Tillering potential of wheat covered with soil

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High winds and blowing soil can cause soil to pile up in unwanted places, including in the furrows created by hoe drills. This has happened already this year in western Kansas, where residue levels are extremely low as a result of the extreme drought the past year or two. If this soil blows and drifts shortly after wheat emergence, the crown of the seedlings will get buried to some extent under an unexpected layer of soil. Hopefully there will still be leaves sticking up out of the soil. But even if leaves are visible, the crown will be positioned deeper underground that normal.

This raises a few questions:

1. Will this wheat still be able to tiller? Yes, but there may be fewer tillers than normal. Most tillers form in the axils of leaves, which will be down at the crown level. The crown normally establishes about a half-inch below the soil surface, regardless of how deeply the seed was planted. When the crown is deeper in the soil, it will be cooler and this can reduce the level of tiller initiation activity going on near the crown.

Once a wheat plant has three leaves, the first tiller will be visible in the axil of the first leaf. If the seedling has been covered with soil, this tiller will have to push through more than the usual half-inch of soil to emerge. This takes a little extra effort, but is certainly not impossible. After the next leaf forms, a second tiller will start growing – this time from the axis of the second leaf. This will still be at the crown, however, and so the second tiller will also be starting out under more soil than normal. It’s hard to say how many of these tillers will actually make it through the soil.

There can also be “coleoptilar” tillers, which form at the base of the coleoptile – near the seed and below the crown. When the seed furrow fills in with soil after emergence, the seeds will be so deep that it will be more difficult for coleoptilar tillers to emerge.

2. Will the main shoot and leaves continue to grow normally? Yes, if three or more leaves are present above the soil surface. Any shoots and leaves that make it above the soil surface will grow normally. Potential head size will not be affected by this. If only one leaf is sticking out of the ground (or not at all), however, the plants cannot be expected to develop normally.

3. Should the field be replanted? Accumulations of blowing soil will typically be quite variable from field to field, or within a field. If the stand is good in an affected area and there are three or more leaves visible above the soil surface, then there’s probably no need to replant. You can probably expect fewer tillers per plant, depending on how deep the crown has been buried and the firmness of the soil. That may reduce yield potential somewhat – but not enough to justify replanting. If the stand has been thinned out, however, or if the plants are buried so that no leaves or only one leaf is visible, replanting may be a good idea.

Jim Shroyer, Crop Production Specialist