Evaluation of Waxy Wheat Cultivars Planted in the

Fall and the Spring

O. Steven Norberg

Malheur County Extension Service

Clinton C. Shock, Lamont D. Saunders, and Eric P. Eldredge

Malheur Experiment Station

Oregon State University

Ontario, OR

Steve Petrie, Jeron Chatelain, and Karl Rhinhart

Columbia Basin Agricultural Research Center

Pendleton, OR

Introduction

Sustainable wheat production throughout the Pacific Northwest (PNW) is important to the economic viability of the region. One method of increasing the value of wheat and the potential return to growers is through the introduction of high value traits. Waxy starch is such a trait. Waxy starch absorbs more water, swells to a larger volume, and is crispier when baked than normal starch. Because of these characteristics the snack food industry may prefer waxy starch for the production of items such as "power bars" and breakfast foods.

Normal wheat starch has two components, amylopectin (75 percent) and amylose (25 percent). Amylose is an essentially linear molecule of α-(1→4)-linked glucose, while amylopectin is a highly branched molecule of α-(1→4)-linked glucose chains connected by α-(1→6)-linkages (Fig. 1). A full waxy wheat has no amylose. Partially waxy wheat has a mix of amylose (1-24 percent) and amylopectin (76-99 percent). Currently there are some cultivars of waxy wheat in commercial production. However, little is known about how these and other experimental waxy wheat lines will perform in the Treasure Valley of Oregon and Idaho.

A research project was initiated in the fall of 2006 to evaluate the agronomic performance and characteristics of several waxy wheat varieties under irrigation. Similar research under dryland conditions was conducted at the Columbia Basin Agricultural Research Center (CBARC) under the direction of Steve Petrie, and will be reported in their Special Report for 2007.

Methods

The study was established in the fall of 2006 at the Malheur Experiment Station in Ontario, Oregon. The soil type at the site was an Owyhee silt loam. The field was fallow the previous year. Seedbed preparation included disking, cultivating, and furrowing. Soil samples were collected prior to fall tillage and showed 128 lb/acre nitrogen (N) in the top 2 ft of soil. Urea was applied in the spring at 75 lb/N per acre on February 23, 2007. The wheat was planted with a plot drill on 30-inch beds with 3 rows per bed. Plot size was 5 by 20 ft.

The treatment design was a split-plot design. Three planting dates were the main plots and consisted of October 19, 2006 (normal fall seeding), November 10, 2006 (dormant seeding), and March 6, 2007 planting dates. The subplot treatment was wheat variety and consisted of 14 wheat varieties. These 'Waxy Pen', 'IDO629', 'IDO630', seven hard red advanced lines from Nebraska (Robert Graybosch, ARS; '459', '114', '115', '205', '315', '395', and '489'), and the check varieties 'Stephens', 'Goetze', 'Alturas', and 'WB936'. The experimental design was a randomized complete block design with three replications.

Field management included furrow irrigations on October 30 (Oct. 19 planting only), April 19, May 10, May 24, June 5, June 19, and July 5 (Mar. 6 planting only). Weeds were controlled with Buctril^® at 1 qt/acre on March 15 and Bronate^® at 1 qt/acre on April 3.

Agronomic characteristics measured were emergence, spring plant vigor, plant height, and lodging. Emergence data were collected by counting plants in a 3-ft section of the middle row in the bed on November 21, March 2, and March 23 for the October 19, November 10, and March 6 plantings, respectively. Spring plant vigor was evaluated on April 27 using a scale of 1-10, with 10 being excellent. Plant height was measured in four places in the plot using a measuring stick on June 13. Lodging was estimated on July 12 by determining the percentage of the plot leaning more than 45 degrees.

Plots were trimmed to size with a sickle bar mower to help eliminate border effects after heading. At maturity, wheat was harvested using a Hege combine on July 20. Response variables were compared using ANOVA and least significant differences at the 5 percent probability, LSD (0.05). Differences between response variables should be equal to or greater than the corresponding LSD (0.05) value before any variety is considered different from another in this trial.

Results

Data, averaged over all planting dates, were analyzed and a significant planting date by variety interactions were found. Therefore, each planting date was further analyzed individually.

"Normal" Fall Seeding, October 19

Stephens, a soft white winter check variety, had the highest average yield, 154.3 bu/acre (Table 1). It was significantly higher than all the other varieties and lines evaluated at this planting date. Among the waxy wheat varieties, IDO630, IDO629, Waxy Pen, and the experimental lines 459, 114, and 315 all performed well. IDO630 had the highest waxy wheat yield at 124.5 bu/acre. While these waxy varieties and lines performed well, they did have significantly less yield than Stephens, 29.8-42.3 bu/acre less. Similarly, the waxy wheat varieties also showed no yield advantage compared to the winter check variety Goetze or the spring check variety Alturas.

Dormant Seeding, November 10

Goetze, a soft white winter wheat check variety, had the highest average yield at 141.3 bu/acre (Table 2). The varieties Stephens, Alturas, and Waxy Pen all had similar yields compared to Goetze. Among the waxy wheat varieties and lines, only Waxy Pen, IDO630, and IDO629 performed well. The winter waxy lines from Nebraska did not perform well in this planting and several also had severe lodging due to their height.

Spring Seeding, March 6

Waxy Pen had the highest average yield at 123.9 bu/acre (Table 3). However, the spring check varieties Alturas and WB936 had similar yields compared to Waxy Pen. Both IDO629 and IDO630 performed poorly compared to the other varieties.

When comparing waxy varieties, one thing to keep in mind is that Waxy Pen, like it's parent 'Penawawa', is susceptible to stripe rust. IDO630 and IDO629 are considered moderately resistant to stripe rust. If a producer was planting in the spring, Waxy Pen would be the waxy variety of choice if stripe rust is not a problem. If it is a concern, IDO629 or IDO630 would be a better choice for a waxy wheat variety.

Conclusion

Waxy wheat can be successfully grown in the Treasure Valley region of Oregon and Idaho. Among the waxy wheat varieties evaluated, Waxy Pen and IDO630 performed the most consistently across the planting dates. However, Waxy Pen like its parent Penawawa, is susceptible to stripe rust. This makes IDO630, which is moderately resistant to stripe rust, a better overall waxy wheat variety for this region.

There was a significant yield reduction when fall planting IDO630 waxy wheat compared to the soft white winter check variety Stephens. Yield reductions ranged from 29.8 bu/acre in the "normal" fall planting to 5.7 bu/acre in the dormant fall planting. The lower yields of waxy wheat imply that there must be a premium for waxy wheat before growers will choose to plant it. Fall planted spring wheat also increases risk and needs compensation. Planting IDO630 as a dormant seeding improved spring vigor rating and increased yield 5 bu/acre over the October planting. Many acres in the Treasure Valley in eastern Oregon are often dormant seeded as irrigation water is turned off and soils are typically very dry at planting.

In the spring, yield reductions for IDO630 and IDO629 compared to spring check variety Alturas were 13.3 and 9.1 bu/acre, respectively.

Further research needs to be conducted to confirm these results. For waxy wheat to be at its full potential in this region, a high yielding, disease resistant winter waxy wheat needs to be developed.

Acknowledgements

This research was supported by a grant from the Oregon Wheat Commission. The seven advanced winter waxy wheat lines were supplied by Dr. Robert Graybosch, ARS Research Geneticist (Plants) Lincoln, Nebraska. Waxy Pen was supplied by Dr. Craig Morris, ARS Supervisory Research Chemist, Pullman, Washington. IDO629 and IDO630 were supplied by Ed Souza with the University of Idaho.

Figure 1. Molecular arrangement of amylose and amylopectin in wheat starch.