Seeding date can have an effect on everything from fertilizer use to disease development.
By Robert Klein, University of Nebraska-Lincoln
Seeding date can have a major effect on winter wheat yields. Wheat seeded early uses more soil water in the fall, leaving less in the profile for yield production. One research study showed a 50 bu./acre yield difference in the same field between a low-lying area with sufficient moisture and the rest of the plot where moisture was limited. Also, early planted wheat will face insect, weed, and disease pressures for a longer period in the fall.
How Seeding Date Affects Tiller Development
Date of seeding greatly affects development of tillers in winter wheat, the source of as much as 70% of the grain yield in a normal year. Seeding during the optimum period enables wheat to form sufficient but not excessive tillers. Early seeding results in too many fall tillers, which may compete with each other, become diseased, and deplete soil moisture so that grain yields are low. Late seeding gives plants little time to develop tillers, resulting in an inadequate numbers of spikes (heads) for high yields the following spring.
Senescence and death may eliminate excessive tillers that form during the fall. Conversely, if too few tillers develop during fall, additional tillers may form during spring; however, the yield potential may differ between tillers that develop during fall and those that develop during spring.
Tillering also enables the plant to adapt to different conditions. Few tillers develop when moisture, nutrition, and other conditions are poor, whereas numerous tillers that increase the yield potential form when conditions are favorable.The recommended seeding date represents a goal for seeding completion. As farm size and the number of acres increases for individual farmers, so does the length of time needed to complete seeding. The goal should be to have all the wheat planted by the ideal date. Plan your field order for planting accordingly. For example, plant higher elevation fields and those containing sandy soil first and leave lower fields and those with higher clay content until last.
How Planting Date Affects Fertilizer Use
If the seeding date is delayed or growing conditions prevent or delay root growth to the dual placement fertilizer band, seed fertilizer placement is the preferred application method. Poor root growth for whatever reason limits root-fertilizer contact and tillering, which affects yield.
How Planting Date Affects Disease Problems
Delayed planting dates also may be due to a need to avoid wheat streak mosaic virus, Russian wheat aphid, crown and root rot, and too much fall growth. Excessive fall growth causes excessive moisture use and stress. There are several other reasons for planting early. One is to get adequate ground cover to avoid erosion from wind and water. Another is to get adequate plant growth to assure winter hardiness. A third reason is to quicken maturity the following summer and avoid excessive heat stress.
Research Shows Effect of Wheat Planting Date on Yield