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a Dep. of Crop and Soil Sciences, Washington State Univ., Pullman, WA 99164-6420
b USDA-ARS Wheat Genetics, Quality, Physiology, and Disease Research Unit, Pullman, WA 99164-6420
c Plant, Soils, and Entomological Sciences, Univ. of Idaho, Moscow, ID 83844-2339. Research was funded in part by the Washington State Grain Alliance
* Corresponding author (kidwell{at}wsu.edu).
ABSTRACT
Stripe rust (Puccinia striiformis Westend f. sp. tritici) resistance is an essential trait for spring wheat cultivars produced in the Pacific Northwest region of the United States. The objective of this research was to develop an adapted spring wheat cultivar with high levels of resistance to stripe rust. ‘Whit’ (Reg. No. CV-1034, PI 653841) soft white spring wheat (Triticum aestivum L.) was developed and released in July 2008 by the Agricultural Research Center of Washington State University. Whit was tested under the experimental designations SW2K067, S0300100U, and WA008008, which were assigned through progressive generations of advancement. Whit is an intermediate-height semidwarf cultivar adapted to the intermediate to high rainfall (>380 mm of average annual precipitation), nonirrigated wheat production regions of Washington and Idaho. Whit is resistant to the Hessian fly [Mayetiola destructor (Say)], has high-temperature, adult-plant resistance to local races of stripe rust, is intermediate in height, is early maturing, and has high grain yield potential. Whit is a partial waxy variety with end-use quality properties similar or superior to ‘Louise’, ‘Alpowa’, and ‘Alturas’.
Abbreviations: HTAP, high-temperature, adult-plant • IT, infection type • PST, Puccinia striiformis Westend f. sp. tritici • WSU, Washington State University
Stripe rust (Puccinia striiformis Westend f. sp. tritici) is a major disease threat of spring wheat (Triticum aestivum L.) grown in the Pacific Northwest region of the United States. Few soft white spring wheat cultivars currently in commercial production have adequate levels of stripe rust resistance to prevent the need for fungicide application under heavy disease pressure. The objective of this research was to develop a soft white spring wheat cultivar with improved levels of resistance to stripe rust compared to current cultivars.
‘Whit’ soft white spring wheat (Reg. No. CV-1034, PI 653841), was developed and released in July 2008 by the Agricultural Research Center of Washington State University (WSU). Whit was named after Whitman County, WA, which is known for its high rainfall and excellent production conditions for soft white wheat. Whit was released as a replacement for ‘Alpowa’ (PI 566596) and ‘Nick’ (proprietary cultivar from WestBred LLC, Bozeman, MT) in nonirrigated wheat production systems in the intermediate- to high-rainfall (>380 mm of average annual precipitation) regions in Washington and Idaho on the basis of its resistance to the Hessian fly [Mayetiola destructor (Say)], high-temperature, adult-plant resistance (HTAP) to local races of stripe rust (Puccinia striiformis Westend f. sp. tritici), intermediate height, early maturity, and high grain yield potential.
Methods
Whit, tested under the experimental designations SW2K067, S0300100U, and WA008008, which were assigned through progressive generations of advancement, is a F3:4 headrow selection derived from the cross ‘Challis’(PI 630935)/5/‘El Gaucho’(PI 352071)/‘Sonora 64’(PI 342969)//‘Spr Luke Mutant’(PI unavailable)/3/‘Centennial’(PI 537303)/4/‘Alpowa’(PI 566596). The final cross for Whit was completed in the greenhouse in Pullman, WA, in 1999. Challis is a soft white spring cultivar released in 2002 by Western Plant Breeders Inc. (Bozeman, MT) with the pedigree ‘Penawawa’(PI 495916)/‘Edwall’(PI 477919). El Gaucho is a wheat cultivar developed in Argentina (Instituto Fitotecnico de Santa Catalina) in 1969 with the pedigree ‘Sinvalocho M.A.’(PI 168731)/‘Riccio’(PI unavailable)//‘Lin Calel’(PI 283881). Sonora 64, a hard red spring wheat, was developed by Instituto Nacional de Investigaciones Forestales, Agrícolas, y Pecuarias, Centro de Investigaciones Forestales y Agropecurarias, Experimental Valle De Mexico in 1964 with the pedigree ‘Yaktana 54’ (PI 258427)//‘Norin 10’(PI 156641)/‘Brevor’(CItr 12385)/3/2* ‘Lerma Rojo 54’(PI unavailable). Spr Luke Mutant is a derivative of the soft white winter wheat ‘Luke’ (CItr 14586), which was developed by the Washington State Agricultural Research Center in 1970 with the pedigree ‘PI 178383’/2*‘Burt’(CItr 12696)//‘CItr 13438’. Centennial is a soft white spring wheat cultivar released by the Idaho Agricultural Experiment Station in 1990 with the pedigree ‘Cowbird sib’(PI unavailable)/‘Sterling’ (CItr 17859). Alpowa is a soft white spring wheat cultivar released by WSU in 1994 with the pedigree ‘Fielder’(CItr 17268)/‘Potam 70’(CItr 15388)//‘Walladay’(CItr 17759)/3/Walladay/Potam 70.
The following modified pedigree-bulk breeding method was used to advance early generation progeny. Bulked seed (30 g) from F1 plants, identified as SW2K067, was used to establish a 3.6-m2 F2 field plot in 2000. Seed from approximately 100 heads selected at random from individual F2 plants were bulked, and a 40-g subsample was used to establish a 7.2-m2 F3 field plot in 2001. Single heads of approximately 150 F3 plants were threshed individually to establish F3:4 head row families in 2002. F1 progeny were advanced at the WSU Plant Growth/Wheat Research Facility on the WSU Campus in Pullman, WA. F2 and F4 progeny were advanced in field nurseries at Pullman, WA, whereas F3 progeny were advanced at the Lind Dryland Experiment Station in Lind, WA.
Following selection among F4 rows for general adaptation, resistance to stripe rust, plant height, and grain appearance, seed from 30 to 50 plants within each selected head row were bulk harvested to obtain F3:5 seed for early generation quality assessment. A 50-kernel subsample of each selected headrow was analyzed for kernel hardness using a Perten single kernel characterization system (SKCS) (American Association of Cereal Chemists, 2000). Samples with acceptable soft white wheat kernel characteristics were retained and evaluated for break and potential flour yield using a modified break flour mill (Micro-mill) designed for small samples (Seeborg and Barmore, 1957).
Selections with high flour extraction rates were advanced to grain yield assessment trials. Four F4 headrow selections were individually advanced to a nonreplicated field trial in Pullman, WA, and grown in 7.4-m2 plots in 2003. Resulting grain was evaluated for yield, grain volume weight, grain protein concentration, disease resistance, and milling and baking quality.
Using seed generated in a nonreplicated field trial, Whit was evaluated in replicated field trials for 15 site-years in preliminary (two locations), state (five locations), tri-state (six locations), and western regional (two locations) trials from 2004 through 2008 in low (<380 mm average annual precipitation), intermediate (380–460 mm average annual precipitation), and high precipitation zones (>460 mm average annual precipitation) and under irrigation in Washington State. The same size plot area and data collection strategy were used for all replicated field trials in either a randomized complete block design (four replications) (2004–2005) or a general alpha lattice design (three replications) (2006–2008) (Mason et al., 2003). Two of the original four F4 headrow selections were advanced to preliminary replicated yield trials in Pullman (high rainfall zone) and Moses Lake (irrigated), WA, in 2004, and state replicated trials at Pullman, Lind (low rainfall zone), Dusty (intermediate rainfall zone), Fairfield (high rainfall zone), and Moses Lake, WA (irrigated), in 2005. One line, designated S0300100U, was selected on the basis of 2005 data to be tested on a regional basis and assigned the new identification number of WA008008 in 2006. From 2006 to 2007, WA008008 was evaluated in the Tri-State Regional Nursery, which was established at nine locations each year in Washington, Oregon, and Idaho, in both rainfed and irrigated environments. Additionally, WA008008 was entered in the Washington State University Extension Uniform Cereal Variety Testing Program and tested in 2006, 2007, and 2008 at 16, 17, and 15 locations, respectively, throughout eastern Washington. WA008008 also was evaluated in the 2007 and 2008 Western Regional Nursery Trials.
Since 2003, WA008008 was evaluated for end-use quality by the USDA–ARS Wheat Genetics, Quality, Physiology, and Disease Research Unit, Pullman, WA, utilizing approved AACC methods (American Association of Cereal Chemists, 2000). WA008008 was evaluated by the Pacific Northwest Wheat Quality Council in 2006.
WA008008 was tested for stripe rust resistance in naturally infected field trials conducted by the USDA–ARS, Wheat Genetics, Quality, Physiology, and Disease Research Unit, Pullman, WA, on the Whitlow Farm near Pullman and Mt. Vernon in breeding nurseries from 2004 to 2006 and on the Spillman, Plant Pathology, and Whitlow farms near Pullman, WA, in 2006 and 2007, and in various breeding nurseries throughout eastern Washington from 2004 to 2007. Greenhouse seedling tests for stripe rust resistance were conducted in 2006 and 2007 under low-temperature cycles (diurnal temperatures gradually changing from 4 to 20°C; Chen and Line, 1992), whereas adult-plant stage resistance was tested at high temperatures (diurnal temperature cycle gradually changing from 10 to 35°C; Chen and Line, 1995).
Breeder seed of WA008008 (Whit) was produced as a reselection, on the basis of phenotypic uniformity, of 2100 F3:9 head rows grown under irrigation in Othello, WA. Selected headrows (5% were discarded) were bulked at harvest, resulting in the production of 922 kg of Breeder seed.
Data generated in 2004 and 2005 field trials were analyzed as a randomized complete block, whereas data from 2006 to 2008 were analyzed using the general lattice (ALS) procedure in Agrobase Generation 2 version 18.3.1 (Agronomix Software, Inc., Winnipeg, Canada). Since four major wheat producing regions with distinct agroclimatic conditions are present in Washington State, data were analyzed across locations within regions instead of over all locations. Location means and ranks from 2006 to 2008 were generated using the arithmetic mean of the ALS adjusted mean. The arithmetic means and ALS adjusted means were subjected to analysis of variance, and breeding lines were advanced based on excellent performance within each location, across locations within a region, and across regions within a year. Once Whit was selected for release, final data analysis only used entries common to the trials across all years. End-use quality data were analyzed by the Student's paired t test procedure (Cochran and Cox, 1957).
Characteristics
Whit is an intermediate-height, semidwarf soft white spring wheat cultivar. It has lax, tapering, erect inflorescence with tan awns and tan glumes that are long in length and medium in width, with wide, square shoulders and medium acuminate beaks. Whit has ovate kernels that are white, soft, and mottled. Seed of Whit has a midsize germ with a shallow crease, rounded cheeks, and a short, noncollared brush. Whit lacks anthocyanin pigmentation in the coleoptile, displays a semi-erect juvenile plant growth habit, and is green in color with a recurved, twisted, waxy flag leaf at Feekes growth stage 10.0 (Large, 1954). The stem of Whit lacks anthocyanin pigmentation, a waxy bloom is absent, the last internode of the rachis is semisolid, the auricle lacks pigmentation, pubescence is absent, and the peduncle is erect with an average length of 32 cm. The heading date of Whit was statistically (P < 0.05) earlier than ‘Louise’ (PI 634865; Kidwell et al., 2006) by 2 d, earlier than Alpowa by 4 d, and similar to Nick (Table 1 ). Whit was similar to or taller than Nick and statistically (P < 0.05) shorter than both Louise and Alpowa by 5 to 10 cm (Table 1). As precipitation levels increased, the height differential between Whit and Alpowa or Louise also increased (data not shown).
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On the basis of results from controlled environment insect screening trials conducted at the University of Idaho and natural field infestations from 2005 to 2008, Whit is resistant (95%) to Hessian fly biotypes E, F, and GP. On the basis of pedigree and natural field infestation ratings from Pullman, WA, Whit is susceptible to the Russian wheat aphid [Diuraphis noxia (Mordvilko)].
Agronomic Performance
When data were averaged over 15 site-years of evaluation in breeding nurseries, Whit produced significantly higher grain yields than Louise and ‘Alturas’ (PI 620631; Souza et al., 2004), another partial waxy soft white wheat (Table 2
). Average grain volume weight of Whit was similar to Louise and Alturas in these breeding trials (Table 2).
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End-Use Quality
Personnel at the USDA–ARS Western Wheat Quality Laboratory in Pullman, WA, assessed the end-use quality of Whit using grain produced in 26 breeding and commercial variety testing trials in Washington from 2004 through 2007. Louise, Alpowa, and Alturas were used as checks in these evaluations. Grain protein content and flour protein of Whit were similar to Alpowa and Alturas and were significantly (P < 0.01) higher than Louise (Table 3
). Flour yield and break flour yield of Whit were significantly (P < 0.01) higher than Alpowa and Louise and similar to Alturas (Table 3). Whit had significantly (P < 0.01) higher flour ash content than Alpowa, Alturas, and Louise (Table 3). The milling score of Whit was similar to Alpowa but significantly (P < 0.01) lower than Alturas and Louise (Table 3). Whit was similar to Alpowa, Alturas, and Louise for mixograph water absorption (Table 3). The cookie diameter for Whit was significantly (P < 0.01) larger than Alpowa, similar to Alturas, and significantly (P < 0.01) smaller than Louise (Table 3). Limited data (n = 3) indicate that Whit (1295 cm3) was similar to Louise (1315 cm3) for sponge cake volume. Flour swelling volume indicates that Whit has partial waxy starch type (Table 3). This attribute does not affect wheat quality potential from the cookie and cake perspective, but for noodle products, partial waxy varieties have a distinct advantage for noodles with soft bite texture, such as Japanese udon (Baik et al., 2003).
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Availability
Foundation seed of Whit 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. Small quantities of seed may be obtained for research purposes by contacting the National Plant Germplasm System. U.S. Plant Variety Protection status for this cultivar is pending.
Acknowledgments
We greatly appreciate the dedicated assistance of the following support personnel who assisted with field testing, quality assessment, and disease screening during the development of this cultivar: Tracy Harris (WSU), Dave Wood (USDA–ARS), Kelley Richardson (USDA–ARS), and Dennis Schotzko (University of Idaho). We also thank Dr. Craig Morris, USDA–ARS Wheat Genetics, Quality, Physiology, and Disease Research Unit, Pullman, WA, and John Burns, WSU Extension Agronomist, for providing access to facilities, equipment, and personnel for conducting end-use quality and agronomic evaluations, respectively. We are grateful to the Washington State Grain Alliance and the Washington State Agriculture Research Center for providing funding for this research.
Footnotes
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.
Received for publication January 5, 2009.
References
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