Onion alias onion head, jade onion, onion head, round onion, ball onion, onion head. Onion is a perennial herb of the lily family, genus Allium. Native to western Asia, China and abroad are widely cultivated. It is one of the main vegetables in China. China's onion origin mainly in Fujian, Shandong, Gansu, Inner Mongolia, Xinjiang and other places. Onion for food for the underground parts of the fat bulb (i.e. onion head). In foreign countries it is known as the "queen of vegetables", high nutritional value.

Onion:

Onion's embryonic root will shrink soon after entering the soil, so there is no main root, the root is string-like fibrous roots, born in the base of the shortened stem disk, the root system is weaker, no root hairs, the root system is mainly dense distribution in the topsoil layer of the 20cm, so drought tolerance is weaker, the ability to absorb the ability of fertilizer and water ability is weaker. Root growth temperature is lower than on the ground, the ground temperature of 5 degrees Celsius, the root system began to grow, 10 to 15 degrees Celsius optimal, 24 to 25 degrees Celsius when the growth is slow.