Dynamics of gladiolus leaves growth

Botova Anastasiya Vladimirovna Student, Department of Garden and Park Design, Botany and Dendrology, Volga State University of Technology 424000, Russia, respublika Marii El, g. Ioshkar-Ola, ploshchad' Lenina, 3 kudashkina.nastya.00@mail.ru

Mukhametova Svetlana Valer'evna ORCID: 0000-0001-7892-6450 PhD in Agriculture Associate Professor at the Department of Garden and Park Design, Botany and Dendrology of Volga State University of Technology 424000, Russia, Mari El Republic , Yoshkar-Ola, Lenin Square, 3, aud. 245 MuhametovaSV@volgatech.net Other publications by this author

Introduction. The genus Gladiolus (Gladiolus L.) has about 260 species, of which 10 grow in Eurasia, 250 in sub-Saharan Africa ^[1]. The genus Gladiolus, whose name comes from the Latin word "sword", belongs to the class of monocotyledons and belongs to the family of Iris, or Kasatikov. This extensive family includes perennials with a rhizome, a corm, or a tuberous rhizome. Gladiolus belongs to the group of geophytes, the unfavorable period of the season carries underground in the form of a modified tuber stem. This form was developed as an adaptation to the dry period of South Africa. Wild species of more northern latitudes suffer an unfavorable winter period in the form of a corm underground and actively germinate at the onset of a warm period. The cultured gladiolus comes from African species and does not winter in the open ground in a more severe climate. In autumn, the corms are dug out, stored and planted again in the spring. The annual regrowth of the aboveground shoot occurs from a kidney formed on the corm of the last season (maternal), which is dying this year, having used up the reserves of nutrients. In its place, a new (daughter) corm is formed ^[2].

The entire range of gladiolus (over 8 thousand varieties) belongs to the hybrid species Gladiolus ? hybridus hort. ^[2]. The varieties are characterized by a huge variety in the height of the peduncle, the color scheme and the corrugation of the flowers ^[3]. Currently, breeding is relevant for the aroma – traits lost by gladioli during evolution ^[4], as well as for resistance to diseases and pests ^[5], an increase in the duration of flowering and the number of simultaneously open flowers in the ear, an increase in the strength of the peduncle and resistance to lodging ^[6].

The inflorescence is a simple loose spike. The flowers can be arranged one-row, two-row, alternately, bilaterally, spirally. The number of buds in the ear depends on the variety. As the flowers open from the bottom up, the inflorescence grows. The flower is bisexual with perianths of 6 lobes arranged in 2 tiers. The color is varied, monophonic or multicolored, with spots, border, strokes ^[3].

Gladioli are one of the main cut crops of open ground ^{[7, 8, 9]}. In many countries, gladioli are grown on an industrial scale for use in bouquet products and arrangements ^[10], in the world trade in cut flowers it occupies the 8th place ^[11]. Gladiolus can be used in landscaping areas of various stylistic directions: both in regular (curbs and rabatki), and in landscape (mixborders and group plantings). It is also possible to use gladioli in container gardening ^[10].

One of the advantages of gladioli is the timing of flowering in August–September, when a small number of ornamental perennials bloom. The disadvantage of this crop is the complexity of cultivation due to the annual digging and planting of corms, the need to store them under certain conditions, compliance with all agricultural techniques and the fight against diseases and pests ^[7].

Varietal gladioli are propagated vegetatively, by corms and their parts, by tubers (children). The most powerful and healthy plants with large inflorescences develop from corms that have not yet formed juvenile flowers. There are no traces of the dead peduncle of the previous year on them, the optimal size in diameter is 3.5–4.5 cm. The optimal period of productive cultivation of corms is 3-4 years, after which their viability and immunity decrease ^[12].

Gladiolus has three types of leaves. The corm is surrounded by 2-3 scaly (lower) leaves that do not have a leaf blade. They are located underground, only in some cases the tip of the last leaf rises slightly above the soil level. The assimilating apparatus of gladiolus consists mainly of 5-9 (10-12) well–developed true leaves, which have a green color and a typical gladiolus shape and structure - an expanded base (vagina) and a leaf blade with a pointed sword-shaped tip. Usually 5-6 pieces of them start from the corm, the rest are located higher on the stem (stem leaves). There are 2-3 (4) leaves directly near the inflorescence. The stem leaves have a short length, light green color and filmy leaf blades ^{[13, 14]}. Stem leaves, in addition to the photosynthetic role, perform a hormonal function and contribute to the formation of generative organs, flowering and maturation of seeds ^[2]. Gladiolus leaves contain 0.5% vitamin C from their raw weight ^[3]. The deployment of the first leaf of plants of different varieties of gladiolus occurs on 13-20 days, the second leaf – on 15-20 days, the third leaf – 17-43 days ^[15]. Starting from the stage of four leaves, the formation of a new corm begins above the old one, but during the formation of leaves and peduncle, the growth and development of the corm is limited. Only after harvesting the peduncles, intensive growth of a new corm occurs due to the accumulation of photoassimilates ^[16]. The length of the peduncle positively correlates with the height of the plant, the duration of flowering and the number of flowers in the inflorescence. The number of flowers in the inflorescence positively correlates with the number of leaves in the plant and the mass of the corm ^[17].

The purpose of the study is to study the growth dynamics of real gladiolus leaves in the open ground.

Materials and methods. The study was conducted in 2021.Corms were planted on ridges in grooves on May 5, on a sandy cushion (Figure 1). The number of corms in each variety varied from 15 to 35 pieces . Leaf height measurements were carried out after 15 days, taking into account the height of the longest leaf.

Figure 1 – Planting gladioli: a) planting of corms in ridges on a sand cushion,
b) ready-made beds, c) shoots of gladioli

The objects of the study were 9 varieties of hybrid gladiolus. Varieties 'Garnet Bracelet', 'Hail Kitezh', 'Maiden Secrets', 'Maya Plisetskaya', 'Tanyusha', 'Monomakh's Hat' were obtained from the G.A. Demidov Memorial Botanical Garden (Solikamsk) in 2008-2011, varieties 'Aurora' and 'Noon Moon' – from a private person (Moscow Yoshkar-Ola). The long-awaited Debut variety arrived from Riga in 1989.

'Aurora' is a red flower with white moire in the throat. A large, cutting variety. Author V.P. Fotin ^[18]

'Hail Kitezh' is a rich lilac flower with a salad spot in the throat on the lower petals. It is strongly corrugated with folds-pinches at 2/3 of the depth of the petals. Forms a lush dense ear. Height 160 cm. The inflorescence is 75 cm long, contains 21-22 buds (8-9 are open at the same time). The diameter of the flower is 14 cm . It was withdrawn in 1994. Author V.F. Dybov ^[18].

"Garnet bracelet" – flowers of dark red color, the edges of the petals are slightly turned up, not much corrugated. The fabric of the petals is velvety. Height 150cm. Inflorescence 70-75cm, 21-23 buds (7-8 open at the same time). The diameter of the flower is 14cm. It was withdrawn in 1986. Author A.V. Murin (Moldova) ^[18].

"Maiden secrets" – cream-pink flowers 14.5–15 cm, with smooth edges, large dark cherry spots on the three lower lobes. Height 145 cm, inflorescence 55 cm, double row, Author A. A. Volfovich ^[19].

The long–awaited debut is a salmon-orange flower with large lemon-yellow spots on the three lower petals. In the throat, on top of the spots, there is a dark crimson dusting along the veins and a clear arrow almost to the edge of the spot. It is corrugated with pinches and folds at the edges of the petals. Height 165 cm . The inflorescence is 85-90 cm, contains 22-24 buds (9-10 are open at the same time). The diameter of the flower is 16 cm . It was withdrawn in 1984. Author A.N. Gromov ^[18].

'Maya Plisetskaya' is a light fawn flower with a faint salmon hue and a transparent, silky-waxy texture of the petals. There is a crimson spot in the throat. It is strongly corrugated with large deep pinches along the edges of the petals ^[20]. Height 150cm. Inflorescence 80cm, 24 buds (9-11 open at the same time). The diameter of the flower is 14.5 cm. It was withdrawn in 1977. Author A.N. Gromov ^[18].

'Tanyusha' is a light pink flower, with a creamy yellow spot outlined by a thin dark pink border on the lower petal. The slightly fringed edges of the petals are outlined by a wide, barely noticeable smoky border. The corrugation is strong with folds and pinches. The petals are dense. Height 140 cm, inflorescence 70 cm, contains 20 buds (9 are open at the same time), flower diameter 14 cm. It was withdrawn in 1999. Author V.F. Dybov ^[18].

'Monomakh's hat' – the flowers are bright red with white moire on the lower petal. Author N.A. Miroshnichenko (Ukraine) ^[21].

'Noon Moon' is a flower of a bright, acidic tone of saturated cadmium yellow. The bud is wide open, the edges of the petals are slightly turned up. It is corrugated with rare large and more frequent small pinches-folds in the throat. The petal fabric is dense, durable. Height 145 cm, inflorescence 70 cm long, contains 21-22 buds (8-9 are open at the same time), flower diameter 13.5 cm. It was withdrawn in 1982. The author is Fisher ^[18].

Research results. The data obtained are shown in the table. On the 20th day after planting, the gladioli reached about 1/3 of their final height, and on the 35th day - already half. By the 65th day of the study, the height was almost 90%.

Table – Leaf height of gladiolus varieties

On the first accounting date, the height values of the studied varieties varied to the greatest extent. In the future, their height became more aligned. This is probably due to the different timing of the emergence of seedlings. The materials of the table are clearly reflected in Figure 2.

Figure 2 – Height of gladiolus leaves on accounting days

At each date of the study, the highest height was characterized by the variety "Maiden's Secret", its final average height was 81.9 cm. The lowest height in most accounting days was distinguished by the variety "Grad Kitezh", the final average height was 60.8 cm. Correlation analysis revealed a direct correlation between the heights on different accounting days, that is, the height of the studied varieties changed accordingly on different accounting days – taller varieties remained tall, short – stunted.

The amount of increase is shown in Figure 3. Most varieties were characterized by the greatest increase in the first accounting period, while the "Garnet bracelet" – in the second, while the length of its increments was maximum (on average 27.3 cm). In the future, the amount of increments in all varieties decreased, reaching the minimum value in the last accounting period (on average for all varieties 3.4 cm). Obviously, this is due to the transition of growth processes to generative development. In general, the lowest average values of the increments were characterized by plants of the Grad Kitezh variety.

Figure 3 – The length of the growth of gladiolus leaves

Conclusion. Thus, the most intensive growth of gladiolus leaves occurred after the emergence of seedlings. On the 20th day after planting, the plants reached about 1/3 of their final height, and on the 35th day - 50%, after 2 months – the height was almost 90%. Most varieties were characterized by the greatest increase in the first accounting period, in the future its value decreased, reaching a minimum in the last accounting period. In the process of growth, the taller varieties remained tall, the shorter ones remained stunted. At each date of the study, the highest height was characterized by the variety "Maiden secrets", the lowest – "Hail Kitezh". The data obtained can be used in the cultivation of gladioli in nurseries and landscaping facilities.