Traditional Culture Encyclopedia - Photography and portraiture - What is the growth cycle of grapefruit? In what kind of environment can it be grown?

What is the growth cycle of grapefruit? In what kind of environment can it be grown?

1. Biological characteristics

(1) Growth and fruiting habits

① Root system Root system distribution: The crown of the real tree is tall and the main root is developed; the lateral roots of the grafted tree are developed. The horizontal distribution is larger than the crown projection area, and the root group near the outer edge of the crown projection is the densest. In addition to biological characteristics, the distribution of root systems has a certain relationship with farming measures such as fertilization and cultivating. Root growth: The occurrence of new roots and the growth of new shoots alternate, so there are several peaks of rooting in a year. The first peak of rooting occurs after the spring shoots stop and before the summer shoots grow, which is the largest number of roots in the whole year; the second peak occurs after the summer shoots stop and the number of roots is smaller; the third peak occurs after the summer shoots stop. After the shoots stop in autumn, the growth peak of fine roots appears, and the amount of roots is also less. The upper limit temperature for root growth is 37°C. If the temperature is too high, root growth is inhibited. Grassing the garden in summer can lower the soil temperature and reduce water evaporation, which is beneficial to the growth of the root system.

② Branch tips: Grapefruit saplings grow vigorously and can sprout four shoots in one year in spring, summer, autumn and late autumn. The number of branches is large and the crown expands rapidly. When 4-5-year-old grapefruit enters the fruiting period, the canopy has a large number of fruiting parts, which is an important reason for the high early yield of grapefruit. After entering the fruiting period, generally only spring shoots will be drawn, and summer shoots will not be drawn. Trees with less fruit will produce a small number of autumn shoots, and the crown expansion speed gradually slows down and enters the stable fruiting period.

Spring shoots: The new shoots that sprout from the beginning of spring to the beginning of summer are called spring shoots. Spring shoots sprout neatly and concentratedly, with large numbers, dense internodes, short, strong and substantial branches with a length of 10-20 cm. They are the main new shoots that bear fruit and create and accumulate nutrients that year. The strong spring shoots can become the base branches for summer and autumn shoots, and the medium-growing ones can develop into the fruit-bearing mother branches of the following year; the spring shoots developed from mixed buds develop into the fruit-bearing branches of the current year. The quantity and quality of spring shoots depend on the nutritional status of the tree. If the tree body has sufficient nutrient accumulation in the previous year, the number and quality of spring shoots will be large, and the quantity and quality of spring shoots will determine the quantity and quality of the current year's fruiting branches and the next year's fruiting mother branches. Cultivating a large number of spring shoots with good quality is a prerequisite for obtaining high and stable yields.

Summer shoots: Hair sprouts from the beginning of summer to the beginning of autumn. Young trees that have not yet produced fruit can produce numerous summer shoots, accelerating the expansion of the canopy. The summer shoots are 20-40 cm long, have large leaves, and grow quickly, allowing them to cultivate good backbone branches. The summer shoots of first-fruiting trees with well-developed tissues can also become the mother-bearing branches of the next year.

Autumn shoots: Hair sprouts between the beginning of autumn and the beginning of winter. Young trees and trees with few fruits often produce more autumn shoots. Autumn shoots are generally 20-40 cm long, with slightly larger leaves and insufficient tissue development. Late autumn shoots are often frozen to death. The shoots with abundant shoot tissue in early autumn can also develop into the fruiting mother branches of the next year. (3) Flowering and fruiting habits: Grapefruit trees generally begin to bear fruit in 8-10 years, grafted trees bear fruit in 4-5 years, and enter the full fruiting period 1-2 years after the first fruit. The yield of a grafted tree of Citrus aurantium in 5-7 years old is 15-50 kilograms, and in 8-10 years it can reach 50-100 kilograms.

① Fruiting mother branches: Both the spring shoots of grapefruit and the well-organized summer and autumn shoots can develop into the fruiting mother branches of the coming year. Spring shoots are the main fruiting mother branches. The leaf axils of each node of the fruiting mother branch can differentiate into flower buds and produce fruiting branches, and more fruiting branches are produced at the top nodes. According to the survey, 23.7% of the fruiting branches were drawn out in the first section, and 72.7% were drawn out in sections 1-4. The fruiting branches with several nodes at the top have large number of flower buds and a high fruit setting rate. Therefore, the fruits are mostly concentrated on the fruiting branches at the apex of the fruiting mother branches. When pruning, avoid shortening the fruiting mother branches. An investigation into the fruit-bearing ability of different lengths of fruiting mother branches showed that the fruiting mother branches with a length of 10-20 cm had the strongest fruiting ability, accounting for 56.9% of the total number of fruits.

② Fruiting branches: Grapefruit flower buds are mixed buds, which bloom after sprouting in spring. The fruiting branches can be divided into four categories according to their shapes: inflorescence branches with leaves, inflorescence branches without leaves, single-flowered branches with leaves, and single-flowered branches without leaves. There are single flowering branches with leaves, that is, there are fruiting branches with one flower bud on the top of the leafy spring shoots. They bloom slightly later, have a high fruit setting rate, and the fruit quality is good, but the quantity is small. The fruit setting rate of leafy fruiting branches is higher than that of leafless fruiting branches. There are many leafless fruiting branches and the fruit setting rate is low. Those with strong tree vigor will have more leafy inflorescence branches and leafy single-flowered branches; those with weak tree vigor will have more leafless inflorescence branches. Therefore, cultivating strong tree vigor and good fruit-bearing mother branches, and striving to produce more leaf-bearing branches, especially more single-flower branches with leaves, can reduce the amount of flower buds and nutrient consumption, and increase the fruit setting rate, which is helpful for achieving high and stable yields. important meaning. According to surveys, the ratio of vegetative branches to fruiting branches of grapefruit is 11-18:1. These vegetative branches are the preliminary branches that will bear fruit in the next year. The existence of a large number of preliminary branches is an important reason why grapefruit can produce high and stable yields every year. The inner branches of grapefruit have strong fruiting ability, and the inner branches with weak light intensity can differentiate and develop normal flower buds and bloom and bear fruit. This is also one of the important factors for the good yield of grapefruit.

③Blooming and fruiting: Grapefruit flowers are solitary or in racemes. Flowering begins in late April and peaks in early May. Normally developed male and female stamens produce fruit with seeds after pollination and fertilization. Pomelo also has the ability of parthenocarpy, and the ovary that has not been pollinated and fertilized can also expand and develop into a fruit without seeds. Physiological fruit drop: Physiological fruit drop of grapefruit basically ends from mid-May to the end of June.

Fruit drop accounts for 17.8% of the total fruit drop in mid-May, and 40.6% in late May. It is the peak period of physiological fruit drop. Fruit drop accounts for about 90% of the total fruit drop from mid-May to mid-June. By early July, physiological fruit drop is basically the same. result. Pomelo fruit matures around the beginning of winter and is spherical, oblate or pear-shaped. The average weight of a single fruit is about 250 grams. The top of the fruit is flat and sometimes has annular rings. The fruit pedicle is slightly concave, with 7-8 radial grooves, and 8-12 capsules that are easy to peel off. The capsule is slightly thick and easy to peel off. The juice cells are spindle-shaped and orange-yellow. The fruit is seeded or seedless, and the seeds are single or multiple embryonic.

3. Suitable conditions

(1) Climatic conditions The annual average temperature in the place of origin is 17.5℃, the extreme high temperature is 40.5℃, the extreme minimum temperature is -9.2℃, and the frost-free period lasts for 238 days. The annual precipitation is 1725.3 mm, and the annual sunshine is 1898.6 hours. Grapefruit has a stronger tolerance to low temperatures than sweet oranges, orange mandarins, and Wenzhou mandarins.

(2) Topography and topography

Pomelo has no strict requirements on terrain. Plains, beaches, hills, low mountains, and mountains with an altitude of less than 500 meters and a slope of no more than 25 degrees are all suitable. Can be planted. Grapefruit is of better quality. When growing grapefruit in mountainous areas, it is necessary to take advantage of the "inversion layer" phenomenon that occurs due to radiation heat dissipation in winter, and avoid planting in low valleys at the bottom of the basin where cold air is easy to accumulate to prevent freezing damage. Mountainous areas close to large reservoirs often form a microclimate that is conducive to grapefruit, which is especially suitable for development.

(3) Grapefruit does not have strict soil requirements, and the soil pH value is 5.5-6.5. Alluvial soil, red and yellow soil, purple sand soil and vegetable garden soil can be planted as long as the soil layer is deep and the drainage is good. The best soil quality is sandy loam. The soil is heavy, with poor drainage and poor ventilation, which is extremely detrimental to the growth of grapefruit and is prone to frost damage.

(2) Cultivation technology

1. Seedling cultivation:

The best rootstock is this stock, which will grow quickly after grafting, produce early fruits, high yield, and good fruit quality. excellent. Sowing is usually carried out at the spot where the seeds are harvested, and a small plastic shed should be built to keep the seeds warm. The seedlings will emerge that year and can be budded the following autumn, which can be one year in advance. Grafting is usually carried out from early March to early April, and the scion is an autumn shoot or spring shoot about 15-25 cm long; bud grafting is carried out from August to October, and "T" shaped bud grafting is often used. After the bud grafting survives, in early to mid-March of the following year, cut off the buds 3-5 cm above the buds. When the growth of the spring shoots stops, all the interface anvils will be cut off.

2. Construction of the garden:

(1) Slotting after soil preparation.

After the soil is prepared, the slot is 100 cm wide and 60-80 cm deep. Apply base fertilizer in layers, that is, use garbage, straw, branches, leaves, turf, etc. in the bottom layer at a dosage of 5,000-10,000 kilograms per mu. Apply fertilizer, compost, cake fertilizer, etc. in the upper layer at a dosage of 250 kilograms per mu. Fertilize in layers and fill soil in layers. For final planting, the soil surface should be 20-30 cm higher than the soil surface.

(2) Planting

Pomelo density: Grapefruit grows vigorously and has a large crown. The grafted tree will enter the fruiting period in 6-7 years, so the planting density in the patch should not be too dense. For sloping land above 20 degrees, 45 plants should be planted per mu; for 10-20 degree sloping land, 40 plants should be planted per acre; for gently sloping land below 10 degrees, about 35 plants should be planted per acre. Arrange pollinating trees: Grapefruit has a strong ability to set fruit, but cross-pollination can increase the fruit setting rate and increase the size of the fruit. Therefore, it should be configured as a single-line mixed planting when planting. Planting time: Grapefruit can be planted in spring (March) or autumn (November). It is better to plant in early to mid-March. Planting should be done on cloudy or sunny days in the evening. It is not suitable for planting on rainy days or when the soil is too wet.

3. Fertilization

(1) Fertilizing saplings

Saplings without fruit have shallow root systems and weak fertilizer absorption capabilities. The principle of applying fertilizer frequently. Fertilize once a month from March to July and November. Among them, spring shoot fertilizer in March, summer shoot fertilizer in May, and winter shoot fertilizer in November are essential. Young trees mainly use organic nitrogen fertilizers, such as human excrement, decomposed manure, cake fertilizer, combined with appropriate amounts of urea and other chemical fertilizers. Fertilizing saplings is mainly to promote shoot growth in spring, summer and autumn, accelerate the formation of canopy, and pay attention to regulating vegetative growth and reproductive growth to enhance drought and frost resistance.

(2) Fertilizing adult trees

Fertilizing adult fruit-bearing trees is mainly to achieve high quality, high and stable yields, and to regulate the relationship between vegetative growth and reproductive growth. Generally, fertilize at least 3 times a year. Germination fertilizer: Apply 10-15 days before germination in early March, mainly using fast-acting nitrogen fertilizer, with an appropriate amount of phosphorus and potassium fertilizer to promote the emergence of large number and good quality spring shoots. This fertilization is related to the yield of the current year and the next year, so it must be applied promptly, early and in sufficient quantity. The amount of fertilizer applied accounts for about 30% of the year. Generally, 0.50-0.75 kg of urea and 0.25 kg of superphosphate are applied to the plant. Fruit-strengthening fertilizer: Apply fruit-strengthening fertilizer during the fruit expansion period from June to August, mainly nitrogen, supplemented by phosphorus and potassium. The amount of fertilization accounts for about 30% of the whole year, and the specific amount should be determined by the number of fruits that year. It has many fruits and requires a large amount of fertilizer. It can be applied twice in June and August. Generally, 0.5 kg each of urea and compound fertilizer or 0.75 kg of urea is applied to the plant, and 0.25 kg each of superphosphate and potassium chloride is applied. If there are few fruits, it may be appropriate or not to apply fruit-strengthening fertilizer to prevent sudden growth of autumn shoots. Fruit-picking fertilizer: Apply in early November, and the application amount accounts for about 40% of the whole year. The growth of grapefruit fruit consumes a lot of nutrients, which need to be replenished in time to restore the tree's vigor, improve its ability to withstand cold and overwinter, promote flower bud differentiation, and lay the foundation for the next year's growth and fruiting.

Fertilizer for fruit picking should be a combination of quick-acting fertilizer and organic fertilizer, nitrogen fertilizer and phosphorus and potassium fertilizer. Generally, 0.5 kilograms of urea and compound fertilizer, 5 kilograms of cake fertilizer, and 100 kilograms of compost and other soil fertilizers are applied to the plants. In addition, an appropriate amount of urea and potassium phosphate can be applied in combination with spraying for extra-root top dressing to replenish the tree's needs for nitrogen, phosphorus and potassium in a timely manner.