Grapefruit is an excellent fruit tree variety with large fruit shape, storage stability, easy management, high yield and stable yield, and high fruit yield. It is also the largest fruit variety and yield in Shanghang County. However, in the current production of grapefruit, fruit farmers in some areas reflect the phenomenon of grapefruit cracking. The mid-fruit cracking of grapefruit caused a lot of fruit drop, and the fruit cracking in the later stage caused the fruit to be perishable, and it was not resistant to storage and transportation. The value of the commodity was seriously reduced and the economic loss was large. After investigation and understanding and observation and analysis, the main reasons for the cracking and prevention measures are as follows for reference in production.
I. Current status of grapefruit production in our county
Shanghang County has a large area of ​​pomelo cultivation, and the quality of pomelo fruit produced is good, especially in recent years. It has become a characteristic fruit industry for local farmers. The main varieties of grapefruit in this county are red meat honey pomelo, Shatian pomelo and Hangtai honey pomelo. In 2013, the total area of ​​grapefruit was 38,700 mu, and the output was 11,500 tons. The annual output value was about 46 million yuan. It is the only fruit tree variety with the largest area and the largest output in the county. The main towns and towns are towns and towns such as Putian, Xiadu, Lincheng and Zhongdu.
The area and quality of Shatian pomelo in Shanghang County is the most common in the following townships, and there are certain areas in the surrounding towns and towns such as Zhongdu. The market is known as “Xiadu Shatian Pomeloâ€, which was developed in the 1990s and became the characteristic of this county. The brand name fruit tree variety. Shatian pomelo is sweet and brittle, extremely resistant to storage and does not crack fruit, but has many seeds and less water. Especially the hard-branched strains are poor in dry quality and low in price.
Red meat pomelo is a variety of honey pomelo introduced from Pinghe County in the province. It is currently the largest variety of Guanxi honey pomelo varieties, and the area of ​​Putian Town, which is mainly produced in this county, covers an area of ​​15,000 mu. The Guanxi honey pomelo series includes the original white meat type Guanxi honey pomelo. In recent years, it has planted more red meat honey pomelo, and the newly selected yellow meat honey pomelo, red cotton honey pomelo and three red honey pomelo have five varieties. In addition to the difference in the color of the meat, other traits are not much different. Its common feature is that it is listed in the early Mid-Autumn Festival at maturity. It has no seeds and is sweet and sour. However, there are heavier fruit cracking phenomena. In general, the rate of fruit cracking is 20%-30%, and the high year is 50%, resulting in large yield loss. At the same time, there are about 30% of the split petals, juice granulation and cork formation, the bigger the more serious, affecting the quality and price.
Hangdong Honey Pomelo is a new late-ripening pomelo variety with independent intellectual property rights, which is selected by Shanghang County Jingcai Station. The fruit is nearly round in shape, the fruit is juicy and slag, the taste is sweet and sour, the quality is excellent, and the maturity is late. The variety does not crack and does not crack, and it is the new late-ripening white meat pomelo variety with the best comprehensive traits in China. Hang night honey pomelo juice cells are particularly crisp, and the taste is very good in the short-term after picking, but the juice cells become soft after storage. When the petals are opened, the juice cells are easy to break and flow, giving the meat a rotten feeling. In addition, the sweetness and acidity of Hangtai Honey Pomelo is similar to that of Guanxi Honey Pomelo series. Some sweet people do not like it, which has certain influence on planting and sales. In addition, the price of fruit in recent years is low, the enthusiasm of farmers is affected, the area of ​​contiguous pieces is small, and the advantages of varieties have not yet been exerted.
Second, the reason for grapefruit cracking fruit
The grapefruit cracked fruit is a grapefruit fruit that is cracked from the center and is hollow, and then gradually splits to the top of the fruit, causing a crack at the top. There are many factors in grapefruit cracking, and the mechanism is closely related to the endogenous hormone level of pomelo fruit. The variety is the fundamental factor. Secondly, it is affected by fruit development characteristics and fruit tissue structure. At the same time, it is related to many factors such as water, mineral nutrition and soil texture. Among the external factors, the influence of water is the greatest, and the high temperature sunburn, serious pests and diseases, and improper management can also cause cracking.
1. Variety issues. The difference in weight and weight of different varieties of grapefruit cracking was significant, and the Wendan pomelo strain was more severe than the Shatian pomelo and grapefruit strains. Such as Zhejiang's Yuhuan pomelo, Fujian's ?gxi honey pomelo and other cracked fruit are heavier, the general year's cracking rate is 20%-30%, up to 50% in special years. The annual fruit cracking rate of Tongxian pomelo, Jiangjin red heart pomelo, sweet grapefruit, Zhongjiang honey pomelo and Meiwan pomelo in Sichuan Province is 30%-40%, and 70%-80% in severe cases.
The study believes that the grapefruit cracking fruit is related to the species inheritance. The intrinsic reason of Yuhuan pomelo and ?gxi honey pomelo cracking fruit is that the seed is highly aborted into seedless or a little seed, which cannot produce gibberellin, resulting in cracking of the inner edge of the capsule. Therefore, the seedless variety has a heavier fruit. The fruit shape is also related to the cracked fruit. The g-small pomelo line is oval-shaped and small fruit-shaped and easy to crack. The fruit of the Yuhuan pomelo has a "three-crack" phenomenon of central column cracking, capsular cleft cracking and fruit top cracking.
2. Fruit development period. In the middle stage of fruit development, that is, during rapid cell division and expansion, the growth rate of pericarp cells and flesh cells is inconsistent, leading to fruit cracking, which will cause a large number of fruit drop, which has the greatest impact on yield. The fruit cracking at the late stage of fruit development mainly affects the quality of pomelo fruit. For example, the rate of fruit cracking in Duan Wendan pomelo fruit is higher at the near maturity stage. The cracking flap of ?gxi honey pomelo, in the fruit ripening stage, due to the central column hollow, the juice cell swelling caused the inner edge of the balloon to crack, the bigger the more serious, and the juice granulation and cork formation, seriously affecting the pomelo fruit quality.
3. External factors. External factors such as moisture, light, temperature, and soil all affect the growth and development of the fruit and cause cracking. Moisture conditions are the most important external factors of pomelo fruit cracking. The most common ones are high temperature drought or long drought, which causes cracking when sudden rain or irrigation. In addition, the excessively strong light causes the peel to burn and necrosis. Zinc deficiency in the soil results in a thin skin and a cracked fruit. Long-term partial application of nitrogen and phosphate fertilizers, the soil lacks potassium, calcium, zinc and other elements, and the fruit is poorly developed to produce cracked fruit. The effects of pests and diseases, such as early infection of scab, anthrax or insect mouth wounds, after the wound heals, the skin hardens and scars cause cracking.
Third, measures and countermeasures to prevent grapefruit cracking
1. Choose an excellent variety. Breeding the varieties with reasonable peel structure and showing crack resistance is the most fundamental way to solve the problem of cracked fruit. Such as the selection of a new variety of Hangzhou honey pomelo, fruit juice and slag, the quality is excellent, no cracking fruit is not cracked. Shatian pomelo soft branch type is sweet and brittle, extremely resistant to storage and does not crack fruit. The fruit-type Guanxi honey pomelo has the advantages of beautiful fruit shape, high yield and low fruit cracking rate.
The newly built orchard is selected from high purity, medium fruit type and excellent grafted seedlings. Varieties with high fruit cracking rate in old orchards can be improved by high-replacement methods. In addition, the allocation of pollination trees, using cross-pollination, can fully develop the central column of the fruit, avoiding the hollow fruit cracking, but there are disadvantages of increased seeds.
2. Pay attention to water management. Maintaining a stable and suitable soil moisture condition in the orchard and reducing the variation of soil water content are the main measures to prevent the grapefruit from cracking. If there is a long period of drought, it is necessary to properly irrigate the water in a timely manner to keep the soil moist and to ensure the water demand of the teak. Drought and little rain, and the high temperature should be sprayed with water throughout the plant to balance the water absorption inside and outside the fruit. In case of heavy rain and thunderstorms, the water is removed in time to prevent the fruit from absorbing too much water and aggravating the cracking fruit.
3. Strengthen cultivation management. Spray borax or boric acid and potassium nitrate during the flowering and young fruit periods to avoid partial application of nitrogen fertilizer to prevent cracking. In the early stage of fruit growth, control of nitrogen fertilizer, increase of calcium fertilizer, increase the calcium content in the tree, combined with external fertilization, supplement magnesium, zinc and other trace elements, can reduce the cracking. Increase the application of organic fertilizer, promote the moderateness of the tree, balance the internal and external development of the fruit, and reduce the cracking. Strengthen the work of fruit thinning, remove the deformed fruit during the young fruit period, remove the cracked fruit in time, and reduce the loss. In the early stage of Guanxi honey pomelo, the large fruit was removed, and the middle fruit crack was kept lighter.
This article URL: The cause of grapefruit cracking and prevention countermeasures
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