Selection, Handling, and Storage of Sorghum for Propagation in Africa: Best Practices

Selection, Handling, and Storage of Sorghum for Propagation Purposes in Africa

Introduction

Sorghum is indigenous to Africa and has been the main staple crop on the continent for centuries. However, the spread of maize, especially hybrid cultivars, has shifted this, dominating the market and becoming the preferred cash crop from the mid-1950s to the 1970s, primarily due to its higher yield potential than sorghum and other millet varieties. Maize hybrids yield, on average, 5 to 10 tons per hectare, whereas sorghum hybrids typically yield 2 to 5 tons per hectare under excellent management.

Sorghum, however, despite coming second after maize, has a higher tolerance to drought and high temperatures than wheat, rice, maize, and other cereals grown in Africa. With abiotic stresses becoming increasingly common challenges faced by farmers today due to climate change, a resurgence in the cultivation of both sorghum and other members of the millet family is happening across drought-challenged parts of Africa.

A key aspect in the cultivation and production of sorghum is the propagation techniques and, before that, the selection, storage, and handling of what will be used as seed.

Selection of seeds for planting sorghum

Before a farmer chooses propagation material to plant the crop, he/she must first select a variety with characteristics suitable to the target market, use, and adaptive to the local environmental conditions and agricultural systems. There are open-pollinated, hybrid varieties, early, medium, late maturing, tall, medium height, semi-dwarf, dwarf, sweet, non-bitter, bitter, less prone to bird damage, large, medium, and small-headed, amongst many other characteristics of hundreds of cultivars grown not only in Africa but all over the world.

Seed Propagation

This is the most common method for propagating sorghum. Seeds are sown directly into the soil, either by broadcasting or by planting in rows. Sorghum seeds have a tough seed coating and are generally sown at 2-5 cm depth. Proper seed rate (around 40 kg/ha) and spacing are essential for achieving optimal plant density and yield. Thinning is a key follow-up practice (in the case of planting with broadcasing) to obtain the desired plant population of 40 to 70,000 plants per hectare, depending on variety and agroclimatic conditions.

Vegetative Propagation

While less common than seed propagation, some sorghum varieties can be propagated vegetatively. This involves using parts of the plant other than seeds, such as cuttings or tillers, to propagate new plants. This method is not widely practiced in comparison to seed propagation but may be used in specific situations, such as for small-scale crop production or for certain varieties.

Harvest and Post-Harvest Handling of Sorghum

When is the best moment to harvest sorghum?

Harvest sorghum seeds when they are mature and dry. Avoid harvesting when seeds are too wet or immature, as this can reduce germination rates and seed quality.

Cleaning the sorghum seeds

Remove debris, chaff, and other impurities using impurities from the seeds using appropriate seed-cleaning equipment. This helps improve seed purity and reduce the risk of contamination.

Drying

Dry seeds to a moisture content suitable for storage (usually around 10-12 degrees centigrade). Proper drying prevents mold growth and ensures seed longevity.

Threshing

Separate seeds from plant material (panicle) using threshing equipment. Care should be taken to avoid damaging the seeds during this process.

Grading

Grade Seeds based on size, weight and quality parameters to ensure uniformity. This helps in achieving consistent germination and plant establishment.

Storage of sorghum seeds for propagation

Store sorghum seeds in clean, dry, and breathable containers such as cloth or paper bags or sealed containers that allow air circulation. Avoid storing seeds in plastic bags or airtight containers, as they can retain moisture.

Temperature

To maintain viability, store seeds in a cool and dry environment. Ideally, temperatures should be around 10-15 degrees centigrade. Avoid storing seeds in areas prone to temperature fluctuations or direct sunlight.

Relative Humidity

Maintain low relative humidity (RH) levels to prevent seed deterioration. RH levels below 50% are recommended for long-term storage.

Ventilation

Ensure adequate ventilation to prevent moisture buildup around the seeds. This helps maintain seed quality and prevent the growth of mold.

Monitoring

Monitor stored seeds regularly for signs of deterioration, such as mold discoloration or unusual odors. Rotate seeds periodically to ensure even air circulation and reduce the risk of pathogen infestation.

By following these seed handling and storage methods, sorghum can be effectively preserved, maintaining its viability and ensuring successful propagation in subsequent planting seasons.

Further reading

Tags: harvest sorghum

Wilhelm Hesse

Experienced farmer and Agronomist

Verified

With 20 plus years farming experience in Zambia, ranging from the production of Commerical Arable crops such wheat, maize and soya beans to providing small scale farmers Agriculture inputs plus technical advice on how best to improve their yields. Wilhelm Hesse has experience in the marketing of Agricultural commodities (both inputs and grains), aware of the challenges farmers face with regard to uncertain market prices and changes to Govt policies on cross border trade that can greatly impact the long term sustainable agricultural production of various crops. A strong believer in the need for farmers at all levels to embark on value addition, the processing of their farm produce as key to long term economic sustainability of farming in Zambia and Africa as a whole.

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