The growth and development dynamics of small fraction bulbs of Hyacinthus orientalis

Okach Mariya Aleksandrovna ORCID: 0000-0001-7147-1676 Educational master, Botanical Garden-Institute, Volga State University of Technology 424300, Russia, respublika Marii El, g. Ioshkar-Ola, ul. Mira, 2b OkachMA@volgatech.net

Egoshina Evgeniya Alekseevna Student, Department of Landscape Gardening, Botany and Dendrology, Volga State University of Technology 424000, Russia, respublika Marii El, g. Ioshkar-Ola, ploshchad' Lenina, 3 egoshina_ev@bk.ru

Introduction. Hyacinth oriental (Hyacinthus orientalis L.) is an early flowering bulbous plant with linear-lanceolate, bright green, fleshy leaves forming a basal rosette. The flowers are bell-shaped, simple or double, collected in a cylindrical spike up to 20-35 cm high. The bulbs are spherical or broadly cone-shaped with numerous succulent storage covering scales. The roots are located along the perimeter of the bottom, do not have branches and root hairs. In culture since 1562 ^[1]. Oriental hyacinth is widely used in landscaping urban spaces in countries with warm and mild climates ^[2]. In its wild form, it grows in the countries of the Eastern Mediterranean (Iran, Iraq, Syria, Palestine), in north Africa, where there is no frost in winter. However, for several centuries the main commercial plantings of this crop have been concentrated in Holland ^[3].

The modern assortment of Oriental hyacinth varieties is represented by a wide variety of perianth coloration, flower shape, inflorescence density, flowering dates, the number of inflorescences in one bulb. Despite the variety of varieties, this crop in Russia is practically not used in flower arrangements of open ground. In our country, hyacinths are mainly grown indoors as a pasture crop ^{[4, 5]} and only in the southern regions they are used in the design of urban flower beds in the open ground ^{[2, 6, 7, 8]}. Hyacinths are grown with annual digging of bulbs in summer and planting them in autumn, propagated by baby bulbs, bulbous scales and leaf cuttings ^[9], as well as in vitro ^{[10, 11, 12, 13]}. One of the reasons why this flower crop is used in gardening is limited is the high price of planting material. The high price of hyacinth bulbs is associated with a low natural coefficient of vegetative reproduction in the open ground ^[14]. The ability of hyacinths to form daughter bulbs is the basis of accelerated artificial reproduction techniques, as a result of which a large number of small bulbs (children) are formed) ^{[1, 5, 15, 16, 17]}. The study of the growth characteristics of small fraction bulbs will allow us to develop effective methods of growing hyacinth babies to commercial bulbs and further use them to expand the range of spring-flowering plants. The results of the initial introduction tests in the conditions of the Republic of Mari El showed high decorative qualities of this crop and the ability to natural vegetative reproduction ^{[18, 19]}.

The purpose of this work is to study the growth of baby varieties of hyacinth Oriental in the conditions of the Republic of Mari El.

Objects and methods of research. In the collection of the Botanical Garden-Institute of the Volga State Technological University, 30 varieties of Oriental hyacinth are being introduced. To study the growth dynamics of hyacinth bulbs, 6 varieties were selected from the collection: ‘L'innocence’, ‘Carnegie’, ‘Lady Derby’, ‘Rosette’, ‘Eros’, ‘Madame Sophie'. The reconciliation of the names of varieties and their distribution into groups were carried out according to the data of the Royal Horticultural Society ^[20] and the Royal General Association of Producers of Bulbous Plants ^[21].

‘L'innocence’ – flowers are simple narrow-ringed, creamy at the beginning of flowering, pure white by the end, the inflorescence is dense, the bulb with white covering scales, the duration of flowering is up to 16 days. ‘Carnegie' – the color of a simple perianth is white, the inflorescence is dense, the bulb with white covering scales, the duration of flowering is up to 18 days. ‘Lady Derby' – flowers are simple light pink with a slight orange tint, inflorescence is loose, bulb with purple covering scales, flowering duration is up to 14 days. ‘Rosette’ – the color of the perianth is pink with a bright central vein, the shape of the flower is double, the inflorescence is dense, the bulb with purple covering scales, the duration of flowering is up to 13 days. 'Eros' – flowers are dense, bright pink in color, the inflorescence is dense, the bulb with purple covering scales, the duration of flowering is up to 15 days. ‘Madame Sophie' – double flowers with pure white color, dense inflorescence, bulb with creamy-white covering scales, flowering duration up to 15 days.

The experience of studying the growth of children was carried out from 2016 to 2018. Before planting, the bulbs of the small fraction were divided, depending on the weight, into the baby 1, 2 and 3 parsing. The bulbs of each analysis were divided into two groups. The first group was dug out annually for two years, and the second group of bulbs was cultivated in one place for two years, without annual digging. After digging, the weight of the bulbs was taken into account. The bulbs were calibrated according to the current standards ^[22]. The bulbs were grown in the same edaphic conditions. The field materials were processed by descriptive statistics methods using the Microsoft Excel application program at a 95 percent reliability level.

The climate of the Republic of Mari El is moderately continental, with a long cold winter, dry spring, and wet autumn. The soils are fresh, slightly podzolic, medium and heavy loamy on cover clays and loams ^[23].

Presentation of the results. The dynamics of the mass of bulbs by analysis is shown in the table.

Table – Dynamics of hyacinth bulb mass by analysis

The first analysis included bulbs weighing from 7.3 g to 8.5 g. With annual digging, bulbs of varieties with pink perianth increased their mass more intensively. In the first year of cultivation, the weight of these bulbs ranged from 20.0 g to 26 g, in the second year - from 29.4 g to 38.1 g. With annual digging, the formation of children was noted only in the varieties ‘Eros’ and ‘Lady Derby’, the reproduction coefficient was 2.0 and 2.15, respectively. Bulbs cultivated without digging for two years increased the average weight by 4.8 times. The maximum weight of bulbs in this cultivation variant is set for the variety ‘Lady Derby’ (59 g), the minimum – for ‘L'innocence’ (27.4 g). The reproduction coefficient for two years of cultivation without digging was 2.04 for the variety ‘Lady Derby’, 1.43 for ‘Madame Sophie’, 1.21 for ‘Carnegie’. The baby of the first analysis for two years of cultivation in all variants of the experiment grew to bulbs of 4 analysis.  

The second analysis consisted of a bulb weighing from 3.8 g to 4.5 g. During the first year of cultivation, the weight of bulbs of this analysis increased by an average of 1.6 times, the exception was the ‘Carnegie’ variety, in which the weight of bulbs increased by 2.1 times. The maximum weight of bulbs for the second year of cultivation was observed in the variety ‘Lady Derby’ (12.7 g), the minimum – in ‘Rosette’ (8.3 g). With a two-year culture without digging, the weight of bulbs of the ‘Lady Derby’ variety increased 5 times and amounted to 20.1 g, while over two years of annual digging, the weight of bulbs of this variety increased only 3 times. In two years of cultivation, the bulbs of the second analysis reached the size of the children of the 1st analysis.  

Bulbs weighing from 1.3 g to 1.9 g were selected for the third analysis. Their weight in all variants increased by an average of 3 times, with the exception of the varieties ‘Rosette’ and ‘Madame Sophie'. In these varieties, the bulbs grew more intensively during two-year cultivation without digging. Within two years, the weight of the baby increased from the third analysis to the second analysis.

Conclusions:

1. With two-year cultivation without annual digging, the baby hyacinth of the first analysis in the studied varieties reached the mass of bulbs of 4 analysis.

2. Baby hyacinth with a weight of bulbs from 3.8 g to 4.5 g in two years of cultivation reaches the mass of a baby of 1 analysis.

3. Baby hyacinth with a weight of bulbs up to 2 g is able to increase its weight 3 times in two years.

4. For the children of the first and second analysis of the ‘Lady Derby’ variety, a high rate of weight gain was noted for two years of cultivation.