Breeding Management techniques of Rhododendron

Propagation methods: rhododendron can be propagated by sowing, cutting, grafting, striping and other methods.

1. The seed setting rate of rhododendron is high, there are many seeds, the germination rate is high, and the plasticity and vitality of seedlings are strong, but the growth is slow, the culture is difficult, and the offspring are not necessarily ideal, so seeds are rarely used in production. It can only be used in the following cases: first, to cultivate rootstocks; second, to obtain new varieties by cross breeding; and third, to introduce excellent wild species.

(1) seed harvest: the fruit of Xiao changes from green to brown. When the upper part is just cracked, the fruit is picked and dried indoors. After all the petals are cracked, the seeds can be harvested and stored in the indoor dry place.

(2) sowing: sowing in pot in spring. Use shallow basin, wooden box or in the ground bed, use torn water moss as sowing substrate, wet water moss should be compacted, up to 3x4 of the original thickness, remove a layer of 3mm thick loose water moss on the surface, spray water with fine spray pot, sow with sowing method because the seeds are small. After insertion, it does not need to be covered with soil, it can be covered with glass, covered with a layer of newspaper, kept at 15: 20 ℃, and can germinate in 2 to 3 weeks.

(3) Management: after germination, the mulch can be removed, and ventilation can be gradually strengthened to improve the resistance of seedlings. Keep the basin soil moist, wait for the seedlings to grow to 2-3 true leaves, high 1.5~2.5cm can be transplanted, plant distance 4~5cm, after autumn when 3~4cm is high, can be transplanted once. At the seedling stage, pay attention to avoid strong light, strong winds and other adverse environment.

2. Cuttage propagation

(1) cutting cuttings: take the short and sturdy semi-lignified branches of the current year's internodes as cuttings, grow about lOcm, cut off the lower leaves, leaving the upper 2-3 leaves, some have to cut off the top tip, and the lower incision is just under the node.

(2) cutting: West cuckoo from late May to early June, rhododendron from early to mid-June, summer cuckoo cutting substrate from mid-June to late June can use less bacteria, sterilized orchid mud, Huangshan soil, river sand or vermiculite, perlite and so on. A small number of available basin inserts, a large number of available bed inserts. First make a hole in the substrate with a stick, and then insert the cuttings with a depth of 1 to 3 or 2 to the length of the cuttings. Spray water with fine mist after insertion and spray through. Pot insertion will cover the flowerpot with plastic bags, tied around tight, maintain air humidity and temperature, often keep the pot soil moist.

(3) Management: prevent direct sunlight after insertion, but not too much shade, lack of light slow growth, weak, maintain a temperature of 25: 30 ℃, often spray, increase air humidity, pay attention to avoid stagnant water, take root in about a month, pot in the second year, and blossom in the third year.

3. Grafting propagation

The grafting method is usually split at the top of twigs, which is from May to June. Rootstock selection of rhododendron or its varieties, such as "Mao Ye Qinglian", "Jade Butterfly", "Purple Butterfly" and so on. The 2-year-old single stem plant was selected as the rootstock. The tender shoots of 3~4cm were cut off from the mother plant of rhododendron, the lower leaves were removed, and the upper 2-3 leaves were left, and the base was cut into a smooth wedge of 0.5~lcm. Cut the new shoot 3~4cm of the rootstock in the same year, remove the leaves, cut lcm longitudinally from the flat cut, insert the scion, align it with the cambium, fasten it with plastic tape, and then bag it to keep warm and moisturize.

There are other methods, such as cutting method, leaning method, budding method and so on.

4. striping propagation is generally carried out by high-pressure method after the flowers of spring and summer cuckoos are withered, it usually takes 3 months to take root, and the survival rate is higher.

Cultivation and management: due to the wide variety of rhododendrons, some can be planted in the open field or potted, and some can only be potted, such as rhododendron. The following are described separately:

1. Open-field cultivation such as rhododendron, eastern rhododendron, summer cuckoo and so on.

The acid upper soil with deep and fertile soil layer and pH4~5.5 should be selected. If the upper soil is not suitable, it should be improved. According to ecological habits, shading measures should be taken to avoid summer exposure in the planting area. Watering should be adequate, but avoid stagnant water. With the advent of winter, the deciduous cuckoo enters the dormant period and needs to be watered once, after which the number of watering can be reduced. Evergreen cuckoos should be watered normally in winter. With the advent of winter, cuckoos planted in the ground should take measures to prevent the cold in order to ensure their safety through the winter. During the growth of cuckoos, pruning should be combined with pruning, such as heart-picking and pruning. Heart picking is mostly carried out in young plants, and the terminal bud or flower bud is artificially removed to save nutrients and promote the early development of new branches below. Pruning is used to arrange the shape of the tree, which can trim the branches of diseases and insect pests, overlapping branches, cross branches, bald branches and winter frostbite branches. In order to make rhododendron grow healthily, topdressing should be combined to make flowering luxuriant and colorful, and root fertilization should pay attention to the effect of soil acidity and alkalinity. Topdressing outside the root can be carried out in the sunny evening, the concentration should not be too high, spray should be thoughtful and uniform, to avoid rainy days or windy weather.

2. Potted plants are like cuckoos. The pot selection of rhododendron should not be too large, because rhododendron is the fibrous root system, the root system is shallow, the growth is slow, if the pot is too large, it is easy to lose control of fertilizer and water, which is disadvantageous to growth. The basin is generally better to burn the side with a strong water and air permeability. The basin soil should be well drained, loose, fertile and acidic soil between pH5.5~7, such as pine needle soil, rotten leaf soil, orchid mud, sawdust and so on. Potted cuckoos usually go out of the room in spring or enter in winter on the urn, first put a coarse-grained drainage layer at the bottom of the urn, and then fill in the culture soil, one hand to support the seedlings, the other to fill the soil, do not fill too much, to leave room for watering. After putting on the basin, first put it in a cool place to strengthen the management of spraying and watering, so that it can slow down the seedlings quickly, and it can be put in an appropriate position to enter the normal management after 5-7 days. It is better to water non-alkaline and clean river or pond water. if tap water is used, it should be stored in a water tank for 1 ~ 2 days to make the discharge of chlorine and water temperature close to the soil temperature. The amount of watering should be determined according to the weather conditions, the dry temperature of the basin soil, and the needs of the growth and development stage. It is better for cuckoo to fertilize with bean cake water and fishy water, thin fertilizer should be applied frequently, and ferrous sulfate should be added properly to adjust the pH value of soil. Cuckoo pruning is mainly sparse pruning, seedlings in 3 years to accelerate the formation of tree shape, often pick off flower buds, do not make it blossom, heart, remove new shoots, promote the germination of new branches. Adult trees should cut off disease and insect branches, excess branches, cross branches and so on.