Crossing and Increase
Each year, about 600-800 crosses are made during two plantings (fall and
spring) in the greenhouse in Brookings. Roughly 50% of the crosses made in the
fall are increased to the next generation in the spring greenhouse to allow
for more rapid generation advance. The majority of the remaining crosses are
made using lines from other winter wheat programs in the region or, on
occasion, from other production regions (domestic and international) to
broaden genetic diversity and address specific program objectives. To
accelerate hard white winter wheat development efforts, we are also using
"off-season" nursery environments in Colorado and Arizona, primarily
for increase of F1 and F2 cross populations.
Year 2 (F2 bulks)
Each year, about 600-800 F2 populations are field planted in three row plots.
Planting is done at two locations (Brookings and Highmore) to avoid complete
loss from winter-kill or hail. Plots are bulk-harvested and advanced to the
next generation with selection primarily based on pedigree and visual
observations.
Year 3 (F3 bulks)
Each year, about 300-500 F3 populations are planted in standard seven row
plots. Planting is done at two locations (Brookings and in spring wheat
stubble at the Dakota Lakes Research Farm near Pierre) to avoid complete loss
from winter-kill or hail. Based largely on pedigree and visual observations,
roughly 50-100 individual heads are selected from desirable populations for
advancement to head-rows (the seed from a single head will be one head-row the
following year). Following harvest, yield and test weight of the bulk plots
(relative to check varieties) are used as additional selection criteria. Over
the winter, quality screening (mixographs, NIRs-protein, and SDS
sedimentation) is done on the remnant seed.
Year 4 (Head-Row Nursery)
Each year, roughly 20,000 - 30,000 head-rows are planted at the Dakota Lakes
Research Farm near Pierre. Appropriate check varieties (for disease reaction,
heading date, and plant height) are included between each population to aid in
selection. Each year, approximately 800-1000 head-rows are selected and
advanced as new lines to the next generation. At this point, each new line is
assigned a number corresponding to the year of selection. For example,
'SD98001' was the first line selected from the head-row nursery during 1998.
Year 5 (Early Yield Trial - EYT)
Lines selected from the head-row nursery are planted in unreplicated three row
plots (with check varieties) at three locations in South Dakota (Selby,
Winner, and Brookings). Each year, about 80-100 lines are advanced to the next
generation based on field performance (yield and test weight), field disease
reaction, greenhouse stem rust screening, agronomic adaptation, and quality
screening done over the winter months on the remnant seed sample from the
head-row.
Year 6 (Preliminary Yield Trial - PYT)
Lines selected from the EYT are planted in a replicated nursery (with check
varieties) at five field environments (Brookings, Selby, Winner, Wall, and in
pea stubble at the Dakota Lakes Research Farm near Pierre). During the winter
months, greenhouse disease screening, coleoptile screening, and quality
testing are done using remnant seed samples from the previous year. Each year,
approximately 25-35 lines are advanced to the next generation, based on field
performance and these other screening activities.
Year 7 (Advanced Yield Trial - AYT)
The AYT is grown at nine field environments; seven of these are in South
Dakota (Brookings, Highmore, Selby, Winner, Wall, and two production
environments at the Dakota Lakes Research Farm near Pierre), one is at a
dryland site in the Nebraska Panhandle (in cooperation with the breeding
program in Nebraska), and one is at a dryland site in Hettinger, North Dakota
(in cooperation NDSU agronomists). The AYT includes lines selected from the
PYT the previous year, potential release candidates previously advanced, and
standard check varieties.
Milling and baking tests are done on all lines by the USDA-ARS Regional
Quality Lab. About 30 of these lines are also entered in the Regional
Germplasm Observation Nursery (RGON) which is grown as a single-row
observation (primarily for disease screening) at 20 sites throughout the Great
Plains. Based on field performance and various cooperative screening tests,
roughly three to six lines are advanced each year for further testing in the
AYT, the SDSU Crops Performance Testing (CPT) Variety Trial, and the Northern
Regional Performance Nursery (NRPN).
Year 8 (AYT, CPT, NRPN)
The CPT Variety Trial is planted at 15 environments across South Dakota while
the NRPN is grown at 20 environments across the northern Great Plains (from
Nebraska to Alberta, Canada). At this stage, promising elite lines from the
program are entered for comprehensive quality testing by the Wheat Quality
Council (WQC). Based on performance and various cooperative evaluations,
promising elite lines at this stage are advanced for further testing and
subject to preliminary seed increase (3-6 acres) to prepare for possible
release.
Year 9 (AYT , CPT Variety Trial, NRPN)
A line that continues to perform well in the second year of statewide (AYT and
CPT Variety Trial) and regional (NRPN) testing is presented to the variety
release committee with a recommendation to increase Foundation seed
(approximately 50-100 acres) with the intent to release the following year.
Year 10 (AYT, CPT)
If no unexpected problems arise during a third year of statewide testing in
both the AYT and the CPT Variety Trial, the line is presented to the variety
release committee with a recommendation to release as an improved cultivar.
