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What are macadamia nuts?
Dragon Ophthalmology Evergreen Fruit Tree and Macadamia Tree. Also known as Queensland Chestnut, Macadamia Nut, Babbage Fruit and Australian Walnut (Taiwan Province Province). The scientific name is macadamia nut.

Origin and distribution

Native to the rain forest along the southeast coast of Queensland, Australia and the northern valley of New South Wales. 1882 was introduced to Hawaii and developed rapidly after 1946. Australia began to develop actively in the 1960s. Hawaii and Australia are the main commodity producing areas. Mexico, Central America and Southeast Africa are also developing actively. It is also grown in California and Florida. 19 10 introduced seedlings from China, planted a small number of specimen trees in Taiwan Province province, Guangzhou, Nanning and other places, and tried planting in Yunnan and Sichuan. During the period of 1979, 9 clones, such as Kaohou, were introduced for trial planting in Yuexi Experimental Station of South China Tropical Crops Research Institute (Zhanjiang City, Guangdong Province).

Features and characteristics

Height10 ~15m. 3 ~ 4 whorled leaves, length 12 ~ 36 cm, width 2.5 ~ 5.5 cm. They are needle-like, leather-like, smooth, and have alienated spiny serrations on the edges. The raceme is axillary, the flowers are beige, the pedicel is 1.5 mm long, and the perianth is hairy, about 8 mm long. The fruit is spherical, about 3 cm in diameter, leathery, with hard endocarp and beige to light brown nucleolus (see figure).

The optimum growth temperature is 15 ~ 30℃. When the temperature is higher than 30℃, the growth will be seriously affected by the sun, and the growth will stop at 10℃. Mature trees can withstand short-term low temperature of -4 ~-5.6℃. It is most suitable for cultivation in tropical areas with annual precipitation 1300 ~ 3000 mm and obvious dry and wet seasons and warm and frost-free subtropical areas. Drought or moderate low temperature is beneficial to flowering and fruit setting. It is not suitable for planting in areas with no irrigation conditions below annual precipitation 1 140mm. Deep soil layer, fertile and loose soil, good drainage, pH 4.5 ~ 6.5 and elevation below 770 meters are the most suitable gardens. If the altitude is too high, the shell will thicken, the growth will be slow and the yield will decrease. It has strong adaptability to soil, but the newly cultivated poor red soil with high manganese has poor growth and low yield.

Species and varieties

Only two species of this genus are edible, namely, whole-leaf marigold, four-leaf marigold and their hybrids. Light-shelled species are widely cultivated economically. The processing characteristics of coarse shell species are poor and can only be produced in small quantities. Seven excellent strains were selected from 654.38+10,000 seedlings in Hawaii Agricultural Experimental Station, namely Keauhou, Ikaika, Kakea, Keaau, Kau, Mau-ka and Makai.

Key points of cultivation techniques

Seedlings can be propagated by grafting or cutting. Take sunny, robust and mature branches of 10 ~ 22 cm, keep the top 2 ~ 4 leaves, insert them in a sand bed with constant humidity, and culture them at 24℃; Before cutting, soak the base of branches with 500ppm indolebutyric acid to promote rooting. Row spacing 10 ~ 12m, plant spacing of 4 ~ 5m, plant 165 ~ 255 plants per hectare, which can be slightly dense in South China, and plant other crops or fruit trees in the early stage. Young roots are shallow and few, and their wind resistance is poor, so they can be supported by stone pillars. Dwarf and transparent trees have stronger wind resistance, so attention should be paid to shaping and pruning. The ideal tree should grow 60 ~ 90 cm above the ground, and then branch every 45 ~ 60 cm to make the main branches evenly arranged. When pruning, it should be cut short on leafless nodes to promote strong branches: the main branches should choose side leaf buds with large branching angles. In Xiaweituo, the application ratio of N, P and K is 1 ∶1for young trees and1for fruit trees, and the fertilization period is mainly before the flower bud peak period and in summer and autumn. The annual fertilization amount is calculated according to the compound fertilizer 10: 10: 15, and the trunk base diameter150g/cm. Drought and proper low temperature are beneficial to flower bud differentiation. Nearly 20 kinds of pests and diseases have been found in various cultivation countries.

Grafted seedlings begin to bear fruit 5-6 years after planting, and the high-yield period is 40-50 years. The fruit ripens after June 65438+ 10, and the dark brown inner membrane of the peel is a sign of maturity. Fruits can be picked manually or by hand, and large orchards are collected by mechanical shaking. Fruits should be shelled within 1 ~ 3 days after harvesting, dried or put in a ventilated place to dry, or dried quickly with shells to avoid deterioration. The water content of commercial seeds should be below 3.5%. Shelling and shell-kernel separation in production gardens are mostly mechanical operations. Seed kernels were classified by specific gravity method, and those floating in clean water were classified as Grade I, those floating in salt water with specific gravity of 1.025 were classified as Grade II, and the rest were classified as Grade III. The processed seeds are generally fried with 135℃ for 40 ~ 50 minutes or with 12 ~ 15 minutes, and then eaten with salt or used as raw materials for candy, cakes and cooking. If the water content of fried seeds is kept at 65438 0.4%, the color and flavor of fried seeds can remain unchanged for 65438 08 months at room temperature.

economic value

The kernel contains 60-80% oil, 9% protein and 9% carbohydrate respectively, and is rich in calcium, phosphorus, iron, vitamin B 1 and B2, etc. This product is nutritious, sweet and delicious, and is well received by consumers. In 1980s, the price of raw nuts in the world market was $8,000 per ton, which had high economic value. South China can be developed through trial planting. In addition, macadamia nuts are also beautiful street trees and landscaping trees.