Candidate Biol.Sci. N.A. Slepchenko

The State Research Institution All–Russian Scientific and Research Institute of Floriculture and Subtropical Crops of the Russian Academy of Agricultural Sciences, c. Sochi, Russia, e-mail: slepchenko@vniisubtrop.ru

Sternbergia lutea (L.) Spleng.

on the Black Sea coast of Russia

В статье оценивается возможность использования Sternbergia lutea (L.) Spleng. в качестве элемента садово-парковых ландшафтов, приводятся сведения по морфологии, фенологии и экологии вида в условиях Черноморского побережья России, предлагаются приёмы ускоренного вегетативного размножения.

Ключевые слова: Sternbergia lutea, Amaryllidaceae, луковичные цветочные культуры, вегетативное размножение.

Bulbous cultures have captured attention since olden times, and they are still the same popular nowadays, being used in ornamental horticulture. Among the numerous species of bulbous cultures, a special place belongs to the family of Amaryllidaceae Jaume Saint-Hilaire. Various shapes and colours, as well as unique biological features of these plants allow to use them in different methods of flower designing, including rooms, for forcing treatment. An amazing feature of this family representatives is the ability to bloom almost in all seasons of the year.

Over the past years, the range of bulbous flower plants has significantly expanded in the world, including Russia. One of the sources in assortment expanding is attraction of ornamental species from natural flora. The given field has been researched in All–Russian Scientific and Research Institute of Floriculture and Subtropical Crops since 1990s. A great work has been conducted in order to attract rare wild species of ornamental plants and develop new methods for their mass breeding [1]. The recommendations on 30 species have been developed to accelerate mass reproduction [2].

One species of Amaryllidaceae Jaume Saint-Hilaire family can be referred to those quite promising, viz. Sternbergia lutea (L.) Spleng..

Sternbergia genus was named in honor of Kaspar Maria Sternberg (1761-1838) – a famous Czech botanist, geologist and politician. It was originally described by K. Clusius in 1601, and called "autumn narcissus", and later on, in 1753, K. Kluzius called it "amaryllis yellow". Sternbergia had had such names until the early XX century [5]. In nature, there are 7-8 species of this genus, common in the Mediterranean, Eastern Europe, Asia Minor, the Caucasus and Iran [4].

Sternbergia lutea is one of the most late-blooming representatives of the given genus. In humid subtropical Black Sea coast of Russia, it profusely blooms in September-October, and in November, in some years, forming a bright yellow "carpet". Up to 4 single, funnel-shaped, lemon- yellow florets can develop on one plant. Peduncles are 10-20 cm long. The floret of Sternbergia lutea is very similar to that of the crocus. Sternbergia lutea can be distinguished from crocus by the number of stamens. Sternbergia lutea has got 6 stamens, while crocus has got 3 stamens. Flowering period of one floret lasts 5-6 days.

Leaves up to 30 cm long, linear, dark green, glossy and thick, appear during the mass flowering period, and by January, they form a solid bright green shiny carpet that does not lose its ornamental effect until mid-spring. By late April, the leaves die, and the plants enter a dormant period until the end of summer. The bulbs of S. lutea are pear-shaped, with dark colored induviate scales.

The best places for S. lutea growing are sunny and wind -protected areas; in humid subtropical Black Sea coast of Russia, it grows in partial shade as well. Cultivation zone should be well drained, with light and humus-rich soil. The plant is drought-resistant and does not stand water stagnation, it responds positively to the extra watering during dry seasons though, which are often recorded in the region in September - during floret formation and flowering period. It is resistant to adverse weather conditions of winter if the optimal growing conditions are observed during the vegetation. The bulbs can grow in one place without transplantation during 4-5 years.

On the Black Sea coast of Russia, S. lutea does not form any seeds, but has a proper vegetative propagation. Under favorable conditions and correct care, it gives a large number of daughter bulbs. In order to obtain a planting stock, the bulbs should be planted at a depth of 10 cm, and at a distance of about 15-20 cm from each other. Planting is carried out in the first ten-day period of September. During the vegetation period, it is necessary to carry out 2-3 extra nutritions, which include a full range of mineral fertilizers. After the vegetation period ends in May - mid-June, the bulbs should be dug up, and then, after cleaning, put in a dry, cool place for storage. Reticulate boxes are optimal for the storage.

Studies have shown that if large bulbs of S. lutea are planted under the conditions of Sochi, the multiplication factor is equal to 1.9 for one year of vegetation, and an output of large-sized bulbs is 177% (table 1).

Table 1

Sternbergia lutea reproductive ability

under the conditions of Russian humid subtropics

Circumference of mother bulbs, cm	Multiplication factor	Bulbs output depending on circumference, cm, % from the number of the planted mother bulbs
		16+	13-16	10-13	8-10	6-8
16+	1,9	13	87	77	13	0
13-16	1,4	0	55	67	7	11
10-13	1,3	0	0	54	46	30

Apart from the traditional breeding mode, we have developed a resource of S. lutea accelerated breeding by the method of double scales. This method was accurately developed in All–Russian Scientific and Research Institute of Floriculture and Subtropical Crops, using Нippeastrum hybrida and Narcissus cultures, which also belong to the Amaryllidaceae family [3].

Large healthy bulbs, which had preliminary been dried during 5-7 days, were selected with the aim to divide. The division was carried out by slitting the bulbs into 4-8 or more pieces, which is made by a sharp knife from a top to an ending. The obtained segments were cut into double scales, consisted of scales, connected by a piece of fundus. After dividing the segment into 2 pieces, each of the obtained parts was called a "half-segment", which consisted of 2-3 scales in S. lutea. Depending on scales position in a bulb, a half-segment, which consisted of scales, that are closer to the growing point, was named the "inner" and the other one was named the "external", respectively. The segments, which consist of two scales, fastened with a piece of fundus, are called double scales. Before planting, the segments were treated with 1-2 % fundazol solution for 30 minutes. Then they were gently dried and planted into a box with a moist substrate that consisted of peat and perlite. The segments were thickly planted at a depth of 2/3 and 1/3 of their height. The investigations were carried out at different times (from June till October), using large bulbs (diameter was more than 3 cm).

The experiments have ascertained that the best term for dividing the bulbs is September, when the best survival ability of the double scales was recorded. The observations have shown that rooting ability of the double scales depends on the size of the initial mother plants. In case with S. lutea, these are the bulbs, which are 3,0-3,9 cm in diameter.

Unlike Нippeastrum hybrida, which is also propagated by double scales, the fundus of S. lutea is relatively small in large bulbs (5-6 dense scales), and as a consequence, there is a very low survival rate of the double scales. An optimal size of the segments i.e. 1 cm wide was established as a result of the experiment.

The bulbs propagated in this way can bloom in 3 years, i.e. 2 times faster than the natural seed propagation.

Using the method of double scales in S. lutea breeding promotes accelerated production of planting stock, as well as preservation of the gene pool of the given species.

Due to the ornamental properties, S. lutea is used in designing of rockeries and rock gardens, in combination with other cultures, as well as in separate groups on green lawns. We recall that S. lutea shows its ornamental qualities in late-autumn and winter periods. At this time, the range of flower cultures, which can become bright accents in landscape, is limited. This fact adds value to S. lutea, as an element in planting of greenery.

References

1. Евсюкова, Т.В. На пути сохранения растительного разнообразия природной флоры Северо-Западного Кавказа / Т.В. Евсюкова, Н.А. Слепченко // Сб. докл. Сочинского отд. Рус. геогр. общ-ва. – Сочи, 2007. – Вып. 4. – С. 79–83.

2. Евсюкова, Т.В. Декоративные травянистые виды природной флоры Северо-Западного Кавказа. Биологические особенности и рекомендации по их размножению / Т.В. Евсюкова, В.В. Козина, Н.А. Слепченко; Россельхозакадемия; ВНИИЦиСК. – Сочи, 2009. – 35 с.

3. Рекомендации по технологии размножения гиппеаструма гибридного / В.И. Болгов, Ю.Ф. Кулибаба, И.А. Кравцов; Гос. агропромышленный комитет СССР, В/О «Союзплодопитомник». – М., 1987. – 41 с.

4. Flowering Plants. Monocotyledons: Lilianae (except Orchidaceae) (The Families and Genera of Vascular Plants) / Edited by K. Kubitzki. – New York: Springer-Verlag Berlin Heidelberg, 1998. – P. 101/

5. Штернбергия (Sternbergia). – [Electronic data]. – Access mode: http://amarillisovie.narod.ru/sternbergia.html