23 | 03 | 2018


Seed Production - Page 2 PDF Print E-mail
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Seed Production
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Sowing density

Most producers use 1-1.5 kg seed per ha with the aim of getting 3-7 plants per 300 mm in a row. A sowing density of 300 g/ha has, however, been used with great success.

Soil fertility

Fertilisation will mainly depend on the fertility of the soil and the soil analysis. Small quantities of nitrogen and phosphate (15-20 kg/ha) can be applied at or before planting time to encourage growth and development of the young plants, which are not yet at a stage where they can fix sufficient N for themselves.

This is recommended only for lucerne intended for seed production, with a limited lifespan, not for hay or grazing. Most hair roots occur in the upper 15-30 cm of soil, and these are responsible for 85% of the nutrient uptake of the plant. Foliar feeding has a relatively small influence on seed production.


The land must be surrounded by an isolation area which:

  • If it is intended to produce basic seed, must be at least 200 m wide where the area intended for production is 2 ha or less, and at least 100 m wide where the area intended is more than 2 ha, and
  • If it is intended to produce certified seed, must be at least 100 m wide where the area intended for production is 2 ha or less, and at least 50 m wide where the intended area is more than 2 ha

Such an isolation area must be free of any plants of any lucerne cultivar or any species of Medicago which flowers at the same time as the plants on the piece of land concerned, unless:

In the case of planned production of basic seed, these plants have been established from breeders seed of the same cultivar, and

In the case of planned production of certified seed, these plants have been established from basic seed of the same cultivar.

Management of Established Stands

  • Irrigation

Whether lucerne intended for seed production should be irrigated is determined by soil texture and depth, rainfall, evaporation, temperature, length of growing period and cultivation practices. The highest production is obtained when irrigation practices prevent stress and encourage slow but sustained growth throughout the growing period without excessive stimulation of vegetative growth.

There must be sufficient water through the spring and summer to prevent stress while the flowers are being pollinated and the seed is ripening.

The seed producer must know the water-holding capacity of his soil and its fertility potential.

Heavy soil with a good water-holding capacity will give a good seed yield with a single irrigation just before flowering, while lighter soil will need a second irrigation during flowering.

The flowering stage is critical and it is here that moisture can determine the harvest.

Factors such as pollination, abortion of flowers and seed weight are directly linked to correct irrigation management.

Lucerne plants draw their water from a soil depth of 1.2 m, but the best results in seed production are obtained when water absorption up to 0.5 m is well controlled.

Overhead irrigation can be used successfully in seed production, especially on sandy soil where specific volumes of water must be given.

Seed producers must irrigate lucerne till before flowering, and again after pollination is complete. If used during flowering time, overhead irrigation can so reduce pollination that losses of up to 15% may result.

After seed has set there is need to guard against too high a moisture content in the air, which  may result in seed damage. Once seed is nearly ripe, irrigation should be completely stopped.

Because there may be more than one cycle of flowering and seed formation, it is best to use soil that can provide sufficient water for an entire growing season.

  • Weed control

Weeds reduce the stand and the yield, complicate harvesting, increase cost of cleaning and may contaminate successive crops.

It is simpler to control weeds when lucerne is still at the seedling stage.

The presence of weeds may result in downgrading and consequent financial loss. The most important weeds to note are dodder (Cuscuta), tongblaar (Plantago), wild oats (Avena), ryegrass (Lolium), hondebos (Chenopodium), misbredie (Amaranthus), kiesieblaar (Malva), predikantsluis (Bromus) and stinkblaar (Datura).

  • Insect control

The most common insects found on lucerne are the lucerne caterpillar, the American bollworm, sand mite, earth flea and various types of aphids.

  • Pollination

Good pollination comes before a good harvest.

Honey bees are the only insects in South Africa which can successfully pollinate the lucerne flower with its trigger mechanism.

Only about 2% of pollination is the accidental result of other insects.

The timing of placement of the hives in the lands is very important because early placement may result in the bees searching for other sources of food. Too late, and many flowers will wither before they can be visited.

After the lucerne is cut in the spring, the regrowth will begin flowering within 30-40 days, depending on cultivar.


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