Sorghum (Sorghum bicolor) is one of the most important traditional cereal crops of the hotter and drier regions of the tropics and subtropics. In areas with uncertain and erratic rainfall, sorghum is a preferred crop.
Sorghum has many attributes that make it withstand drought conditions. These are:
it has an extensive root system than other cereal crops
has less leaf surface area than maize and the leaves are covered with wax and this helps reduce water loss through evapotranspiration
can stay dormant when conditions are not favourable
There are two different types of sorghum. One type with tropical adaptation for high rainfall areas (1000-1400mm). These sorghums should be semi- to photoperiod sensitive and must possess high resistance to soil acidity and anthracnose. The second group should be sub-tropical in adaptation (300 – 700mm). These varieties must be photo-period insensitive with good levels of resistance to moisture-stress, heat and several diseases i.e. leaf blight, sooty stripe, downy mildew.
Both open pollinated varieties and commercial hybrids are now available at Zambia Seed Company premises and outlets. Hybrids give higher and more stable yields across seasons, locations and management levels, as they can face adverse growing conditions better than open pollinated varieties.
Traditional varieties of sorghum require a long growing season, have low yield potential, and are tall and non-responsive to improved management. Improved sorghums, however, are high yielding, input responsive, and far more resistant to drought.
Several varieties that are high yielding (4.5 – 8 tons/ha) and ideal for various end-uses (Forage, food and brewing types) have been released to the different categories of farmers. The maturity of these varieties ranges from 110 – 130 days.
This is an early, short, white grain variety with tan plants and with excellent milling properties. It is widely adapted to low rainfall areas with good resistance to most diseases in Zambia, except for anthracnose. Height: 140-170 cm; Maturity: 100-115 days. High yield potential 3 – 5 tons/ha. The variety has been evaluated in the neighbouring countries with successful results.
A medium – tall, medium-late, tan plants, white grain variety with juicy and sweet stalks for dual purposes – grain and forage; it is well adapted to all three agro-climatic regions of Zambia and moderately resistant to diseases. Height: 210-230 cm; maturity: 110-120 days. Potential yield: 3 – 6 tons/ha. This variety also does well in the neighbouring countries.
A widely adapted, white-grained variety, excellent grain quality and good levels of resistance to all diseases – an improvement over Kuyuma variety for the drier areas. Potential yield 3 – 5 tons/ha. Height: 140 – 160; maturity 100 – 112 days.
ZSV – 16
The variety has white-grains and is open-pollinated, with short plant height, juicy stems and an enhanced stay-green trait. The stems are not as sweet as Sima. Plant height: 140-200cm; Maturity: 115 – 120 days; Potential yield: 5-6 tons/ha. The stay green trait in sorghum is associated with resistance to several diseases as well as to termites, lodging and to grain moulds. This is due to plants remaining green and active even after physiological maturity of grain.
ZSV – 17
This is a short white grain sorghum variety with tan plant. It has long semi-compact cylindrical panicles with medium-size hard-grain. The variety is juicy and remains green (stay Green) even after physiological maturity conferring resistance to a lot of diseases and lodging. Plant height: 100 – 140cm; Maturity: 112 – 118 days; Potential grain yield: 4 – 5 tons/ha.
ZSV – 36R
ZSV 36 R is an early maturing open pollinated variety and of medium height with red grains. It is suitable for food (nshima/ugali) and brewing. It is widely adapted to low rainfall areas. Height: 130 – 170cm; Maturity: 110 – 120days. Potential grain yield 2 – 5 tons/ha. Yield losses due to bird damage are minimal. Birds shun the grain because of the bitter tannins in the seed coat.
Height: 210-240 cm; Maturity: 110-120 days. Widely adapted in Zambia and the region, high potential, brown grain hybrid with moderate levels of tannin and good resistance to all diseases of Zambia except for Downy mildew. 4 – 8 tons/ha. Recommended for the entire country.
Height: 210-240 cm; Maturity: 110 – 116 days. A widely adapted in Zambia and the neighbouring countries. High yield potential and brown grain hybrid with higher tannin content and excellent malting properties; resistant to most diseases. 5 – 10 tons/ha. This hybrid is recommended for the entire country and some neighbouring countries as well.
A tan, early, medium-height, white grain hybrid with good grain quality and high yielding; widely adapted to dry areas, resistant to most diseases except for anthracnose. Potential grain yield 3 – 6 tons/ha.
This is a short hybrid (130 – 140cm) that matures in 100 – 115 days. It is red seeded with a thin pericarp without a testa. Not easily attacked by birds. Fairly resistant to downy mildew, leaf blight and gray leaf spot. Not easily attacked by birds. Exhibits stay green trait. Potential yield of 4 – 6 tons per hectare.
Soils – Water and Soil Requirements
Sorghum does well in semi-arid tropics. It is tolerant to harsh weather conditions better than other cereal crops. It grows well at temperatures above 10OC. Some sorghum varieties are sensitive to day length, especially the local types.
The soil pH should not be allowed to fall below 4.5 on sandy soils and 4.7 on clay soils. Sorghum is adapted to a wide range of soil types but sandy loam soils with good drainage and with organic matter are the best. The crop can also withstand some water logging giving desirable results.
Moisture conservation is critical in areas where sorghum is grown. To prevent soil evaporation, the soil surface must be tilled with a harrow to form a fine surface. Weeds use a large quantity of water and should be removed. In areas with sandy soils it is advisable to use a ripper instead of a plough. Minimum tillage practices should be employed to conserve water and the soil structure.