1. Introduction

The tulip is an herbaceous, beautifully flowering plant that belongs to the bulbous group. According to biological characteristics, the tulip is a perennial, wintering in the open ground, despite the fact that it has an aboveground part and roots are annual. In spring, the plant has a short growing season, entering a dormant period in summer, after the death of the aboveground part [1, 6].

According to scientific research, the determining criterion for the decorative effect of beautiful flowering plants are flowers: their size, terry, color [4, 8]. Prolonging the duration of flowering and identifying the optimal size of bulbs is currently relevant, which is what our research was devoted to.

The bulbs of tulips, like those of other bulbous crops, are divided by analysis. The analysis allows you to determine the quality of the bulb and the depth of its planting. Most varieties of tulips tolerate winter well. They are also not afraid of spring temperature changes. Therefore, the plants are highly resistant to frost and harsh winters [7, 10, 11] .

The research was carried out in the central zone of the Krasnodar Territory, in a greenhouse of a personal subsidiary farm.

The bulbs of «extra» or 1-st analysis weighing 30 g are suitable for distillation — for varieties from the Darwin hybrids class and at least 25 g — for varieties from other classes. It is impractical to use bulbs of smaller sizes, since this dramatically reduces the decorative qualities of flowers and the number of flowering plants [10]

We started preparing the bulbs for distillation even during their growth in the open ground: careful care was carried out for the plants intended for distillation, which contributed to the increased accumulation of nutrients in the bulbs. The care consisted in the implementation of a full range of agro technical measures and mandatory decapitation of the bulb.

Prior to the start of the distillation process, bulbs of all sorts were cleaned from the outer, covering scales in order to identify the observed foci of the disease and timely culling of the affected planting material, as well as to accelerate the rooting process [4, 9]  . If the dense covering scales are not removed, the roots will grow along the bulb, thereby pushing it to the surface, which, ultimately, will lead to a decrease in the decorative qualities of tulip flowers.

To carry out distillation in order to obtain tulip flower products, it is recommended to use extra, 1-st and 2-nd parsing bulbs. However, the required high-quality planting material is not always available. At the end of the growing season, large bulbs divide; often many daughter bulbs are formed, smaller than recommended.

2. Materials and methods

The laying of the experience was carried out in the conditions of a personal subsidiary farm. The planting of tulip bulbs of the Black Parrot variety was carried out on 10.20.2021, after soaking in KMnO₄ solution in order to disinfect the planting material.

Bulbs of different sizes, well-formed, were selected for planting all variants of the experiment. Due to the fact that the size of the bulbs in the variants of the experiment was not the same, in order to overcome the differences in the standards of their assessment, we adopted a unified approach in assessing the quality of bulbs by analysis: D-1, D-2 (baby); L-1, L-2, L-3 (bulbs 1, 2 and 3 parses) [2, 3, 6]. To study the influence of the size of bulbs on the decorative qualities of plants, the following options are outlined: 1 – D-1 (the smallest), 2 – D-2 (small), 3 – L-3 (medium), 4 – L-2 (large), 5 – L-1 (the largest).

In this experiment, we used 5 fractions of the variety, 10 plants per plot. Each faction presented a variant. In total, 5 options were studied. The repetition of the experience is threefold. The plots were placed in the variants of the experiment in one tier. Plots in one repetition are 5 by 2 m long, 10 plants on the plot. The area of one plot was 0.20 m², and the repetition was 2 m². The experimental plot occupied 10 m².

3. Results and Discussion

The growth and development of plants are influenced by various indicators, including the quality of planting material. Therefore, in our experiment, we determined whether the formation of plants and their decorative effect depends on the size of bulbs and observed the development of plants in the experimental variants (Table 1).

Table 1

The size of different fractions of bulbs of the Black Parrot variety

When growing corm and bulbous plants, and in particular the tulip, one of the important agronomic techniques is the use of high-quality planting material (bulbs), which affects the conditions of growth and vegetation of plants.

Bulbs of the studied variety of parrot tulip began to grow in the first decade of March 2022 (Figure 1). Observation of experimental plants showed that the onset of the leaf regrowth phase depended on the size of the bulb.

In our studies, this information has been confirmed and is presented in Table 2.

Figure 1. Planting of tulip bulbs, 20.10.2021 g	Figure 2. Flowering of the Black Parrot tulip in the experimental site

Table 2

The regrowth of tulip leaves in the Black Parrot variety when planting 20.10.2021 g

When planting bulbs of all fractions in the soil at the same time, on October 20, the leaves began to grow earlier than everyone in the first version of the experiment – D-1 (02.27.2022 g). In the second variant of the experiment (the bulbs of a large baby (D-2) were germinated, we noted the regrowth of leaves 2 days later.

The regrowth of tulip leaves of the L-3 fraction began on 03.05.2022, 6 days later than the D-1 fraction and 4 days later than the D-2 fraction. When planting bulbs of the L-2 fraction, we noted a single regrowth of leaves on 03.07.2022, and in the fifth variant of the experiment, bulbs of the L-1 fraction began to grow later than all – on 03.10.2022 – 3 days later than the plants of the previous version of the experiment.

As the results of numerous studies have shown [5, 6, 9], with an increase in the size of the bulbs, the phase of regrowth of the leaf apparatus came later. The phase of regrowth of mass leaves in tulip plants in all variants of the experiment occurred with the same regularity.

The development of plants in the variants of the experiment was also different. The data in Table 3 indicate that with an increase in the size of the planting material, the development of tulip plants was delayed.

When planting the smallest bulbs (D-1), the appearance of buds was noted on 29.03.2022.g., flowering – 02.04.2022 g. April, 4 days later. In the second variant of the experiment (D-2), the formation of buds was noted on 30.03.2022, 1 day later than the previous one, and the formation of flowers 2 days later (04.04.2022).

Table 3

Formation of generative organs in Black Parrot tulip plants, 2022 g

An increase in the size of bulbs (L-3) caused the appearance of buds on 04.02.2022, 2 days after the previous variant and 4 days after entering the budding phase by plants of the first variant of the experiment.

4. Conclusion

It should be noted that with an increase in the size of the bulbs, the buds appeared in fewer days than in the first versions. The flowers appeared in the second variant after 3 days, an increase in the size of the bulbs caused the appearance of flowers after 5 days, compared with the second variant, in the fourth variant – 1 day after the third variant, in the fifth – a day after the fourth.

Thus, with an increase in the size of bulbs, the growth and development of plants is delayed. Moreover, with an increase in the size of the bulbs, the difference between the options is smaller.