Thinopyrum Intermedium - Breeding For Grain Production

Breeding For Grain Production

Intermediate wheatgrass, Thinopyrum intermedium, has been widely hybridized with wheat in efforts to transfer traits like disease resistance or perenniality to wheat. But attempts to directly domesticate the species as a grain crop did not begin until workers at the Rodale Research Center began to evaluate collections in 1983. After evaluating 300 collections, the best 20 based on grain yield and seed quality were selected in 1989. The selected collections were allowed to intermate, and 380 progeny were evaluated between 1991 and 1994. The best 11 plants, plus three from another evaluation, were interemated, and a second cycle was begun. Seeds from the best plants in the second cycle were passed to scientists at The Land Institute, where the research has continued.

In 2001 and 2002, seed from the first and second breeding cycles of the Rodale Research Center was planted at The Land Institute. In the fall of 2003, 1000 individuals were dug up and vegetatively propagated to obtain three clones of each plant. The 3000 resulting plants were randomly transplanted to the field on a three foot by three foot grid. In this manner, genetic differences between plants were separated from the environmental influences. In 2005, heads were harvested from every plant and threshed to remove the seeds. The seeds were both counted and weighed to determine the yield per seed head and weight per seed. The fifty highest plants with the highest yield and largest seed were selected to intermate in 2004.

In the fall of 2004, 4000 progeny were planted to establish the second cycle of breeding at The Land Institute. In 2008, these plants were harvested separately by using a power sythe and threshed in a combine. Again the best 50 plants were selected, this time based on yield per head, seed size, shortness, and free threshing ability.

The selection methods described above have increased seed size and yield by about 10 to 18% per cycle. But perhaps of greater importance has been the discovery of two Mendelian traits. The first is dwarfing, which results in stems about 30 cm shorter than wild type plants and short, erect leaves (see photo). The second is a more subtle change in head shape which results in thick, non-brittle heads and slightly larger seeds (see photo). Both of these traits appear to be controlled by dominant genes.