Rye is a long-day plant, i.e. it requires increasing day length to induce flowering. It shows a shorter growth period than other winter and spring cereals. Maturation date of rye varies according to soil moisture, but vegetative growth stops once reproduction begins. In general, rye matures earlier than oat. At seed set, 15-20 % of the photosynthetic area is provided by leaf blades, which are much lower than for maize, wheat, and oat. Stems and sheaths have lower rates of photosynthesis and export of assimilates than do leaves. For winter rye, photosynthetic area decreases rapidly after seed setting, and does not achieve a plateau near the maximum, as seen with other grains.