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Successful stand establishment is prerequisite for optimum crop yields. In some low-precipitation zones, wheat (Triticum aestivum L.) is planted as deep as 200 mm below the soil surface to reach adequate soil moisture for germination. To better understand the relationship of coleoptile length and other seed characteristics with emergence from deep planting (EDP), we evaluated 662 wheat cultivars grown around the world since the beginning of the 20(th) century. Coleoptile length of collection entries ranged from 34 to 114 mm. A specialized field EDP test showed dramatic emergence differences among cultivars ranging from 0-66% by 21 days after planting (DAP). Less than 1% of entries had any seedlings emerged by 7 DAP and 43% on day 8. A wide range of EDP within each coleoptile length class suggests the involvement of genes other than those controlling coleoptile length. Emergence was correlated with coleoptile length, but some lines with short coleoptiles ranked among the top emergers. Coleoptiles longer than 90 mm showed no advantage for EDP and may even have a negative effect. Overall, coleoptile length accounted for only 28% of the variability in emergence among entries; much lower than the 60% or greater reported in previous studies. Seed weight had little correlation with EDP. Results show that EDP is largely controlled by yet poorly understood mechanisms other than coleoptile length.

Wheat ( Triticum aestivum L.) is the most widely-grown crop in the Mediterranean semi-arid (150–400 mm) cropping zones of both southern Australia and the inland Pacific Northwest (PNW) of the United States of America (United States). Low precipitation, low winter temperatures and heat and drought conditions during late spring and summer limit wheat yields in both regions. Due to rising temperatures, reduced autumn rainfall and increased frost risk in southern Australia since 1990, cropping conditions in these two environments have grown increasingly similar. This presents the opportunity for southern Australian growers to learn from the experiences of their PNW counterparts. Wheat cultivars with an obligate vernalization requirement (winter wheat), are an integral part of semi-arid PNW cropping systems, but in Australia are most frequently grown in cool or cold temperate cropping zones that receive high rainfall (>500 mm p.a.). It has recently been shown that early-sown winter wheat cultivars can increase water-limited potential yield in semi-arid southern Australia, in the face of decreasing autumn rainfall. Despite this research, there has to date been little breeding effort invested in winter wheat for growers in semi-arid southern Australia, and agronomic research into the management of early-sown winter wheat has only occurred in recent years. This paper explores the current and emerging environmental constraints of cropping in semi-arid southern Australia and, using the genotype × management strategies developed over 120 years of winter wheat agronomy in the PNW, highlights the potential advantages early-sown winter wheat offers growers in low-rainfall environments. The increased biomass, stable flowering time and late-summer establishment opportunities offered by winter wheat genotypes ensure they achieve higher yields in the PNW compared to later-sown spring wheat. Traits that make winter wheat advantageous in the PNW may also contribute to increased yield when grown in semi-arid southern Australia. This paper investigates which specific traits present in winter wheat genotypes give them an advantage in semi-arid cropping environments, which management practices best exploit this advantage, and what potential improvements can be made to cultivars for semi-arid southern Australia based on the history of winter wheat crop growth in the semi-arid Pacific Northwest.

This article is an overview of recent advances in dryland cropping in the region of the Inland Pacific Northwest of the United States (PNW) that receives <300 mm annual precipitation. The climate of the region is Mediterranean‐like with wet winters and dry summers. For the past 130 yr, monocrop 2‐yr winter wheat (Triticum aestivum L.)–fallow (WW–F) has been the dominant rotation practiced on >90% of rainfed cropland throughout this region. Rapid advances in technology in the past several decades and the realities of dryland farm economics prompted most farmers to expand their land area and adopt conservation tillage and no‐tillage practices. Three relatively new crops have gained some foothold in the past decade. These crops are winter pea (WP) (Pisum sativum L.), winter canola (WC) (Brassica napus L.), and winter triticale (WT) (X Triticosecale Wittmack). Like WW, all three of these “new” winter crops need to be planted in late August–early September into carryover soil moisture after a 13‐ to 14‐mo fallow period to achieve optimum yield potential. Researchers and farmers have experimented with a multitude of spring‐planted crops but, to date, all have shown high year‐to‐year variability in yield and none have been economically viable in the long term. The focus of this paper is to summarize major research conducted on WP, WC, and WT, as well as farmers’ attitudes on the potential of these three winter crops for wheat‐based rotations in the PNW drylands.

Triticale (X Triticosecale Wittmack) is a cereal feed grain grown annually worldwide on 4.2 million ha. Washington is the leading state for rainfed (i.e., non-irrigated) triticale production in the USA. A 9-year dryland cropping systems project was conducted from 2011 to 2019 near Ritzville, WA to compare winter triticale (WT) with winter wheat (Triticum aestivum L.) (WW) grown in (i) a 3-year rotation of WT-spring wheat (SW) -no-till summer fallow (NTF) (ii) a 3-year rotation of WW-SW-undercutter tillage summer fallow (UTF) and (iii) a 2-year WW-UTF rotation, We measured grain yield, grain yield components, straw production, soil water dynamics, and effect on the subsequent SW wheat crop (in the two 3-year rotations). Enterprise budgets were constructed to evaluate the production costs and profitability. Grain yields averaged over the years were 5816, 5087, and 4689 kg/ha for WT, 3-year WW, and 2-year WW, respectively (p < 0.001). Winter triticale used slightly less water than WW (p = 0.019). Contrary to numerous reports in the literature, WT never produced more straw dry biomass than WW. Winter wheat produced many more stems than WT (p < 0.001), but this was compensated by individual stem weight of WT being 60% heavier than that of WW (p < 0.001). Spring wheat yield averaged 2451 vs. 2322 kg/ha after WT and WW, respectively (p = 0.022). The market price for triticale grain was always lower than that for wheat. Winter triticale produced an average of 14 and 24% more grain than 3-year and 2-year WW, respectively, provided foliar fungal disease control, risk reduction, and other rotation benefits, but was not economically competitive with WW. A 15–21% increase in WT price or grain yield would be necessary for the WT rotation to be as profitable as the 3-year and 2-year WW rotations, respectively.

Seedling emergence (SE) is an essential trait in wheat (Triticum aestivum L.) that allows desirable stand establishment even when adequate seed-zone soil moisture is present at depths of 10 cm or greater. The SE trait bestows several other advantages, including lodging resistance and improved water use efficiency. The aim of this study was to understand the genetic basis of SE. It has previously been reported that the cultivar Spinkcota has a high rate of SE and Bounty 309 has a slow rate of SE. An F2 population of 190 plants from a cross between these two parents was developed and evaluated for coleoptile length (CL) and in a specialized field SE test. The population was genotyped by simple sequence repeat (SSR) and genotyping-by-sequencing (GBS) for genetic mapping and marker discovery of the two traits. The GBS analysis was performed using 128,848,348 sequence reads with an average of 671,085 per F2 plant. From a total of 2,639 raw SNPs discovered in the F2 population, 243 high-quality SNPs along with 68 SSR markers were utilized to construct a genetic linkage map of wheat spanning 5,532.9 cM on the 21 chromosomes. Using this map, eight QTLs linked to CL and SE were detected on chromosomes 1A, 1B, 2B, 3A, and 7D. Bioinformatic dissection of the intervals under these QTLs on the wheat whole-genome sequence led to the identification of ~ 60 genes. Validated markers may enhance the understanding of this critical trait and provide a basis for marker-assisted selection.

Farmers in Mediterranean climate regions are increasingly growing canola (Brassica napus L.) in wheat (Triticum aestivum L.)‐based systems to break soil‐borne pathogen disease cycles, control weeds, and enhance crop marketing opportunities. A 6‐year rainfed cropping systems experiment was conducted near Ritzville, Washington USA from 2015 to 2021. The objective was to compare performance of winter and spring canola, winter triticale (× Triticosecale Wittmack) (WT), and winter wheat (WW) and measure their effects on soil water dynamics and subsequent performance of spring wheat (SW). Overwinter soil water gain in canola stubble was significantly reduced compared to water gain in WT and WW stubble. The more winter precipitation, the greater the differences in soil water among treatments in early spring. There was a trend in all years for diminished overwinter soil water gain in canola stubble. Averaged over years, grain yield of SW was 1940, 2340, and 2210 kg/ha grown on canola, WT, and WW stubble, respectively (p = 0.045). Coefficients of determination from regression analysis conducted each year showed a high correlation between water content in the 180 cm profile in early spring and SW grain yield, except in one year of extreme drought. This paper provides a first report in a Mediterranean climate region of decline in wheat grain yield after canola versus after a cereal crops, primarily due to reduced overwinter soil water storage. Core Ideas Canola is an important rotation crop in rainfed wheat‐based rotations. We conducted a 6‐year study to determine performance of spring wheat grown after canola, triticale, and wheat. Overwinter soil water storage was significantly reduced in canola stubble versus the stubble of triticale and wheat. Soil water at time of planting was closely correlated with spring wheat grain yield.

Insufficient stand establishment of winter wheat (Triticum aestivum L.) is a major problem in the low-precipitation (<300 mm annual) dryland summer fallow region of the inland Pacific Northwest, USA. Low seed zone water potential, deep planting depths with 15 cm or more soil covering the seed, and soil crusting caused by rain before seedling emergence frequently impede winter wheat stands. A 2-yr study involving laboratory, greenhouse, and field components was conducted to determine seed priming effects on winter wheat germination, emergence, and grain yield. Two cultivars were used because of their strong (Edwin) and moderate (Madsen) emergence capabilities. Germination rate was measured in the laboratory by 44 treatment combinations (two cultivars × three priming durations × seven priming media + two checks). Germination rate differed between cultivars as well as by priming duration, priming media, and concentration of priming media. The most promising laboratory treatments were advanced to greenhouse and field experiments where emergence and grain yield (field only) were measured in 10 treatments (two cultivars × four priming media + two checks) from wheat planted deep with 16 cm of soil covering the seed. In the greenhouse, seed primed in potassium chloride (KCl), polyethylene glycol (PEG), and water led to enhanced emergence of Madsen, but not of Edwin, compared with checks. Rate and extent of seedling emergence was greater for Edwin compared with Madsen irrespective of priming media in three of four field plantings at Lind, WA. None of the seed priming media benefited field emergence or subsequent grain yield in either cultivar compared with checks. Overall, results suggest that seed priming has limited practical worth for enhancing emergence and yield of winter wheat planted deep into summer fallow.

In the semiarid dryland wheat (Triticum aestivum L.) region of the U.S. inland Pacific Northwest, winter canola (WC) (Brassica napus L.) is an economically viable rotation crop. Winter canola produces marketable end‐products while improving soil health and disrupting pest and disease cycles. Although annual production of WC in Washington State has increased in the recent decade, little regional fertility research has been conducted. As a result, WC is commonly fertilized in a manner similar to hard red spring wheat. Compared with wheat, WC has a deep and aggressive tap root system that can grow to depths of 180 cm to reach nutrients and water. Thus, WC requires a different N management strategy than wheat. Field experiments were conducted to evaluate the influence of soil residual N and fertilizer N application rate (range, 0–240 kg N ha−1) and timing (fall, spring, or split fall/spring) on WC yield and oil and protein concentrations. The study took place over a 2‐yr period at seven locations across four agroecological classes. There was no yield response to N rate at six of the seven sites due to canola's high N uptake efficiency and the soils’ high residual N (92–224 kg inorganic N ha−1) after wheat–fallow. Increasing N rates and split or spring application resulted in lower oil/protein ratios. In addition, maximum yields correlated with total available water. Therefore, N management for WC should be based on soil test residual + mineralizable N, total available water, and end‐use quality.

Climate-friendly best management practices for mitigating and adapting to climate change (cfBMPs) include changes in crop rotation, soil management and resource use. Determined largely by precipitation gradients, specific agroecological systems in the inland Pacific Northwestern U.S. (iPNW) feature different practices across the region. Historically, these farming systems have been economically productive, but at the cost of high soil erosion rates and organic matter depletion, making them win-lose situations. Agronomic, sociological, political and economic drivers all influence cropping system innovations. Integrated, holistic conservation systems also need to be identified to address climate change by integrating cfBMPs that provide win-win benefits for farmer and environment. We conclude that systems featuring short-term improvements in farm economics, market diversification, resource efficiency and soil health will be most readily adopted by farmers, thereby simultaneously addressing longer term challenges including climate change. Specific ‘win-win scenarios’ are designed for different iPNW production zones delineated by water availability. The cfBMPs include reduced tillage and residue management, organic carbon (C) recycling, precision nitrogen (N) management and crop rotation diversification and intensification. Current plant breeding technologies have provided new cultivars of canola and pea that can diversify system agronomics and markets. These agronomic improvements require associated shifts in prescriptive, precision N and weed management. The integrated cfBMP systems we describe have the potential for reducing system-wide greenhouse gas (GHG) emissions by increasing soil C storage, N use efficiency (NUE) and by production of biofuels. Novel systems, even if they are economically competitive, can come with increased financial risk to producers, necessitating government support (e.g., subsidized crop insurance) to promote adoption. Other conservation- and climate change-targeted farm policies can also improve adoption. Ultimately, farmers must meet their economic and legacy goals to assure longer-term adoption of mature cfBMP for iPNW production systems.

Ecological instability and low resource use efficiencies are concerns for the long-term productivity of conventional cereal monoculture systems, particularly those threatened by projected climate change. Crop intensification, diversification, reduced tillage, and variable N management are among strategies proposed to mitigate and adapt to climate shifts in the inland Pacific Northwest (iPNW). Our objectives were to assess these strategies across iPNW agroecological zones and time for their impacts on 1) winter wheat (Triticum aestivum L.) productivity, 2) crop sequence productivity and 3) N fertilizer use efficiency. Region-wide analysis indicated that WW yields increased with increasing annual precipitation, prior to maximizing at 520 mm yr-1 and subsequently declining when annual precipitation was not adjusted for available soil water holding capacity. While fallow periods were effective at mitigating low nitrogen (N) fertilization efficiencies under low precipitation, efficiencies declined as annual precipitation exceeded 500 mm yr-1. Variability in the response of WW yields to annual precipitation and N fertilization among locations and within sites supports precision N management implementation across the region. In years receiving less than 350 mm precipitation yr-1, WW yields declined when preceded by crops rather than summer fallow. Nevertheless, WW yields were greater when preceded by pulses and oilseeds rather than wheat across a range of yield potentials, and when under conservation tillage practices at low yield potentials. Despite the yield penalty associated with eliminating fallow prior to WW, cropping system level productivity was not affected by intensification, diversification, or conservation tillage. However, increased fertilizer N inputs, lower fertilizer N use efficiencies, and more yield variance may offset and limit the economic feasibility of intensified and diversified cropping systems.