How high is our confidence in High Cotton? 

Although High Cotton appeared in the Oklahoma State University wheat variety trials for the first time in 2023, it had been tested in statewide yield trials within the OSU wheat breeding program for the past six years. Just think about the conditions the Oklahoma wheat crop was exposed to during that period: a debilitating April freeze in 2018, high-yielding conditions in 2019 and 2020 but with some pushback from spring freezes and leaf spotting diseases, severe stripe rust and moderate leaf rust in 2021, and the droughts of 2022 and 2023.

 

That six-year period captured the essence of Oklahoma wheat production and provided the Wheat Improvement Team the necessary window to foresee performance in the immediate future. Against this backdrop, the yield rankings of High Cotton versus its expected primary competitor, Showdown, are shown in Table 1. If you want to know how high the High Cotton variety will go in yield competitiveness, just ask Showdown. Its average yield rank, among approximately 35 lines per year, was 8.7, whereas High Cotton’s average yield rank in head-to-head competition was 3.0. An average yield rank of 3 is unusually good. A line that ranks first for yield across all years would have an average yield rank of 1, an unrealistic expectation. 

 

Table 2 provides WIT’s most recent valuation of High Cotton’s trait portfolio against that of Showdown. A few key differences should be noted. First, Hessian fly resistance is lacking in High Cotton, though testing is limited to greenhouse trials. Second, High Cotton provides an anticipated earlier time to first bite, combined with average winter dormancy retention. This combination should lead to higher wheat grazing preference by dual-purpose wheat producers. Thus, the higher yield ceiling in grain-only systems and overall better graze-ability of High Cotton will likely draw broad appeal among Oklahoma wheat producers. 

 

 

OSU CoAXium wheat is right on schedule 

For the first time, 131 AXigen lines believed to carry two mutations conferring quizalofop-P-ethyl herbicide resistance were tested in multi-site, single-replicate trials at Stillwater, Yukon, Lahoma, Chickasha, and Tipton in 2023. The trials at Stillwater and Lahoma received a single application of the herbicide Aggressor (commercial name for quizalofop-P-ethyl) at a 2x dose, with a methylated seed oil surfactant. All lines in this set of trials were produced on an accelerated schedule using double haploidization (DH) at Heartland Plant Innovations in Manhattan, Kansas, and seed increase at Yuma, Arizona, prior to 2023. Crescent AX and AP18 AX were included as replicated checks in the 2023 field trials. 

 

Among the 131 original DH lines, 31 lines were advanced for further testing in 2024 based on desirable herbicide tolerance, grain yield, test weight, canopy hygiene, leaf rust resistance, maturity pattern, plant stature, straw strength, and grazing tolerance, along with DNA marker analysis for other immeasurable traits, in 2023. Yield and test weight of the selections were equal to or better than the two checks (Table 2), making it conceivable that one or more of these 31 lines will have the potential to be commercialized. Of particular interest is that resistance to leaf rust, barley yellow dwarf, or Hessian fly is already identified in several of these lines, though currently available CoAXium varieties do not feature these traits. 

 

^aStillwater, Lahoma Chickasha, and Tipton, OK

^bStillwater and Lahoma, OK; 2x rate of Aggressor with MSO

^cStillwater and Chickasha, OK

^d31 candidate lines

 

Common OSU wheat varieties present in the pedigrees of the 31 lines include Baker’s Ann, Smith’s Gold, and Uncharted, and other elite experimental lines not released. All 31 lines will be thoroughly tested in 2023-2024 for yield, quality, Hessian fly resistance, and resistance to multiple diseases common to Oklahoma. Of those, 22 candidates were placed under preliminary increase by Oklahoma Foundation Seed Stocks in fall 2023 to avoid any delay in commercial seed availability once a final candidate has been named and approved sometime in 2025. 

 

Sights are reset on the Oklahoma panhandle 

As WIT reported in the 2022 Partners in Progress wheat report, selection for wheat streak mosaic (WSM) and Triticum mosaic (TM) resistance has been largely accomplished by genetic markers and validated with field screening in artificially curl mite-inoculated nurseries near Mead, Nebraska, in cooperation with the University of Nebraska–Lincoln. Validation of agronomic potential in a natural field environment in the Oklahoma panhandle has been sorely lacking since 2020. Without this validation, selection could not be applied for the background genetics surrounding the targeted disease resistance traits. 

 

The 2022-2023 crop year provided an outstanding opportunity for field-based selection in the panhandle to couple with our wealth of knowledge of genetic markers and disease phenotypes. This nursery was established near Balko, Oklahoma, and within two miles of the OSU Extension wheat variety performance tests conducted annually at Balko. The 2023 dryland breeding trial near Balko contained 2,460 yield-estimable plots (a nursery size like others in the state), with an average yield of 51 bu/ac and 60 lbs/bu test weight. 

 

Summarized in Table 4 are six advanced lines with the highest probability for a panhandle-targeted release in the next two years. Additional testing at Balko in 2023-2024 will allow WIT to better differentiate these candidates for agronomic and end-use quality potential, aside from their well-documented reactions to the WSM/TM complex. This germplasm is expected to soon provide effective and unique alternatives or replacements for Breakthrough, a WSM/TM-resistant variety released by OSU Ag Research in 2020. No other variety exists in the southern and central plains that carries gene Wsm1, which when alone, is preferred over gene Wsm2 for protection against WSM/TM but encumbered with greater yield drag. Gene Wsm3 is also non-existent in HRW varieties. Its origination in a wheat wild relative means it will also show some degree of yield drag. 

 

 

Ox wheat varieties carry unprecedented dough strength 

Three HRW varieties were approved in early 2023 by OSU Ag Research for commercial seed and grain production under more stringent protection afforded by pending utility patents. Their unique functionality, typically revealed by a recording dough mixer, such as a farinograph, is manifested in very high mixing tolerance and higher water absorption of the dough. According to the Wheat Marketing Center in Portland, Oregon, all three varieties may serve as blending wheats, i.e., as ingredient flours, to increase the strength of commodity HRW wheat intended for products requiring greater gluten strength, such as pan bread, noodles, and frozen dough. To deliver this value from seed producer to end user – and thus for Oklahoma wheat producers to capture part of this value – the wheat and derived flour must be protected throughout the wheat supply chain and maintained separate from commodity HRW channels with a vastly different expectation of functionality. 

 

The value of the Ox varieties to the baking industry may derive from the displacement of certain additives or dough improvers or vital wheat gluten commonly seen on a sandwich bread label. Removal of these components may have a secondary benefit of longer shelf life and stability. A better product with a cleaner label with less food loss brings value. Farm Strategy, OSU’s partner in the post-release handling of these varieties, has been the key to determining their value proposition and locating entities in the food industry who wish to seize upon it. 

 

From the 2023 crop, approximately 65,000 bushels of Paradox and Breadbox were destined for commercial milling with another 30,000 bushels targeted for organic flour milling. In 2024, about 4,500 acres are planted with these Ox varieties. Growth in production acreage of this germplasm will depend in part on end-use optimization – on the go – within the milling and baking industries. There is no HRW precedent on which optimization may be determined. This simultaneous occurrence of adjustments in the milling industry and seed multiplication within the seed industry has truly complicated the launch of the Ox varieties. 

 

Whereas all three varieties have been heavily scrutinized within the OSU wheat breeding program for field performance since 2017, the 2023 season presented the first opportunity for the public to see Paradox and Firebox in head-to-head competition with contemporary HRW germplasm in the OSU Extension wheat variety performance tests. Breadbox was not included due to its agronomic similarity to Paradox with the main distinction of providing resistance to the wheat soilborne mosaic/wheat spindle streak mosaic complex. 

 

Varieties within a given column containing the same letter are not significantly different (p=0.05).

 

Across eight locations in 2023, Paradox exceeded Firebox in grain yield (Table 5), but Firebox had the higher test weight by almost one pound. Both showed yielding ability commensurate with contemporary HRW germplasm. Firebox produced higher wheat protein than Paradox, but both are well within the expected range of HRW wheat. The launch of this germplasm will represent a first-time opportunity to change the face of HRW wheat production and utilization in the bulk of the southern plains – from Texas to southern Kansas – with no step backward in agronomic performance. 

 

Doing the two-step with Doublestop CL+ 

A breeding project was initiated in 2013 to transfer barley yellow dwarf resistance from OK12621 to Doublestop CL+ via marker-assisted selection (MAS) for the Thinopyrum-derived gene Bdv2 now present in the variety Uncharted. Other desirable traits from OK12621 (Duster/ P961341A3-2-2) were targeted, such as leaf rust resistance, Hessian fly resistance, grazing tolerance, and canopy stay-green but without the benefit of MAS (Figure 1). Simultaneously, we wanted to create progenies differentiated by the presence or absence of two AHAS genes conferring imazamox herbicide resistance. The presence of two AHAS genes constitutes the CL+ trait. Hence, two closely related families of several hundred progenies were produced, hereby distinguished as CL- (no AHAS genes) and CL+ (two AHAS genes). 

Figure 1. Crossing scheme used to produce progenies from Doublestop CL+, either with (CL+) or without (CL-) imazamox herbicide tolerance. The recipient parent used on both sides of the cross was OK12621, which provided novel genes for resistance to Barley yellow dwarf (Bdv2), leaf rust (Lr34ab), and Hessian fly (TaHf-A1). Other traits expressed in the progenies are shown on the corresponding side of the cross with Doublestop CL+. 

 

Fast-forward to 2023 where this two-step breeding process remains active but now essentially only two CL- progenies and one CL+ progeny remain. The latter will be thoroughly tested in 2024, along with another CL+ experimental line called OK198417C, with a decision pending to release one or both CL+ lines in 2024. The two CL- progenies, named OK16107133-19-3 and OK16107133-19-4, have challenged us in the past few years to arrive at a clear consensus as to which one should be launched. Each line, as usual, has its faults, but their shortcomings wash out in a tied ball game that is now deep into extra innings. This is best visualized with direct trait comparisons summarized in Tables 6 and 7. 

 

 

^aAPR, adult-plant resistance, determined in a greenhose

^bStripe rust responses determined in Oklahoma, Kansas, and Washington

^cNumeric scale equates to highly resistant (0) to highly susceptible (5 or 6)

^dS, susceptible; I, Intermediate; MR, moderately resistant; R, resistant; VR, very resistant

 

OK16107133-19-3 and OK16107133-19-4 provide a definitive bump up in yield over Doublestop CL+, but at a 1-2-pound loss in test weight relative to Doublestop CL+’s consistently high test weight. Noted improvements exist also for Hessian fly resistance (GP biotype) and stripe rust resistance. Data are insufficient to confidently call resistance to the new Texas Hessian fly biotype(s). Based on marker analysis, OK16107133-19-3 carries the novel gene for BYD resistance from Thinopyrum, whereas OK16107133-19-4 does not; however, their BYD reactions are alike and similar to Doublestop CL+. All considered, OK16107133-19-4 is a tenuous favorite moving into the final year of pre-release evaluation in 2023-2024, given its slightly higher yield tendency and slightly better in-field responses to leaf rust. Both candidates have mellow dough strength. End-use quality may be the deciding factor in the final decision to release. 

 

Figure 2. In-field visual comparison of Doublestop CL+ and its two advanced line progenies, OK16107133-19-3 and OK16107133-19-4, at Lahoma in May 2023. Note the difference in chaff color emerging between parent and offspring and that the offspring are about 4-6 inches shorter than Doublestop CL+.