(1) Botanical characteristics: Barley belongs to the genus Panicum. Fibrous roots, buried as deep as 1m, are mainly distributed in the soil layer of 30 ~ 50 cm. The stem is stout, smooth and hairless, erect, with 4-7 nodes, and the plant height is 80- 160 cm. Leaf sheaths loosely attached to stems, mostly glabrous or pilose at base; There are two lanceolate auricles on both sides; Ligule membrane, length1~ 2mm; The leaves are flat, 9 ~ 20cm long and 6 ~ 20mm wide. The spike is terminal, 3 ~ 8 cm long, 0/0 ~/0/5 mm wide, with dense spikelets, and 3 spikelets are attached to each node of the spike axis, all of which are fully developed; Spikelets sessile, containing 1 floret, long 10 ~ 15 mm; Glumes are lanceolate, pubescent outside, and the top awn is 8 ~ 16 mm long; The lemma is oblong, long 10 ~ 1 1 mm, hairless on the back, awn-shaped at the top, long10 ~/5 mm, and pointed at the top. When the clove is ripe, it is attached to barnyard grass and difficult to separate. Cell chromosome: 2n= 14.

(2) Biological characteristics: The lowest temperature of barley seed germination is 0 ~ 3℃, the highest temperature is 30 ~ 35℃, and the optimum temperature is 18 ~ 25℃. Under other suitable conditions, barley seeds can germinate when they absorb enough water equivalent to about 50% of their own weight. Under suitable conditions, it takes 1 ~ 2 days for seeds to germinate by water absorption, and it takes about 3 ~ 7 days from sowing to emergence. Tillering began when the main stem of barley formed the third and fourth leaves, and stopped around jointing stage. Under normal circumstances, spring barley can produce more than 4 tillers, and winter barley can produce as many as 16 tillers. Under the conditions of deep tillage, rich fertilizer efficiency and large nutrient area, each winter barley plant can produce more than 180 effective tillers. The differentiation of stem nodes of barley plants has been completed, but their elongation does not begin until the light stage is completed. With the elongation of the first internode, the second internode begins to elongate; About 5 ~ 10d after the first internode elongation stops, the second internode elongation ends. Followed by elongation between the third and fourth joints. Due to the elongation of the second internode, especially the fourth internode, the ear protrudes from the leaf sheath. This period needs more water and fertilizer, which can increase the number of grains per spike and fatten wheat grains. Flowering immediately after heading. 6-8 am and 3-5 pm are two busy hours every day. A plant blooms for 8-9 days. After 7 days of flowering and fertilization, barley seeds will reach their proper length. After that, the dry matter of seeds will gradually increase and the water content will gradually decrease. On the 24th day, the weight of seeds will increase to the highest, and then they will mature due to the disappearance of water content. It takes about 1 month from heading to maturity. Barley seeds are easy to lose ears and grains when they are ripe, and it is appropriate to harvest them when wax is ripe.

Barley is not strict about temperature. Spring barley seedlings can tolerate the low temperature of 3 ~ 4℃ or even -6 ~-9℃ without being hurt. Some spring barley varieties can tolerate the low temperature of-10 ~- 12℃, but they will suffer when the temperature is-1 ~-2.5℃ during flowering. Winter barley has stronger cold tolerance than spring barley, and it is suitable to grow winter barley in areas with winter temperature of 5 ~ 10℃. Its tillering can save energy and can withstand-10 ~- 12℃ or lower temperature. Barley is suitable for loam with medium viscosity and neutral soil acidity is suitable; It has strong resistance to saline-alkali soil, and the soil can still grow well when the salt content is 0. 1% ~ 0.2%. But it is sensitive to acidic soil, and the seedlings die when the pH value is 3.35. However, after heading, the sensitivity to acidity weakened.

The water requirement of barley is less at seedling stage, the most at tillering to heading stage, and gradually decreases after heading. In the growing period, if there is too much rain and insufficient sunshine, the stems and leaves will grow in vain and easily lodging, causing diseases. Too much rain after heading affects fertilization and maturity, resulting in reduced production.