Effect of sweet potato cracking on sale and storage how to prevent sweet potato cracking

In recent years, some farmers continue to report the occurrence of root cracks in sweet potato tubers. Root crack not only affects the storability of sweet potato, but also significantly reduces the commodity value of sweet potato, causing huge economic losses to potato farmers.

Sweet potato cracking

I. the cause of crack in sweet potato cubes

1. Imbalance of soil nutrient elements: in terms of fertilization, in recent years, many farmers have reduced or even not applied organic fertilizer, only nitrogen, phosphorus and potassium three-element compound fertilizer has been applied, and some elements such as boron have not been made up because of the serious lack of organic fertilizer in the soil. the root of sweet potato is thin and long or abnormal and the skin is rough due to boron deficiency. The application of calcium superphosphate decreased, resulting in a serious shortage of soil calcitonin. Calcium is an important part of the cell wall. Calcium deficiency in soil directly affects the root development of sweet potato, reduces the material accumulation of sweet potato, makes the skin of sweet potato thinner, the elasticity decreases, and the potato is easy to crack.

two。 Imbalance of water supply: due to the influence of adverse weather, the soil moisture is dry and wet, and the soil is suddenly flooded after a long period of drought, resulting in the rapid growth of potato meat, while the growth rate of potato skin is slower than that of potato meat.

3. Disease and pest harm: sweet potato is infected with stem nematode disease, harms potato lumps and causes cracking. Sweet potato stem nematode is mainly transmitted by seed potato and soil, and potato tuber and potato vine will suffer. For example, for soil transmission, nematodes invade from the skin of potato blocks, and the injured potato skins fade first, then turn green, slightly sunken or have small cracks, and the subcutaneous tissue becomes brown and shriveled, and then gradually cracked.

4. The soil is too sandy and sticky, the soil layer is thin, the potato block cover soil is less; the soil is hardened, not loose, and the air permeability is poor; the temperature and humidity change greatly, especially drought and high temperature, sudden low temperature and rainy, it is easy to occur sweet potato block crack phenomenon.

II. Preventive measures for cracks in sweet potato blocks

1. Selecting suitable sandy loam soil to grow sweet potato, over-sand and over-sticking are not suitable for growing sweet potato. Deep ploughing increases the depth of the soil layer, with a tillage depth of 25ml / 30cm to improve soil permeability, enhance the decomposition of soil nutrients and soil water storage capacity. Deep ploughing is the most suitable for deep ploughing before freezing in autumn and winter, so that the soil has a long ripening process. Spring ploughing must be early if there are no conditions. Winter ploughing should be deep, spring ploughing should be early and shallow.

two。 Bottom application of organic fertilizer and topdressing of calcium fertilizer: bottom application of organic fertilizer to supplement the content of soil organic matter. Generally, 3-5 square meters of organic fertilizer are applied at the bottom of each mu. In the period of exuberant growth of sweet potato, calcium deficient plots should be combined with watering or spraying calcium sulfate 20-30 kg per mu before rainfall, which can prevent potato block cracking.

3. After the round sweet potato, due to the high temperature and large evaporation, it is easy to cause insufficient soil moisture, so it should be watered to meet the water needs of sweet potato.

4. Prevention of diseases and insect pests: select disease-resistant varieties, establish disease-free seed land, and cultivate disease-free and strong seedlings. The sweet potatoes were disinfected with warm water of 50 ℃-54 ℃ for 10 minutes. Soak the sweet potato seedlings with 50% phoxim 300 times solution for 30 minutes before planting. Change the crop rotation. The effect of rotation between disease area and peanut is better, and it can be rotated for one year. The rotation time with corn and sesame is longer, 2-3 years is better.