(1) Definition of Onion-type Garlic Onion-type Garlic is garlic with onion-like bulb structure formed by abnormal physiological metamorphosis of garlic bulb. Its bulb is mainly composed of thick leaf sheath base and thickened outer scales of scale buds. No fleshy scales or extremely underdeveloped fleshy scales (such as soybean) can form or differentiate garlic bulbs, and it has no edible value. After the bulb is exposed to the sun, the hypertrophic bracts and scales are dehydrated into a film shape, and the whole bulb feels soft and shrinks when pinched by hand, so it is vividly called "bread garlic" or "gas garlic".

(2) Reasons for the Formation of Onion Garlic According to Liu Shiqi's preliminary research, the formation of Onion Garlic is influenced by soil, moisture, fertilization and varieties. The formation of onion garlic can be induced by soil viscosity, high groundwater level, high long-term soil water content, excessive partial application of nitrogen fertilizer and phosphorus fertilizer. In addition, the factors inducing secondary growth can also promote the formation of onion garlic. The specific points are as follows:

① Improper selection of garlic seeds. Heredity is the main factor that causes this situation, and improper varieties are easy to form onion garlic. Therefore, garlic varieties suitable for local cultivation should be selected, and garlic planting should have large garlic head and garlic cloves. Garlic cloves are obviously split and so on.

② Improper storage conditions of garlic seeds. If garlic seeds are stored at14 ~16℃ or 0 ~ 5℃ and the air relative humidity is 75% ~100% 30 days before sowing, low temperature and high humidity will increase the secondary growth and the yield of bread garlic.

③ Inappropriate sowing date. Garlic petals are formed by the development of lateral buds in the axils of the leaves on the bulb disc, and are influenced by temperature, light, nutrients and so on. Blind early sowing is also one of the reasons for the secondary growth and bread garlic.

④ Improper cultivation and management measures. Garlic has strong adaptability, but it is very sensitive to environmental conditions, nutrients and moisture during the growth process. Partial application of nitrogen fertilizer in the management process will cause secondary growth and bread garlic.

(3) Preventive measures for onion garlic

① Select suitable planting soil. In order to control the abnormal growth of garlic, loam or light clay loam should be selected.

② Early sowing at suitable time. According to the research results and production practice for many years, it is confirmed that the suitable sowing date for Cangshan garlic and jinxiang garlic is from September 25th to1October 10.

③ Choose suitable garlic. Garlic should be planted in the same year, stored in natural conditions, and the size of garlic cloves should be 4 ~ 6 grams.

④ Rational application of base fertilizer. By applying base fertilizer, the soil nutrient content reached available nitrogen 1 10.53 mg/kg, available phosphorus 60.22 mg/kg, available potassium 136.77 mg/kg, available sulfur 8.4 1 mg/kg and available boron 0.85 mg/kg respectively.

⑤ Reasonable close planting. The number of 2 plants per 667m in jinxiang garlic should be kept at about 25,000, that of Cangshan garlic at about 29,000, and that of bolting garlic at 42,000-45,000.

⑥ timely irrigate green water and topdressing green fertilizer. Water and fertilize from March 28th to April 5th.