Using pre-harvest sprouted wheat grain as seed
Editor’s note: This article is from the archives of the MSU Crop Advisory Team
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Some wheat production areas of the state experienced significant levels of pre-harvest sprouting this season. There is interest in saving some of the grain for use as seed if its viability can be reasonably predicted.
Pre-harvest sprouting occurs when the grain breaks dormancy and begins to behave as a seed. This germination process starts with the kernel absorbing water triggering enzyme activity that breaks-down starch into glucose for the embryo. The sprout eventually splits the seed coat and becomes visible.
Pre-harvest sprouted kernels are generally viable. To an extent, these sprouted kernels are demonstrating their viability albeit to the detriment of the commodity. The difficulty is that the wheat producer needs to largely arrest the process through drying. Then, after two to three months of storage, the kernels are placed underground with the hope that the embryos are undamaged and the kernel has the wherewithal to successfully restart and sustain the process.
Historically, red or white soft wheat having less than 5 percent sprouts has usually been reliable as seed. The difficulty is predicting the quality of grain having sprout levels well above this. In the past, discussions surrounding seed quality loss might have referenced the percent of sprouting, the length of the sprouts or test weight. Today, low falling number scores can also suggest compromised seed quality. Regardless of the level of these indicators, confirmation through germination testing is very necessary.
As already implied, the germination test should be done just prior to planting, as the viability of sprouted seed almost always declines during storage. It is best to use the services of a testing laboratory. In addition to a standard germination test, a stress or vigor test should be performed. The vigor test can either be the TZ (tetrazolium) test or the AA (accelerated aging) test. For pre-sprouted seed, a vigor test may give a more accurate indication of the percent of productive seeds than the standard test.
The Michigan Crop Improvement Association (www.michcrop.com) offers seed testing services. A representative seed sample consisting of a pound of clean grain can be mailed to:
Michigan Crop Improvement
P.O. Box 21008
Lansing, MI 48909
The standard germination test costs $10 and takes approximately 10 days. The TZ and AA tests cost $13 each and require one day and 10 days, respectively. Prospective seeds having a standard germination test of less than 80 percent or a vigor test of less than 65 percent probably should not be used.
In addition to seed testing, growers electing to use pre-sprouted grain should increase seeding rates to compensate for any compromise in germination percentage. Also, growers should attempt to minimize seed stress by using it on the first fields to be planted, avoiding the over application of seed treatments, and adjusting equipment to insure that the seed is not planted excessively deep.
N.R. Foster et al: http://www.oznet.ksu.edu/library/crpsl2/srl115.pdf
Randy Judd, Michigan Crop Improvement, personal conversation