SORGHUM  Sorghum bicolor

Sorghum is a crop that originated in Ethiopia .  Sorghum has greater heat and drought tolerance than corn and provides mankind with the same basic necessities that corn does in wetter environment.

 

	Understand how the center of origin of sorghum helps to explain the crop characteristics of sorghum.
	Learn the climatic and edaphic requirements of sorghum and how this influences sorghums distribution
	Understand the advantages sorghum has over corn in hot/dry climates and which plant structures give sorghum this advantage.
	Learn both the positive and negative characteristics of sorghum and how this affects sorghum production

Sorghum is a C-4, short day plant like corn.  Sorghum produces food for people, feed for animals, and is even used as a building material.  Sorghum fits in the same social/economic niche as corn, but is found in hotter and drier places.

The reason sorghum has the advantage over corn in hot/dry places has to do with origins. Corn comes from the humid tropics, sorghum the semi-arid tropics.  To adjust to the drier climate, sorghum has 2 times the roots of corn, can go dormant in a drought, and has better water use efficiency than corn.  Sorghum is best adapted to 17-25 inches of rainfall where corn prefers 20-40 inches.  Sorghum can also continue to respire and photosynthesize to 95 degrees F, where corn shuts down at 87 degrees F.

When planted head to head in corn-adapted land, sorghum will not compete with corn.  But in environments where corn is not well adapted, sorghum out produces corn.  Sorghum is the world's 5th cereal in acreage, after wheat, rice, corn, and barley.

 

1.  Center of diversity - Ethiopia
 
2.  Progenitor - Sorghum verticilliflorum

• African tropical forest grass
• Great variation
• Readily crosses with S. bicolor
• Found in areas where sorghum cultivated
• Yields well

Geographic spread - history
1.  From Ethiopia where domesticated in 3000 BC.  Spread to Arabia 1000-800 BC
 
2.  Later went to India (First century AD) and by track routes to China (3^rd century AD)

4.  To America by slaves

5.  Cultivation after introduction of varieties 1853-1857

6.  Widespread growth - Oklahoma, Texas, of milos 1880s.

7.  800,000 Acres of sorghum (1919-21)

8.  Dwarf sorghum - combine height
 
9.  Mid 1950's - commercial hybrids - derived from milo-kafir cytoplasmic male steriles

1.  Temperature

• Best mean growth 37 degrees C - min 15 degrees C.
• Less cold tolerance but stands heat better

• Short day plant
• Widely adapted -growing season 90-140 days

• Extensive fibrous root system
• Well adapted to 17-25 in rain/year
• Under extreme drought - goes dormant
• Bolliform cells near midrib - folds like butterfly
• Better water use efficiency

 

Crop	kg H2O/kg dry matter
Sorghum	322
Corn	368
Barley	434
Wheat	514

 
• H₂O requirement increases with growth - peaks during flowering, declines
• Can stand wet feet

• Some lines very responsive, some unresponsive to N fertilizers

1.  Yield potential of rice, wheat, maize

2.   Highest field yields 11,000 kg/ha, 246 Bu/A
 
3.  Worldwide - 3-4,000 kg/ha in better conditions; 300-1,000 kg/ha when moisture limiting

5.  Area increasing

6.  Among major cereals - 5th in area sown

7.  Production in some locations (Latin America) increasing dramatically

8.  Leading producers: U. S., India, Nigeria, Argentina, Mexico, Sudan

9.  Grown in all countries except cool N. W. Europe
 

10.  World utilization:  Human food Animal feed Building material Fuel Molasses Brooms Popcorn Wine, beer "Ear roast"

CONCEPT  Where sorghum is the major cereal it does it all.  Similar to the role of corn (maize) in cultures where corn is the precominant crop.

 

Crop	Average Yield (World) kg/ha	Crop	Average Yield (World) kg/ha
Maize	2829	Wheat	1774
Rice	2428	Rye	1683
Barley	2030	Sorghum	1179
Oats	1666	Millets	707

• Droughty soils, summer dry spells
• Crop-animal agriculture allows ready feeding of silage, green chop, grain
• Frequently flooded river bottoms - sorghum better
• Long growing season for maturation

  CONCEPT These characteristics make sorghum a valuable addition to a cropping system.  
Con factors for sorghum production
 
• High humidity - favors disease, grain molds
• Yield depressions with continuous culture
• Grain markets, value
• Need to crush, "cook" grain for maximum benefit
• Tannins
• Prussic acid (cyanide)
• Need grain dryers to store
  CONCEPT These problems limit the use and acceptance of sorghum in much of the developed world.

Sorghum has the yield potential of wheat, rice, and corn.  However, sorghum is usually grown in soils and climates that are too hot and dry for the other cereals.  Sorghum's yields are often low.  Sorghum really carries the ball in many developing countries, especially in Africa and India.  Sorghum is used for practically all mans' needs: food, animal feed, building materials, fuel, molasses, brooms, popcorn, beer, etc.

 

	Compare origin of corn and sorghum and explain how this makes the two crops different.
	What characteristics of sorghum make it do better in hot/dry climates than corn?
	How is sorghum used?  What niche does sorghum fill and why?
	What are some negative crop characteristics of sorghum?