Registration of ‘Zak’ Wheat
(2000 Release)

‘Zak’ soft white spring wheat (Triticum aestivum L.) (Reg. No. CV- __________, PI 607839) was developed by the
Agricultural Research Center of Washington State University in cooperation with the Agricultural Experiment Stations (AESs) of the
University of Idaho and Oregon State University, and the United States Department of Agriculture-Agricultural Research Service
(USDA-ARS). Zak was jointly released by the AESs of Washington, Idaho and Oregon and the USDA-ARS. Zak was released as a
replacement for ‘Wawawai’ in the intermediate to high rainfall (>457 mm of average annual precipitation), non-irrigated wheat
production regions of Washington State based on its tolerance to the Hessian fly (Mayetiola destructor (Say)), high grain yield and
superior end-use quality.
Zak, tested under the experimental designations WA007850, W9400154 and K89792, is a F4:5 head row selection derived from
the cross PAVON “S”/5/PI167822/CI13438 113-6//IDAED/MARFED 68-5/4/LEMHI 66/3/YAKTANA 54A*4//NORIN
10/BREVOR/6/WALLADAY/7/PI506355/8/TREASURE. The following modified pedigree-bulk breeding method was used to
advance early generation progeny. Bulked seed (30 g) from several F1 plants was used to establish an F2 field plot. Approximately
100 heads were selected at random from individual F2 plants, and a 40 g sub-sample of the bulked seed was used to establish a single
F3 plot. Seed from the F3 plot was bulk harvested, then a 60 g sub-sample was used to establish an F4 field plot. Single heads from
150 F4 plants were threshed individually to establish F5 head row families. Following selection for general adaptation, plant height and
grain appearance, seed from 30-50 plants within each selected head row was bulk harvested to obtain F6 seed for grain yield
assessment. F1, F2, F4 and F5 progeny were advanced in field nurseries in Pullman, WA, whereas F3 progeny were advanced at the
Lind Dryland Experiment Station in Lind, WA. Breeders seed of Zak was produced as a reselection, based on phenotypic uniformity,
of 1700 F10 head rows grown with irrigation in Othello, WA in 1999.
Zak is an intermediate height, single-gene semidwarf with lax, fusiform heads with white awns. It has medium length, white glumed
spikes with midlong to long kernels that are white, soft, and ovate. Seed of Zak has a midsize germ with a narrow, mid-deep crease,
rounded cheeks and a short, non-collared brush. 
Among the major pests of spring wheat in the Pacific Northwest, USA, Zak has non-race-specific, high-temperature, adult plant
resistance to stripe rust (caused by Puccinia striiformis Westend.) to races common in North America, based on results from
non-inoculated and inoculated field disease screening trials conducted in Mt. Vernon, WA and Pullman, WA for four crop years. Zak
also has moderate adult-plant resistance to leaf rust (caused by P. recondita Rob. ex Desm.). Based on insect screening trials
conducted at Kansas State University and field trials conducted in Walla Walla, WA and Pullman, WA, Zak is tolerant to the Hessian
fly. Based on pedigree and natural field infestation ratings from Pullman, WA, Zak is susceptible to the Russian wheat aphid
(Diuraphis noxia (Mordvilko)).
Zak was evaluated in replicated field trials under fallow, non-irrigated annual crop and irrigated conditions in Washington, Oregon
and Idaho from 1995 to 2000. Grain yields of Zak typically equal or exceed those of other soft white spring wheat entries in
non-irrigated as well as irrigated field production. In 53 tests conducted over 4 years in Washington State, the grain yield average of
Zak was 4470 kg ha-1, and Zak produced from 67 to 739 kg ha-1 more grain than Wawawai (4352 kg ha-1), ‘Alpowa’ (4389 kg
ha-1) and ‘Penawawa’ (4199 kg ha-1), depending on variety and location. Grain volume weight of Zak averaged 773.5 g l-1, which
was 10.3 to 16.7 g l-1 lower than those of Wawawai (787.6 g l-1) and Alpowa (785.1 g l-1), and 1.3 to 10.3 g l-1 lower than
Penawawa (777.3 g l-1). Thousand kernel weight averages of Zak, Wawawai, Alpowa and Penawawa were 42.6 g, 45.0 g, 37.3 and
41.9 g, respectively. The average plant height of Zak was 89 cm, and Zak was 5 cm shorter than Wawawai (94 cm), equal to Alpowa
(89 cm) and 5 cm taller than Penawawa (84 cm), depending on location. Lodging percentages of Zak were lower than those of
Wawawai and comparable with those of Alpowa and Penawawa. Zak headed 1 to 2 days later than Wawawai (168 julian days), on
the same date as Penawawa (170 julian days) and 1 to 2 days earlier than Alpowa (171 julian days).
In tests conducted by the USDA-ARS Western Wheat Quality Laboratory (WWQL) in Pullman, WA using grain produced in
breeding and commercial variety testing trials in Washington State from 1994 through 1999, protein content of Zak (10.3 %) was
consistently lower than the soft white checks Wawawai (10.7 %), Alpowa (10.4%) and Penawawa (10.5 %). Flour yield of Zak (69.5
%) was higher than Wawawai (68.9 %), Alpowa (68.3 %) and Penawawa (67.1 %), whereas flour ash content for Zak (0.37 %) was
higher than that for Wawawai (0.32 %) and Alpowa (0.35 %) but lower than that for Penawawa (0.40 %). Zak had a higher average
milling score (86.1) than Alpowa (85.4) and Penawawa (80.8) but lower than Wawawai (88.5). Average cookie diameter for Zak
(9.6 cm) was larger than Wawawai (9.4 cm), Alpowa (9.3 cm) and Penawawa (9.4 cm), and average sponge cake volume of Zak
(1295 cm3) was larger than Wawawai (1251 cm3) and Penawawa (1283 cm3) when the baking quality of flour extracted from grain
samples collected across production regions were compared.
Seed of Zak will be maintained by the Washington State Crop Improvement Association under supervision of the Department of
Crop and Soil Sciences and the Washington State Agricultural Research Center, and may be obtained by contacting the corresponding
author or through the National Plant Germplasm System. U.S. plant variety protection status for this cultivar is pending.
K.K KIDWELL*, G.B. SHELTON, V.L. DEMACON, C.F. MORRIS,
D.A. ENGLE, J.W. BURNS, R.F. LINE AND C.F. KONZAK (1)
References and Notes
1. K.K. Kidwell, G.B. Shelton, V.L. DeMacon, J.W. Burns and C.F. Konzak (retired), Dep. of Crop and Soil Sciences, Washington
State Univ., Pullman, WA 99164-6420. C.F. Morris and D.A. Engle, USDA-ARS Western Regional Quality Laboratory, Pullman,
WA., and R.F. Line (retired), USDA-ARS Cereal Disease Laboratory, Pullman, WA. Registration by CSSA. Accepted XX
XXXX. 2001. *Corresponding author (kidwell@mail.wsu.edu).

Text provided by Kim Kidwell, 10/01.