Silking is one of the most critical yield development windows in a corn crop's life cycle. A corn plant's reproductive cycle has a lot more to it than what meets the eye. Silk growth, pollen shed and fertilization are all key phases we’ll address to help you understand the reproductive process of a corn plant.
How Does Corn Reproduce?Corn contains both a male part, known as the tassel, and a female part, known as an ear. As a monoecious plant, corn reproduces sexually, using the following three phases:
- Silk Growth
- Pollen Shed
- Fertilization
Silk GrowthAlthough tassels and silk can emerge at the same time, it is common for tassels to emerge first, followed by the silk 2 to 3 days later. Silks can grow up to 1.5” per day, starting from the base of the ear, and will likely slow to around 0.5” per day. Complete silk emergence from the ear will occur over a 4- to 8-day span. Silks continue to lengthen or grow for up to 10 days after they emerge from the husks, or until pollination occurs. When silks are clipped from insect feeding, they will re-grow until a pollen grain lands on them.
Pollen ShedIndividual tassels produce approximately 6,000 anthers, which contain pollen grains that shed through anther pores. The central spike is first to shed pollen, with the bottom lateral branches going last. All of the pollen from one anther can shed in as few as 3 minutes, while a tassel can shed pollen for 5 to 6 days. It usually takes an entire cornfield 10 to 14 days to shed pollen because of plant variability within the field.
Since temperatures above 86
o F greatly slow pollen shed, this process typically takes place in the morning or late afternoon. When the anther is covered by dew, the pollen cannot be shed. When temperatures are high, pollen can rapidly degrade since the pollen grains are composed of roughly 60% water by weight, and viability greatly decreases if moisture content falls below 40%.
A pollen grain is one of the largest particles in the air and falls at a rate of 1’/second. In 15 mph winds, a pollen grain can travel up to a 1/2 mile in just minutes. But most pollen falls within 40 to 50 feet of the plant from which it shed and remains viable for 1 to 2 hours. Within a field, an estimated 97% of pollination is done by neighboring plants instead of self-pollination.
FertilizationFertilization occurs when a pollen grain lands anywhere on the silk. Silks have small, sticky hairs to capture pollen grains that do not wash off. It takes mere minutes for pollen grain to germinate after landing on the silk. After germination, a pollen tube will grow down the silk channel to reach the ovule, or eventual kernel. The pollen tube contains the male genetic material to fertilize the female ovule.
While only 400 to 600 kernels per ear are typically harvested, there can be up to 1,000 ovules per ear. Once the pollen grain lands on the silk, it typically takes 24 hours for fertilization to take place. Within 1 day of fertilization, the silk detaches from the ovule and falls off, and is a sign of successful fertilization.
Contact your
Golden Harvest Seed Advisor with questions or for additional agronomic insights.
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