Environmental Engineering Reference
In-Depth Information
sorghum bicolor (l.) Moench
Kingdom
Plantae —Plants
Subkingdom
Tracheobionta —Vascular plants
Superdivision
Spermatophyta —Seed plants
Division
Magnoliophyta —Flowering plants
Class
Liliopsida —Monocotyledons
Subclass
Commelinidae
Order
Cyperales
Family
Poaceae —Grass family
Genus
Sorghum Moench—sorghum
Species
Sorghum bicolor (L.) Moench—sorghum
19.2.3 p lant d EScription
Sorghum is a summer annual that is coarse and erect with much variability in growth characteristics.
The culms are solid or sometimes with spaces in the pith, 0.6-5 m tall (Figure 19.1), depending on
the variety and growing conditions. It is 5 to over 45 mm in diameter (Figure 19.2) and is either dry
at maturity or has a sweet, insipid juice.
Vanderlip (1993) has defined the growth of the sorghum plant from emergence (stage 0) to
physiological maturity (stage 9). The timing of various stages of development and the condition of
the plant at each stage can be affected by soil fertility, insect or disease damage, water stress, plant
population, and weed competition. As the total number of leaves increases and gives rise to a greater
leaf area index, the growth rate of the sorghum plant increases. Leaves arise alternately at nodes
along the stem and can be as much as 1 m long and 10- to 15-cm wide (House et al. 1995). Most
leaf growth occurs between stages 3 and 5, when the upper eight to ten leaves develop (Vanderlip
1993). Leaves can number from 7 to 18 or more, and the total number is determined by the length
of the vegetative period (Bennett et al. 1990). The flag leaf is the first leaf below the panicle and it
holds the boot before extension. Flowering begins at the tip of the panicle and continues to the base,
taking 4-5 days. Although primarily known as a self-pollinating crop, 2-20% cross-pollination can
FIGure 19.1 (see color insert) Sweet sorghum plants reach 450 cm in September 2007 at Lincoln, NE.
The plants were rainfed and were grown in rotation with soybean.
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