Introduction

In recent years there are more and more studies on the effect of different growth regulators on plants. In conditions of intensive chemicalization in agriculture, the increase in yields of fruit-and-vegetable and flower products is accompanied by the increase in the removal of all elements of mineral nutrition, which forms the need for the fertilizers and plant growth regulators application. Studies of Zemnitskaya D. E. showed the reaction of plant test systems to pollutants of anthropogenic origin in order to rationally address issues of protection of natural ecosystems [3, 9, 12]. The first synthetic hormone imitating the natural one was ethylene, which was widely used in agricultural production and in low concentrations increased the fruit-vegetable and ornamentals fruits set-up, causing the formation of female flowers; it was involved in the response of plants to stress factors, caused aging of leaves and flowers, leaf and fruit fall, and also regulated the plants growth [1, 8].

Lately the world has produced a large number of plant growth regulators (PGR). Currently in agriculture PGR is actively used to obtain, distribute and use new knowledge and technical solutions in innovative activity. Biostimulators market growth has reached $2.5 ml USA. PGRs are safe for humans and environment. Organic origin and environmental friendliness of biostimulators increased the demand for them among agricultural producers. PGR have a significant impact on the growth, physiological and shaping processes occurring in plants, and that accounts for the sharp growth the biostimulants market.

A wide range of growth regulators effects is as follows: maturation and improved fruit setting accelerates, mechanized harvesting is fascilitated, drought and frost resistance of plants increases, vegetative plant propagation improves, plants immunocorrection yielding capacity and quality of grown products increases,, as well as product safety [2, 4, 5, 6].

In this regard we have studied the effect of plant growth regulators on seeds and vegetating plants of three Antirrhinum varieties grown in the central zone of the Krasnodar Territory.

Antirrhinum (Antirhinum) or Snapdragon, belongs to the genus of herbaceous plants of the plantain family. In the wild these plants are found in the zones with a warm climate, and most species are found in North America. In Russia the popular name of Antirrhinum is “sobachki”, which means “dogs”.

The genus Antirrhinum combines many species of perennial plants, including climbing plants. In nature there are dozens of species and even more are bred in the course of many years of breeding work.

Gardening is one of the main methods of radical transformation of the natural conditions of entire regions. Today the issue of flower beds design is one of the most urgent. Growers love Antirrhinum for its brightness, color saturation and diversity in the use of its varieties and hybrids. This accent plant is included in the assortment of summer plants for landscaping balconies and for planting in various flower beds, including in ornamental gardens. It can be grown in a pot, on a flower bed, in natural gardens, in which the reservoir mirror will play the role of a lawn. Some varieties with high peduncles are especially valuable for florists, so that even the cut Antirrhinum continues blooming for up to two weeks [5, 7]. Studies of Konik O. G., Lysenko S. G., Utyakina T. A. confirm that the duration of flowering is one of the most important characteristics of ornamental plants [10, 11, 13].

Results and discussion

Describing the period of research we can say that the conditions of the central zone of the Krasnodar Territory are favorable for the growth and development of Antirrhinum and if the optimal timing of sowing and planting, high crop cultivation, the use of a scientifically based fertilizer and irrigation system is observed high-quality products of this ornamental plant can be obtained.

According to the bush height and shape the studied varieties belong to the tall and semi-tall groups.

According to literature sources, the height of  Antirrhinum  plants belonging to a tall group ranges between 60-80 cm, the shape of the bush is pyramidal, the main shoot is located lower than that of the gigantic ones, but higher than the first emerged shoots.  Antirrhinum varieties belonging to the semi-tall groups – are highly branched plants with the height of 45-60 cm. The main shoot of this group plant is at the level of the first order shoots. In both groups there are early -, medium-and late- flowering varieties.

When choosing varieties for a flower garden, we took into account not only the color of the flowers and the height of the plants, but also the degree of their branching.

We conducted field experiments in the period from 2017 to 2019 in the Botanical Garden of the “I. T. Trubilin Kuban State Agrarian University” with the following varieties of antirrhinum: «Tsvetochniy dozhd’», «Brazilskiy carnaval» and «Snezhinka». Before sowing, the seeds were soaked in solutions of growth regulators, which contributed to an increase in their germination energy by    15-20 %, and their germination rate by 5-15 % (Table 1).

Table 1

Growth regulators effect on sowing qualities of Antirrhinum seeds (average for 3 years).

During the study, phenological observations were made. In Table 2 the following data are presented: date of sowing, germination, emergence of leaves, formation of buds and flowers, the beginning and the end of flowering; and the biometric measurements: determination of plants height, leaves length and width, pedicle length and flower diameter, the main shoot branches number.

The repeatability of the experiment is 3 times. The plants were placed on a plot of 10 m2, the planting scheme is 50×25 cm. The feeding area of one plant is 0.125 m2. The placement on a flower bed is sector-based. The area of the experimental plot was 0.37 m2, plants care growing on it was carried out according to the generally accepted method.

When observing the growth and development of plants, it was found that the varieties we studied differed in many ways. The control variant was the «Brazilskiy Carnaval» variety, well adapted to the conditions of the central zone of the Krasnodar Territory. Landscape designers have been using this variety of Antirrhinum in the design of flower beds since 2003.

«Tsvetochniy Dozhd’» appeared in the garden centers of our region in 2009, and «Snezhinka» — in 2011.

Seeding of Antirrhinum varieties was carried out in cassettes No. 84. The soil mixture for growing seedlings consisted of turf, peat, sand in a ratio of 3:1:1 Compost or humus were not added, because this plant responds poorly to organic fertilizer (seedlings will be unstable to «Black Leg» disease).

Biostimulators reduced the number of days from germination to the beginning of flowering.

When sown on January 30, 2017, the earliest seedlings appeared on February 08 in the «Tsvetochniy Dozhd» variety, the later ones — on February 10 and 11 in the «Brazilskiy Carnaval» and «Snezhinka» varieties. The same trend was observed in the next two years (2018 and 2019). The difference between the options for the seedlings emergence in 2-3 days may be due to the influence of micro-conditions of the Kuban State Agrarian University Botanical garden greenhouse. Leaves, the first  buds, and flowers appeared in the same order. Data in Table 2 for the average of, 3 years of research, show that biostimulators (table. 2 and 3) shorten the period from sowing to the emergence of  single and mass seedlings .

Table 2

Biostimulators effect on the phases of single and mass seedlings emergence of Antirrhinum varieties, 2017-2019 (average for 3 years)

Table 3

Biostimulators effect on the development of Antirrhinum seedlings, 2017-2019 (average for 3 years).

The growth and development phases used to occur earlier in the «Tsvetochniy Dozhd» variety. A little later, these phases started in the varieties «Brazilskiy Carnaval” and «Snezhinka». Planting seedlings in the open ground was carried out in the third decade of April as one of the main advantages of Antirrhinum is its cold resistance.

The flowering phase came first in the «Tsvetochniy Dozhd» variety. Flowering in  the varieties «Brazilskiy Carnaval” and «Snezhinka» came 2-2. 5 weeks later. The  height of the plants ranged from 45 to 75 cm. The Diameter of the flower – from 2 to 3 cm. The largest flowers in the inflorescence were in the variety «Brazilskiy Carnaval”. The largest number of flowers in the inflorescence was in the variety «Snezhinka» (11 PCs.) and the smallest – in the variety «Tsvetochniy Dozhd» (7 PCs.). Decorative qualities of the studied varieties of Antirrhinum are presented in Table. 4.

Table 4

Decorative qualities of Antirrhinum varieties, 2017-2019 (average for 3 years)

In the observed varieties of Antirrhinum, the height of the stem increased by 5.2-10.1%, the diameter of the flower – by 10-13%, the number of simultaneously blooming flowers up to 18 %. The results obtained in our experiments are consistent with the data of the researchers studying the action of plant growth regulators.

The flowering of the plants we studied stopped in the third decade of November, with the onset of the first frosts.

Conclusion

Thus, the varieties of Snapdragon studied by us differed in decorative qualities and flowering duration and are recommended for use in landscaping areas of the central zone of the Krasnodar Territory. For use in phytodesign and Floristics the varieties belonging to the tall group – «Brazilskiy Carnaval” and «Snezhinka» are recommended. The biostimulants we used reduced the number of days from germination to the beginning of flowering, allowing the extension the flowering period of the varieties Antirrhinum using different variants, which should be taken 9into account and used when making flower beds of continuous flowering.