Practical Agronomy! Why Are There Taller Sorghum In The Field?

Common in any Sorghum field are sights of taller and towering plants which rise above the rest by one to three feet.
While these tall stalks seem like an eyesore in what is otherwise a beautiful field of evenly growing Sorghum, Agronomists say there is really nothing to worry about.
Brent Bean, a Sorghum Checkoff Agronomist from Lubbock, Texas, wrote an article in the Sorghum Checkoff website where he explained the presence of Off-Types in the field.
I am sharing here excerpts from his article hoping that by doing this, Filipino farmers will have a deeper understanding of Sorghum, a grains crop which I believe will be a game changer in Philippine Agriculture.
“Sorghum fields sometimes have plants or stalks that are uneven in maturity or in height and appearance. Assuming uniform emergence, the difference in maturity is often caused by the ability of sorghum to tiller and grow additional basal stalks that produce heads later than the main stalk. This difference is largely influenced by early season environment and, to some extent, the genetics of the hybrid.”
“Tall Mutants. As the name implies, these plants are 1-3 feet taller than normal plants and are the most common off-types. However, other than the height difference, they are identical to the normal plants. Four dwarfing genes control plant height, and the tall height mutant is a result of the dw3 gene becoming unstable. Parental genotypes will vary in their frequency of producing tall mutants. With the use of genetic markers and other modern techniques, seed companies can greatly reduce the frequency of tall mutants by indentifying stable versions of the dw3 gene. However, since these tall mutants have no effect on yield, some seed companies place more emphasis on this characteristic than others.”
“Grain Outcross or Off-color Panicles. These plants are usually similar in height to the desired hybrid but may have very different seed color or panicle shape. Seed colors may be red, bronze, yellow, brown or intermediate shades. These off-type plants are a result of foreign pollen, which is usually from grain sorghum, that contaminates the seed production field. Since these plants are grain sorghum, they are of little consequence in most commercial fields.
“Forage Types or Grain Forage. This group exhibits characteristics associated with forage sorghum, meaning that the plants are normally tall and single stalked with a typical grain sorghum-type panicle. Their maturity may be similar to the planted hybrid or much later. These plants originate from outcrosses from forage sorghum pollen in or near the seed production field. Because of their height, these plants can be pushed under the combine carrying the planted grain sorghum hybrid and result in lost grain. Since the seed from these off-types are not harvested, they can serve as a source of volunteer the following year.
“Open Head Forage, Grassy Sorghum or Shattercane. The pollen source for this outcross type is usually from sudangrass , sorghum-sudangrass or shattercane in or near the seed production field. Plants can vary greatly in height and plant appearance and typically produce numerous tillers. The panicles are more grasslike, in that they are loose and open, and are usually taller than the grain sorghum. The seed are highly fertile and easily ‘shatter’ from the panicle. The seed are covered by long, dark brown to black colored glumes that protect the seed in the soil allowing them to remain dormant for a number of years. Research conducted at the University of Nebraska found that seed from shattercane can remain dormant in the soil for as long as 13 years.”
#farmingisendlesslearning!