Cultivation value
Kiwi originated in China, and became a new fruit tree because of its rich vitamin C content. This kind of fruit contains vitamin C several times to ten times higher than that of apples and sweet oranges, and also contains vitamin P (rutin) and proteolytic enzymes, which can lower blood pressure and help digestion. It is a kind of health food. In terms of medicinal value, according to modern medical clinical trials, its fresh fruit and juice have certain preventive and auxiliary effects on leprosy, digestive tract cancer, hypertension and cardiovascular diseases.
In addition to fruit picking, kiwifruit is also suitable as a decorative tree species for courtyards, flower stands, hedges and other buildings, and is an ideal climbing plant. At present, in addition to hotels in big cities, the supply of high-quality kiwifruit in the market is small and needs to be developed.
Main types and varieties
There are many kinds of kiwifruit, among which Chinese kiwifruit and delicious kiwifruit have the largest fruits and the highest economic value. The hair on the fruit of Actinidia chinensis is short and soft, and almost all the fruit falls off when it is ripe, so the peel is smooth (sometimes slightly rough); The hair on the delicious kiwi fruit is long and hard, and it falls off late. After the fruit is ripe, the bristles still exist, so the peel is rough and generally has good storage resistance.
Kiwifruit was originally wild in the mountains, but it was cultivated late in China. In recent years, a number of excellent strains and varieties have been bred from wild kiwifruit and imported varieties. Among them, the excellent varieties (lines) with good comprehensive properties and good storage resistance are Lushan Xiang, Kuimi, Jinfeng (Jiangxi 79-3), Wuzhi No.3, Henan Gaowei, Hubei Tongshan No.5, Xiangyi, Wanmi and Okra. These varieties are superior to New Zealand's fine variety Hayward in many aspects. In addition, Jin Kui and Xu Xiang are also varieties (strains) with good comprehensive characters. Qionglu is an excellent variety for processing fruit juice. Hayward (a delicious kiwifruit) is the first variety introduced from New Zealand. It is famous for its delicious taste and storability, but its yield is low. In recent years, China has cultivated and introduced several excellent male pollination varieties.
The standard of excellent varieties (strains) requires that fruits have good appearance and internal quality, and can be stored at room temperature for more than 10 ~ 15 days (that is, the shelf life) without softening. We should also pay attention to the adaptability of varieties when introducing them from all over the country.
Growth and fruiting habits
Kiwifruit is a deciduous vine fruit tree with long branches winding counterclockwise at the top, which can climb on other plants or supports to grow. The annual growth of new shoots is very large, sometimes reaching more than 3 meters, so it can quickly cover the surface of the frame in the later stage of growth, and the top will wither. The root system is fleshy, the main root is underdeveloped, and the lateral root is shallow and wide, which should be reported to be particularly developed and not tolerant of drought and flood.
Generally, the fruit begins to bear fruit 3 ~ 5 years after planting. When young trees reach fruiting age, it is easy to form flower buds on annual branches. All branches can become fruiting mother branches except those that grow too vigorously, and blossom and bear fruit in the next year. Long and strong fruiting mother branches can form mixed buds from the leaf axils of the 2 ~ 3 nodes to more than 20 nodes at the base, and the new shoots with mixed buds in the middle are the best, and the incidence of new shoots will decrease after 15.
Kiwifruit is a dioecious plant, occasionally dioecious. Although they are all hermaphroditic flowers in shape, the flowers on the male plants are small, the ovaries are degenerated, the pollen is abundant, and the flowers on the female plants are large and the stamens are degenerated. Female flowers are mostly solitary in the axils of new buds, and mostly in the axils of the second to sixth leaves. Female flowers can generally bear fruit after pollination and fertilization, and there are few physiological fruit drops. Each new shoot can bear 2 ~ 5 fruits. After fruiting, medium-long fruit branches can often become the fruiting mother branches of the next year and continue to bear fruit. No matter long, medium or short fruiting branches, because there is no bud in the axils after fruiting, the fruiting parts on them will become blind (bud) nodes.
Characteristics of cultivation techniques
1. In breeding production, grafting or cutting is often used to raise seedlings, so as to maintain the excellent varieties of the female parent and control the ratio of male and female seedlings. Rootstocks are raised with seeds.
Kiwifruit seeds are small, so be careful when raising seedlings. Choose fully ripe fruits, take out the seeds after ripening and softening, wash them and keep them in the shade. Soak the seeds in warm water for 2-3 hours 40-50 days before sowing, and then store them in a small container at low temperature. The container can be placed in a cold place, covered with straw, and the seeds are turned once every 20 days, so that the humidity is uniform and the air permeability is good. When 30% ~ 50% of the seeds start to germinate in white, they can be planted in the border, and the middle and lower reaches of the Yangtze River are about early and middle March. Soaking seeds in gibberellin solution 100 ppm (100PPm) for 6 hours before sowing can improve the seed emergence rate.
The surface soil strength of kiwifruit seedlings is poor, so the seedbed soil should be fine and the border surface should be flat. Before sowing, the surface of the border should be filled with water, and then sowing should be carried out after soaking under water. Generally, wide-width drilling can be carried out according to the row spacing of 15cm and the sowing width of 20cm. Master the sowing amount of about 1 g per square meter of bed surface, and sow with the wet sand in the sand bank. After sowing, cover 2 mm to 3 mm with fine soil, and cover with straw or plastic film for moisture retention. If the soil is short of water, use a watering can to spray water in time. Usually, the seeds can extend out of the radicle in about 7 days, and the seedlings can emerge in about 15 days. At this time, the plastic film should be removed in time to ensure the smooth emergence of seedlings. Seedlings are not resistant to strong light, so they need to cover the front shed for proper shading after being unearthed.
The seedlings grow to 2 ~ 3 true leaves at a time, and gradually remove the shade. When 4 ~ 5 true leaves are reached, seedlings are fixed with the spacing of 10 cm ~ 15 cm. Intercropping can be transplanted to make up for the deficiency. When the diameter of seedling base reaches 0.6 cm ~ 1 cm, it can be used for grafting. Grafting can be used in June-August, and cutting can be used in spring to avoid bleeding.
Cutting is also often used to propagate kiwifruit seedlings. In the growing period, green branches with leaves are easier to take root than hard branches in spring. However, it is necessary to build a shade shed on the bed and do a good job of moisturizing and cooling. When grafting and cutting, attention should be paid to the cutting and reproduction of male and female plants to avoid confusion.
2. Actinidia chinensis and Actinidia deliciosa like warm and humid climate conditions, grow well in loose and fertile soil with sufficient water and rich humus, and have wide adaptability. Jianghuai basin, especially in hilly and mountainous areas, is most suitable for development and planting.
When planting kiwifruit, the ratio of male and female plants is generally 8: 1, and the male plants should be evenly distributed. The planting spacing varies from frame to frame, and the single hedge frame cultivation keeps 3-5 meters between rows and 2-4 meters between plants, and 500- 1600 plants are planted per hectare. Horizontal greenhouse cultivation, row spacing of 4 ~ 6 meters, plant spacing of 4 ~ 5 meters, planting 330 ~ 620 plants per hectare. At present, single fence frame is often used in production. In addition, there is a 1 m ~ 1.5 m long beam standing on the top of the column of a single hedge frame, and the iron wire is pulled up to form a T-shaped shed frame. This framework can make full use of space and increase the output per unit area. In recent years, V-shaped frame is adopted abroad, and two main branches are left to climb left and right on a 60-degree inclined frame, which is suitable for close planting, high yield and mechanized farming. Fruit farmers in Hanjiang County, Jiangsu Province adopt vertical single trunk shaping method, and the main branches and vines are tied or hung with bows, which is especially suitable for close planting. The investment in frame materials is less. Please refer to the book Grapes for the specific setting of the hedge frame.
3. Plastic trimming and other management Plastic trimming varies from frame to frame. In hedge cultivation, horizontal shaping with both arms can be used. When planting, select branches with strong growth potential as the trunk and cut them short at 10 cm ~ 15 cm below the first iron wire. When cutting in the winter of the following year, the branches extracted from the cut buds continue to extend vertically and are cut off under the second iron wire, and the left and right branches are selected as the first layer of main vines. In the following years, according to the requirements of plastic surgery, the second and third layers of main vines were separated and tied on both sides. Choose to leave fruiting mother branches on each layer of main vines every 30 cm ~ 40 cm. When the new shoots grow vigorously, they can also be picked early to promote branching, so that the main vines and fruiting mother branches of each layer can be formed.
Pruning According to the fruiting habit of branches, for robust branches that can become fruiting mother branches, generally cut 10 ~ 15 knots. When the number of branches is large, some branches are cut short, leaving 3 ~ 4 buds as spare branches. Young trees can achieve early high yield by appropriately leaving more fruiting mother branches.
Long and medium fruit branches that have already borne fruit can often bear fruit continuously. When pruning in winter, 2 ~ 4 buds are left above the last bearing position according to the strength of branches. Short fruit branches are generally not cut short after fruiting, so as not to dry up, and weak ones need to be thinned out. Branches that have been bearing fruit for 2 ~ 3 years should be contracted to the strong parts of cadres and updated in time. For long branches, they can be thinned or cut short according to their plucking parts, or 5 ~ 6 buds can be left as regenerated branches. When pruning in winter, all slender branches and dense branches should be thinned.
During the growth period, new shoots should be managed, and flowers and fruits should be thinned. Before lignification and winding of branches, the core should always be removed and knotted, and the length of core removal should generally be 15 ~ 20 knots according to the space on the shelf surface. If secondary buds or tertiary buds are produced, 2 ~ 4 leaves are left for repeated coring. The vigorous branches begin to taper from the base or surround at about 1 m to inhibit growth and promote the plumpness of the lower buds. When the new shoots of the whole tree are vigorous, a growth retardant such as Bubijiu, ethephon or paclobutrazol can be sprayed before the rapid growth of the new shoots. For long fruit branches and empty fruit branches, 7-8 leaves are left in front of the uppermost fruit, or the top is bent and fixed to inhibit the top advantage. Results When the new shoots on the mother branch are too dense, the branches should be properly thinned, and 1 new shoots with fruit should be selected every 30 cm.
Kiwi is an insect-borne flower. Artificial pollination should be carried out when low temperature and continuous rainy weather affect insect activities at flowering stage. When the weather is normal and there are too many fruits, flowers and fruits should be thinned as soon as possible. On the same branch, the buds and young fruits at the base become thinner, leaving the middle and upper fruits. Generally, 2 ~ 5 fruits are left on each branch of medium-long fruit branches, and 1 fruit or no fruit is left on each branch of short fruit branches.
The application of base fertilizer can refer to grapes. Topdressing before germination15 ~ 20 days and at the early stage of fruit growth after fruit setting can promote flower bud differentiation, flower organ development, new shoot growth and rapid fruit expansion.
Main pests and diseases and their control
There are fewer pests and diseases that harm kiwifruit. Common diseases are brown spot disease and root-knot nematode disease. Common pests are mainly omnivorous pests, such as scarabs, leaf rollers, scale insects, spotted wax cicadas, moths and so on. At present, the production basically does not cause great economic harm. Generally, comprehensive control methods based on agricultural control can be adopted.
Harvest, storage and processing
When kiwifruit is ripe, the external changes are not obvious. When the fruit is long, the seeds are brown and the fruit is easy to pick from the tree, it is a suitable maturity. If the fruit is harvested too early, the decay rate will be high during storage. If the fruit is harvested too late, it is easy to soften and be hurt by early frost. Usually, when the content of soluble solids in fruit reaches more than 7%, it is appropriate to harvest before frost.
Fruits need to be ripened for 4 ~ 7 days before they can be eaten. However, once ripe, the fruit quickly becomes soft and has a short shelf life. Fruits stored for a short period of time should be harvested when they are eight ripe, and treated with SM preservative to slow down the decline of fruit hardness and reduce rot. The storage area should be cool and ventilated.
Wild kiwifruit is rich in resources, and these wild resources can be fully processed and utilized in addition to optimizing individual plants for reproduction. There are many processed products of kiwifruit, such as juice, jam, preserved fruit and jelly. Cause and effect are rich in pectin, which is most suitable for jam. Choose fruits that are ripe in the eighth and ninth years as raw materials, wash them, peel them when they are ripe and soft, do not remove seeds, and break the pulp for later use. Then the sugar in the same proportion as the fruit is made into 75% sugar water and filtered. First, pour 1/3 sugar water into the pot and boil it. After adding the pulp, cook for 20-30 minutes with high fire. When the pulp is boiled and transparent without white pits, the remaining sugar water is added and boiled for 20-25 minutes for concentration. After that, cook with low fire to avoid coking in the paste pot. When the sugar content of the refractometer reaches 66% ~ 68% or the taste is good, it can be cooked immediately for short-term personal use.
Cultivation Techniques of Kiwifruit [Source] (Excerpted from Practical Gardening Manual edited by Wu Zhixing)