P.M. Anderson, E.A. Oelke, and S.R. Simmons
Barley ( Hordeum vulgare L. ) originated in the Eastern Mediterranean region. Barley can be distinguished by differences in head type and growth habits. In a six-rowed barley, three kernels are formed at each node of the head while in a two-rowed type, only a single kernel forms at each node ( figure 1 ).
Barley is also classed by its requirement for cold temperatures. Winter barley must be planted so that seedlings will be exposed to cold (vernalized), which enables it to later produce heads and grain normally. Winter barley is usually sown in the fall for exposure to low temperatures during the winter and then development is completed during the following spring and summer. Spring barley does not require exposure to winter temperatures and can be sown in spring. Winter types usually mature somewhat earlier than spring types. Growth and development of the six-rowed spring barley commonly grown in Minnesota will be considered here. Figure 2 shows major developmental stages in spring barley with the approximate time and heat units required to reach each stage. Differences in maturity exist among varieties.
Barley production has become more intense and complex in recent years. Crop managers must understand barley development and be able to recognize growth stages because of the increased use of growth stage sensitive production inputs such as chemical fertilizers, pesticides, and growth regulators.