RESEARCH: SUPER DWARF
CULTIVAR STUDIES: WHEAT
'USU-Apogee' Wheat -
Bruce Bugbee, G. Koerner, R. Albrechtsen, W. Dewey and S. Clawson
'USU-Apogee' is a full-dwarf hard red spring wheat (Triticum aestivum
L.) (NSSL Reg. no. 331390.01; PI 592742) cultivar developed for high
yields in controlled environments. USU-Apogee was developed by the
Utah Agricultural Experiment Station in cooperation with the National
Aeronautics and Space Administration and released in April 1996. NASA
is interested in improved food crops for bioregenerative life support
systems in space.
Apogee is the point in an orbit
farthest from the earth. USU-Apogee is a shorter, higher yielding
alternative to 'Yecora Rojo' and 'Veery-10', the short field cultivars
previously selected for use in controlled environments (Bugbee and
Salisbury, 1988). USU-Apogee (45-50 cm tall, depending on temperature)
is 10 to 15 cm shorter than Yecora Rojo and 2 to 5 cm shorter than
Veery-10. USU-Apogee was also selected for resistance to the
calcium-induced leaf tip necrosis that occurs in
USU-Apogee originated from the cross 'Parula'/'Super dwarf', both of
which were obtained from the CIMMYT germplasm collection in 1984.
Parula has the pedigree:
where FKN = 'Frontana'/'Kenya58'//'Newthatch'.
Parula was selected for its small leaf size. Super dwarf has the
CIMMYT germplasm number CMH79.481-1Y-8B-2Y-2B-0Y; and the pedigree:
T. sphaerococcum/2*H-567.71/3/'Era' /'Sonora64'//2*Era.
Super Dwarf was selected for its dwarf stature (25 cm tall).
Single head selections were made in the F2 to F4 generations for short
height (less than 0.5-m tall), vertical tillering habit, reduced
tillering, and small leaves. The segregating dwarf-lines tended to
have plagiotropic (horizontal) tillers, which cause undesirable
interplant competition in communities. For the same reason, the
formation of secondary tillers is an undesirable trait at high
planting densities in optimal environments (Donald, 1968; 1979). Small
leaves are often more photosynthetically efficient than large leaves
and 2 small leaves may be better than one large leaf (Morgan et al.,
1990; LeCain et al., 1989; Bhagsari and Brown, 1986).
Mass selections were made in
the F5 to F8 generations. All selections were made in a CO2-enriched
temperature-controlled greenhouse that had 350 µmol m-2 s-1 of
supplemental lighting from high pressure sodium lamps. The photoperiod
was 24-h (continuous light). The root-zone was a hydroponic soilless
medium watered twice daily with nutrient solution. Continuous
cultivation made it possible to evaluate 3 to 4 generations per year.
Yields in this environment are typically double that of the best
irrigated field yields (about 16 Mg ha-1; 240 bushels per acre).
Yield evaluations, in the
near-optimal conditions of the CO2-enriched greenhouse, were begun in
the F5 generation in 1988. USU-Apogee was tested under the designation
CPL-20-1-41. Mice got into the greenhouse prior to harvest in the F8
generation and attacked all six replicate plots of USU-Apogee. No
other plots were damaged. Selective seed consumption by mice among
field breeding lines has occurred previously at Utah State University,
and may be caused by subtle differences in volatile compounds among
lines. USU-Apogee had the least leaf tip necrosis, but had
considerable variability for plant height, so 67 single heads selected
from the F9 generation were grown as head rows. Additional selections
were made in the next six generations (F10 to F15) for short height
and high yield. In the F16 generation, 100 heads were selected and
grown as head rows. After roguing off-type and nonuniform rows, the
remaining 90 F16-derived lines were harvested and bulked as Breeder
PROPERTIES USU-Apogee is resistant to
the severe leaf tip chlorosis that occurs in wheat under rapid growth
conditions, particularly continuous light. This chlorosis (caused by a
calcium-deficiency) can kill the top 30% of the flag leaf. The problem
is severe in Veery-10 and also occurs in Yecora Rojo. Calcium
deficiencies, such as tip burn in lettuce and blossom end rot in
tomatoes, are common in controlled-environment crop production because
Ca has low phloem mobility and is thus not sufficiently translocated
to rapidly growing meristems. Foliar Ca applications and increased
root-zone Ca are not effective because they do not reach the
meristematic leaf tissue. USU-Apogee has significant rates of
guttation during dark periods and guttation occurs even during the
light period when the stomates are partly closed by elevated CO2.
Significant amounts of Ca can be translocated by guttation. The
segregating lines with the smallest leaves had the least chlorosis.
Measurements indicated adequate calcium in the top 30% of small leaves
(0.4% Ca), but inadequate amounts (0.05% Ca) in large leaves.
USU-Apogee has smaller flag leaves (11 to 20 cm long, depending on
temperature) than Yecora Rojo and Veery-10 (20 to 30 cm long).
USU-Apogee has an extremely
rapid development rate. Heads emerge 23 days after seedling emergence
in continuous light with a constant 25 C temperature. Heads of Yecora
Rojo and Veery-10 emerge about 6 days later under these conditions. In
field conditions, USU-Apogee heads about 3 days earlier than Yecora
Rojo and 6 days earlier than Veery-10.
COMPARISONS The yield advantage of USU-Apogee is greatest
in conditions favorable to a rapid development rate (warm
temperatures, 23 C). The yield of Yecora Rojo and Veery-10 are
similar, so most of our studies compared USU-Apogee to Veery-10.
USU-Apogee out-yielded Veery-10 by an average of 29±2% in 2 studies at
23 C (60 day life cycle), but by an average of 13±10% in 3 studies at
17 C (95-day life cycle). USU-Apogee outyielded Veery-10 by 8% in a
replicated study in a growth chamber under high light (1200 µmol m-2
s-1; 24-h photoperiod; 51.8 mol m-2 d-1, equivalent to full sunlight
at the summer solstice). USU-Apogee outyielded Veery-10 by 15±3% in
replicated field trials in 1994 and 1995, and outyielded Yecora Rojo
by 14% in 1995. The yield of USU-Apogee was 160% of Super Dwarf in the
1995 field trial. In 1995, the field yield was 100.1% of the yield of
Fremont, an adapted semi-dwarf Utah wheat cultivar. Neither Veery-10
nor Yecora Rojo are specifically adapted to Utah field conditions.
significantly from Veery-10 in the relative contribution of yield
components. Heads per m2 and seeds per head are approximately 25%
higher in USU-Apogee, and mass per seed is about 25% less. The harvest
index is 5 to 15% higher than that of Veery-10.
BREADMAKING PROPERTIES Breadmaking quality was evaluated
by the USDA-ARS Western Quality Wheat Laboratory at Pullman, WA.
Milling and Baking tests indicated that USU-Apogee has similar quality
to Veery-10 and slightly lower quality than Yecora Rojo. Breeder seed
of USU-Apogee will be maintained by the Crop Physiology Laboratory at
Utah State University.
REFERENCES AND NOTES
1. Bugbee and Salisbury. 1988.
Exploring the Limits of Crop Productivity. P. Physiol. 88:869-878.
2. Bhagsari, A. and R. Brown.
1986. Leaf Photosynthesis and its Correlation with Leaf Area. Crop
3. Donald, C.M. 1968. The
Breeding of Crop Ideotypes. Euphytica 17:325-403.
4. Donald, C.M. 1979. A Barley
Breeding Program Based on an Ideotype. Jour. Agric. Sci. Camb.
5. LeCain, D., J. Morgan, and
G. Zerbi. 1989. Leaf Anatomy and Gas exchange in Nearly isogenic
semidwarf and tall winter wheat. Crop Sci. 29:1246-1251.
6. Morgan, J., D. LeCain, and
R. Wells. 1990. Semidwarfing Genes Concentrate Photosynthetic
Machinery and affect Leaf Gas Exchange of Wheat. Crop Sci. 30:602-608.
7. Crop Physiology Laboratory,
Utah State University, Logan, UT 84322-4820. Contribution of the Utah
Agriculture Experiment Station and The National Aeronautics and Space
Administration. Journal Paper no. 4908. Registration by CSSA.