Seeds per head is simply the product of the number of seeds per spikelet and the total number of spikelets per head. Oklahoma wheat averages between 2 grains and 2. Factors such as variety, emergence time, grazing, tiller population density, fertility, foliar disease, insect infestations, weed control and moisture availability will affect the final number of seeds per head.
If a yield estimate is being calculated during or after grain fill, seeds per head can be estimated very precisely by counting seeds in random head samples from across the field.
Estimates of seeds per head earlier in the year will be less reliable, as they rely upon several assumptions that may or may not prove to be correct as the crop year progresses. It is also important not to count seeds that are shriveled or light, as these will likely not make it to the combine tank and will not contribute much to yield if they do.
The list of factors that can influence seeds per head also influence seed weight. Within a given environment, however, variety probably has the largest effect on seed size. Even though seed size influences final grain yield, it is important to note that small-seeded varieties frequently compensate by producing more heads and more seeds per head than larger-seeded varieties.
Given these caveats, most hard red winter wheat produced in Oklahoma will have between 13, and 16, seeds per pound. Each method relies on several assumptions that may not be accurate for every season or situation. These assumptions presume that soil moisture and nutrients are adequate, and that weeds, insects and diseases are not affecting yields. Method 1 The first table Table I is easy to use; however, it relies on several assumptions that are required to make a yield estimate in the fall or early spring prior to extensive tillering or stem elongation.
These assumptions included: that wheat plants, on the average, develop about five heads; that each head, on average, develops about 22 kernels; and that there are an average of 16, kernels per pound. Late-planted wheat and wheat seeds that do not germinate until later because of dry conditions will tiller less and have fewer heads. To use Table I , count the number of plants per foot of row. It is best to use at least 5 feet of row in at least five sites within the field and calculate the average number of plants per foot of row.
If the stands are uneven, for example the stand is better or worse in the wheel tracks, make sure your percentage of samples in these areas accurately represents the proportion of these areas in the whole field. Locate the column in the table that corresponds to your average number of plants per foot of row and then move down that column until it intersects with the row corresponding to your row spacing.
This is your estimated yield. Table I. Estimated wheat yield potential. These tours were conducted near May 1, prior to head emergence in most of the state. Table II. Estimating winter wheat yield after stem elongation for the Nebraska Panhandle. In addition, the table becomes unreliable in situations of extremely low or extremely high tiller counts, or in years when crop development as of May 1 is well ahead or behind normal.
For later season yield estimates, yield predictions can be made by substituting the actual number of heads per foot for tillers per foot. To use the table, count the number of tillers per foot of row. Again, it is best to use at least 5 feet of row in at least five sites within the field and calculate the average number of plants per foot of row.
The method presented here is one that can be undertaken relatively quickly and easily Steps are as follows: Select an area that is representative of the paddock. Using some type of measuring rod or tape, measure out an area of 1m 2 and count the number of heads or pods.
Table 1. Grain weights expressed as weight per grains. Leaves Wheat leaves form at each node and include a leaf sheath that wraps around the stem and a leaf blade. Wheat has small auricles. These wrap around the stem at the point where the leaf sheath meets the leaf blade. Spike The spike also called the ear or head forms at the top of the plant.
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