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ISSUE 14  August 1, 2002



An open invitation is extended to soybean producers, their family and friends to the annual soybean plot tours and suppers scheduled for September 5, 17 & 18th, 2002. The events are free of charge and sponsored by the North Dakota Soybean Council, the North Dakota Soybean Growers Association, and Agri Business leaders in the area.

The evenings will commence with field tours followed by research updates on the latest developments for the future of the soybean industry. The Council has invested checkoff dollars in a series of promising research endeavors from production issues to industrial uses.

The plot tours are scheduled to begin at the following locations and times given below:

Thursday, September 5th - 5 pm - Jeff and Maxine Leinen Farm ( mile west of Great Bend, ND just off I-94

Tuesday, September 17th - 4 pm - Carrington NDSU Research/Extension Center (Carrington, ND)

Wednesday, September 18th - 5 pm - Gebeke Farms (Hwy 18 north of Casselton, to County Road 34, west on County Road 34 for 2 miles, then north on gravel road 1.2 miles).

Following the research portion of the program, all participants are invited to enjoy cold beverages and an evening meal.

Duane R. Berglund
NDSU Extension Agronomist




With uneven maturity common in many fields, you may have to wait for late grain to mature. While hoping ripe grain does not shatter. Looking at head color and kernel color will enable one to cut as soon as late grain is mature.

Lack of green in the flag leaf - the uppermost leaf - indicates that a wheat or barley plant has reached 95% of its ultimate yield and that the final stage of development is under way.

Green disappears from the glumes (bracts at the bases of the spikelets) about 1 1/2 days before maturity.

Lack of green in heads and the darkening of a pigment strand in each kernel, seen most easily when kernels are cut open crosswise, signal 100% maturity. The pigment strand begins to appear about a half day before physiological maturity.

A whole field won't lose its color at the same time, so check thoroughly. Also, check bottom kernels on heads because top kernels lose green first.

Straight cutting may help reduce harvesting costs by eliminating the swathing operation.

Most small grains are mature at about 35 percent moisture but will dry down to 20 percent to 22 percent moisture in only a few days with good drying conditions. At 20 percent moisture, straight combining can begin.

If harvesting is done at 20 percent moisture, drying facilities will be needed. Combines with 30-foot headers may be difficult to use on hilly fields. One end of the header may be digging the soil and the other end may be above the grain heads. Twenty foot to twenty four foot headers may be best to harvest short plants.

Duane R. Berglund
NDSU Extension Agronomist




Corn is now in the midst of pollination and fertilization of ovules result in corn kernels and will eventually determine the grain yield potential of this years corn crop.

The grain fill period begins with successful pollination and initiation of kernel development, and ends approximately 50 to 55 days later when the kernels are physiologically mature. During grain fill, the developing kernels will be the primary sink for concurrent photosynthate produced by the corn plant.

What this means is that the photosynthate demands of the developing kernels will take precedence over that of much of the rest of the plant. In essence, the plant will do all it can to 'pump' dry matter into the kernels, sometimes at the expense of the health and maintenance of other plant parts including the roots and lower stalk. A stress_free grain fill period can maximize the yield potential of a crop, while severe stress during grain fill can cause kernel abortion and lightweight grain.

Kernel development proceeds through several relatively distinct stages. Silking Stage (Growth Stage R1). Some may argue whether silking should be labeled as a kernel growth stage, but nonetheless silk emergence is technically the first identifiable stage of the reproductive period. Silks remain receptive to pollen grain germination up to 10 days after silk emergence. Silk receptivity decreases rapidly after 10 days if pollination has not yet occurred. Natural senescence of silk tissue over time results in collapsed tissue that restricts continued growth of the pollen tube. Silk emergence usually occurs in close synchrony with pollen shed, so that duration of silk receptivity is normally not a concern. Failure of silks to emerge in the first place (for example, in response to silkballing or severe drought stress) does not bode well for successful pollination.

Kernel Blister Stage (Growth Stage R2). About 10 to 14 days after silking, the developing kernels are whitish 'blisters' on the cob and contain abundant clear fluid. The ear silks are mostly brown and drying rapidly. Some starch is beginning to accumulate in the endosperm. The radicle root, coleoptile, and first embryonic leaf have formed in the embryo by the blister stage. Severe stress can easily abort kernels at pre_blister and blister stages. Kernel moisture content is approximately 85 percent.

Kernel Milk Stage (R3). About 18 to 22 days after silking, the kernels are mostly yellow and contain 'milky' white fluid. The milk stage of development is the infamous 'roasting ear' stage, that stage where you will find die_hard corn aficionados standing out in their field nibbling on these delectable morsels. Starch continues to accumulate in the endosperm. Endosperm cell division is nearly complete and continued growth is mostly due to cell expansion and starch accumulation. Severe stress can still abort kernels, although not as easily as at the blister stage. Kernel moisture content is approximately 80 percent.

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. By dough stage, four embryonic leaves have formed and about 1/2 of the mature kernel dry weight is now in place. Kernel abortion is much less likely once kernels have reached early dough stage, but severe stress can continue to affect eventual yield by reducing kernel weight. Kernel moisture content is approximately 70 percent.

Kernel Dent Stage (R5). About 35 to 42 days after silking, all or nearly all of the kernels are denting near their crowns. The fifth (and last) embryonic leaf and lateral seminal roots form just prior to the dent stage. A distinct horizontal line appears near the dent end of the kernel and slowly progresses to the tip end of the kernel over the next 3 weeks or so. This line is called the 'milk line' and marks the boundary between the liquid (milky) and solid (starchy) areas of the maturing kernels. Severe stress can continue to limit kernel dry weight accumulation. Kernel moisture content at the beginning of the dent stage is approximately 55 percent.

Physiological Maturity (R6). About 50 to 55 days after silking, kernel dry weight usually reaches its maximum and kernels are said to be physiologically mature and safe from frost. Physiological maturity occurs shortly after the kernel milk line disappears and just before the kernel black layer forms at the tip of the kernels. Severe stress after physiological maturity has little effect on grain yield, unless the integrity of the stalk or ear is compromised (e.g., ECB damage or stalk rots). Kernel moisture content at physiological maturity averages 30 percent, but can vary from 25 to 40 percent grain moisture.

Harvest Maturity. While not strictly a stage of grain development, harvest maturity is often defined as that grain moisture content where harvest can occur with minimal kernel damage and mechanical harvest loss. Harvest maturity is usually considered to be near 25 percent grain moisture.

Related Reference: Ritchie, S.W., J.J. Hanway, and G.O. Benson. 1993. How a Corn Plant Develops. Iowa State Univ. Sp. Rpt. No. 48.

Duane R. Berglund
NDSU Extension Agronomist


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