PLANTING
Soil: rye grows well in a very wide range of soils, including poorly drained and
infertile, sandy soils. Tolerant of acid soils. Relatively resistant to lodging, even
under high Nitrogen conditions. Responds well to fertiliser; may need N and P in
sandy soils.
Seed rate: 40–50 kg/ha on dryland, 55–70 kg/ha on irrigated land. Up to 200 kg/ha
may be used, on fertile soils in Northern Europe for example. Higher rates are used
for spring sown types.
Seed spacing: 17.5–38 cm between rows.
Depth: 1.2–5 cm (4–5 cm in dry, sandy soils).
Rotation: Ideally rye follows a summer fallow or a root crop. It should never follow
an oat crop. Because the seed head shatters readily volunteer plants often appear in
the next crop, which may be a problem if Ergot is present—see “Diseases”, below.
GROWTH CONDITIONS
Day length: long-day.
Growth period: 180–220 days. Rye should be harvested when the seed is at the
“wax-ripe” stage because much seed is lost from shattering if the seed heads are left
to full maturity.
Temperature: winter sown types require vernalisation (1Fg). Rye is the most
winter hardy of all the cereals, and needs only about 15–20C for its seed to mature.
Rainfall: relatively drought resistant, though shattering increases if drought occurs
when the seed heads are maturing. Optimum is 600–1000 mm a year, while it can
grow with between 400 and 2000 mm. Often grown under irrigation, especially in
South Africa and America; irrigation at flowering time is especially beneficial.
Altitude: up to 4000 m.
Pests: the same as for wheat and barley.
Diseases: rye is resistant to the Smut diseases. The most serious disease is Ergot
(Claviceps purpurea) a fungus which produces large, misshapen purple growths in
place of the seed. These ergots contain the alkaloid ergotoxine, poisonous to both
man and animals. Control is by the use of clean seed. To remove ergots from a seed
sample, the whole sample can be immersed in a 20% salt solution; the seed falls to
the bottom, the ergots float to the surface and are skimmed off. The seed is then
rinsed in clean water and dried.
YIELD
The global average for rye in 2004 was estimated by FAO at 2.5 MT/ha, ranging
from an average of 6.7 MT/ha in Switzerland to 310 kg/ha in South Africa.
2–3000 kg/ha of straw is a good yield in optimum conditions. To reduce loss of
seed from shattering, harvesting is often done at dawn and dusk.
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134 TONY WINCH
Premature harvesting leads to low quality, low germination seed. Delayed
harvesting can lead to large losses of seed from shattering.