmental factors (abiotic and biotic).
This paper presents an analysis of the variability of the traits of seed productivity of the narrow-local Dagestan endemic Allium charadzeae, collected from different heights above sea level and grown under experimental conditions on two bases.

Methods
The material for the research was A. charadzeae plants obtained by sowing seeds collected at different altitudes (1000, 1240 and 1450 meters above sea level) in the vicinity of the village of Arkas, Buinaksky district of the Republic of Dagestan. A. charadzeae is a narrow-localized endemic to Dagestan, found in the middle mountain zone. It grows on rocky places on the southwestern slopes, within 1200-1500 m above sea level. Experimental studies were carried out for three years (2018-2020) at various altitudes at the Tsudahar (1100 m) and Gunib (1750 m) experimental bases of the Mountain Botanical Garden. Seed productivity was assessed according to generally accepted methods [9,10].
The potential seed productivity was determined by the number of ovules formed on the plant, and the real one was determined by the number of ripened seeds. Percentage of fruit blossoming -the ratio of the number of fruit set to the number of flowers in the inflorescence, expressed as a percentage. The coefficient of semenification is the ratio of the indicators of the real seed productivity to the potential one. The reproductive effort efficiency is the ratio of the mass of seeds in the inflorescence to the mass of the inflorescence. To analyze the dimensional, numerical and weight characteristics, 10 umbrellas were collected in the phase of full seed ripening. In laboratory conditions, cameral processing (measurements and counting) of the collected material was carried out. The mass of the inflorescence, the mass of seeds in the inflorescence, and the mass of 100

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BIO Web of Conferences 43, 0101 (2022) seeds were determined by weighing on an electronic balance.
Phenological observations were carried out throughout the growing season according to the generally accepted method, which is based on the registration of successive phases of development and growth of plants, characterized by clearly expressed morphological changes during the year [11]. The beginning of the mass onset of the phase was considered the moment at which at least 50% of the composition of the sample of plants taken under observation entered.
Statistical processing of the obtained data was carried out using variance, correlation, discriminant analyzes [12], using the statistical software package Statistica v. 13.

Results
A. charadzeae -a narrow-local Dagestan endemic was described by N. B. Cholokashvili [13] based on the collection of herbarium material above the village of Arkas (Untsukulsky district) near a spring on the rocks, referring to the section Daghestanica (Tschlok.). However, later by G. A. Kudryashova [14], this species was reduced to the synonym A. gunibicum. The studies carried out -morphological and molecular genetic [15,16] revealed that the description as a separate species was justified.
The degree of conformity of ecological conditions and the vital state of the population can be assessed on the basis of the potential and actual seed productivity. The results of studies of the variability of the traits of seed productivity of A. charadzeae at different altitude levels are shown in Table 1. Note: X -mean, ± Sx -standard error, CV -coefficient of variation in % (the same note in Tables 3,6,9).
Studies have shown that with an increase in the height above sea level of the experimental patch, the average values of the weight and numerical traits of seed productivity of A. charadzeae decrease ( Table 1). Mass of inflorescence from 93 mg to 46.5 mg; the number of fruits from 14.9 to 8.5 pieces; the number of flowers from 24.7 to 12.1; the number of seeds in the umbrella from 26.6 to 19.0; seed mass per inflorescence from 32.0 mg to 21.2 mg; the mass of 100 seeds decreases slightly from 121.2 mg to 114.4 mg. At the same time, the relative indicators, the percentage of fruit blossoming from 60.5 to 71.2, the coefficient of semenification from 0.17 to 0.27, and the reproductive effort effeciency of from 0.34 to 0.45 increases. The most variable traits are: the mass of seeds in the inflorescence, the coefficient of seed production, the number of seeds per one fruit (CV = 23.1-42.6%), and the most stable traits are the percentage of fruit blossoming and the mass of the inflorescence (CV = 8.9-15.8%).

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BIO Web of Conferences 43, 0101 (2022) To clarify the effect of the conditions of the test sites at different altitude levels, an analysis of variance was carried out. The results of the analysis showed that the factor "height of the experimental patch" significantly and highly reliably affects the characteristics of the inflorescence mass, the number of fruits, the number of flowers, the number of seeds in the inflorescence, the mass of seeds in the inflorescence, the percentage of fruit blossoming, the reproductive effort efficiency. The share of the influence of this factor is from 29.1 to 91.8%. No reliable influence of the factor on the traits was found for the mass of 100 seeds and the number of seeds per one fruit.  Tables 4, 7).
At different altitude levels, the ecological factors of the habitats of plant species vary greatly in different years within the same time periods. Among the multitude of abiotic factors, the main and significant role in the variability is played by the terrain, the exposure of the slope, the steepness of the slope, including the height difference. And as a result of fluctuations in different-year environmental conditions in a particular cenopopulation of plants, variability of the characteristics of individuals of this species arises. How the temperature changed over the time of observations in 2017-2019 at the Tsudahar experimental base is shown in Figure 1. Characteristics of the traits of seed productivity of A. charadzeae in different years are presented in Table 3. Indicators of seed productivity are different from year to year. The maximum values were obtained in 2018, and by 2020 they are decreasing. The decrease in the number of fruits of set seeds can be caused by several probable reasons, including unfavorable environmental conditions during the period of laying of reproductive organs and fruit formation and an insufficient number of pollinators in 2020. At the same time, the mass of 100 seeds, the percentage of fruit blossoming, the coefficient of semenification, the reproductive effort efficiency of increase.
As a result of the analysis of variance, it turned out that different-year conditions significantly and highly reliably affect the traits of inflorescence: mass of inflorescence, number of fruits, number of flowers, number of seeds in an inflorescence, mass of seeds in an inflorescence, and per mass of 100 seeds (Table 4). blossoming, the coefficient of seed production, the reproductive effort efficiency of and the number of seeds per one fruit was found. To determine the relationships between the studied traits of seed productivity at different test sites in A. charadze individuals, the correlation coefficients were calculated (Table 4).
Correlation coefficients (r) between the traits of seed productivity of A. charadzeae tested in more severe conditions at an altitude of 1750 m above sea level (Gunib plateau), in most cases, increase (Table 5). Table 5. Correlation coefficients between the traits of seed productivity of A. charadzeae in different test patches. The degree to which the ecological conditions of modern habitats correspond to the biological requirements of the species and the vital state of the population can be assessed on the basis of the potential and actual seed productivity. Characteristics of the traits of seed productivity of three samples from different altitude levels of A. charadzeae are presented in Table 6.  The analysis of the obtained data revealed significant differences in the parameters of seed productivity of A. charadzeae individuals (the number of semenification) both among themselves and the differences between the populations in terms of these indicators, depending on the height of the place of collection of the material. The factor "height of the material collection patch" is understood as the origin of samples collected along the vertical gradient, the aggregate of biotic and abiotic factors of the natural habitat, under the influence of which the formation of the genotype of the population took place. In a comparative analysis of the average values of some elements of seed productivity of samples of different heights, it was found that the traits of inflorescence (mass of inflorescence, number of fruits, number of flowers in an inflorescence, number of seeds in an inflorescence) decrease with an increase in the height of the collection patch. This significantly increases the mass of 100 seeds and the reproductive effort efficiency -the ratio of the mass of seeds to the mass of the inflorescence. The level of variability of the elements of seed productivity is different. The most variable are the traits: mass and number of seeds in the inflorescence, the coefficient of seed production. Less variable -the mass of 100 seeds, the percentage of fruit blossoming ( Table 6).

Traits
As a result of the one-way analysis of variance for each of the studied characters, interpopulation differentiation was revealed for a number of quantitative characters of A. charadzeae (Table 7). 14 -It turned out that the greatest contribution to inter-population differentiation during the introduction on the Tsudahar experimental base, taking into account the factor "height" (the place of collection of material), is made by the following characteristics: the number of flowers, the number of fruits, the percentage of fruit blossoming (Figure 2). Inter-population differences by traits: the mass of seeds in the inflorescence, the coefficient of semenification and the number of seeds per fruit are not reliable. Fruiting efficiency of A. charadzeae in the studied populations, the high is 60-75%.
Discriminant analysis showed that the greatest differentiation between populations is determined by the following features: mass of inflorescence, number of fruits. The rest of the traits turned out to be of little information (Table 8, Figure 3).  Thus, the following diagnostic features have been determined: mass of inflorescence, number of fruits, which are the most delimiting populations of A. charadzeae.

Discussion
In our previous works, we carried out studies concerning the seed productivity of A. gunibicum [17]. A comparison of the seed productivity of two closely related species grown under the same culture conditions showed that the mass of inflorescence, the number of seeds per inflorescence, and the mass of seeds per inflorescence in A. gunibicum are significantly higher than in A. charadzeae. For the rest of the characteristics of seed productivity, these species do not differ significantly.
It is also interesting that high rates of fruit setting were also established for other species of the genus Allium. Thus, for A. grande, these indicators are 60-65% [18], for A. gunibicum -70-80% [17].
As a result of a comparative analysis of the variability of the traits of seed productivity of the narrow-local endemic of Dagestan, A. charadzeae, significant differences were revealed in the indicators of seed productivity of individuals (the number of fruits, ovules, seeds, the percentage of fruit blossoming, the coefficient of semenification) both among themselves within one year of research and over the years. As a result of the one-way analysis of variance, a significant influence of the conditions of the year, altitude, on the studied characteristics was revealed.
The system of correlations between morphological characters in plants changes under the influence of ecological conditions and genotypic rearrangements. Deterioration of environmental conditions and a decrease in adaptability in most cases causes a general increase in the strength of connections [19].

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BIO Web of Conferences 43, 0101 (2022) Correlation coefficients between the characteristics of A. charadzeae tested in more severe conditions at an altitude of 1750 m above sea level in the Gunib plateau, in most cases, increase. The mobilization of the system and tight connections between the elements ensure the preservation of the species in adverse conditions. The most efficiently separating populations were identified: the mass of the inflorescence and the number of fruits.

Conclusions
The study of the structure of variability of seed productivity is of great importance for understanding and evolution of the structure of populations in the process of speciation. It is known that high seed productivity is one of the conditions for maintaining the optimal number of individuals in populations. During the evolution of populations and the emergence of intra-specific differentiation, the very structure of seed productivity changes, i.e. the ratio between different components: between the number and weight of seeds, the number of fruits and seeds, and the number of generative shoots. The study of certain components of seed productivity makes it possible to judge the effectiveness of reproduction systems in specific environmental conditions.