Presentation on theme: "Corn growth & development. Growth Stages of Corn."— Presentation transcript:
Corn growth & development
Growth Stages of Corn
Corn Growth Stages & Development 1.Typical corn plants develop 20 to 21 total leaves 2.silk about 65 days after emergence 3.mature around 125 days after emergence
C oleoptile reaches the soil surface and exposure to sunlight causes elongation of the coleoptile and mesocotyl to stop. Embryonic leaves rapidly develop and grow through the coleoptilar tip. Seminal root growth begins to slow and nodal roots are initiated at the crown.. VE - Emergence
Lowermost leaf (short with rounded tip) has a visible leaf collar. Nodal roots begin elongation V1 - First leaf collar
The growing point remains below the soil surface as little stalk elongation has occurred. Lateral roots begin to grow from the nodal roots and growth of the seminal root system has ceased. All leaves and ear shoots that the plant will produce are initiated at this stage. V3 - Third leaf collar
V5 & V6 V5: At this stage the uppermost ear and tassel is initiated followed by kernel row number determination. The growing point nears the soil surface as stalk internode elongation begins. V6: The tassel/growing point is now above the soil surface making plants increasingly vulnerable to above-ground damage. Ear shoot initiation has begun.
During the V7 and V8 growth stages the rapid growth phase and kernel row determination begins. Senescence of lower leaves may occur if plant is stressed, but must still be counted when staging plants. V7 - Seven leaf collar
At the V9 and V10 growth stages the stalk is in a rapid growth phase accumulating dry matter as well as nutrients. The tassel has begun growing rapidly as the stalk continues to elongate. Many ear shoots are easily visible when the stalk is dissected. V10 - Ten leaf collar
Initiation of the VT stage begins when the last branch of the tassel is visible and silks have not emerged. This stage begins about 2-3 days before silk emergence. The plant is almost at its full height and pollen shed (anthesis) begins. Pollen shed typically occurs in the morning or evening. Plants at the VT/R1 are most vulnerable to moisture stress and leaf loss (hail). VT - Tasseling
This stage begins when any silk is visible outside the husk. Falling pollen grains are captured by the silk and grow down the silk over a 24 hour period ultimately fertilizing the ovule. The ovule becomes a kernel. It takes upwards of three days for all silks on a single ear to be exposed and pollinated. The number of fertilized ovules is determined at this stage. If an ovule is not fertilized, it will not produce a kernel and it eventually degenerates. R1 - Silking
Occurring approximately days after silking, all kernels on the ear have attained maximum dry weight. A black or brown layer has formed where the kernel attaches to the cob, indicating physiological maturity has been attained. The stalk of the plant may remain green, but leaf and husk tissue has lost its green color at this stage. R6 - Physiological M aturity
Stages in Kernel Development
Silking Stage (R1) Emergence of silk Every ovule (potential kernel) on the ear develops its own silk (the functional stigma of the female flower) Silks remain receptive to pollen grain germination up to 10 days after silk emergence
Kernel Blister Stage (R2) About 10 to 14 days after silking, the developing kernels are whitish "blisters" on the cob and contain abundant clear fluid
Kernel “Milk Stage” (R3) About 18 to 22 days after silking, the kernels are mostly yellow and contain "milky" white fluid
Kernel “Dough Stage” (R4) About 24 to 28 days after silking, the kernel's milky inner fluid is changing to a "doughy" consistency as starch accumulation continues in the endosperm. The shelled cob is now light red or pink
Kernel “Dent Stage” (R5) About 35 to 42 days after silking, all or nearly all of the kernels are denting near their crowns. Kernel moisture content at the beginning of the dent stage is approximately 55 percent. A distinct horizontal line appears near the dent end This line is called the "milk line" and marks the boundary between the liquid (milky) and solid (starchy) areas of the maturing kernels.
Harvesting As a guideline Sweet corn; 21 days after silking. Also known as ‘milk stage’. About 70 days after planting.
Harvesting As a guideline grain corn; days after planting. Stalk and husks on ear are dry and turn brown.