Rye
Established plants will survive temperatures as low as -25°C. Rye has a very deep and well developed root system often reaching to depths of 2m. It withstands adverse conditions better than other cereals.
Due to these properties, rye is an excellent cover crop during the winter months. It will show vegetative activity when temperature moves above 0°C, and can even grow under snow cover. The extensive root mass will reduce soil compaction and secure an efficient nutrient uptake. This reduces the leaching of N and increases the general absorption of nutrients.
Winter Rye is by far the most dominant type. It will rapidly produce a ground cover that protects the soil against the forces of wind and water, thus preventing erosion. To get from the vegetative growth phase to the generative phase, a cold stimulus is necessary. At temperatures from 0 to +5 °C the successful vernalization is reached after 30 to 50 days.
In spring the plants will develop fast, and the density of the rye plants are often high enough to reduce the need for herbicides. Rye varieties are photoperiodic long day plants, though without an absolute requirement for a specific day length.
Pollen and female flowers mature at different times, so rye is a cross pollinator, unlike the self-pollinators wheat and barley. The flowering period is normally May or June. In order to mature, rye requires a heat sum of about 1500 °C. (heat sum = number of growth days x daily mean temperature).
After ripening, rye seeds have very little to no dormancy at all. Harvesting during prolonged rain lead to a risk of germination of the grains within the ear and if so the crop can only be used as a feed grain.
For this reason, mature rye should be harvested as soon as possible in humid weather, and then artificially dried. With more than 15-20% humidity in the grains, a rapid drying is important. Humidity in the storage bins can promote toxin producing fungi.
Spring rye does not require vernalization to induce flowering. Varieties of spring rye in general are less productive than winter rye.