All the Stages of a Corn Seed

R1 Silking

• Silking is the beginning and the most critical stage in the development of the corn or kernel. It occurs around eight and a half to nine weeks after the last stage of vegetative phase which is emergence phase. During this period, silks have emerged from the tip of the ear shoot and can be seen outside the husks. They grow 1 to 1 1/2 inches every day until fertilization has happened. In around 24 hours, pollen grain moves down the silk and fertilize the ovule. The fertilized egg is now a kernel. Kernel is white from outside and clear inside. It generally takes two to three days for all silks on a single ear to emerge and be pollinated. This stage requires most watering and is essential for the proper development of kernel.

R2 Blister

• Blister stage occurs about 10 to14 days after silking (R1stage). At this stage, starch is just beginning to accumulate in the watery endosperm of the kernels and they appear white. Relocation of nutrients from the leaves and stem to the ear begins in this stage. Moisture at this time is around 85 percent.

R3 Milk

• Milk or R3 stage occurs about 18 to 22 days after silking. During this period, rapid grain filling happens and kernels begin to have exterior yellow color. The inner fluid is milky white. The endosperm cell division in each seed is complete, and remaining growth is due to cell expansion and starch accumulation. The kernel has about 80 percent moisture in this period.

R4 Dough

• Dough stage occurs about 24 to 28 days after silking. During this stage top of kernel begins to firm up and there is reduced fluid and increased solids within thus providing a doughy consistency to it. Kernels have accumulated 50 percent of their dry weight and have about 70 percent moisture.

R5 Dent

• This stage is begins 36 days after silking. During this period, all kernels are dented or are denting. Drying kernels have a small, hard, white layer on top. Shortly after denting, a white line (known as the milk line or starch line) can be seen across the kernel. Kernels at this stage have about only 55 percent moisture.

R6 Physiological maturity stage

• This stage occurs after 56 days from silking. During this stage, the plant has reached physiological maturity. All kernels on the ear have attained their maximum dry weight, and the hard starch layer has advanced completely to the cob now; a black or brown layer has formed. At black layer the average kernel moisture is 30 to 35 percent.