J. Nyachiro, J. Zantinge, J.H. Helm, P E. Juskiw, D. Salmon, and M. Cortez

Alberta Agriculture, Food & Rural Development
Field Crop Development Centre
5030 50 Street, Lacombe, AB T4L 1W8
Phone (403) 782-4641
Fax (403) 782-5514
Our website: http://www.agric.gov.ab.ca/ministry/pid/fcdc/index.html

    Pre-harvest sprouting resistance (PHSR) is the inability of viable kernels to germinate in intact spikes when subjected to favorable conditions of moisture, oxygen, and temperature. Seed dormancy (SD) is the failure of viable embryos to germinate when subjected to optimum conditions of moisture, oxygen, and temperature. The PHSR may involve not only dormancy but also mechanisms related with the intact spike and factors associated with the kernel other than dormancy. Assays to determine PHSR may involve natural or artificial rain simulation treatments followed by an assessment of the level to which germination has progressed, whereas SD is measured by germination tests on threshed kernels. In barley, PHSR and SD are complex traits that are expressed depending on the genotype and environment. To study and understand PHSR and SD in barley requires lines or populations with genetic variability in PHRS and SD.

Development of barley populations with variability in PHSR and SD

    Populations of hulless barley lines with variable sprouting resistance were developed from crosses with Samson in the background. Samson is semi-dwarf six-row barley that has good sprouting resistance under wet-swath conditions. These lines, T89?. series, were crossed with hulless Falcon (6-row) and Phoenix (2-row). For comparison purposes, another population was developed from crossing TR118 (a line from Dr. B. Harvey) and T89049007. Incorporation of PHSR or SD trait was made into the hulless germplasm and selection made using a rain simulator test. The aim of this study was: (1) to determine the heritability of PHSR and SD in barley, (2) to determine selection efficiency for PHSR and SD, and (3) to identify and develop potential molecular markers linked to PHSR and SD and assess their application to marker assisted selection (MAS).

1997: The first crosses were made as outlined in Table 1. The four lines were selected for dormancy and sprouting resistance.

Table 1. Outline of crosses

    In 1998, F₁ seeds were planted to increase F₂ seed for planting in the field near Lacombe. The F₂ seed of six-rowed crosses was space planted at 70 plants per cross to generate F₂-derived F₃ lines. The two-rowed crosses were space planted at 300 plants per cross. All plants were harvested and thresh on a per plant basis.

    The F₂ -derived F₃ lines were planted as 260 single seed/populations in one location near Lacombe. Prior to harvest, the phenotype of each population was described as hulled/hulless, 2- or 6- row, awn type, glume awn length, spike attitude, & height). A total of 260 seeds were planted, 249 seeds emerged. A single head was collected from each population. In the fall, F3-derived F4 lines were planted in pots (3 seeds/pot) in growth chambers at FCDC, Lacombe. All seeds were treated with GA to ensure that all planted seeds germinated and that there was no indirect selection against PHSR or SD.  A single head was collected from each population.

    The F₄-derived F₅ lines were planted in pots (3 seeds/pot) in a growth room at FCDC. At least 1 head from each population will be harvested.  The F₅-derived F₆ lines will be planted in headrows near Lacombe (perhaps at 2 locations) to check for uniformity of populations and continued segregation. Notes will be taken on each population. F₇ seed will be analyzed and phenotyped for dormancy in the fall of 2002. Several tests are planned to address the objectives of the study. The highest and lowest 10% dormant populations will be pooled for use in AFLP bulk segregated genetic marker analysis. If we develop markers for PHSR and SD in our study populations, this will be an additional valuable tool in our breeding program.

    The lines with the desired levels of PHSR and SD will be incorporated onto the breeding program for further selection and yield testing or deployed into the germplasm program for use as parents in various crossings.

References

Harvey, B.L., B.G. Rossnagel and R.P. Muderwich.  1982.  Sprouting resistance in barley.  P.239-243.  In.  Int. Symposium on PHS of Cereals.  6-11 June 1982.  Westview Press, Inc. Boulder, CO.
Romagosa, I. F. Han, J.A. Clancy and S. Ullrich. 1999. Individual locus effects on dormancy during seed development and after ripening in barley. Crop Sci. 39: 74-79.
Strand, E. 1989. Studies on seed dormancy in small grain species. I. Barley. Norwegian J. Agric. Sci. 3: 85-89.
Salmon, D.F. and J.H. Helm.  1985.  Pre-harvest and post-harvest dormancy in spring triticale.  Agron. J.  77:649-652.