Crop News

Posted: June 7, 2019

Vegetative stages of corn

Tiffany Hanson

VE-V1:  VE occurs when the coleoptile pushes through the soil surface.  The growing point (stem apex) is 1 to 1.5 inches below the surface.  The seminal roots are growing out from the seed, although they do not do much work yet.  Nodal roots begin to grow.  The first leaf that develops at the first collar and is usually more rounded at the tip than the rest.  Cell elongation has not begun yet, so the growing point which is below ground give the plant the energy to grow the first leaf.

V2:  The 2^nd collar and leaf develop.  The growing point is still below the soil surface and energy for growth still comes from the seed storage

V3-V4:  The growing point is still below the soil surface.  Root hairs start growing off of the nodal roots and seminal roots stop growing.  Root and ear shoots start to be initiated.

V5:  The number of potential ear and leaf shoots has been determined.  The number of kernel rows and columns is being determined.  The growing point is still below the surface.

V6:  The growing point and tassel rise above the soil surface.  The stalk begins to elongate.  The nodal root system grows from the 3 to 4 lowest stalk nodes. Some ear shoots or tillers are visible.

V7-V8:  Rapid growth stages

V9:  Tassel is developing rapidly but is not visible yet.  The number of kernel rows has been determined.  Many nodes have an ear shoot.  Stalks lengthen and internodes grow.

V10:  The time between leaf stages shortens.

V11-V12:  Nutrients and water are in high demand to meet nutrient needs.  All leaves are full sized- about half are exposed to sunlight.  Brace roots are developing.  The tassel is almost full size but not visible yet.  Moisture and nutrient deficiencies can have impacts on yield.

V13+:  Brace roots grow from the nodes above the soil surface to help support the plant and take in water and nutrients during the reproductive stages.

VT:  Tasseling.  Arrives when the last branch of the tassel is completely visible.  Happens about 2-3 days before silk emergence.  Pollen shed begins.  Lasts about one week but can lengthen with drought stress.

R1:  Silking.  Begins when silk is visible outside of the husks.  One of the most critical stages when determining yield potential (how many kernels will be pollinized).  K uptake complete, N and P uptake occurring rapidly. 

R2:  Blister.  The embryo (kernel) is still developing.  The cob is close to full size.  Silks are darkening and beginning to dry out. Starch has just begun to accumulate in the watery endosperm. Kernels are beginning to accumulate dry matter. Seed-fill is beginning.  Stress can affect yield potential and kernel abortion- especially drought.

R3:  Milk.  Kernels contain about 80% moisture.  Kernels are yellow and clear fluid turns milky white as starch accumulates.  The embryo is growing rapidly.  The effects of stress are not as severe after this stage, but can still result in shallow kernels, stalk cannibalization, or lodging.  Silks are brown and dry or becoming dry.

R4:  Dough.  Kernels contain about 70% moisture.  Continued starch accumulation in the endosperm causes the milky inner fluid to thicken to a pasty consistency. Usually 4 embryonic leaves have formed as the embryo has grown dramatically from the R3 stage.  The fifth (last) embryonic leaf and the lateral seminal roots have formed.  Stress can produce unfilled or shallow kernels and "chaffy" ears.

R5:  Dent.  Kernels contain about 55% moisture.  The kernels are drying down from the top, where a small hard layer of starch is forming. 

R6:  Black layer/maturity:  Kernels have attained their maximum dry weight or dry matter accumulation. The hard starch layer has advanced completely to the cob. A black or brown abscission layer is formed.  Dry weight is at 30 to 35% moisture.  Total yield has been determined; frost has no impact on yield.