Scientific name: chestnut B 1. Also known as chestnut, big chestnut and hairy chestnut. Chestnut, FAGACEAE.

Form and use

Tree, 20 meters high, DBH 1 meter. Branchlets without terminal buds, covered with gray fluff. The leaves are 9 ~ 18 cm long and 4 ~ 7 cm wide, with serrated edges, awns on the teeth and short gray hairs below. The diameter of the shell bucket is 6 ~ 8 cm, and the diameter of the nut is 2 ~ 3.5 cm. Flowering in April-May; The fruit ripens in September.

Chestnut is one of the famous dried fruits in China. From banpo village (Yangshao Cultural Site) in Xi 'an, it is found that the fruits of wild chestnut trees have been used in clan society (6000 years ago). Sima Qian's Biography of Historical Records of Huo Zhi in the Western Han Dynasty records that "Yan Qin is a thousand chestnuts, and this person is like a thousand households". Chestnut kernel contains sugar, starch 70. 1%, protein 10.7% and fat 7.4%. It is nutritious and delicious. Wood is hard, straight in texture, rough in structure, resistant to decay and moisture, and suitable for sleepers, columns, vehicles, shipbuilding, furniture and other materials.

(Xu Yongzhen)

Geographical distribution and biological characteristics

Chestnut is distributed between18 30' ~ 40 30' north latitude and 99 ~ 124 east longitude, including Jilin, Liaoning, Hebei, Beijing, Inner Mongolia, Shandong, Henan, Anhui, Jiangsu, Zhejiang, Fujian, Taiwan Province, Guangdong, Guangxi, Jiangxi and Hunan. Vertical distribution, the lowest is the alluvial plain in Tancheng, Shandong, Xinyi, Jiangsu and Shuyang, with an altitude of less than 50 meters, and the highest is Weixi, Yunnan, with an altitude of 2,800 meters. Its natural distribution spans tropical margin, subtropical zone and warm temperate zone. However, it is widely distributed and cultivated in the provinces of North China in the Yellow River Basin and Yangtze River Basin. Chestnut has no strict requirements on climatic conditions. It can grow under the climatic conditions of annual average temperature of 8 ~ 22℃, extreme maximum temperature of 35 ~ 43℃, extreme minimum temperature of -35℃ and annual precipitation of 500 ~ 1900 mm ... but at annual average temperature of10 ~/4℃, the annual precipitation is 600 ~/kloc. It grows well in the range of pH 4.5 ~ 7.0. If the pH is greater than 7.6 and the salt content is greater than 0.2%, the growth will be poor. It can be cultivated in mountains, hills or alluvial sandy land, but the soil with deep soil layer, rich organic matter, loose texture and good drainage is suitable. Chestnut has developed root system and is more drought-resistant and waterlogging-resistant. Generally speaking, northern varieties are more drought-tolerant than southern varieties, and southern varieties are more waterlogged-tolerant than northern varieties. Chestnuts prefer sunshine to darkness. In the valley with less than 6 hours of sunlight, the crown grows upright, the leaves are thin and the branches are thin, and the yield is low. During flowering, insufficient light is easy to cause physiological fruit drop. Excessive shading for a long time will make the branches and leaves in the inner room turn yellow and thin, or even die; Or the branches move out, which affects the yield. When planting, it is advisable to choose sunny sunny slopes or open valleys.

(Hu)

type

The main goal of chestnut breeding is to make nuts with high yield, diverse quality, short tree shape and strong adaptability.

There are more than 300 excellent chestnut varieties in China. There are nine species in Wuxian County, Jiangsu Province, scorched in Yixing, Chu Shuhong in Liyang, Singapore Airlines pepper in Guangde, Anhui Province, and shallow-thorn chestnut in Zigui, Hubei Province, but the quality is generally not as good as that in the north. The main producing areas in North China have long used seedlings for propagation. Although there are names such as "Ming chestnut", "Mao chestnut", "You chestnut" and "Autumn equinox chestnut", in fact, no stable cultivated varieties have been formed so far. The variation among plants is large, but it has great potential in improved variety breeding. Seedling selection began in the 1960s, and a number of excellent plants were selected in Hebei, Shandong, Beijing and other places. By popularizing high plant grafting and clonal grafting propagation, obvious results have been achieved. In addition to cultivated species, wild chestnuts are widely distributed in the low mountains and hills of the Yangtze River basin. It has been a long history for people to graft them into the garden as rootstocks. Although the nuts of wild chestnut and its relative species, Li Mao, are small, they all have the characteristics of short crown, early fruiting and many fruits. Castanea henryi is mainly used for wood, and it is also cultivated in Zhejiang and Fujian. There are many kinds of chestnut and these wild relatives, and there are many natural hybrids. For example, "Caogouli" cultivated in Lanxi, Zhejiang Province is a natural hybrid of chestnut and Castanea henryi. These are valuable breeding resources.

Chestnut trees cultivated in the world include European chestnut, Japanese chestnut and American chestnut. American chestnut is not only used as wood, but also an important source of tanning materials. At the beginning of the 20th century, it was fatally hit by chestnut blight, and now it has become an endangered tree species. The United States began to cross American chestnut with Japanese chestnut and chestnut with strong disease resistance on 1924. European chestnut and these two Asian chestnuts are also used for ink disease resistance breeding. After the discovery of 194 1, the chestnut gall wasp spread rapidly, and more than half of the cultivated varieties died, which seriously threatened production. After crossing with insect-resistant varieties, many new varieties resistant to chestnut gall wasp were obtained and have been applied in production.

The chromosome number of all kinds of chestnuts is 2n=24. Interspecific hybridization is generally not difficult. The hybrid offspring showed obvious heterosis in growth rate and nut size. The subculture and early fruit of chestnut are dominant. The susceptibility of American chestnut is generally incomplete dominant. The resistance of Japanese chestnut to chestnut gall wasp is completely dominant. Pollen allelopathy also exists in cross breeding of chestnut. Pollen affects the weight of seeds, the difficulty of seed coat peeling and the color of embryos. It is promising to carry out cross breeding of chestnut on the basis of seed selection. In addition, the seedlings of chestnut, Japanese chestnut and American chestnut treated with colchicine were more likely to obtain polyploid branches.

(Zhang)

Afforestation technology

(1) Seed collection: When collecting seeds, select excellent single plants with high and stable yield, early fruiting, good quality and strong growth. Chestnuts fall off naturally when they are fully mature. Choose full, full, pest-free seeds. Generally, sand storage method is adopted. Sowing time is divided into spring sowing and autumn sowing. After thawing in northern China, that is, from the vernal equinox to Qingming, it can also be broadcast before freezing in early winter. In the south, it is mostly carried out from the middle and late February to the middle and early April. (2) Seedling raising: The nursery should choose flat sandy loam with convenient irrigation, fertile soil and loose soil. Carefully prepare the soil first, apply sufficient base fertilizer, then make the border, furrow at the row spacing of 20 ~ 30 cm, and sow at the plant spacing of 12 ~ 15 cm. The sowing amount per hectare in the north is 1 125 ~ 1500 ~1875 kg in the south. The height of 1 year-old seedlings can reach 40 ~ 100 cm, which can be planted in nursery. ③ Grafting propagation: rootstocks are mostly used in the north, and 2-3-year-old seedlings are used as rootstocks. Habit of in-situ grafting with 5-8-year-old wild chestnut as rootstock in the Yangtze River basin. Castanea henryi is used as rootstock in some areas of Hunan province, and its survival rate is high. Scions should be cut from mature superior plants with strong growth, many fruits and good quality. In order to prolong the grafting time properly, the experiment proved that the scion was cut 45 days before bud germination and stored in the basement or kiln, the temperature was 3 ~ 5℃, and the water content of the filler was 30 ~ 35%, so the grafting effect was good. The grafting period varies according to the method. Grafting is generally carried out when the buds of rootstocks begin to sprout and the bark is easy to peel off. For example, Hebei is generally in the middle and late April and Guangxi is in the middle and early March. In addition, grafting should generally choose sunny days, and the temperature 18℃ is better. Autumn grafting in the Yangtze River basin is generally suitable from September to 10, and abdominal grafting is mostly used. Some also use bud grafting. Nursery grafting can adopt cutting grafting, skin grafting, tongue grafting, abdominal grafting, root grafting, latent bud covering budding, and spring budding. High grafting is carried out on big trees with thick rootstocks or improved rootstocks. If the main branches and side branches are exposed, peeling grafting or mosaic grafting should be used for grafting. (See grafted seedlings, tree grafting) ④ Afforestation: The afforestation site is selected in neutral or slightly acidic soil with deep, moist and fertile leeward. Planting density depends on soil, topography, variety and management level. When seedlings are planted, 150 ~ 2 10 plants can be planted in fertile soil and 240 ~ 330 plants can be planted in poor soil. Reasonable close planting of chestnut is an effective way to realize early high yield. Grafting with dwarf rootstocks, 600 ~ 800 plants per hectare in mountainous areas and 300 ~ 600 plants in flat land. Chestnut is a cross-pollinated tree species. Self-pollination often leads to infertility or extremely low fertility. Therefore, when planting chestnut forest, different varieties should be selected for mixed planting. Generally, the main varieties are 4-8 rows, and 1 row pollination tree species are configured. ⑤ Tending management: Peanut, mung bean, broad bean and other crops can be intercropped within 1 ~ 5 years after afforestation. After the crown of the forest is enlarged, green manure crops and medicinal plants can be planted under the forest. In spring and summer, when weeds grow vigorously, they are cultivated in chestnut garden or raised in lumps. Chestnut is very sensitive to fertilization and irrigation. The effect of applying available nitrogen fertilizer at flowering stage is more obvious. Organic fertilizer should be given priority to, combined with chemical fertilizer, and mixed application of nitrogen, phosphorus and potassium is the best. Fertilization methods vary from season to season. Generally, organic fertilizer is applied to the annular furrow in winter, with a width of 15 ~ 20cm and a depth of 25cm. In summer, top dressing should be radial or hole-shaped, and the depth is about 15cm. Plastic pruning is an important measure to cultivate good tree skeleton, adjust nutrient distribution, promote fruit and prevent diseases and pests. Young trees are usually shaped in two ways: natural heart shape and sparse trunk shape. Generally, varieties with weak dryness adopt natural joy. The height of trunk is 60 ~ 100 cm. Select 3 main branches evenly distributed around the trunk, and select 2 ~ 3 robust branches as side branches at 60 ~ 70 cm on the main branch. The trunk is sparse, the central main branch is obvious, the crown is tall and layered, and the spatial effect is fully utilized. The stem height is 60 ~ 100 cm, with 5 ~ 6 main branches, 2 ~ 3 in the first layer, 0 ~ 2 in the second layer and 0 ~ 2 in the third layer. There are 2 ~ 3 lateral branches on each main branch, and the spacing between layers is1~1.5 m. There are two pruning methods for adult trees: "cleaning and pruning" and "pruning". "Clear the bore and clear the Sichuan tree", that is, all the male flower branches, slender branches, developing branches, pest branches and long branches in the crown are thinned, leaving only the fruiting branches outside the crown. This method will make the result part move outward, reduce the result area, and lead to the result every other year. "Solid chamber pruning" is to enrich the chamber with young branches (developmental branches sprouting from latent buds in the chamber), increase the bearing parts, and cultivate successor branches (preparatory branches) on the main branches for rotation and renewal. Compared with "indoor cleaning and pruning", it can increase plant yield by 30 ~ 50%. The regeneration ability of chestnut trees is very strong, and the method and degree of regeneration should be determined according to the specific situation. Generally, the main and side branches should be replaced step by step year by year and updated in batches. In some old chestnut producing areas, pruning and scraping bark can also play a role in the regeneration of old trees. Inferior trees are grafted by high grafting and multiple grafting, and inferior trees become high-quality trees. Timely harvest can increase yield and improve quality. Due to different regions and varieties, the maturity is inconsistent, so the harvesting time is also different. Generally, it can be harvested when the bulbs turn from cyan to yellow and about 30% of them crack slightly. The harvested bulbs were stored in the shade for several days, and most of the bulbs were cracked and chestnuts were taken out for classified storage.

The main pests and diseases are powdery mildew, chestnut black spot, chestnut gall wasp, chestnut aphid, chestnut weevil, peach moth, leather moth and so on.

(Hu)

Chestnut aphid

(Chestnut Aphid)

(Cao Chengyi)

Scientific name: Lachnus tropicalis (Vandergut). Also known as chestnut aphid and tropical black aphid. Homoptera, Aphidae. Wingless parthenogenetic aphid, gray-black, 3 ~ 4 mm long; The abdomen is round and the antennae are short, which is about 1/2 of the body length. There are 2 ~ 5 circular sensory holes at the ends of the 3rd ~ 4th joints, and the tibiofibular joint of the hind foot is 0.97 times the body length. The wings of winged parthenogenetic aphids are black, and only the tibial vein area and the middle of the wings have transparent bands; There are 9 ~ 2 1 sensing holes in the third section of the antenna (see figure). Distributed in China, Jilin, Liaoning, Beijing, Hebei, Shandong, Henan, Jiangsu, Zhejiang, Hubei, Jiangxi, Taiwan Province and Southwest provinces, Korea, Japan and Malaysia. Harm chestnut, white oak, oak, etc. It occurs more than 10 generations a year in Taian, Shandong Province, and overwinters with eggs on the shady side of branches. From late March to early April of the following year, the overwintering eggs hatch into aphids and gather buds to do harm. In late April, dopted mother gave birth to winged and wingless aphids. At the beginning of May, winged parthenocarpy trees began to move to the branches, leaves and flowers of Robinia pseudoacacia. From early June to early July, the population of aphids surged, and in the middle and late July, due to the influence of rainy season, the number dropped sharply. From August to September, the fruit stalks of chestnut bracts are clustered, which is harmful and often causes early fruit drop. 65438+1sexual aphids mate and lay eggs in late October. Eggs are produced on branches and stems, and thousands or even tens of thousands of eggs are densely arranged in pieces. Prevention and control methods: scraping old bark and artificially removing eggs; The overwintering eggs are near the incubation period and coated with high concentration of stone and sulfur mixture; Spraying 40% dimethoate EC 1000 ~ 2000 times or 50% dichlorvos 1000 ~ 2000 times at the peak of nymph.

Chestnut has wings, unisexual antennae and front wings.