poplar

poplar

This data is reviewed by the project of data compilation and application of Science Encyclopedia of science popularization in China.

Populus, the general name of Populus in Salicaceae, originated in the northern hemisphere. Other Populus plants are distributed in the higher part of the north. They are famous for their leaves swaying in the breeze and very straight trunks. Because of the fast tillering, many trees grow into forests, rare individual trees are very beneficial to the natural landscape. Its bark is gray green and smooth, with natural branches; its green leaves are dense and turn to bright yellow; it is dioecious and its catkin leaves open first in spring. Bark usually gray white, smooth, only rough at base of old trees. Buds villous or smooth. Leaves tomentose, at least beneath long branches; short branches tomentose or smooth; petioles laterally oblate or subcylindrite. Bracts striped, margin hairy, stigma 2-4-lobed; stamens 5-20, anthers not apiculate. Capsule oblong, usually 2-valved. Populus alba group, 1 species (1 hybrid), 13 varieties and 7 forms in China.

morphological character

Deciduous tree, about 30 meters high, diameter at breast height about 1 meter, trunk straight, bark gray green to gray white, lenticel diamond, old tree base black gray, longitudinal crack. Young branches hairy, glabrescent. The leaf buds are ovate, the long branches and leaves are broadly ovate or triangular ovate, 10-15 cm long, the apex is short acuminate, the base is heart-shaped or truncated, with deep teeth or wavy teeth, the lower part is densely covered with villi, then gradually falling off, the upper part of the petiole is flat, 3-7 cm long, and the top often has 2-4 glands; the short branches and leaves are ovate or triangular ovate, the apex is acuminate, the lower part is glabrous, with deep wavy teeth, the petiole is flat, slightly shorter than the leaf The film. Flower bud ovoid or subglobose, male inflorescence 10-14 cm long, bracts densely hairy, stamens 6-12; female flower long elliptic, inflorescence 14 cm long. Fruit conic or long ovate, 2-lobed. The flowering period is from March to April, and the fruiting period is from April to May.

Subspecies

Populus can be divided into five groups, namely Populus alba, Populus davidiana, Populus cathayana, Populus nigra and Populus euphratica.

(1) Poplar school Sect.Leuce The bark is usually gray white, smooth, and the base of old trees is rough. The leaves are tomentose or hairy under the long branches and leaves, and the short branches and leaves are tomentose or glabrous. Bracts striped, lobes margin hairy. Fruit oblong, 2-lobed. In addition to Populus tomentosa, there are Populus alba, Populus davidiana, Populus Hopei, Populus xiangyeensis, Populus xiangmaoensis, triploid Populus tomentosa and Populus 84K. In Yanling, most of them are cultivated as follows:

① The biological characteristics of triploid P. tomentosa are similar to that of diploid P. tomentosa, but its growth is faster than diploid P. tomentosa, its resistance is stronger than diploid P. tomentosa, and its material quality is better than diploid P. tomentosa.

② Poplar 84K is a hybrid clone of Populus alba X. glandularis bred in Korea. The tree is tall and straight, with beautiful shape, smooth trunk, green gray skin, and buds close to the trunk. Leaf blade round, adaxially dark green, abaxially densely white tomentose, gradually falling off. It is a male clone, no "catkins", will not pollute the environment. It has the advantages of easy rooting, fast growth at seedling stage and young trees, good material quality, strong wind resistance and resistance.

(2) Big leaf poplar school Sect.Leucoides The bark is flaky and rough. Buds conic, slightly mucilaginous, smooth. The short branch and long branch are nearly round, the base is heart-shaped or deep heart-shaped; the petiole is only slightly flat at the apex. Disk deeply lobed, persistent; stamens 12-40, anthers oblong, apiculate; ovary pilose, style long, stigma 2-3-lobed. Capsule hairy, 2-3 (4) - valved.

There are 5 species and 3 variants in China.

(3) Qingyang school Sect.Tacamahaca The bark splits longitudinally. The buds are big, sticky and have strong fragrance. The leaves are green on the top and white on the bottom, with different shapes of long and short branches and leaves. The base is wedge-shaped, round to shallow heart-shaped, and the edge does not have a translucent narrow edge; the petiole is round or nearly quadrangular, with grooves and different lengths. Stamens 8-60, anthers oblong to globose; stigmas 2-4-lobed; styles short or absent. Capsule 2-4 (5) valved, disk persistent.

There are 37 species (1 hybrid), 29 varieties and 11 forms in this group.

① The bark of P. simonii young trees is gray green, dark gray when old, and longitudinal split. Branchlets and young shoots of young trees have edges, while branchlets of old trees are round and glabrous. Buds slender, apex long pointed. Leaves rhombic ovate, rhombic elliptic or rhombic obovate, 3-12 cm long and 2-8 cm wide. The petiole is round and has the characteristics of cold resistance, early tolerance and wind resistance.

② P. purdomii is called Populus deltoides in Henan Province. Bark brown, flaky, glabrous. Buds glabrous, sprouting branches and leaves long ovate, 25 cm long and 15 cm wide; short branches and leaves ovate or broadly ovate, 7-14 cm long, apex acuminate, base rounded or subcordate.

(4) Black poplar school Sect.Aegeiros The bark splits longitudinally. The buds are rich in mucilage. Leaves are usually triangular ovate or rhomboid ovate, apex long acuminate, base truncate or broad cuneate, margin serrate, with transparent narrow edge, both sides are green, with stomata. Stamens 15-30, anthers subglobose or elliptic, stigmas 2, without style. Capsule disk 2-4-lobed, persistent.

There are 8 species (4 hybrids), 5 varieties and 10 Cultivated Varieties in China.

The main cultivation methods in Yanling are as follows

① The crown of P. xeuramericana is broad, conic, with sparse lateral branches and nearly whorled; the bark is gray to gray brown, and the base is shallow. Long branches and sprouts angulate, grayish green to grayish white, short branches yellowish brown. Buds triangular conic, short branches triangular or triangular ovate, 8-ll cm long, 6-9 cm wide.

② The hybrid of Populus euramericana cv. 107, originated in Italy, was introduced to China in 1984. The trunk is tall and straight, the bark is gray and thick, the branch angle is small, the crown is narrow, the lateral branches are fine, the leaves are small and dense, the crown is full, and the female plant is small. It has the advantages of fast growth, cold resistance, disease resistance and insect resistance.

③ The artificial hybrid of Populus deltoides and Populus deltoides originated in Italy and was introduced into China in 1984. The trunk is straight with small taper and narrow crown. Fast growing, strong wind resistance, disease and insect resistance, excellent material, drought and low temperature resistance. Compared with poplar 107, the growth is similar, but more cold resistant.

(5) Populus euphratica Sect.Taranga Buds without mucilaginous, hairy. The leaf shape is varied, both sides are gray blue, only there are stomata below; the petiole is round. Disk membranous, shallow or deeply lobed, acutely toothed, caducous; stamens 15-35, anthers long, apex apiculate; ovary long ovate, stigma large, 3-4-lobed; bracts spatulate, membranous, nearly white, apex lilac. Capsule long, stipitate, 3 (2) - valved. There are 2 species in our country.

Growth environment

Strong positive tree species. I like warm, cool and humid climate. In early spring, where the temperature difference between day and night is relatively large, the bark is often cracked, commonly known as "broken stomach disease". In the warm and rainy climate, it is easy to be damaged by diseases and insect pests and grow poorly. It is not strict to the soil and grows fast on the deep and fertile, moist loam or sandy loam. In arid, barren, low-lying and waterlogged saline alkali land and sandy wasteland, it is easy to form "small old trees" because of its poor growth and serious diseases and insect pests. It is resistant to salt and alkali, resistant to water and humidity, deep root, developed root system, strong rhizosphere sprouting, fast growth, resistant to dust and pollution. Life span is the longest tree species in Populus, with a life span of 200 years.

Distribution range

It is native to China and widely distributed, ranging from southern Liaoning and Inner Mongolia in the north to the Yangtze River Basin in the south, with the middle and lower reaches of the Yellow River as the suitable area. It is vertically distributed below 1200 meters above sea level, mostly in the deep soil layer of low mountains and plains. There are big trees near the ditch dike at 1900 meters above sea level near Kunming, which grow well.

Methods of reproduction

Most of them are asexual propagation, and the methods of grafting, burying strips, retaining roots, layering and tillering are often used. Populus canadensis can also be used as rootstock for budding or branch grafting with high survival rate.

Sowing: the seeds should be collected immediately after the fruit is ripe. The 1000 seed weight is 0.45g and the germination rate is about 96%. Before sowing, the soil should be carefully prepared, sown, covered with 0.5cm soil, and pressed after sowing. The average height of 1-year-old seedlings was 62.6 cm, and the ground diameter was 0.35-1 cm.

The lateral buds should be removed in time to protect the high growth of terminal buds.

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Land preparation]:

The machine ploughed land with a depth of 25-30 cm in autumn is selected, and more than 3000 kg of base fertilizer per mu is applied, and then the next spring, the fine ploughing is used as the border. The border surface should be broken, flat and clean. The border should be neat and uniform, and the ridge should be solid to facilitate irrigation. Cutting with mulching film can improve the seedling rate.

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[seedling picking and cutting]:

It is suggested that one year old and healthy flat stubble seedlings should be used as cuttings. The panicle is 0.5-3cm thick and 14-17cm long, with 3-5 robust buds. The upper incision should be even, the lower incision should be horseshoe shaped, and the incision should not be split. Cut cuttings should be stored immediately, and avoid direct sunlight and air drying.

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[cutting]:

Cutting in spring is better. The nursery is cut by 60 cm line spacing, then cuttings or shovel are used to cut the soil. The angle between the cuttings and the ground is 45 degrees, and 1-2 buds are exposed above the ground, with 6000 cuttings per mu. The planting density should be controlled at about 450 plants per mu, the row spacing should be 1-6m, and the plant spacing should be 1m. Before cutting, the cuttings should be soaked in water for one day and night. No matter dry cutting or wet cutting, the seedlings of cuttings must be upward instead of backward cutting, and the buds should be kept flush with the ground. Cuttings with different thicknesses should be cutted in separate beds.

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[watering]:

After cutting, small water immersion irrigation method was used to irrigate. Before the second watering, the damaged ridge should be repaired to facilitate water storage, and then once a week, three times in a row. Water the fourth time, 2 weeks apart and combined with seedling planting and then water, after each

Chinese PinYin : Bai Yang