How are Catalpa bungei seeds selected? What are the seedling raising methods?

Catalpa bungei, also known as Zitong, Jinsiqiu, and Shuitong, is a major tree species in China's reserve forests and one of China's precious timbers. Catalpa bungei has good wood quality, high toughness and high decay resistance, and grows fast, reaching 3 cm in a year. In landscaping it can be used as a street tree, and as an ornamental tree it can purify the air, making it one of the excellent tree species for greening cities and improving the environment. So how are Catalpa bungei seeds selected? What are the seedling raising methods? Let's take a look together below.

1. How are Catalpa bungei seeds selected?

For Catalpa bungei, collect seeds from vigorous mother trees 15-30 years old. When the fruit turns from yellow-green to grayish brown and the tip cracks slightly, it indicates the seeds are already mature; you can cut off the small fruiting branches and pick off the fruits. For spring sowing in March, before sowing soak the seeds in 30-degree warm water for 4 hours, remove and air-dry them, then mix them evenly with wet sand 3-5 times the volume of the seeds, pile them indoors for germination promotion, sprinkle water and turn them regularly so the temperature inside and outside is uniform. After about 10 days, when 30% of the seeds have split open at the mouth, they can be sown.

2. What are the seedling raising methods for Catalpa bungei?

1. Seedling propagation

For seedling propagation, collect seeds from vigorous mother trees 15-30 years old. When the fruit turns from yellow-green to grayish brown and the tip cracks slightly, it can be picked. The seed yield rate of Catalpa bungei is about 10%, seed purity is generally 75%-80%, germination rate is 40%-50%, the thousand-seed weight is 4-5 g, the sowing rate per mu when raising seedlings is 1-2 kg, and the seedling output per mu is 10,000-15,000 plants.

2. Root burial seedling raising

Catalpa bungei sets little seed and seed collection is difficult, but its sprouting ability is strong, and root burial seedling raising is one of the main propagation methods. The root segments come from the roots of large trees and seedling roots. Cut root segments 1-2 cm thick into 15-20 cm long pieces; insert them as they are dug in winter, while for spring insertion the root segments must be stored in sand. When burying the roots, insert the thick end upward into the soil; if the thick and thin ends cannot be distinguished, just lay them flat and bury them in the soil, cover with 1-1.5 cm of soil, and press firmly and tamp down.

3. Cutting propagation

For cuttings, use root sprout shoots from mother trees and 1-year-old seedling stems as the propagation material, cut them into 15-20 cm long pieces, store the pieces in sand in winter, take them out for cutting in March-April; the seedling height can reach 1-1.5 m in the same year, and the effect is even better if treated with ABT No. 1 rooting powder.

4. Grafting propagation

It can be done in both winter and spring, and bud grafting can be done from spring to late autumn. In winter, using the slack farming season, dig out the Zi rootstock and graft indoors; after grafting, stack them neatly indoors or in a kiln, store with wet sand, and promote healing of the graft union. In early spring, move them to the nursery field for planting, with a spacing of 1 x 0.4 m, 1,500-2,000 plants per mu. Grafting around "Qingming" in spring is best. In the nursery field, cut back, graft, and cover with soil as you go; the grafting survival rate is generally about 90%. Grafting methods

Grafting is mainly by cleft grafting and bud grafting. For cleft grafting, first leave one round of buds on the scion, cut it off 25px above the bud and 3-125px below, trim the lower part into a wedge shape and hold it in the mouth until grafting. Cut off the Zi rootstock 3-125px above the ground, choose a smooth side and split it 3-125px deep along the pith; when pulling out the knife, pinch the scion tightly with thumb and index finger and insert it into the cut. Be careful to align the cambium of the scion and the rootstock. If the rootstock and scion are not clamped tightly, they can be bound with hemp rope and plastic strips, then seal the wound with wet soil. In 10-15 days, buds will sprout and shoots will grow. Bud grafting is mainly by chip budding.

The above is an introduction to Catalpa bungei. Catalpa bungei is one of China's precious tree species, with a graceful tree shape and large, brilliantly colored flowers, and it is often used for garden ornament. Its wood is good, its uses are wide, and its economic value is high, ranking first among the hundred trees. It is mainly produced in China's Hebei, Shanxi, Shaanxi, Gansu, Jiangsu, Zhejiang and other places. It is cultivated in Guangxi, Guizhou, and Yunnan.

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