Overview: Watermelon (Citrullus vulgaris) belongs to Cucurbitaceae. Annual vine herb. The fruit is crisp and tender, sweet and juicy, rich in mineral salts and vitamins, and it is the main summer fruit. Watermelon can clear away heat and relieve summer-heat, and it has an auxiliary effect on treating nephritis, diabetes and cystitis. The peel can be pickled, preserved, jam and feed. The oil content of seeds is up to 50%, which can be used for pressing oil, frying food or making pastry ingredients.
Characteristics: Watermelon main root system, the main root depth is more than 1 m, the root groups are mainly distributed in the plough layer of 20 cm-30 cm, the roots are slender and easy to break, the regeneration is weak, and it is not resistant to transplantation. The stem of the seedling stands upright, elongates after 4-5 internodes, creeps after 5-6 leaves, has strong branching, and can form 3-4 grade lateral branches. Leaves alternate, deeply divided, shallowly divided and entire. Dioecious flowers are the same plant. Male flowers appear in the 3rd-5th section of the main stem, and female flowers appear in the 5th-7th section. A few hermaphroditic flowers can appear in the blooming period. Corolla yellow. The ovary is inferior, and the placenta is lateral membrane. Both male and female flowers have nectaries, and the flowers are insect-borne flowers, which open in the morning and close in the afternoon. Fruits are spherical, oval, elliptical, cylindrical and so on. The fruit surface is smooth or furrowed, and the epidermis is green-white, green, dark green, dark green and black, with fine reticulation or bands between them. The pulp is milky white, light yellow, dark yellow, light red, bright red and other colors. The meat is divided into meat and sand pulp. Seeds are flat, ovoid or oblong, smooth or cracked. Seed coat is white, light brown, brown, black or brown, monochrome or variegated. 1000-seed weight: large seed type100g-150g, medium seed type 40g-60g, small seed type 20g-25g. Melon type150g-200g.
Watermelon cultivation likes high temperature and dry climate. The suitable temperature for growth is 25 ~ 30℃, and it is vulnerable to cold damage at 6 ~10℃. Open cultivation is only feasible in areas where the monthly average temperature is above 19℃ and the annual average temperature is more than 3 months. It is a long-day plant, which likes strong light and has a light saturation point of 80 thousand lux. Suitable for dry and hot climate, with strong drought tolerance, sandy loam with good drainage and deep soil layer is required. The soil pH is 5 ~ 7. There are many ways to cultivate watermelons in China. There are dry pond cultivation and sand field cultivation in the northwest, flat border cultivation in North China and high border cultivation in the south of the Yangtze River. Protected areas include wind barrier cultivation in Beijing, reed hair cultivation in Baoding, plastic film mulching cultivation, plastic greenhouse cultivation and greenhouse cultivation. No matter whether cultivated in open field or protected field, seedlings are raised in protected field first in spring, and then planted. Organic fertilizer is the main base fertilizer, and calcium superphosphate and potassium sulfate can improve the sugar content of fruit. The planting density is generally 500 ~ 600 plants per mu. North China is pruning, one plant, one vine and one melon; Without pruning in South China, one plant has many vines and melons. It takes about 80 ~120 days from sowing to harvesting, and about 30 ~ 50 days from female flower opening to fruit ripening. The main diseases are Fusarium wilt, anthracnose, powdery mildew, etc. The main pests are aphids, flies and melons.
Origin can be cultivated in most parts of the country. There is a large number of cultivation in Laixi, Shandong Province. Nanlan watermelon produced in Hetoudian Town, Laixi City is famous for its pulp, sweet taste, plenty of water and rich nutrition.
Uses Watermelon fruit is the main fruit in summer. Mature fruit contains a lot of water, and the sugar content of pulp is generally 5 ~12%, including glucose, fructose and sucrose. Sweetness increased with the increase of sucrose in the late ripening stage. Almost no starch is contained, and the sweetness will be reduced due to the hydrolysis of disaccharide into monosaccharide during storage. Melon seeds can be used as tea food, and melon skin can be processed into watermelon sauce. In traditional Chinese medicine, melon juice and peel are used as medicine, which can clear away summer heat and relieve fever.
Also known as summer melon and cold melon, it can be called the king of melons. Because it was introduced from the western regions in the Han Dynasty, it was called watermelon. Watermelon also belongs to Cucurbitaceae panicum miliaceum, which is native to Africa. At present, it is planted all over China except in a few remote and cold areas, with sweet fruit and cold nature.
Watermelon is a typical fruit and the main fruit in summer, so we should cherish it more.
In hot summer or hot tropical nights, as long as there are frozen watermelons, it has the effect of eliminating summer heat.
Variety: Watermelon can be divided into three categories according to different uses: ordinary watermelon, melon seed melon and small watermelon.
The origin of watermelon name
China is the largest watermelon producing area in the world, but watermelon does not originate from China. Watermelon is native to Africa. It was originally a wild plant of Cucurbitaceae, and was cultivated artificially to become an edible watermelon.
As early as 4,000 years ago, the Egyptians planted watermelons, and then gradually moved northward, first from the Mediterranean coast to northern Europe, and then southward to the Middle East, India and other places. In the fourth and fifth centuries, watermelons were introduced to China from the western regions, so they were called "watermelons".
According to Xu Guangqi, a scientist in the Ming Dynasty, the book "Agricultural Administration Encyclopedia" records: "Watermelon is named after it is planted in the western regions." Ming Li Shizhen recorded in Compendium of Materia Medica: "According to Hu Jiao in Uighur, you get a kind of melon, which is called watermelon. Watermelon began to enter China in the Five Dynasties; There are both north and south today. " This shows that watermelon cultivation in China has a long history.
How to get seedless watermelon
Now seedless watermelons cultivated in production are all triploid watermelons. It is a first generation hybrid produced by crossing tetraploid (4X) watermelon as female parent and diploid (2X) watermelon as male parent. At present, seedless watermelons are not completely seedless, and there are undeveloped small white seed coats like tender cucumber seeds, which taste seedless, so they are called seedless watermelons.
Other methods of producing seedless watermelon
1.natural hormone method
According to the characteristics of parthenocarpy of watermelon, this method stimulates the ovary of diploid watermelon with seeds by using the natural hormones contained in the flowers of tetraploid watermelon with few seeds, so that the fertilization process does not occur, and promotes the common (diploid) watermelon plants to sit and grow into seedless watermelons through their inherent physiological functions, which is a new way to produce seedless watermelons quickly. It has the characteristics of easily obtained materials, simple method, convenient operation, etc. Seedless watermelon can be produced in the same year, and the fruit shape is correct, the skin is thin and not hollow. The texture and flavor of watermelon are the same as those of the original common watermelon varieties, and no special cultivation measures are needed from growth to maturity, thus avoiding the problems of low germination rate, low seedling rate and low seed setting rate of seedless watermelon.
The experiments of Hubei Academy of Agricultural Sciences for many years have proved that the seedless watermelon produced by this method is similar to the triploid seedless watermelon, and the fruit only contains white, tender and edible seeds, with a lining content of 9% ~10%, and the peel thickness and flavor are the same as those of the selected common watermelon varieties. The results showed that the seedless watermelon produced by using Xingcheng Red as the female parent was the best, with thin skin, crisp meat, high sugar content, good flavor and small and few white seeds. Seedless watermelons produced with Mibao and DuNo.3 watermelons as female parents are the second, and the specific production technical points are as follows:
(1) Choose a good parent: A few-seed watermelon selected as the male parent requires a variety with a large number of seeds in the fruit and good pollen quality, and requires the plant to grow healthily. The common watermelon selected as the female parent requires a variety with less seeds in the fruit, thin skin, high sugar content and good quality, and requires the plant to grow healthily.
(2) Timely pollination: both the male flowers selected as the male parent and the female flowers selected as the female parent should be bagged or artificially bunched in the afternoon before flowering. When the male and female flowers open the next morning, pick the male flowers in time, remove the bagging or binding, and pollinate the female flowers artificially. Pollination should be done fully and carefully to avoid damaging the female flowers. After pollination, the female flowers are still bagged or bunched to prevent the pollen of ordinary watermelon from falling on the stigma. Generally, after 3 days of pollination, the bagging should be removed in time when the young melon sits down to promote the normal growth and development of the young melon.
(3) Removing heteromorphic melons: In the melon field where seedless watermelons are produced by using natural hormones, after the melons sit, they should stay and patrol Gua Tian, and promptly remove the naturally seated melons without artificial pollination to prevent the generation of heteromorphic melons and seedless watermelons. Otherwise, due to the strong competitiveness of ordinary watermelons and the weak competitiveness of hormone watermelons, young watermelons will not grow up or turn into melons.
(4) Strengthen the management of fertilizer and water: Because the seedless watermelon stimulated by natural hormones is grown from unfertilized embryos, its growth and development are fragile, so it is necessary to give good fertilizer and water conditions and strengthen the work of arranging vines to promote its normal growth and development.
(5) Timely harvesting: The seedless watermelon produced by this method has a suitable harvesting period of about 30 days after flowering, which is premature, with low sugar content and poor quality; If the fruit is harvested too late, the seeds in the fruit will increase, which will affect the taste. Picked seedless watermelons should be sold or eaten immediately, and it is not easy to store for a long time, otherwise the seeds in the fruit will become hard and the quality will deteriorate.
2. Synthetic hormone method
Practice has proved that artificial induction with some hormones can also make common diploid watermelons bear melons, and the formed watermelons only have white and tender seed coats without embryos, which tastes like seedless watermelons. The specific production points are as follows:
(1) Selection of fine varieties: Experiments have proved that Zaohua is an excellent variety for producing seedless watermelon by using artificial synthetic hormones at present. When other measures are taken, the seedless watermelon rate can reach 90%, which is basically the same as the seedless watermelon rate produced by artificial pollination of this variety. Other varieties, such as Zhengzhou No.3, Lemi 1, Zhongyu No.6 and Luxigua 1, are also better.
(2) Treatment method: firstly, distilled water is used to prepare 100ppm sodium naphthylacetate, 25ppm gibberellin and 25ppm 2,4 ~ D respectively. Then, the same amount of mixed solution of these three solutions (the mixing ratio is1:1:1) was used to treat watermelon female flowers. The mixed liquid is required to be prepared as needed, and used up on the same day after mixing. The ten thousand ways to deal with female flowers are to bag or clip flowers in the afternoon before the female flowers open (if bisexual flowers should be castrated strictly), and when the female flowers open the next morning, take off the bag or binding objects and dip them into the mixed solution with a new brush and apply them to the stigma and the base of the ovary of the female flowers. The dosage of each flower is about 1 ml. After application, the corolla must still be clamped or bagged for protection. Removing the bagging on the fourth day after application, and applying the mixed solution once, or applying 20ppm cytokinin 6 ~ furaminopurine solution, have obvious effects on improving the mature rate of melon. The experiment proves that it is the most ideal to treat the second female flower of the main vine (double vine pruning). The application should be done in sunny days. If it rains after application, it should be reapplied 1 time after rain.
(3) Fine field management: the plants should be strong before flowering. After coating, the lateral vines and growing points at the axils of the main vines should be pinched off immediately, and the melon vines should be pressed well to promote the transport of nutrients into the melons. After the first application, if it is found that the skin of young melon is dark, it should be applied again 1 time, which can effectively prevent melon from melting. The growth point of the second melon vine can be pinched off about 10 day after the first coating treatment. Don't keep young melons that haven't been treated with chemical solution on the two vines of the same plant, because there are seed melons and seedless melons on the same plant at the same time, and nutrients are easily contested by seed melons, which will cause seedless melons to turn into melons. It is necessary to remove other female flowers in time to prevent seed melons from sitting. After the first coating treatment 12 days or so, when the safety period is reached, watering and topdressing should be carried out. However, the amount of watering should not be too large, and it is advisable to water it frequently with small water. Generally, 3 ~ 4 cubic meters can be poured per mu at a time, and every 2 ~ 3 days. Topdressing should be furrowed on one side of the plant, and 30 ~ 40 kg ternary compound fertilizer should be applied per mu.
3. Cutting cultivation method
See the "Cutting Cultivation" section for details.
4. Tissue culture method
Tissue culture is a new propagation method that uses a certain part of plant tissue or organ to cultivate into a complete plant under aseptic conditions. China started this work from 1979. At present, many units in Shanghai, Beijing, Shandong, Hebei, Shanxi, Gansu and Heilongjiang provinces and cities have used this method to produce a large number of seedless watermelons with high quality and high yield for the market, and achieved remarkable economic and social benefits. The specific method is:
(1) Culture materials: According to reports at home and abroad, seed embryos, shoot tips, root tips, pollen and ovaries of watermelon can be used for tissue culture, but at present, the tissue culture of seed embryos and shoot tips is the most widely used.
(2) Culture medium: The materials and culture stages of watermelon tissue culture genes are different. Generally, it can be divided into three kinds: bud differentiation medium, seed embryo medium and rooting medium.
① Watermelon bud culture medium: There are 500 mg of ammonium nitrate (NH4NO3), 500 mg of potassium nitrate (KNO3) 1000 mg, 440 mg of calcium chloride (CAC12), 370 mg of magnesium sulfate (MgSO4 7H2O) and potassium dihydrogen phosphate (KH2PO4) in each liter of culture medium. There are 55.7g of ferrous sulfate (FeSO4 7H2O), 22.3mg of manganese sulfate (MnSO4 4H2O), 6.2mg of boric acid (H3BO3), 0.83mg of potassium iodide (KI), 0.25mg of sodium molybdate (Na2moo4 7H2O) and zinc sulfate (ZnSO4·7H2O)8.6 Contains organic inositol 100 mg, vitamin B 10.4 mg, vitamin B60.5 mg, glycine 2 mg and nicotinic acid 0.5 mg; Containing hormone IAA1mg, 6- benzylpurine (6-BA)0.5 mg; Contains 7 grams of agar, 30 grams of sucrose or 50 grams of edible sugar. Adjust the pH to 5.5 ~ 6.4.
② Watermelon embryo culture medium: Macroelements, trace elements, vitamins and organics are all the same as those in ①, but the hormones are free of IAA and 6- benzylpurine (6-BA). Sugar is changed to 20g per liter (33.3g of edible sugar). Adjust the pH to 6 ~ 6.4.
③ Watermelon rooting medium: Except for removing the hormones 6- benzylpurine and indoleacetic acid in ①, IBA1mg was used instead, and other elements were completely the same as those in ①.
(3) culture method: firstly, sterilize the culture materials. If the materials are seeds, first soak the seeds in warm water at 70 ~ 80℃, stir to about 30℃, soak for one day and night, then disinfect with 75% alcohol for 30 seconds, peel off the seed coat under aseptic conditions, disinfect with 0. 1% mercuric chloride for 2 minutes, then rinse with sterile water for 4 ~ 5 times, inoculate on the culture medium, and put in the culture room for culture. The radicle germinated first, and after two weeks, when the two cotyledons unfolded and turned green, the germ with the cotyledons was cut off and transferred for culture. Cutting every 3-4 weeks, separating the terminal bud from the lateral bud, and then subculturing.
If shoot tips or lateral buds are directly taken from triploid watermelon seedlings in the field, the materials should be washed with tap water first, then disinfected with 75% alcohol 10 second, then disinfected with 0. 1% mercuric chloride for 2 hours, finally washed with sterile water for 4-5 times, inoculated on the culture medium, and cultured in the culture room.
(4) Culture medium and culture conditions: The basic media used are M5 and 1/2MS. According to the specific requirements of seedling differentiation, growth and rooting, different hormones, 3% sucrose and 0.7% agar are added respectively, and the pH value is adjusted to 5.8. Sterilize at high temperature for 20 minutes under the pressure of 1 kg/cm2, then inoculate, and then culture the inoculated explants in a culture room with the temperature of 26+1℃, the light intensity 1000 lux and the light intensity 14 hours/day.
(5) Grafting and management: Bud seedlings proliferated by tissue culture can be directly cultivated into mature seedlings for production, or can be grafted into grafted seedlings for production, and the latter is better. If grafted seedlings are cultivated, the differentiated buds need to be heightened before grafting. The method is to transfer the bud seedlings to MS+IBA 0.5 ~1.0+GA 0.5 rooting medium without kinetin, so that the base of the bud seedlings gradually takes root. With the growth of roots, the young stems quickly grow taller and develop healthily, and the quality of the scion is improved. The rootstock used for grafting is planted in a plastic nutrition bowl filled with ordinary soil, and when the cotyledons of the rootstock are unfolded and the true leaves are slightly exposed, the terminal buds of the rootstock are cut off for grafting. For the selection of rootstock and grafting operation method, please refer to the "Grafting Cultivation" section. Immediately after grafting, the grafted seedlings were transferred to a healing shed for healing. The temperature in the shed was 25 ~ 35℃ and the relative humidity was above 95%. Under this condition, the grafted seedlings could heal in about 10 day, and then transferred to a greenhouse for exercise for 3 ~ 4 days. Attention should be paid to ventilation in this period to gradually enhance its adaptability. Finally transplanted to the field. Field cultivation management measures are similar to seedless watermelon cultivation management measures, which can be implemented by reference.
When was watermelon introduced to China?
Watermelon, native to Africa. Watermelon has been cultivated in Egypt for five or six thousand years. In the past, some people quoted Ouyang Xiu's Appendix to the History of the New Five Dynasties and Four Aliens in the Song Dynasty as saying: In the Five Dynasties, Heyang County, Tongzhou, ordered Hu Jiao to enter the Khitan to "eat watermelon at first", "When the Khitan broke Uighur, it was planted in a shed covered with cow dung, which was as sweet as China wax gourd" and "Zhou Guangshun was three years old (953) …………………………………………………………………………………………………………………………… Therefore, the idea that watermelon was introduced into China from the Western Regions in the Five Dynasties seems to be a final conclusion. In recent years, many articles about watermelon in newspapers and periodicals hold this view. 198 1 There is a section "Watermelon began in the Five Dynasties" in the extracurricular reading of middle school students published by Hunan People's Publishing House in. In fact, this statement is not accurate.
Li Shizhen in Ming Dynasty pointed out in Compendium of Materia Medica: Watermelon is also called cold melon. "Tao Hongjing (Northern and Southern Dynasties) notes that Guadiyan Yongjia (the year of Emperor Huaidi) has a large cold melon, which can be hidden until the spring sound, that is, this is also. Before the Five Dynasties, melon seeds had entered the east of Zhejiang, but there was no name of watermelon, which did not spread all over China. " "The Biography of Nan Shi Teng Tan Gong" said that Tan Gong "was five years old, and his mother Yang suffered from fever, thinking about eating cold melons, and the local customs were not productive. I can't get a visit through the calendar, and I am sad. When I met a mulberry door and asked him why, I was ready to tell him. Sangmen said,' I have two melons, one for each.' I was also amazed by my mother, and I looked for Sangmen, and I didn't know where it was. " In the Tang Dynasty, Duan Chengshi's "Youyang Miscellaneous" Volume 19 recorded the poem "Hangyuan" written by Yin Hou (Shen Yue): "The cold melon is lying on the long side, and the autumn pu is full of bitterness. Purple eggplant is rotten, and green taro is uneven. " When it comes to the cold melon lying in the poem, it is in line with watermelon. In addition, in old Beijing, watermelons listed first were called "water melons" and those listed later were called "cold melons". Today's visit to the old farmer also said that late watermelons do have the name of "cold melons". It seems that the above-mentioned documents can confirm Li Shizhen's statement. However, Li Shizhen's statement did not seem to attract people's attention for hundreds of years. 1976, watermelon seeds were found in the silt of the tomb of the Western Han Dynasty in Guixian, Guangxi; 1980, watermelon seeds were found in the lacquer barns of Han tombs in Hanjiang County, the western suburb of Yangzhou, Jiangsu Province. The owner of the tomb died in the first three years of Emperor Xuandi of Han Dynasty (the first 7 1 year). This irrefutably proves the reliability of Li Shizhen's records.
Watermelon, as its name implies, is a melon from the western regions. Five generations ago, since it had been introduced to the southeast coastal areas of China, it was not called watermelon, but called cold melon because of its cold and antipyretic nature. Therefore, it seems doubtful that watermelon was introduced into China from the Western Regions. So, from what route did it enter China?
The author speculates that it was introduced into China by the Maritime Silk Road. Emperor Wu of the Han Dynasty once sent "translators" to raise businessmen, take silk and go to western countries by sea boat "the pearl of the city, the displacement of the wall, the strange stones and foreign objects. Ships set sail from Leizhou Peninsula, sailed along the west coast of Beibu Gulf and the coast of Vietnam, bypassed the southern tip of Vietnam, then went south along the coast of Malay Peninsula along the Gulf of Siam, arrived in Singapore, turned west, crossed the Straits of Malacca, and reached the country along the Bay of Bengal. "The translation of Chinese into English has been repaid ever since" (History of Han Geography); This sea route is the so-called "Maritime Silk Road".
Where is the "no country" today? Most scholars think it is Sri Lanka, and some people say it is Abyssinia in eastern Africa. No matter which statement is correct, it shows that the sea route for traffic between China and Africa has been opened in the era of Emperor Wu of the Han Dynasty. Because in the Han Dynasty, Arabs had mastered the secret of the trade winds in the Indian Ocean and were able to sail east and west through the Indian Ocean. In this way, it is entirely possible for Sri Lanka and Nanyang Islands to become transit points for China and Africa. Watermelons from Africa can be introduced to China via Sri Lanka or Nanyang Islands. Watermelon seeds unearthed from Han tombs in Guangxi and Jiangsu are evidence of non-cultural exchanges in the maritime Silk Road communication.
In addition, according to1Guangming Daily on February 24, 959, watermelon seeds were also found in the Neolithic site in Shuitianfan, Hangzhou, Zhejiang. If this archaeological harvest is really reliable, the history of watermelon in China is at least more than 4 thousand years, and the statement that watermelon originated in Africa is another matter.