Zinnia Plant: Introduction, Origin/history, Botany, Chemical constituents, Classification, Varieties, Diseases and Insect-Pests
There are stunning decorative plants of the genus Zinnia. The aesthetic and commercial worth will be greatly enhanced by the plant’s novel bloom hues. Like chrysanthemums or sunflowers, it is not well-known. Due to its ability to be purchased as a cut flower in many different countries’ flower marketplaces, Zinnia hybrids have been bred into an excessive number of cultivars. Historically speaking, zinnia is a widely grown decorative plant. Numerous breeding organisations have developed brand-new cultivars with a variety of appealing physical traits. The difficulty in classifying zinnia cultivars is because many of the defining characteristics, such as height, bloom size, and leaf form, are qualitative and are strongly influenced by the environment. Moreover, zinnia hybrids are multiplied by seedlings. Therefore, parent cross-breeding is used to create zinnia plant seeds. In that case, cultivar conservation is challenging. Additionally, one form of propagation technology called in vitro culture offers rapid observation of genetic diversity and plant multiplication. Because there is little information on zinnia cultured in vitro, the conditions needed for doing so were established.
The International Space Station commander Scott Kelly tweeted on January 17, 2016, “First ever flower grown in space makes its debut,” referring to the zinnia, which is the first flower to blossom in space. The zinnias are the second plant to be tested in zero gravity; the first being lettuce the previous year.
Species: Zinnia acerosa, Zinnia angustifolia, Zinnia anomala, Zinnia elegans, Zinnia grandiflora, Zinnia haageana, Zinnia maritima, Zinnia peruviana Etc.
Origin/History of zinnia
About 20 species of Asteraceae annual and perennial plants make up the genus Zinnia, which originated in scrub and arid grassland in regions ranging from the Southwest to South America, but mostly Mexico. The plants were not particularly attractive even after zinnia seeds were sent back to Europe in the 18th century. The genus Zinnia had to wait until the late 19th century to become more successful as a garden annual. It was named after German botanist Dr Johann Gottfried Zinn (1727-1759), who gave the first description of the flower. Breeding via selection took place in Germany, Holland, and Italy. Two selections from the ‘Pumila Mixed’ strain, ‘Mammoth’ and ‘Striata,’ were imported to Europe and had considerable popularity with gardeners. However, the dahlia-flowered “Giant Dahlia” developed by Bodger Seeds Ltd. in 1920 marked the beginning of the zinnia’s actual popularity. The enormous, flat-flowered “California Giant” strain was chosen from the strain after John Bodger discovered it as a spontaneous mutation in a field of “Mammoth.” It was marketed as a new trend in plant behaviour and floral appearance, and it was offered in distinct colours. The Royal Horticultural Society of England awarded it a gold medal.
Zinnias are half-hardy annual, perennial, or sub-shrubby plants that are erect but highly branched, 15–90 cm high, with hairy stems; opposite, large, oval or heart-shaped, pointed, mostly entire, rough-surfaced, and light green leaves; inflorescence a terminal head or capitulum, and florets of two types, including fertile pistilate ray florets that are mostly brilliantly coloured, and bi (rarely-2).
According to phytochemical analysis, Z. elegans includes coumarin, tannins, alkaloids, cardiac glycosides, sitosterol, and triterpenes. When given orally to female rats with ovariectomies, the alcohol extractions of several zinnia components (leaves, stems, and flowers) show activity that is similar to oestrogen. In contrast to the flower extraction, which has significantly less activity, the zinnia leaves and stems had a stimulating impact on the isolated rat uterus (Sharada et al, 1995).
Genetics and Breeding
The most often cultivated species of Zinnia, Z. elegans, has a basic chromosome number of x = 12, while Z. linearis has x = 11. The majority of organisms are diploid. The B chromosome was found in all but one of the eight types of Zinnia elegans investigated by Bhattacharya and Ghosh in 1978. Zinnia linearis and Zinnia elegans were crossed to create a hybrid (2n=23) by Ramalingam et al. in 1976. Treatment with colchicine can make the hybrid fertile again.
Species and Varieties
The height and bloom forms of zinnias can be used to categorise them. Sizes of several flower types, including solitary, semi-double, and double, range from 2.5 to 15.0 cm across. Zinnia pumila, Zinnia nana, and Zinnia compacta, according to trade catalogues, are medium-height cultivars that are 45-60 cm tall, and dwarf kinds, which are 15-45 cm and are of two types, are tall cultivars that vary from 75 to 90 cm with a maximum of 15 cm flower diameter (Pompons or Liliputians and Tom Thumbs). While Tom Thumbs are the most dwarf-like plants with the largest flowers on them, pompons grow higher and have smaller flowers. The variety of colours available in zinnias is also astounding. While most varieties are solid colours, some, like Z. haageana, have contrasting colours at the tips of each petal.
Although the classification of varieties is very perplexing—for example, California Giants include dahlia-flowered types, and Liliputs include the Thumbelina—it is required for the convenience of producers and the trade. According to Pizzetti and Cocker (1975), zinnia elegans hybrids can be classified into a wide range of varieties or classes based on the plant height and flower size of the individual plants.
Double: Plants grow to a height of 75 cm, and the flowers have a diameter of 7 to 10 cm. Varieties include “Blaze,” “Burpy Hybrids,” “Canary Bird,” “Orange King,” “Persian Carpet,” “Purity,” “Scarlet Flames,” “Super Giants,” and “Violet Queen.”
Lilliput or Pompon: Bushy, compact, 45 cm high, with flowers that have a diameter of 3-5 cm. Canary Yellow, Peach Blossom, Rose Gem, White Gem, and other varieties are available.
Thumbelina: A relatively new variety with early blooming, ultra-dwarf, compact growth habit, double or semi-double 3.5 cm in diameter blooms, and a need for a sheltered location.
California Giant: A plant that is at least 90 cm tall and has the largest flower of any zinnia hybrid, with a diameter of at least 15 cm. “Brightness” and “Cherry Queen” are two varieties. such as “Lavender Gem,” “Orange Queen,” “Purity,” “State Fair,” and “Super Giant.”
Scabiosa Flowers: The typical scabiosa flower type has flowers that are 8 cm in diameter and 80 cm high. Cactus-flowered plants are 75–90 cm tall, with blooms up to 10 cm in diameter with petals that are slightly reflexed and recurved. Empress, Red Man, Snowman, Sun Gold, and other varieties are available.
Pumila: Plants that can grow up to 45 cm tall with extremely double, 7 cm broad flowers. Early Wonder, Pink Buttons, Red Riding Hood, and other varieties are available.
Sombrero: Plant height 35-45 cm, single bloom 6 cm wide, petals scarlet-red with golden tips, great for cutting, Dahlia Blue Point and Oklahoma are two popular series for growing cut flowers outside since they produce well all year long in temperate settings and have a modest level of disease tolerance (Dole, 1997; Dole and Wilkins, 1999). The following are significant variations of other groups:
Giant Dahlia: “Canary Bird,” “Dream Meteor,” “Oriole,” “Polar Bear,” etc.
Cupid: “Golbin,” “Pink Button,” “Pixie,” “Snow Drop,” etc. There are various strains of F1 zinnias, including:
Dahlia: These include “Blaze Eskimo,” “Canary Bird,” “Orange King,” “Peter Pan Series,” “Purity,” “Riverside Beauty,” “Scarlet Flame,” “State Fair,” “Super Giants,” “Violet Queen,” etc.
The cultivars of Zinnia
The variety of cultivars that produce different zinnia forms and colours is one factor in the plant’s popularity. Some zinnias have flowers that are white, cream, green, yellow, apricot, orange, red, bronze, crimson, purple, and lilac; zinnias that have striped, speckled, and bicolour petals; zinnias that have double, semi-double, and “pompon” flowers that resemble dahlias; and zinnias that range in height from no tall dwarfs
Diseases and Insect-Pests
Numerous illnesses target zinnias. The main seed-borne fungus is Alternaria alternata, Alternaria zinniae, Glomerella cingulata, Cochliobolus lunatus, Phoma exigua, and Fusarium sp. They make seeds rot, and if seedlings do sprout, they will soon perish.
Blight is caused by Alternaria zinniae, which is isolated from under the seed coat, between, and inside the cotyledons.
Reddish-brown patches with a greyish centre are the symptoms. Additionally seen are stems and flowers. Hot water treatment (66 oC) for 30 minutes has been recommended for illnesses transmitted through seeds.TMTD (Thiram) at 45 g/kg seed and CTP 80 (a uric acid derivative) at 90 g/kg seed can both reduce Alternaria (Imre, 1974). This disease can also be managed using Ferbam and Bordeaux Mixture (Pirone et al., 1960). The optimum control strategy for Alternaria, according to Zamorshi and Milczarek (1977), is the use of Thiram (0.3%) and Captan (0.5%). Dithane M-45 was discovered to be the most effective fungicide for treating seeds (Srivastava and Gupta, 1983).
It is also being tested to control Alternaria biologically. In all the circumstances, i.e. greenhouse and field experiments, Wu and Chou (1995) discovered that Bacillus strain 18 was equally efficient as spraying Pyrifenose in controlling Alternaria carthami on zinnia.
Spraying wettable sulphur or Karathane on the affected area will eradicate powdery mildew (Erysiphe cichoracearum). Through the use of benlate, topsin-in, and karathane, Powell (1974) observed total control.
Zinnias also experience the diseases stem rot (Phytophthora sp. and Sclerotinia sclerotiorum), head blight (Botrytis cinerea), and leaf spot (Cercospora zinniae), whose attack may be minimised with routine and standard sanitation practise. After 3–4 weeks of treatment with Pseudomonas fluorescens strain E6 on zinnia seeds, Yuen and Schroth (1986) observed increased growth and fresh weight (18–41% greater), less Penicillium spp. root colonisation, but higher Fusarium spp. growth. However, growth promotion by strain E6 was associated with a change in the composition of root microflora and a reduction in the harmful effects of minor pathogen
The typical bacteria that infects zinnia is Xanthomonas nigromaculans f. sp. zinniae. Hernandez and Trujillo (2000) discovered that the Zinnia leaf spot is also brought on by Xanthomonas campestris PV. zinniae. A method for identifying the pathogen in zinnia seed was suggested by Strider (1979a). In the glasshouse, he conducted dense sowings of seed in a warm, humid environment. After 5–14 days, distinct lesions were visible on the cotyledons. This form of indexing was made possible by significant pre-emergence dissemination, which caused a very small percentage of contaminated seeds to produce a large number of infected seedlings. Infected cotyledons (or entire seedlings) frequently withered at this time, making it necessary to observe disease development during the first two weeks after seedling because symptoms did not usually reappear on the leaves until after another infection episode. Treating seeds with a 30-minute chlorine bleach soak of 1:2 will lessen bacterial leaf spots (bleach: water). The seeds will suffer if bleach is applied too frequently. The seeds are sown after being rinsed.
Streptomycin was also used to treat this illness. According to Strider (1979b), streptomycin is successful at limiting the pathogen, although it causes chlorosis, slight stunting, and uneven growth in seedlings as they emerge from the soil. But a 30-minute immersion in sodium hypochlorite (10,500 ppm) was quite successful in getting rid of this infection. The most efficient treatment for Xanthomonas and Cercospora leaf spot involved cutting infected leaves after which a foliar spray of streptocycline (0.01%) + carbendazim (0.025%) was applied (Jindal and Meeta, 1991).
The most prevalent viral infections that affect zinnias include curly top, leaf curl, mosaic, and spots of white and yellow. The curly top is caused by Ruga verrucosans, and the spotted wilt is caused by Letham australiense. Spotted wilt has a severe impact on zinnias. The plants initially start to wilt, then their leaves begin to curl. In locations with high rainfall and the northern plains, this disease is particularly prevalent. The highlands, on the other hand, are comparatively free of this illness. It is spread by thrips, so this insect needs to be eradicated right away. According to Kameya et al. (1996), the zinnia plant is susceptible to a novel disease known as the “tomato aspermy virus” that causes chlorotic spots and mosaic symptoms. According to Sastri et al. (1973), Myzus persicae and Aphis gossypii are the carriers of the mosaic disease of zinnia. But Myzus persicae (Sulz.) transmits the zinnia moderate mottle virus, not Aphis salmonella (Padmanabhan and Padmanabhan, 1978). The watermelon mosaic virus is carried by the symptomless plant zinnia (Tewari, 1976). In terms of epidemiology, it might be significant. For the first time in 2003, Farzadfar et al. (2005) from Markazi (Iran) documented TuMV generating mosaic and colour breakdown on Zinnia elegans. The diseased plant should be removed and burned or buried in the ground to prevent future infection because once the plants have been infected by viruses, they cannot be recovered.
Even viral illnesses can be controlled by controlling vectors with efficient pesticides. Black bean aphid (Aphis fabae), red-banded leaf hopper (Graphocephala coccinea), tarnished plant bug (Lygus lineolaris), longtailed mealybug (Pseudococcus adonidum), four-lined plant bug (Poecilocapsus lineatus), and six-spotted leaf hopper are the main insect pests that infest zinnia. Sometimes, the root-knot nematode Meloidogyne incognita and the angular leaf spot pest Aphelenchoides ritzemabosi infest zinnia (Pirone et al., 1960).
The main virus-carrying insects include Aphis gossypii, Aphis salmonella, Myzus persicae, and Bemisia tabaci. Insects known as aphids feed by sucking sap from vulnerable shoots, leaves, and flower buds. As a result, the shoots or foliage become twisted and deformed. Deformed and feeble plants result from the infection. On the foliage, aphids also exude honeydew, which results in sooty mould. All of these pests can be controlled by spraying the infected crop with some potent pesticides, such as Malathion, Rogor, methyl parathion at 0.2%, and Nuvan or Dimecron at 0.024%, but only soil applications of Nemacur or Furadan will control the nematode.
The advantages of Zinnia
Gardening Since zinnias are common garden flowers and are especially beloved by butterflies, many gardeners are interested in zinnias. They are often produced from seeds, ideally in fertile, humus-rich, well-drained soil that receives direct sunlight. Each year, they will reseed themselves. Additionally, zinnias come in a staggering array of hues. All colours besides blue are available in flowers. The majority are solid colours, but some, in particular Z. haageana, have bicolour petals with contrasting tips. Yellow, orange, cherry, pink, purple, scarlet, and white are among the available hues. Planning a garden should take height into account, and zinnias have different growth patterns to accommodate different needs. For the middle or back of a border or in a cutting garden, the tall, 3- to 4-foot kinds work well. Dwarf plants thrive in pots and at the front of gardens, growing to a height of 8 to 14 inches. Z. angustifolia plants have an equal spread but only grow to a height of 8 to 15 inches. They work well as summer-flowering ground covers in the ground, pots, or hanging containers.
In some rural areas of North America, zinnia species are used as a therapeutic herb for conditions like diarrhoea, edoema, and pain. Eye Altschul Anodyne, Menstruation, Poison Anodyne, Digestive stomachache, heartburn that is cathartic, nose, throat, and kidney discomfort Take a bath if you sweat a lot