Want to learn about hydrangea breeding techniques and ornamental gardening?
Wang Neng and so on
Hydrangea, also known as hydrangea, pink flower, hydrangea, is a perennial deciduous shrub of the family Saxifrageae, likes warm, moist and semi-shaded environment, the origin is the Yangtze River basin in mainland China and Japan, and now it is more common to cultivate potted flowers all over the world. Hydrangea inflorescence is large, spherical, flowering period in June - September, flowering flowers, flower color is gorgeous and changeable, pleasing to the eye, is a woody flower with good ornamental effect, and because of its large flower color, excellent ornamental effect, more shade tolerant, can be directly planted in residential quarters, courtyards, parks, green spaces, can also be used for potted flower cultivation, so it is widely used in the field of ornamental horticulture, and the demand for seedlings is large.
In recent years, relevant gardeners have begun to introduce and domesticate excellent varieties of hydrangea abroad, aiming to screen out excellent varieties for production. The breeding methods of hydrangea mainly include tissue culture, cuttings, ramification, stripping, etc., these methods have their own characteristics, but in a comprehensive comparison, the use of tissue culture technology for rapid propagation in vitro has the advantages of less materials, fast breeding speed, and devirus, which is an effective shortcut to obtain high-quality neat seedlings. In view of the excellent characteristics of hydrangea, the author has carried out research on hydrangea breeding technology and its application in ornamental horticulture such as potted plants and greening in recent years, and has achieved many results. The relevant research results are introduced as follows for the reference of relevant landscape workers.
1 The main breeding techniques of hydrangeas
1.1 Tissue culture techniques
1.1.1 Selection of explant materials and primary induction culture
In hydrangea tissue culture technology, the materials that can be used as explants are the shoot segments, shoot tips, and leaves of hydrangeas. After experimental comparison, it is better to use robust shoots and stem segments as explant materials. The specific method is as follows: from April to May, select a sturdy young shoot to cut off part of the leaves, take its stem segments, first place them in a washing powder liquid and shake them for cleaning, rinse them with flowing tap water for 30 min, then treat them with 75% ethanol for 30 s, then sterilize them with 0.1% HgCl2 for 7 min, then sterilize them with saturated bleaching supernatant for 8 min, rinse them with sterile water for 4~5 times, and finally cut a stem segment with petioles about 1.0 cm long on an ultra-clean workbench for primary induction culture. The original induction medium formulation was modified MS+BA 1.0 mg/L + NAA 0.1 mg/L + agar powder 6 g/L + sucrose 30 g/L, pH 5.8. The temperature of the incubation chamber was about 25 °C, the light time was 12 h/d, and the light intensity was about 2 000 lx.
1.1.2 Subproliferation culture
The formula of secondary proliferation medium was modified MS+BA 0.5~1.0mg/L + agar powder 6 g/L + sucrose 30 g/L, pH 5.8. The temperature of the incubation chamber was about 25 °C, the light time was 12 h/d, and the light intensity was about 2 000 lx. Under these culture conditions, the sub-generation value-added culture could be repeated once every 30 days, and the proliferation rate was 1∶(3.0~3.5), and no glass seedlings occurred.
1.1.3 Rooting culture
When the sub-proliferation reaches a certain number and there is no "glass seedling" in the bottle seedlings, the test-tube seedlings can be cut into individual plants and transferred to the rooting medium for rooting culture. The rooting medium formula was 1/2 MS + IBA 0.3 mg/L + agar powder 6 g/L + sucrose 20 g/L, pH 5.8. The temperature of the incubation chamber was about 25 °C, the light time was 12 h/d, and the light intensity was about 2 000 lx.
1.1.4 Domestication of test-tube seedlings
After the test-tube seedlings took root, they were transplanted to the substrate [peat:perlite:coir =2:1:1 (mass ratio, the same below), pH 5.5~6.0] to refine and acclimatize the seedlings to cultivate high-quality test-tube seedlings. After refining seedlings for 2~3 months, the seedlings can be potted for potted flower culture, or planted in a nutrient bowl and then cultivated for 1~2 months for green planting.
1.2 Conventional breeding techniques
1.2.1 Cuttings
Cuttings are one of the main methods in the conventional breeding technology of hydrangea, which has the advantages of convenient material collection, multiple sources and fast rooting. Hydrangea cuttings can be propagated in spring, summer and autumn, and in Shanghai, it is better to carry out the rainy season from June to July, and the survival rate of cuttings can reach more than 90%. The specific method is as follows: select the young shoots that germinate in the current year, cut the stem segments about 15cm long, retain 2~3 nodes for each stem segment, remove the middle and lower leaves, retain the upper 2~3 leaves and cut off half, and then cut the incision under the base and dip it in rooting powder (can be self-formulated, add NAA 1 200 mg, IBA 100 mg, IAA 50 mg per 1 000 g talc, dissolve these three plant growth regulators with alcohol and mix them into talc powder to dry), Then insert the stem segment into the mixed substrate (peat: perlite = 1:1, substrate thickness 8 cm), the insertion depth is about 5 cm, water enough after insertion, cover with a small plastic ring shed for 5~7 days, start foliar spray watering from the 2nd day, watering 3~5 times a day, until the base of the stem segment grows new roots, and the cuttings can be completed after 3~4 weeks of cultivation.
1.2.2 Divides
Dividing should be carried out in early spring before budding of the mother plant of hydrangea (when the sap has not yet flowed). The specific method is as follows: after the ground plant or potted plant is uprooted, the sprouting tiller branches at the base of the mother plant are cut off from the mother plant, and then planted separately.
1.2.3 Beading
The easiest method to grasp is the ordinary stripping method, also known as the branch pressing method, that is, the branches near the ground are pressed down and buried in the soil or substrate to promote their rooting and produce daughter plants. This method is suitable for shrubs, vines and other plants with relatively low plants and soft branches. Hydrangea strip propagation can be carried out throughout the year, but it is preferable to do so in spring or autumn. The specific method is as follows: select the 1~2-year-old strong branches on the mother plant, and then bend the middle of the branch and bury it in the soil; if the potted plant is pressed, the branch can be bent and the branch can be pressed with soil or substrate. Hydrangea branches can be rooted after 2~3 months after 2~3 months to become an independent plant, and can be planted by cutting off the roots of the branches.
2 Hydrangea potted flower cultivation techniques
Hydrangea has many advantages for potted flower cultivation (referred to as potted plants), such as large and beautiful flowers, strong ornamental and adaptable, easy maintenance, and relatively simple seedling breeding. Therefore, hydrangea potted flowers are favored by the horticultural community and the general public, and hydrangea has become one of the important potted plants in Zhejiang, Jiangsu, Anhui, Shanghai, Yunnan, Guizhou, Hunan, Hubei, Jiangxi and other places.
2.1 Flower pots and substrates
Hydrangeas prefer warm, moist environments. At present, the flower pots on the market are suitable for planting hydrangea, but the ceramic pots, enamel pots and plastic pots with a diameter of 20~25 cm are better, and these flower pots have good water retention, fertilizer retention and heat preservation, and are both beautiful and generous. The planting substrate is better to peat: perlite: coconut peat = 2:1:1, the substrate is fully mixed and then loaded into the pot, and the filling is stopped at a height of 2~3 cm from the basin mouth, and then some water is sprayed into the pot slightly to keep the substrate moist.
2.2 Seedling potting and plant type culture
The potting time of hydrangea seedlings is more suitable from March to May, planting 1 plant in each pot, and watering enough live trees after planting. In case of sunny and hot weather after planting, it is necessary to cover with a black shade net with 75% shading rate for 5~7 days, and remove the shade net after the seedlings are alive and grow new roots. When the plant grows to a height of 15 cm, it can be topped to promote the growth of branches, and then erase the excess branches, leaving only 3~5 stout branches. The second topping was carried out when the branches were 10 cm long, so that the hydrangea plant shape was upright and plump, and the branches were strong, and the number of branches should be 8~10. This plant type cultivation method can make the hydrangea bloom in the same year when it is planted. In the spring of the second year, the flowering branches are shortened to promote the development of new branches and make the whole potted flower flourish.
2.3 Fertilizer and water management
Hydrangea hydrangea has fat leaves, large and colorful flowers, and strong transpiration, and needs more fertilizer and water, especially in the flowering period from June to September. Therefore, the fertilizer and water management of hydrangea potted flowers should grasp the principle of "thin fertilizer and diligent application". The specific method is as follows: from March to October, generally apply thin liquid fertilizer (mainly 0.5% nitrogen, phosphorus and potassium ternary compound fertilizer) 1~2 times a month, and then apply 0.2% ferrous sulfate liquid fertilizer and 5%~10% rotted cake fertilizer 3~5 times; Hydrangea likes moisture but avoids stagnant water, in March to October, should be watered more, generally every 5~7 days 1 watering. During the midsummer period from June to July, the foliar surface should be sprayed with water 1~2 times a day to reduce the leaf surface temperature, reduce water loss, and promote the normal growth and flowering of plants. If hydrangeas grow in plastic greenhouses for large-scale maintenance, they can be increased by installing sprinkler systems and atomization systems in the greenhouses from summer to early autumn (high temperature and strong light season), so that the humidity in the greenhouse can be kept at about 75% during the day. In October, when the temperature gradually drops, watering can be reduced to 1 water every 10 days or so. In winter, water is poured once every 15 days or so.
2.4 Light and temperature management
Hydrangea likes light and temperature, is afraid of severe cold, is a short-day plant, the most suitable growth temperature is 21~28 °C, and the temperature of indoor potted flower cultivation in winter is above 5 °C, it can not fall leaves. If hydrangea potted flowers are maintained on a large scale in a plastic greenhouse, it is necessary to pay attention to the high temperature and strong light in summer, and use a black shade net with a shading rate of 75% for shading treatment, and control the temperature in the shed below 30 °C to prevent sunburn on the leaves and flowers. If the hydrangea potted flowers are maintained in the unit or home, they can be moved to a semi-shaded and sunny place to avoid direct sunlight. When cultivating hydrangea potted flowers in winter, it is necessary to ensure that the indoor temperature is above 5 °C, the potting soil is not frozen, and sufficient light should be given.
3 Application of hydrangea in landscaping
Hydrangea is widely used in mainland landscaping, and the history of hydrangea cultivation is relatively early, hydrangea is planted in the Jiangnan gardens built in the Ming and Qing dynasties, and at the beginning of the 20th century, hydrangea is also inseparable from the planting of hydrangea in parks, green spaces, squares and other places. At present, hydrangeas are planted in many modern parks and scenic spots, especially in southern gardens. In landscaping, hydrangeas can be arranged in the sparse shade or beside the boulevard, and because of its low requirements for sunlight, it is suitable for planting in the courtyard, such as planting along the entrance of the building, or planting along the front and back of the building, planting in clusters, all have excellent landscape effects. In addition, hydrangeas are planted in flower beds, flower lands, trees, shrubs, herbs, etc. in residential communities and unit groups, which can play a role in complementing each other, scattered, and spectacular decoration.
4 Major pest and disease control of hydrangea
4.1 Prevention and control of major diseases
Hydrangea for potted plants or landscaping applications, there are diseases, the main diseases are blight, anthracnose, leaf spot and downy mildew, etc., can be used in the early stage of the disease, the use of high-efficiency and broad-spectrum fungicides (1:800 times chlorothalonil or 1:1 000 times carbendazim, tobuzin, etc.) spraying control.
4.2 Major pest control
According to years of practice and observation, the main pests of hydrangea are red spiders, aphids, whiteflies, etc., among which the occurrence of red spiders is more serious (red spiders reproduce for more than 20 generations in Shanghai all year round, and there is parthenogenesis, often lurking on the front and back of leaves and leaf veins, sucking leaf juice with piercing and sucking mouthparts, so that the leaves lose green and yellow or even fall off, and when it is serious, it causes plant shrinkage, which seriously affects the growth and flowering of hydrangea; At the same time, the body of the red spider insect is small, and it is not easy to be detected when it first occurs, and when it is found that there are leaves that lose green, it often occurs in large quantities, so it is necessary to strengthen prevention). The specific control measures are: when the red spider first occurs, immediately spray the front and back of the leaf with acaricide, and use 1:1 500 times the gram mite or 1:1 000 times the insect mite light, and apply the pesticide twice a month until the red spider is completely killed. For pests such as aphids and whiteflies, 1:1 000 times insect mite light and one-time net can be used for control.
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