What to do when a larch improved seed base does not flower and sets little seed? Techniques for flowering and seed setting
The Japanese larch improved seed base in Houzhenzi, Zhouzhi County was established in 1988 and was designated a key forest tree improved seed base by the State Forestry Administration in 2009. The mother tree materials used in the base all came from Liaoning Province in Northeast China. More than 300 superior individual trees were selected from superior larch stands in Liaoning, 286 seed lots from superior trees were collected, and more than 50,000 improved seedlings were raised. A Japanese larch seedling seed orchard and mother tree stand of more than 50 ha were established, laying the foundation for Japanese larch improved seed breeding. Due to differences in climate and geographical location, the introduced Japanese larch grows especially vigorously at the Zhouzhi improved seed base, but flowers and sets seed little and yields are low, making it difficult for the Japanese larch improved seed base to play its proper role. Aiming at the problems of no flowering and little seed setting in the larch improved seed base, this article proposes technical measures and methods to promote flowering and seed setting in the Japanese larch improved seed base.
1 Overview of the Zhouzhi larch improved seed base
The Houzhenzi larch improved seed base in Zhouzhi County is located in the Qinling forest region of Shaanxi Province, with an average altitude of about 1,500 m. It has a warm temperate semi-humid continental monsoon climate, with an average annual temperature of 6.4-8.4 °C and a frost-free period of 150 d. The average annual precipitation is about 1,000 mm, with abundant rainfall. The soil of the improved seed base is mainly brown earth, loose in texture, rich in humus, with a soil layer thickness of 40-80 cm and good permeability, making it especially suitable for the growth of Japanese larch.
2 Analysis of the reasons for the low seed yield of Japanese larch in the improved seed base
The purpose of establishing an improved seed base is to provide high-quality improved seed for forestry production. If the seed-collection mother trees cannot flower and set seed normally and seed yield is low and cannot meet demand, then the purpose of the improved seed base has not been achieved. The main problem currently existing at the Houzhenzi larch improved seed base is that the mother trees have few flowers and do not set seed. Because the Japanese larch establishment materials at the Houzhenzi improved seed base were mainly introduced from Huanren, Qingyuan and other places in Liaoning, differences in climate and site are the main reasons causing late flowering and seed setting or failure to set seed in the mother trees. Liaoning is located in Northeast China and has a mid-temperate continental monsoon climate, with cold winters and hot summers, an average annual temperature of 5.3 °C, a frost-free period of only about 120 d, and an average annual rainfall of 800 mm. As Japanese larch moved south from Northeast China to the Qinling forest region, forestland rainfall increased and the growing period lengthened. The temperature became more suitable, causing Japanese larch to show vigorous growth, with the trees remaining in a state of nutrient accumulation, and the age of flowering and seed setting being postponed indefinitely. In addition, because the seedlings used in the construction of the improved seed base were all seedling-grown stock rather than grafted stock, this further aggravated the delay in flowering and seed setting. In addition, larch grows relatively fast in the early stage, and the initial planting density was relatively high, so the growing space of the larch mother trees was constrained and ventilation and light transmission were poor, which is another main reason affecting larch flowering and seed setting.
3 Main technical measures to promote larch flowering and seed setting
The factors affecting Japanese larch flowering and seed setting mainly include two aspects. One is environmental conditions, such as climatic factors, site conditions, and management measures. The other is factors of the Japanese larch itself, such as tree age, provenance, tree form, and density. Through technical management measures, improving the ventilation and light transmission conditions of the seed-bearing mother trees, regulating the conversion ratio between vegetative growth and reproductive growth, and improving pollination conditions can all promote Japanese larch flowering and seed setting and increase seed yield.
3.1 Fertilization
The growth of forest trees cannot be separated from the nutrients in the soil, and elements such as N, P, and K in the soil are the main elements that promote forest tree growth. Fertilization can improve the soil nutrient structure, increase soil nutrients, and promote rapid forest tree growth. N-containing fertilizer mainly promotes vegetative growth, improves plant photosynthetic efficiency, and promotes taller and more luxuriant tree growth, so N is the main element that promotes increased forest tree volume. The main role of P and K fertilizers is to enhance forest tree resistance and improve the nutrient balance of forest tree growth, and they have an obvious effect on improving flowering and seed setting in middle-aged and young forests. Existing studies have shown that by applying compound phosphate fertilizer in June and compound potassium fertilizer in August every year continuously to larch, the seed setting amount of larch can be significantly increased, with an average yield increase of more than 43%; and the seed quality, 1,000-grain mass, cone seed extraction rate, and seed germination rate of larch are all improved to varying degrees. The characteristic of the Houzhenzi larch improved seed base is that the trees themselves already have excess nutrients and the tree bodies grow relatively vigorously. Therefore, reducing the application amount of N fertilizer and appropriately increasing the application amounts of P and K fertilizers can significantly improve Japanese larch flowering and seed setting.
3.2 Tree body management techniques
The tree body management techniques for Japanese larch mainly include branch thinning and top pruning.
3.2.1 Branch thinning This mainly removes overly dense branches, overlapping branches, diseased and insect-damaged branches, and some water sprouts from larch mother trees. The purpose is to improve the ventilation and light transmission conditions of the larch mother trees, reduce disease and insect damage, and promote flowering and seed setting. However, the amount of branch thinning has a relatively large effect on larch flowering and seed setting. Studies have shown that when 1/4, 1/3, 1/2, and 2/3 of the main branches of adult larch mother trees are removed, as thinning intensity increases, the seed setting amount in the 2nd and 3rd years shows a positive correlation with thinning intensity, and seed quality also improves accordingly. However, high thinning intensity has a relatively large effect on the yield of the mother trees in the current year, so thinning intensity should not be too high, and it is advisable to remove 1/3 to 1/2 each year. At the Zhouzhi larch improved seed base, because the Japanese larch mother trees are still in the middle-aged and young forest stage and the framework of fruiting branches has not yet fully formed, thinning should mainly be light thinning, only removing diseased and insect-damaged branches, dead and dry branches, and overlapping branches from the mother trees.
3.2.2 Top pruning Top pruning is a commonly used tree body management method in improved seed bases. Its main purpose is to inhibit the apical dominance of the tree body, prevent seed-bearing mother trees from producing excessive vegetative growth and rampant growth, and regulate the conversion of mother tree vegetative growth to reproductive growth, thereby promoting mother tree flowering and seed setting. At the Zhouzhi larch improved seed base, due to the influence of climate and site conditions, the vegetative growth of Japanese larch is already very vigorous, so breaking the apical dominance of larch growth and promoting the conversion of vegetative growth to reproductive growth is the main way to promote Japanese larch flowering and seed setting. Top pruning is a very effective method for implementing this approach. Generally speaking, the greater the top pruning intensity, the more obvious the effect, but it should not exceed 1/2 of the tree height. Japanese larch top pruning is generally carried out in spring from March to April. Because the larch trees at the Zhouzhi improved seed base are still in the middle-aged and young forest stage, the portion removed should not be too much, and 1/4 to 1/3 of the tree height is relatively suitable.
3.3 Thinning
In the initial stage of mother tree planting, because the trees are young and occupy relatively little space, the initial planting density is relatively high. As tree age continues to increase, the crown width becomes larger and larger, the forestland gradually closes, the growing space of the mother trees becomes mutually limited, and the mother trees compete with each other for nutritional space such as light, water, and fertilizer, affecting normal mother tree flowering and seed setting. Although reasonable thinning reduces the number of mother trees in the improved seed base, it improves the ventilation and light transmission conditions of the mother trees in the base, promotes mother tree crown growth, increases the effective attachment area for flowering and seed setting, and thereby also increases the flowering and seed setting quantity of the mother trees in the improved seed base.
The principle of thinning is that mother trees with poor growth, more diseases and insect pests, weak resistance, poor seed setting ability, and lower genetic quality should be thinned first, leaving mother trees that grow robustly, have strong seed setting ability, and have high genetic gain. Therefore, thinning also promotes further improvement of the genetic quality of seed from the improved seed base.
The intensity of thinning directly affects the seed yield of the larch improved seed base, and thinning intensity is closely related to larch tree age, crown width, and canopy density. Existing studies have shown that intensive thinning has a very significant effect on promoting larch flowering and seed setting. When carrying out roguing and thinning of larch, the principle of gradual progress should be followed, and each thinning should not exceed 30% of the total amount.
Techniques for establishing a plantation of Aralia elata and planting methods
Aralia elata is an outstanding wild vegetable, with broad market prospects and important economic value. After harvesting, the new shoots sprouted by Aralia elata cannot flower and set seed, or can do so only rarely, and the 1,000-grain weight and germination rate of the collected seeds are also severely reduced. After sowing, seedling yield is low and quality is poor, and after planting, the yield of commercial buds of Aralia elata is low and quality is poor, affecting economic value and seriously affecting the development of the Aralia elata cultivation industry. Therefore, this article develops an improved seed breeding base for Aralia elata to provide superior seedlings for production, which has important practical significance.
1 Plantation establishment techniques
1.1 Selection of plantation site
Choose a plot that is sheltered from the wind and facing the sun, with deep soil, good drainage, no pesticide residues, and avoiding waterlogged land and frost-heaving land. Because root propagation requires repeated digging and use of the root system, a flatland nursery with convenient transportation and irrigation facilities, or a sloped nursery with a slope ≤10°, is also required.
1.2 Land preparation and bed making
For land preparation, deep plowing of the soil is adopted, with a plowing depth of 25-30 cm, and at the same time farmyard manure is applied at 30,000-45,000 kg/ha to facilitate digging and cutting.
For the Aralia elata root system, the planting bed height is 25-35 cm, bed width is 1-1.2 m, and bed length depends on the terrain and convenience of operation. Generally, the bed length is more than 10 m. For convenient management, the operation path between beds is 40-50 cm.
2 Planting techniques
2.1 Plant selection
The selection standards for superior plants transplanted into the root stock garden are: robust 3-5-year-old Aralia elata plants from the wild or transplanted to roadside and homestead-side land, without mechanical damage or disease and insect pests; the current-year height growth must be more than 1.2 m, and stem thickness more than 2.5 cm, with no thorns or few thorns; commercial buds should grow to about 15-20 cm, with a single fresh mass of about 20-35 g, and the tender buds should not be fully expanded, with no prickles or few prickles on the tender stems.
2.2 Planting methods
2.2.1 Planting techniques
2.2.2.1 Plant planting techniques
Planting time is divided into spring and autumn. Spring planting is generally in mid-April, before the terminal buds of Aralia elata sprout; autumn planting is from late October to before the soil freezes, 1 month after Aralia elata defoliates. Before planting, the plant root system must be pruned and dipped in a moisture-retaining agent. After pruning seedling-grown plants, there should be 1 main root more than 30 cm long, and 4-6 fibrous roots more than 20 cm long; for sprout-grown plants, 2-3 lateral roots more than 20 cm long, and 3-5 fibrous roots more than 20 cm long. During planting, the root system should be spread out. Because the planted plants are large, the soil-burying depth may be about 5 cm above the root crown. During the soil-burying process, firm the soil by treading multiple times, and finally cover with a layer of topsoil. After planting, water once thoroughly, so that it infiltrates about 20 cm below the bed surface, with surface runoff being suitable.
2.2.2.2 Root segment planting techniques
In early April, when the soil has just thawed, collect the root system of superior plants, with a thickness of 0.4-1 cm and a length of 13-15 cm, retaining 2 buds on the root stock. Place them in clean wet river sand and store them outdoors in a sheltered, cool place. For planting time, when the surface soil temperature reaches above 10 °C, 1 week after the terminal buds sprout, before planting soak in 0.1% potassium permanganate aqueous solution for disinfection for 30 min. The planting pit is 5 cm deep, 20 cm long, and 20 cm wide. Place 1-2 root stocks horizontally in each pit, with buds facing upward, cover with 4-5 cm of soil, water thoroughly, and cover with a layer of straw curtain to retain moisture.
2.2.2 Planting density
Carry out fixed-point planting on the bed, planting in the middle of the seedbed, with a plant spacing of 150 cm. Aralia elata on adjacent rows should be planted in a staggered manner to facilitate the operation of digging root stocks. According to a plant-row spacing of 60 cm × 150 cm, carry out fixed-point planting.
3 Nursery land management and tree body management
3.1 Nursery land management
3.1.1 Water and fertilizer management
For weed control in the nursery, first carry out hole-shaped weeding around the tree body, then weed the entire nursery. This should follow the principle of "weed early, weed completely, weed small." When weeding, be careful not to damage the roots, the root crown area, or the sprouted suckering seedlings. Determine the amount and frequency of watering according to soil moisture conditions. During the growing season of Aralia elata, keep the soil moist, but prevent water accumulation from causing root rot. Apply fertilizer once in early June and once in mid-July, applying potassium chloride compound fertilizer or superphosphate at the plant roots. Two months after the plants defoliate (mid-November to early December), apply plant ash or farmyard manure in the plantation area to improve the plant growth vigor in the second year.
3.1.2 Disease and insect pest control
(1) If damping-off disease appears in transplanted plants in the plantation area, the diseased plants should be dug out promptly, removed from the plantation area, and directly burned. The root systems of adjacent plants cannot be used as root propagation material in the second year.
(2) If damping-off disease appears in seedlings from root segment propagation, a 0.125%-0.2% concentration dexon solution can be sprayed on the bed surface on cloudy days or in the evening.
(3) If scab disease appears, spray 0.2% concentration sodium pentachlorophenate in mid-November for prevention.
(4) If southern blight appears, before planting, treat the plant root system or propagation root segments by dipping in a 0.2% concentration solution of benomyl or thiophanate-methyl. The main insect pest in Aralia elata growth is aphids. To control aphids, spray 0.1% concentration dimethoate emulsifiable concentrate solution or apply insecticidal pesticide on the branches and trunks where aphids occur to kill the aphids.
3.2 Tree body management
To facilitate the collection of root stocks, the tree body needs to be pruned when transplanting plants. In the second year after planting, when the tree body enters dormancy, retain 20-40 cm of the current-year branches, with 4-6 buds retained, and cut off the rest. In the third year in spring, retain 2-3 robust buds on the branches and trunks, and cut off or remove the other buds. Two months after defoliation in that autumn, cut at 20-40 cm from the fork. In the fourth year, retain 1-2 sprout seedlings; in the fifth year, repeat the cultivation of 1-2 plants, and in early December of that year, cut down the old plants. For root-propagated plants, from Frost's Descent to before snowfall, cut off the aboveground part of the current-year seedlings at 3-5 cm above the ground, cover the roots with a straw curtain for cold protection, and remove the straw curtain before spring sprouting.
4 Collection of root stocks
The principle of root stock collection is to shorten storage time as much as possible and preferably to plant immediately after collection, which can increase the root stock propagation rate. Different planting times also mean different root stock collection methods and times. For superior plants transplanted in spring, collection can begin within 1 week after the terminal buds sprout in the second spring; for superior plants transplanted in autumn, collection can be carried out within 1 week after the terminal buds sprout in the second spring; for superior plants propagated from root segments, the root stock collection time can be before the terminal buds sprout, and the whole plant needs to be dug out for collection. Standards for cutting root stocks for propagation: root segments with a thickness of 0.6-1.2 cm, cut to a length of 13-15 cm. After collection, store them in clean, moist river sand. Before planting, disinfect in 0.1% potassium permanganate aqueous solution for 30 min.
The above are the relevant key planting techniques for Aralia elata. Farmer friends who like it are welcome to study and refer to them more on Huinong Network!
How is ginkgo planted? Early-fruiting and high-yield cultivation techniques for ginkgo
Ginkgo can also be called Gongsun tree. It has an extremely long lifespan, and the whole ginkgo plant is a treasure, and it also has medicinal value. In China, ginkgo cultivation is mainly for fruit use. The following mainly studies the growth and fruiting habits of ginkgo and early-fruiting and high-yield cultivation techniques.
1 Growth and fruiting habits of ginkgo
Ginkgo is dioecious. Once it flowers and is pollinated, fruit setting is very reliable, and the fruiting position is not easy to move outward, and the inner canopy of the crown is not easy to become bare. It is a typical short-branch-type fruit tree. The long branches and short branches of ginkgo can transform into each other. The lateral buds of newly produced long branches can all sprout the following year to form short branches. The lifespan of short branches can reach 20 years, and the terminal buds of some perennial short branches can also produce long branches.
2 Early-fruiting and high-yield cultivation techniques for ginkgo
In recent years, due to the rapid development of the traditional Chinese medicine manufacturing industry, the pharmacological properties of ginkgo have been discovered, the demand for ginkgo has increased greatly, and planting benefits have also risen substantially, greatly stimulating the planting enthusiasm of the people and forming a nationwide ginkgo planting boom. At present, more than 10 million ginkgo trees in China have entered the fruiting stage, and more than 30,000 tons of ginkgo leaves can be picked annually, and more than 300 tons of ginkgo leaf extract can be produced, with a value of more than 1 billion yuan. If calculated at an average fruit yield of 25 kg per tree, the annual ginkgo fruit output can reach 2.5 billion tons, with an output value of more than 9 billion yuan, and the annual contribution of the ginkgo industry exceeds 10 billion yuan. However, because ginkgo has unique growth and fruiting habits, its cultivation is very different from that of other fruit trees, and in actual production its effectiveness has not been fully brought into play. According to the growth and fruiting habits of ginkgo, combined with planting experience from all over the country, relevant experts have proposed early-fruiting and high-yield cultivation techniques for ginkgo, in order to provide reference for production.
2.1 Seedling propagation
Ginkgo has a very long lifespan, so improved varieties must be selected when planting to improve management benefits. For cultivation purposes of seed and leaf use, it is advisable to choose varieties with large seed type (average single kernel weight above 3 g), white kernel, strong glutinousness, rich aroma, and high kernel extraction rate (the percentage of white nuts that can be produced from ginkgo with fleshy outer seed coat) and high kernel yield. Generally, the low kernel extraction rate is below 19%, the high one can reach 25%, and the highest can reach 29%. At present, ginkgo varieties that perform well in production include: Dajinzhui, Changnuobaiguo, Yuanbaiguo, Foshou, Maling, Dabaiguo, Daguo, Jingyin, Hong'anwang, and others.
Ginkgo is easy to propagate, and sowing, division, cuttings, and grafting are all possible. Ginkgo seedling-grown plants enter the fruiting stage late, generally starting to bear fruit only after about 20 years and entering full fruiting stage after about 40 years, with slow returns; while grafted seedlings begin to bear fruit in 5 years and enter full fruiting stage in about 10 years, and the full fruiting stage can last as long as a thousand years. In production, grafted seedlings should be mainly used to establish plantations.
(1) Seedling propagation by sowing
Ginkgo sowing and seedling raising has the advantages of early emergence, uniform emergence, less disease infection, more seedlings, and simplicity and ease of operation. The white nuts used for seedling raising should preferably be collected from production areas or orchard plots with relatively sufficient pollination, and stratified in wet sand in winter. Generally sow in mid-March, pregerminate before sowing, with a sowing rate of about 100 kg per mu, and 50,000-70,000 seedlings per mu.
a. Seed treatment
Ginkgo seed pregermination generally adopts the pit pregermination method. Choose a place sheltered from the wind and facing the sun with good drainage and dig a trench 30 cm deep and 1.2 m wide, with the length determined according to seed quantity. Screen the sand-stored seeds to remove sand, soak the seeds, and remove floating seeds and damaged seeds during soaking. When soaking for more than 24 hours, pay attention to changing the water. Spread 5-10 cm thick sand at the bottom of the trench, then place one layer of seeds and one layer of sand, with each layer about 2 cm thick. When reaching 15-20 cm, cover with 1 layer of wet sand 2-4 cm thick, then cover with plastic film, 5-6 cm from the ground. During pregermination, note that in the first 15-20 days, turn once every 3-5 days, and afterward pick seeds once every 2-3 days; maintain humidity. If dry, water can be added at 9:00-10:00, with water temperature around 30 °C; control the temperature in the trench at 25-30 °C.
b. Seedbed preparation
Choose acidic or neutral sandy loam with high and dry terrain, ventilation and sunlight, and good drainage and irrigation as the seedbed. The plot selected as the seedbed should be plowed in the previous autumn, and during plowing apply decomposed farmyard manure at 3,000-4,000 kg per mu, nitrogen-phosphorus-potassium ternary compound fertilizer at 100 kg, and phoxim granules at 2.5 kg. Before sowing, prepare the beds, with bed width 1.2-1.5 m and height 15-20 cm, and the bed surface level.
c. Sowing
Open shallow furrows on the bed surface at a row spacing of 20 cm, and sow in holes at a plant spacing of 5-8 cm. When sowing, place the seeds flat and cover with 2-3 cm of soil.
d. Seedling stage management
The first topdressing is in early June, applying about 7.5 kg of urea per mu; in July-August, apply topdressing another 1-2 times depending on seedling growth, each time applying about 10 kg of urea per mu. During the seedling growth period, remove weeds promptly to ensure robust seedling growth.
(2) Grafting propagation
Grafted ginkgo seedlings have the characteristics of entering the fruiting stage early and high yield. Generally, common ginkgo is used as rootstock, and superior varieties are grafted. There are many grafting methods, including "T-shaped" budding, double tongue grafting, or bark grafting. Spring is the main grafting season, and the grafting survival rate is high from 5 days before germination to the leaf expansion stage. In production, it can be applied flexibly according to actual conditions.
a. Double tongue grafting or bark tongue grafting
At present, grafting of large rootstock seedlings more than 3 years old is widely used in production, grafting when the rootstock is 50-60 cm high. Scions are collected 10-20 days before the mother tree germinates, and the collected scions should be wax-sealed promptly to prevent water loss and avoid affecting survival. When grafting, the tongue surface length of the scion is 3-4 cm, the cut surface is on the side of the lower bud, and the tongue is 2 mm from the tongue surface. When inserting, expose 2 mm of white to facilitate healing. The lower bud should be close to the rootstock side, so that the base of the scion easily heals together with the rootstock.
b. "T-shaped" budding
Scions are generally collected in combination with winter pruning. Select robust branches without disease and insect pests as scions, bundle 50 scions per bundle, and bury them in wet sand in a shaded place. Graft in spring when the rootstock bark slips, generally starting when the rootstock sprouts and expands leaves. Select plump and full buds for the grafting buds, requiring the bud patch to carry bud-protecting flesh. Cut a "T-shaped" incision on a smooth part of the rootstock, with a horizontal cut 1 cm long and a vertical cut 1.2 cm long, just enough to cut through the phloem of the rootstock. After inserting the shield-shaped scion bud patch, bind it. Start binding from above the bud and wind downward 3 or 4 turns, and the binding should be tight and strict.
Check survival 10-15 days after grafting, and replant promptly if not survived. After the grafted buds or scions survive, promptly remove the sprouts on the rootstock.
2.2 Cultivation techniques
(1) Plantation establishment
To increase early-stage yield, ginkgo can be planted using a transitional close-planting method, with row-plant spacings of 3 m × 2 m, 3 m × 2.5 m, 4 m × 2.5 m, etc., planting 111, 88, and 66 trees per mu respectively. As the crowns grow larger, thin and move them year by year, and finally transform to 33 or 22 trees per mu. Ginkgo is dioecious, and male flowers produce a large amount of pollen, so a small number of male plants can solve the pollination problem. Male plants accounting for about 2% of the total number of plants is sufficient.
Among ginkgo seedlings of the same age, female plants are generally shorter than male plants, while the stems are thicker than those of male plants. Female plants defoliate relatively early and sprout relatively late, and have more lateral branches; female plant leaves are smaller than those of male plants, the serration incisions on the leaf margin are shallow, and there are gaps around the vascular bundles in the petiole cross-section, while male plants do not have these. The angle between the main branches and the trunk of female plants is large, growing laterally around and even drooping, with weaker growth vigor, while the angle between the main branches and the trunk of male plants is small; female plants form crowns early, with messy branch distribution and more large lower branches, and the crown is mostly oval, while male plants form crowns late, with uniform branch distribution and clear layers, and the crown is mostly tower-shaped; female flower buds are thin and slightly pointed, growing at the tip of the pedicel, generally two flowers, shaped like matchsticks, while male flower buds are large and plump, shaped like mulberries. In production, distinction can be made according to the above characteristics to configure pollinating male plants.
(2) Training and pruning
At present, the main tree forms of ginkgo in production include multi-layer trunk form, open-center form, and natural round-headed form. The trunk-setting height is 50-60 cm, with 3-4 main branches, and each main branch retains 3-4 lateral branches. Winter pruning mainly removes overly dense branches. From June to July, branches are pulled and bent to moderate branch growth vigor to promote flower formation. For overly vigorous trees or overly vigorous branches, ring girdling or ring cutting is used to control vegetative growth; in August, pinch the tips of branches that cannot stop growing at the proper time to increase the lignification degree of new shoots.
(3) Soil, fertilizer, and water management
Deeply plow the soil before planting. During deep plowing, apply high-quality farmyard manure at 4,000-5,000 kg per mu, urea at 5-10 kg, and superphosphate at 20-40 kg. For fertilization after planting, use mainly nitrogen fertilizer in the early annual growth period and mainly phosphorus and potassium fertilizers in the middle and late periods. If compound fertilizer is applied, use mainly high-nitrogen compound fertilizer in the early period and mainly high-phosphorus compound fertilizer in the middle and late periods. The fertilization amount is determined according to tree size, and it is applied in trenches dug at the outer edge of the crown. Irrigate after fertilization. Hoe weeds 5-6 times each year to loosen the soil and improve the soil moisture conservation capacity.
(4) Flower and fruit management
For ginkgo trees that have entered the fruiting stage, artificial pollination should be carried out when there are few pollinating trees or the weather during the flowering period is unfavorable. Generally in late April, when male inflorescences turn from green to yellow, collect pollen or flowering branches. Dry the flowering branches in the shade at room temperature, collect the pollen, put it into gauze bags, hang them on bamboo poles, stand on the upwind side, and gently pat the gauze with the hand to pollinate. A pollen liquid can also be prepared from 1 part pollen, 250 parts water, 50 parts granulated sugar, and 5 parts boric acid, and sprayed on female inflorescences with a high-pressure sprayer from 10:00-16:00 on sunny days for pollination.
(5) Control of ginkgo early yellowing disease
Ginkgo has strong disease resistance and no serious disease and insect pests. In production, ginkgo early yellowing disease is relatively common. Yellowing disease affects the yield of the second year, so control should be strengthened.
The causes of ginkgo early yellowing disease are relatively complex. Water accumulation and zinc deficiency can both cause yellowing disease. Usually, when the root system is waterlogged at a depth of 15 cm for 10 consecutive days, it will cause yellowing, defoliation, and root rot, and in severe cases the whole plant dies. When the zinc content in leaves is lower than 15 mg/kg, zinc deficiency yellowing occurs. It generally starts in early June, first with loss of green at the leaf margin, appearing light yellow and glossy, then gradually spreading toward the leaf base. In severe cases, half of the leaf yellows. In July-August, the diseased spots expand rapidly, and the color gradually turns brown and gray, appearing withered and dead.
When yellowing appears in the field, observe carefully and treat according to the cause to improve control effectiveness. For yellowing caused by water accumulation, strengthen drainage after rain to prevent field water accumulation and reduce damage. For yellowing caused by zinc deficiency, after the soil thaws each spring, apply 80-150 g of zinc sulfate per tree according to tree size. During the growing season, spray once every 10 days or so with 70% mancozeb wettable powder 500-600 times solution or 400 mg/kg titanium fertilizer plus 0.3% photosynthetic micro-fertilizer, spraying 3 times continuously to control the damage.
(6) Harvesting, processing, and storage
Ginkgo uses leaves and seed kernels as the main harvest. When harvesting, the appropriate harvest time should be determined according to the different harvest products. Ginkgo leaves contain flavonoids, and these substances have a relaxing effect on the cardiovascular and cerebrovascular systems. The crude product of ginkgo leaves is 1%-3% of dry leaf weight, and the selling price is relatively expensive, so selling ginkgo leaves is one of the main sources of income in ginkgo production. Generally, ginkgo leaves should be harvested in stages from early to mid-October to early November. First pick old leaves on the inner and lower branches of the crown, picking 1/3 of the leaves on short branches each time, and finally pick all of them at once when the ginkgo leaves are about to turn yellow. The collected ginkgo leaves should be dried promptly to prevent heating and molding.
Ginkgo seed kernels generally mature in late September. When mature, the outer seed coat of the seed kernel changes from green to yellow or orange, and the surface is covered with a thin layer of white fruit powder. When pinched by hand, the outer seed coat feels soft; the middle seed coat has completely become bony and can be knocked down with a bamboo pole and collected.
The collected seed kernels should be peeled promptly. Pile the seed kernels on a hard, flat site, with a pile thickness of about 30 cm, cover the pile with wet straw, and after 2-3 days the outer seed coat will gradually rot. Use feet to tread or hands to rub, or tap lightly with a wooden stick to make the outer seed coat fall off. Put the peeled seed kernels into clean water to rinse, removing impurities while stirring. After repeated stirring and rinsing, clean seed kernels can be obtained. To make the seed kernel surface white and glossy, bleaching treatment is carried out on the seed kernels in production. At present, there are 2 bleaching treatment methods. One is the bleaching powder treatment method. First dissolve a certain amount of bleaching powder with 10 times warm water, then dilute with water to 100 times. 1 kg of bleaching powder can bleach 100 kg of seed kernels. Pour the seed kernels into the bleaching powder liquid, soak while stirring, and after 5-6 minutes, when the middle seed coat becomes white, take them out and rinse continuously with clean water several times until there is no trace or smell of the chemical on the surface. After bleaching, spread them indoors or outdoors in the shade to dry promptly. The second is the sulfur fumigation method. Spread the rinsed wet seed kernels on a mat to dry, put them into a vat to 2/3 of the container volume, then light a wine cup of sulfur, put it into the vat and seal the opening, fumigate for 30-40 minutes, then open the seal. At this time the middle seed coat is both white and glossy.
The ginkgo seeds after peeling and bleaching are called white nuts. White nuts need special storage under low-temperature, low-humidity, and airtight conditions to avoid molding, deterioration, hardening, water loss, and loss of vitality. The following methods can be used for storage.
Sand storage method. Choose a cool indoor place, mix white nuts with sand in a ratio of 1 part seeds to 2 parts wet sand for storage, control the pile thickness within 60 cm, and frequently check humidity. It is suitable when it feels moist when held in the hand. This method can store for 3-5 months. Water storage. Completely immerse the white nuts in a water vat or water tank, change the water frequently, and it can be stored for 4-5 months.
Cold storage method. Put the seed kernels into gunny bags, place them in a cold storage, control the temperature at 1-3 °C, and spray water once every half month as appropriate. It can be stored for 5-6 months.
Bag storage method. Put the white nuts into plastic bags 0.05 mm thick, control each bag within 20 kg, and place them in a cold room below 5 °C. It can be stored for 5-6 months.
(7) Post-harvest tree body management
Post-harvest management has a relatively large effect on the safe overwintering of ginkgo trees and the yield of the second year. After harvesting ginkgo, the following measures should be emphasized:
① Apply base fertilizer. Base fertilizer is mainly organic fertilizer, combined with slow-release fertilizers such as phosphorus and potassium. Generally, for fruiting trees, apply high-quality farmyard manure at 3,000-4,000 kg per mu and ternary compound fertilizer at 150-200 kg according to tree size. Usually 5-10 days before harvest, open trenches 30-40 cm wide and 30-35 cm deep at the outer edge of the crown and apply the fertilizer.
② Plow the ginkgo plantation. Plow the ginkgo plantation before the soil freezes, to a depth of about 30 cm, to enhance soil permeability and water storage and retention capacity.
③ Clean the plantation. After defoliation, promptly sweep up fallen leaves and weeds to reduce overwintering sites for diseases and insects.
The above is all the content on ginkgo cultivation techniques. If you are interested in the market planting prospects of ginkgo, then you must first learn its planting techniques well!