- Intermediate (Alternate or Facultative) Wheat
They differ from the winter wheats in that they do not need low temperatures in
order to flower. They differ from spring wheats in that they do not normally develop
during the short, cold winter days. Some varieties will only grow well when sown in
the autumn.
PLANTING
Propagation: by seed. Seed size varies from about 20,000 and 53,000 seeds per kg.
Germination: Optimum temperature is 20–28C, minimum 2–4 C. Seedlings
normally emerge in 5–6 days. Dormancy is short, like other cereals, and is rarely a
problem.
Soil: Wheat grows best in fertile, medium-heavy textured soils that are well drained
and have a good lime content. The plants are prone to lodging; for this reason, and
(60–90 cm tall) or “semi-dwarf ” (90–120 cm tall) types.
Fertiliser: This is a large and complicated subject. Very basically, in general
Nitrogen should be applied at planting time in soils known to be deficient in this
element, and an additional top dressing applied if adequate rainfall is likely and if
the crop appears to be in need. Older, taller varieties can only utilise about 60 kg/ha
of Nitrogen; modern, shorter varieties can utilise almost three times this amount.
Applications of P and K should be based on soil tests. Winter wheat in the UK
receives on average 200:75:120 NPK.
Seed rate: 25–250 kg/ha, average about 65 kg/ha. Not very critical as wheat plants
compensate well, producing either more or less tillers according to the plant
population. Rules of thumb: lower seed rates in low rainfall regions, in clean, weed-
free fields, when planted early and for autumn sown winter wheats; higher seed rates
in higher rainfall regions, in weedy fields, when planted later in the season and for
spring wheats.
Seed spacing: a controversial subject. 15–20 cm between rows, to give a plant
population of 200–400 plants/m^2. In good growing conditions, and when sown early,
wheat plants compensate for low plant populations by producing many tillers, so
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plants are easily overcome by weeds.
Depth: 2.5–5 cm is normal. If sown into very dry soil it is often planted 8–10 cm
deep. In theory this is a good idea, to ensure that the seed only germinates after
adequate rainfall, but in practice trials have shown that 6–8 cm is the maximum for
even the driest soils. Very deep sown wheat also produces fewer tillers.
Intercropping: wheat almost always grows better when in pure stand. Nevertheless,
in India for example it is often intercropped with other crops such as barley, linseed,
mung beans and mustard. Intercropping wheat with legumes may be justified in
some soils low in Nitrogen and where fertiliser is unavailable or prohibitively
expensive.
Weeds: wheat does not compete well with weeds, and also it is difficult to hand-pull
or hoe weeds in the growing crop, so where herbicides are not available the seedbed
should be cleared of all weeds and their seed as much as possible.
Rotation: a crop of wheat that is cultivated the season after the crops listed below
may be expected to perform in the following ways:
Sorghum—wheat yields less than when it is in a highly managed wheat monoculture.
°°
due to the declining value of wheat straw, plant breeders tend to produce “dwarf ”
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150–200 plants/m may be enough. In poor growing conditions widely spaced