Detailed introduction of fruit papaya

Fruit papaya is papaya, which is a kind of small papaya with red meat. Papaya is a perennial semi-woody plant of the genus Carica, with its scientific name Carica Paonpy Linn, English Papaya and Pawpaw. Papaya originated in South America and belongs to tropical high-quality fruit. It is rich in nutrition (rated as the first of the top ten nutritious and health-care fruits by American scientists), widely used (excellent in fruits, vegetables and medicines), fast in fruiting (only about 8 months from planting in suitable areas to harvesting), high in yield (about 3,000 kg per mu if planted well) and good in benefit (the general market price is above 4 yuan/kg).

1. Biological characteristics of papaya

1, root system and its characteristics

Papaya is mainly propagated by seeds, and the root system developed from radicle has strong main roots, strong lateral roots and many fibrous roots. Results The main root of the tree and several lateral roots with a thickness of 3-4 cm constitute the skeleton of the root system, which plays a role in fixing and storing nutrients for plants. The taproot and lateral root are densely covered with fibrous roots with root hairs, which can absorb water and nutrients. With the growth of root system, some fibrous roots develop into first-class lateral roots, some fibrous roots decline and die, and the root system is constantly changing.

The root system of papaya is mainly distributed below the topsoil 10-30 cm; When the average temperature reached 65438 07℃ in March, new roots began to grow (topdressing began to promote growth). From May to June, when the soil temperature is above 30℃, the root system grows most vigorously. In July and August, when the surface soil temperature exceeds 40℃, it is unfavorable for root growth (the border should be covered with plastic film to cool down). After 12 months, the root system grew slowly and stopped.

Another characteristic of papaya root system is that it is fleshy and aerobic, so it needs more water and the soil is well ventilated, but it will die if it is soaked in water and poorly ventilated.

2. Stem and its characteristics

It is hollow and stout, and its lateral buds have pumping ability. When the terminal bud of papaya grows normally, the lateral bud is inhibited. When the terminal bud freezes to death or the terminal bud or the upper part of the plant is cut off, it is easy to produce side branches.

Papaya plants are short and strong, which is beneficial to early fruiting, wind resistance and field management. Therefore, oblique planting is beneficial to inhibit plant growth, make the trunk thicker and bear fruit early; When it is blown off by the wind or the tree is older and the trunk is higher, it can be cut off at the height of 1 m from the ground to promote the lateral buds to grow new stems and blossom and bear fruit.

Under the same environmental conditions and cultivation conditions, monoecious plants grow faster, while bisexual plants grow slower.

3. Leaves and their characteristics

The cotyledons of papaya germinated by seeds are oval, the first and second true leaves are triangular, the fourth and fifth true leaves are divided into three palms, and the ninth and tenth true leaves are divided into five palms. Mature leaves are large, 5-7 palms, dark green or green, long and hollow petiole, green or purple petiole, which is a basis for variety identification.

Papaya is impeller-type growth, pumping at low temperature, slow growth, high temperature, sufficient water and nutrients, many new leaves and fast growth. Generally, the annual output of new leaves is about 60, and those with good fertilizer and water conditions can produce more than 90. It takes only 20 days for leaves to mature in summer, more than 30 days in winter, and the life span of leaves is generally only about 4 months. Prolonging the functional period of leaves and improving photosynthetic efficiency are the key to high yield. Each fruit must have more than one leaf on average to supply nutrients. Therefore, attention should be paid to protecting leaves, cultivating round crowns and increasing leaf area index. However, rotten yellow leaves and weathered leaves should be removed as soon as possible, so as to make the countryside clean and ventilated, and improve the quality and commodity of fruits.

4. Flowers and their characteristics

When papaya plants grow to a certain number of leaves (24-26 leaves of early-maturing varieties) and reach a certain leaf area, and there is a certain accumulation of nutrients, they can gradually differentiate into flower buds, blossom and bear fruit, and can differentiate into flower buds all year round. But when the temperature is low, it will bloom poorly and bear no fruit. In the case of high temperature and drought, it is easy to appear masculine tendency and intermittent results.

The flowers of papaya are divided into female flowers, male flowers and bisexual flowers.

The ovary of female flower is enlarged and the stamens are degenerated. The fruits developed from ovary are mostly round fruits with large cavity, thin pulp and many seeds, which are generally of no commercial value.

The male flower is small, and the ovary degenerates into a needle and cannot bear fruit.

Bisexual flowers can be divided into rectangular bisexual flowers, female bisexual flowers and male bisexual flowers.

Rectangular bisexual flowers are of medium size, with 5- 10 stamens and rectangular ovaries. The developed fruit is oblong, with thick flesh, small fruit cavity and single fruit weight, which is the main commercial fruit.

The hermaphroditic flowers of female flowers are larger than those of female flowers, but slightly smaller. The flower shape is not straight and easy to identify. Stamens 1-5, spindle-shaped or deformed ovary, deformed fruit, of little value.

Male hermaphroditic flowers are smaller but slightly larger than male flowers, with stamens 10, cylindrical or degenerated ovaries, small or deformed fruits and low value.

Plants with only female flowers are called female plants, which have no cultivation significance; Only the plants with male flowers are male, that is, papaya males, which has no cultivation significance; Plants with mainly hermaphroditic flowers are called hermaphroditic plants.

Hermaphroditic plants are affected by environmental conditions, such as the temperature changes from low to high (seasonal change), the flowers change from female hermaphroditic flowers to rectangular hermaphroditic flowers, and then to male hermaphroditic flowers and short-stemmed male flowers; On the contrary, the temperature changes from high to low (seasonal change), and the flower characteristics appear from male bisexual flowers and short-stemmed male flowers to rectangular bisexual flowers and then to female bisexual flowers. Generally, flowers that bloom at 26-32℃ are mostly rectangular bisexual flowers, and females or males are easy to appear below 26℃ or above 32℃.

5. Fruit and its characteristics

The fruit of papaya is a berry with a water content of about 90%. Immature papaya is rich in white milk, and its main component is protease. The fruit shapes of papaya are rectangular, oval and pear-shaped, among which pear-shaped fruit and rectangular fruit have the best quality and commodity. High temperature and drought, low temperature and rainy, too dense fruit setting, insufficient fertilizer and water, phytotoxicity, etc. can be introduced.

With high temperature and sufficient light, the papaya fruit grows and develops rapidly, and the fastest period of fruit weight gain is 62-82 days after flowering; The number of days from flowering to fruit ripening varies with flowering time. For example, it takes about 180 days to mature when it blooms in early April. It blooms in late April and matures in about 160- 170 days. If it blooms in early June, it only takes 100- 120 days to mature; Flowers that bloom after September need 180-2 10 days to mature. Low temperature prolongs the fruit development period, and the pulp has obvious bitterness and poor quality.

6. Seeds and their characteristics

Mature seeds are yellow-brown or black, and the exocarp is wrinkled; The number of seeds per fruit is at least a few, and the maximum is more than 1000. To keep the seeds, we should choose bisexual plants with good fruit setting, pollinate the pollen of bisexual flowers artificially, pick the fruits in Huang Shi, and cut the seeds in Huang Shi.

About 50-65 seeds per gram of dry seeds, the germination rate of new seeds is good, and the germination rate of old seeds is poor; The optimum temperature for seed germination is about 35℃, and lower than 23℃ or higher than 44℃ is not conducive to seed germination. The temperature of 35℃ during the day and 26℃ at night is the fastest, so the optimum temperature for promoting seed germination is 35-37℃.

Second, the requirements of papaya on environmental conditions

1, temperature

Papaya is a tropical fruit tree and likes hot climate. Therefore, papaya is suitable for economic planting in areas where the annual average temperature is 22-25℃ and the monthly average minimum temperature is above 16℃, and the area south of the Tropic of Cancer in Guangxi is the best.

The optimum temperature for papaya growth is 26-32℃, and 65438 05℃ is the lowest temperature for papaya growth. Growth stagnated at 65438 00℃; Papaya will suffer from freezing injury in rainy weather when the daily average temperature is lower than 10℃ for more than 3 consecutive days; Young tissues have been frozen in a short time at 5℃; At 0℃, the robust leaves were frozen. But too high temperature is not conducive to the growth and development of papaya. When the temperature is higher than 35℃, the development of flowers will be affected, and the phenomenon of male tendency will appear, resulting in falling flowers and fruits, which will affect the yield.

It blooms in May-July, and the fruit that ripens in September-165438+10 is better. 9- 10 blooms, and the fruit that ripens in March-April of the following year is hard, light, bitter and of poor quality; 165438+ 10 blooms and matures in May-June of the following year. Its pulp can still be softened, so its sugar content is slightly higher and its flavor is better.

Too high or too low soil temperature is harmful to the surface roots, so it is particularly important to cover the border.

Step 2: Moisture

The normal growth, flowering and fruiting of papaya need sufficient and balanced water. Drought and water shortage are unfavorable to growth and fruit, so it is particularly important to keep the soil moist. However, too much water and poor ventilation in the soil are not good for growth. If plants are soaked in the garden for half a day in a rainstorm, they will be seriously injured and even die. Therefore, papaya cultivation must solve the problems of drainage and water supply.

Papaya grows best when the air humidity is low, so it is extremely important to keep the orchard ventilated and transparent.

3. Lighting equipment

Papaya is a fruit tree that likes light, and it needs plenty of light. In the last 4-5 days when the papaya fruit is fully mature on the tree, the sunshine is sufficient and the quality is the best. Therefore, it is necessary to choose a sunny place to build an orchard, plant it reasonably and densely, and remove dead leaves in time.

4. wind

Papaya root is fleshy and shallow, its stem is hollow, its surface is only semi-lignified, its leaves are large and brittle, its fruit bears a heavy load, and it is extremely afraid of strong winds, especially typhoons.

5. Land

Papaya is not strict with soil, but for high yield and high quality, sandy loam or gravel loam with loose soil, deep soil layer, low groundwater level, good aeration and rich organic matter with pH value of 6-6.5 should be selected. Therefore, when the soil PH value is lower than 5.5, lime should be added; It is best to plant in deep ditches and high ridges.