Brandon Research and Development Centre

A review of studies conducted in a range of plant species indicated the importance of an adequate supply of P during early crop growth and outlined plant adaptations for accessing early season P. Potential implications of the requirement for early season P in the development of management practices to optimize P supply for crop production were also discussed. Phosphorus plays a critical role in energy reactions in the plant. Deficits can influence essentially all energy requiring processes in plant metabolism. Phosphorus stress early in the growing season can restrict crop growth, which can carry through to reduce final crop yield. Deficiencies during early growth generally have a greater negative influence on crop productivity than P restrictions imposed later in growth. Plants respond to P deficiencies by adaptations that increase the likelihood of producing some viable seed. The adaptations increase the ability of the plant to access and accumulate P and include modification of rhizosphere pH, diversion of resources to root production, increased root proliferation in high-P regions, and formation of associations with vesicular arbuscular mycorrhizae. Plants differ in strategies adopted and in efficiency of P absorption. Effective nutrient management for optimal crop production must ensure that P is supplied to the crop in adequate amounts early in the growing season. It is important that we develop methods to accurately predict the early season P supply from the soil, in order to avoid either over-fertilization or crop deficiencies. Practices to provide adequate P early in plant growth include placement of P fertilizer in or near the seed-row and maintenance of adequate concentrations of plant-available P in the soil through a long-term nutrient management strategy. Other possible management practices could include enhancement of seed concentrations of P, manipulation of tillage system and crop sequence, improved activity of mycorrhizae and other microbiological agents such as Penicillium bilaii to increase phytoavailability of soil P, or genetic selection of crops with an enhanced ability for early season uptake of P from both soil and fertilizer sources. As plants differ in relative abilities to access P from the soil and fertilizer applications, nutrient management must be tailored to the specific crop, in order to optimize P supply and crop productivity. By restricting fertilizer applications to situations where P supply is limiting to crop production and by use of effective P management practices, we can optimize the economic of fertilizer use while avoiding negative impacts on environmental quality. Key words: Crop, fertilizer, placement, nutrient, management

Root-zone salinization presents a challenge to plant productivity that is effectively countered by salt-tolerant halophytic plants, but unfortunately, much less successfully by major crop plants. The way in which salt affects plant metabolism is reviewed. Cellular events triggered by salinity, namely salt compartmentation, osmotic adjustment and cell wall hardening are connected to the whole plant responses, namely leaf necrosis, altered phenology and ultimately plant death. The roles of ion exclusion and K/Na discrimination in mediating crop response to salt appear to be central to the tolerance response, but they are by no means essential. The processes involved in regulating ion uptake at the membrane level are considered. Recent work elucidating the interaction between calcium and salinity tolerance is reviewed. Key words: Cell growth, cell turgor, ion regulation, K + /Na + discrimination, osmotic adjustment, salt tolerance

Plants require adequate P from the very early stages of growth for optimum crop production. Phosphorus supply to the crop is affected by soil P, P fertilizer management and by soil and environmental conditions influencing P phytoavailability and root growth. Phosphorus uptake in many crops is improved by associations with arbuscular mycorrhizal fungi. Cropping system and long-term input of P through fertilizers and manures can influence the amount and phytoavailability of P in the system and the development of mycorrhizal associations. Optimum yield potential requires an adequate P supply to the crop from the soil or from P additions. Where early-season P supply is low, P fertilization may improve P nutrition and crop yield potential. Alternately, under low-P conditions, encouragement of arbuscular mycorrhizal associations may enhance P uptake by crops early in the growing season, improving crop yield potential and replacing starter fertilizer P applications. Soil P supply that exceeds P requirements of the crop may preclude mycorrhizal development. To encourage arbuscular mycorrhizal association, threshold levels of soil solution P that restrict mycorrhizal development must not be exceeded. Sustainable P management practices must be applied both in conventional and in alternative biologically based agricultural systems. Key words: Microbiology, fertility, colonization

Information on responses of weeds to various soil fertility levels is required to develop fertilizer management strategies as components of integrated weed management programs. A controlled environment study was conducted to determine shoot and root growth response of 23 agricultural weeds to N fertilizer applied at 0, 40, 80, 120, 180, or 240 mg kg−1 soil. Wheat and canola were included as control species. Shoot and root growth of all weeds increased with added N, but the magnitude of the response varied greatly among weed species. Many weeds exhibited similar or greater responses in shoot and root biomass to increasing amounts of soil N, compared with wheat or canola. With increasing amounts of N, 15 weed species showed a greater increase in shoot biomass, and 8 species showed a greater increase in root biomass, compared with wheat. Ten weed species exhibited increases in shoot biomass similar to that exhibited by canola, and five weed species showed greater increases in root biomass than did canola, as N dose was increased. All crop and weed species extracted > 80% of available N at low soil N levels. At the highest N dose, 17 of 23 weed species took up similar or greater amounts of soil N than did wheat, and 6 weed species took up N in amounts similar to that taken up by canola. These findings have significant implications as to how soil fertility affects crop–weed competition. The high responsiveness of many weed species to N may be a weakness to be exploited through development of fertilizer management methods that enhance crop competitiveness with weeds.

The daily and within-day variation in udder temperature was monitored in dairy cows (n = 10) using infrared thermography (IRT). The initial assessment and prediction of udder surface temperature variation would hopefully form the basis for future development of an early detection method for mastitis. Our initial objective was to determine the magnitude and pattern of udder temperature variation. To accomplish this, we measured daily fluctuations in udder temperature and the influence of environmental factors upon these values in non-mastitic cows. Udder temperature rose significantly after an exercise period (P < 0.05). Within-day monitoring of udder temperature demonstrated there was a distinct circadian rhythm. Lag regression analysis showed that previous daily udder temperatures together with environmental temperature parameters could successfully predict current udder temperature with a high degree of accuracy. The variation between predicted and actual udder temperature was within the detectable range for an inflammatory response. Infrared thermography shows promise in its application if coupled with environmental temperature monitoring as an early detection method for mastitis. Key words: Thermography, dairy cattle, environment, temperature

The objectives were to determine if a diet enriched in alpha-linolenic acid (ALA) would influence ovarian function, early embryo survival, conception rates, and pregnancy losses in lactating dairy cows. Beginning 28 d before breeding, Holstein cows (55 +/- 22 d postpartum; mean +/- SD) were assigned to diets supplemented with either rolled flaxseed (FLAX; 56.7% ALA, n = 62) or rolled sunflower seed (SUNF; 0.1% ALA, n = 59) to provide approximately 750 g of oil/d. Diets continued for 32 d after timed artificial insemination (TAI, d 0) following a Presynch/Ovsynch protocol. Barley silage- and barley grain-based TMR were formulated to meet or exceed National Research Council requirements. Metabolizable protein and net energy for lactation concentrations were similar in the 2 diets. Based upon a mean dry matter intake of 22 kg/d, cows fed FLAX or SUNF consumed > 410 g or < 1 g of ALA, respectively. Pregnancy was confirmed by ultrasound 32 d after TAI. Nonpregnant cows were placed on a second Ovsynch regimen and reinseminated 42 d after first TAI, and received oilseeds for 32 d after second TAI. Relative to prediet levels, FLAX increased the ALA content of milk by 187%. Ovarian ultrasonography was performed in 8 cows per diet; the mean diameter of ovulatory follicles was larger in cows fed FLAX compared with SUNF (16.9 +/- 0.9 vs. 14.1 +/- 0.9 mm), but follicle number, corpus luteum size, and plasma progesterone concentrations remained unaffected. Presumptive conception (progesterone < 1 ng/mL on d 0 and > 1 ng/mL on d 21) rates to first TAI were greater in FLAX than in SUNF (72.6 vs. 47.5%). Pregnancy losses were lower in cows fed FLAX (9.8%) compared with those fed SUNF (27.3%). Including flaxseed in the ration of dairy cows increased the size of the ovulatory follicle and reduced pregnancy losses.

ABSTRACT Ingestion in food is a major pathway of cadmium (Cd) exposure for humans. It is therefore desirable to ensure that Cd concentrations in crops that enter the human food chain do not increase to levels that may lead to health risks. Phosphorus fertilizers contain Cd as a contaminant at levels varying from trace amounts to as much as 300 mg Cd kg–1 of dry product and therefore can be a major source of Cd input to agricultural systems. Fertilization can influence Cd accumulation in crops by direct Cd addition and by indirect effects on soil pH, ionic strength, Zn concentration, rhizosphere chemistry, microbial activity, and plant growth. Cadmium will accumulate in the soils from fertilizer applications if the amount of Cd added in fertilizer is greater than the amount of Cd removal, whether in harvested crop removal or other loss pathways such as leaching, erosion, or bioturbation. Assessment of the impact of fertilizer management practices on the risk of Cd toxicity to the soil ecosystem and the risk of movement of Cd into the human diet must consider both the direct influence of Cd addition as a fertilizer contaminant and the indirect effects of fertilizer application on Cd phytoavailability. Cadmium accumulation in soils and crops can be minimized by adoption of management practices that improve fertilizer-use efficiency while minimizing Cd input.

A series of soil N mineralization indices were evaluated using 153 samples chosen from arable fields representing a wide range of soil types, management practices, and climatic zones. These indices were compared against potentially mineralizable N (N 0 ) determined by aerobic incubation at 25°C for 24 wk. Three different pools of mineralizable N were recognized: Pool I, the mineralization flush on rewetting in the first 2 wk; Pool II, gross N mineralization in the next 22 wk; and Pool III, the potentially mineralizable N, predicted from the fitted curve, that did not mineralize during the incubation period. Pool I was highly correlated with CaCl 2 –N, KCl‐NH 4 , and KCl‐NO 3 , which extract soil mineral N. Pool III was significantly correlated with ultraviolet absorbance of NaHCO 3 extract at 205 and 260 nm (NaHCO 3 –205 and −260), Illinois soil N test, NaOH direct‐distillation N, and hot KCl‐NH 4 , which mostly extract hydrolyzable organic N. All indices except the mineral N based methods, phosphate‐borate buffer method, and microbial biomass C were significantly related to N 0 , which includes both Pools II and III. The NaHCO 3 –260, NaOH direct‐distillation N, and Illinois soil N test had the highest correlations with N 0 ( r 2 = 0.74, 0.61, and 0. 51, respectively). Total organic C and N represent long‐term changes in N 0 and were almost as effective in predicting N 0 as the other indices ( r 2 = 0.60 and 0.67, respectively); however, they would be expected to be less sensitive to short‐term changes in N 0 due to changes in soil management practices and history.

Boreal forests and wetlands are thought to be significant carbon sinks, and they could become net C sources as the Earth warms. Most of the C of boreal forest ecosystems is stored in the moss layer and in the soil. The objective of this study was to estimate soil C stocks (including moss layers) and rates of accumulation and loss for a 733 km 2 area of the BOReal Ecosystem‐Atmosphere Study site in northern Manitoba, using data from smaller‐scale intensive field studies. A simple process‐based model developed from measurements of soil C inventories and radiocarbon was used to relate soil C storage and dynamics to soil drainage and forest stand age. Soil C stocks covary with soil drainage class, with the largest C stocks occurring in poorly drained sites. Estimated rates of soil C accumulation or loss are sensitive to the estimated decomposition constants for the large pool of deep soil C, and improved understanding of deep soil C decomposition is needed. While the upper moss layers regrow and accumulate C after fires, the deep C dynamics vary across the landscape, from a small net sink to a significant source. Estimated net soil C accumulation, averaged for the entire 733 km 2 area, was 20 g C m −2 yr −1 (28 g C m −2 yr −1 accumulation in surface mosses offset by 8 g C m −2 yr −1 lost from deep C pools) in a year with no fire. Most of the C accumulated in poorly and very poorly drained soils (peatlands and wetlands). Burning of the moss layer in only 1% of uplands would offset the C stored in the remaining 99% of the area. Significant interannual variability in C storage is expected because of the irregular occurrence of fire in space and time. The effects of climate change and management on fire frequency and on decomposition of immense deep soil C stocks are key to understanding future C budgets in boreal forests.

Treatment of liquid swine manure (LSM) offers opportunities to improve manure nutrient management. However, N2O fluxes and cumulative emissions resulting from application of treated LSM are not well documented. Nitrous oxide emissions were monitored following band-incorporation of 100 kg N ha(-1) of either mineral fertilizer, raw LSM, or four pretreated LSMs (anaerobic digestion; anaerobic digestion + flocculation: filtration; decantation) at the four-leaf stage of corn (Zea mays L.). In a clay soil, a larger proportion of applied N was lost as N2O with the mineral fertilizer (average of 6.6%) than with LSMs (3.1-5.0%), whereas in a loam soil, the proportion of applied N lost as N2O was lower with the mineral fertilizer (average of 0.4%) than with LSMs (1.2-2.4%). Emissions were related to soil NO3 intensity in the clay soil, whereas they were related to water-extractable organic C in the loam soil. This suggests that N2O production was N limited in the clay soil and C limited in the loam soil, and would explain the interaction found between N sources and soil type. The large N2O emission coefficients measured in many treatments, and the contradicting responses among N sources depending on soil type, indicate that (i) the Intergovernmental Panel on Climate Change (IPCC) default value (1%) may seriously underestimate N2O emissions from fine-textured soils where fertilizer N and manure are band-incorporated, and (ii) site-specific factors, such as drainage conditions and soil properties (e.g., texture, organic matter content), have a differential influence on emissions depending on N source.

Pangenomes are collections of annotated genome sequences of multiple individuals of a species1. The structural variants uncovered by these datasets are a major asset to genetic analysis in crop plants2. Here we report a pangenome of barley comprising long-read sequence assemblies of 76 wild and domesticated genomes and short-read sequence data of 1,315 genotypes. An expanded catalogue of sequence variation in the crop includes structurally complex loci that are rich in gene copy number variation. To demonstrate the utility of the pangenome, we focus on four loci involved in disease resistance, plant architecture, nutrient release and trichome development. Novel allelic variation at a powdery mildew resistance locus and population-specific copy number gains in a regulator of vegetative branching were found. Expansion of a family of starch-cleaving enzymes in elite malting barleys was linked to shifts in enzymatic activity in micro-malting trials. Deletion of an enhancer motif is likely to change the developmental trajectory of the hairy appendages on barley grains. Our findings indicate that allelic diversity at structurally complex loci may have helped crop plants to adapt to new selective regimes in agricultural ecosystems. A pangenome analysis of 76 wild and domesticated barley accessions in combination with short-read sequence data of 1,315 barley genotypes indicates that allelic diversity at structurally complex loci may have helped crop plants to adapt to agricultural ecosystems.

The world swine population produces about 1.7 billion tonnes of liquid manure annually. At an application rate of 20 tonnes per hectare, this could fertilize about 85 million hectares of land annually. Storage and disposal of this material presents a challenge to producers because of the potential for environmental pollution. However, because swine manure contains essential plant nutrients, use of swine manure as a soil amendment for crop production is a practical method to solve the disposal problem. The composition and effectiveness of swine manure as a source of plant nutrients depends on several factors including type of ration fed, housing system, method of manure collection, storage and handling. Research has shown that manure application increased soil N, P, K, Ca, Mg and Na. However, heavy or excessive application of manure increased leaching of NO 3 -N, P and Mg. Swine manure is reported to be effective in increasing the yields of cereals, legumes, oilseeds, vegetables and pastures, and in increasing plant nutrient concentration, especially N, P and K. The efficient use of swine manure can be an agronomically and economically viable management practice for sustainable crop production in temperate regions such as the Canadian prairies where the swine industry is expanding rapidly.

The effects of five diets, with 12–18% crude protein (CP) and 6.6–10.8 g lysine per MJ digestible energy (DE), on live performance, carcass and meat quality criteria were recorded for 90 pigs in a split-plot design involving male castrates and gilts and three replicates, with three pigs per pen. The five diets, differing in the ratio of barley:soybean meal, were fed as pellets, ad libitum from 25 to 98 kg liveweight. A balanced incomplete block design was used with four additional pens to assess the palatability of the diets offered in pairs sequentially over 10 wk. As expected, castrates had a higher intake (2817 vs. 2580 g d −1 ) and daily gain (888 vs. 800 g d −1 ) than gilts and were relatively fatter except when fed the lowest CP diet. While an increase in dietary CP, or lysine:energy ratio, led to significant improvements in growth rate, gain:feed and lean content, there was a concomitant reduction in marbling and sensory appeal. The palatability study suggested that both castrates and gilts tended to favour the intermediate diets (8.8 and 10.1 g lysine per MJ DE) over the others, with a preference for higher CP diets in the early growth period. Estimates of the lysine:DE ratio for maximum live performance indicated that gilts should receive &gt; 10.8 in the pre- − 50 kg period and approximately 10.1 g lysine per MJ DE thereafter. For castrates, the respective ratios were 10.8 and 8.8 g per MJ DE. Split-sex feeding, with gilts receiving about 2% higher dietary protein levels than castrates, was also favoured by the estimates of economic benefits for the producer. Key words: Pigs, lysine, digestible energy, carcass, pork quality

Abstract Cadmium accumulation in crops presents a potential risk to human health. To understand the difference between dicotyledonous and monocotyledonous species in respect of Cd accumulation, and to develop fertilizer management practices to minimise Cd uptake, a growth chamber study was conducted to evaluate the interactive effects of Cd concentration in phosphate and Zn fertilizer on Cd uptake in flax ( Linum usitatissimum L) and durum wheat ( Triticum turgidum L). Cadmium concentration was higher in flax than durum wheat shoots. Cadmium concentration was lower and Zn concentration higher in the flax seed and durum wheat grain than in the root, shoot or straw of both species. These results suggest that flax has comparatively ineffective barriers discriminating against the transport of Cd from the root to the shoot via the xylem, and that both crops may restrict Cd translocation to the seed/grain via the phloem. Commercial grade monoammonium phosphate (NH 4 H 2 PO 4 ) or triple superphosphate (Ca(H 2 PO 4 ) 2 ) produced higher seed Cd concentrations than did reagent grade P in flax but not in durum wheat. Application of P significantly decreased seed/grain Zn concentration and increased seed/grain Cd concentration. Zinc addition at 20 mg Zn kg −1 soil with P decreased seed/grain Cd concentration (average 42.2% for flax, 65.4% for durum wheat), Cd accumulation (average 37.2% for flax, 62.4% for durum wheat) and Cd translocation to the seed/grain (average 20.0% for flax, 34.5% for durum wheat) in both crops. These results indicate that there is an antagonistic effect of Zn on Cd for root uptake and distribution within the plant. Copyright © 2004 Society of Chemical Industry

Pulse crops (annual grain legumes such as field pea, lentil, dry bean, and chickpea) have become an important component of the cropping system in the northern Great Plains of North America over the last three decades. In many areas, the intensity of damping-off, seedling blight, root rot, and premature ripening of pulse crops is increasing, resulting in reduction in stand establishment and yield. This review provides a brief description of the important pathogens that make up the root rot complex and summarizes root rot management on pulses in the region. Initially, several specific Fusarium spp., a range of Pythium spp., and Rhizoctonia solani were identified as important components of the root rot disease complex. Molecular approaches have recently been used to identify the importance of Aphanomyces euteiches on pulses, and to demonstrate that year-to-year changes in precipitation and temperature have an important effect on pathogen prevalence. Progress has been made on management of root rot, but more IPM tools are required to provide effective disease management. Seed-treatment fungicides can reduce damping-off and seedling blight for many of the pathogens in this disease complex, but complex cocktails of active ingredients are required to protect seedlings from the pathogen complex present in most commercial fields. Partial resistance against many of the pathogens in the complex has been identified, but is not yet available in commercial cultivars. Cultural practices, especially diversified cropping rotations and early, shallow seeding, have been shown to have an important role in root rot management. Biocontrol agents may also have potential over the long term. Improved methods being developed to identify and quantify the pathogen inoculum in individual fields may help producers avoid high-risk fields and select IPM packages that enhance yield stability.

Field microplot studies were conducted under zero-till conditions on a fine sandy loam (Orthic Black Chernozem) to determine the effect of the urease inhibitors N-(n-butyl) thiophosphoric triamide (NBPT) and ammonium thiosulphate (ATS) on volatile losses of NH 3 from urea and urea ammonium nitrate (UAN). Two studies were conducted, one in late May and one in early August. Losses of NH 3 were measured on days 1, 2, 4 and 7 after fertilizer application, using ammonia traps. Ammonia losses were higher in the second study due to the higher soil temperatures and lower soil moisture later in the growing season. Total NH 3 losses increased in the order Control &lt; UAN + NBPT = Urea + NBPT &lt; UAN + ATS = UAN &lt; Urea. Total loss of NH 3 during the 7 d after fertilizer application was higher from urea than from UAN, particularly in the first study. Use of NBPT was effective in reducing NH 3 volatilization from both UAN and urea during 7 d after fertilizer application while use of ATS had little influence on NH 3 loss from UAN. The NBPT may delay losses by slowing the hydrolysis of urea, but volatilization may persist for a longer duration. The delay in urea hydrolysis could allow time for rainfall to carry the urea into the soil, thus reducing total volatilization losses from surface fertilizer application. Key words: N-(n-butyl) thiophosphoric triamide, zero tillage

Using competitive crops and cultivars can be an important integrated weed management (IWM) tool, useful in both conventional and low-external-input (LEI) farming systems. Barley is considered a competitive crop, but cultivar competitiveness varies. There are two aspects of cultivar competitive ability; the ability to compete (AC) and the ability to withstand competition (AWC). However, the relationship between these aspects has not been addressed in barley. A study was conducted to explore aspects of barley cultivar competitive ability with oats, and to examine the feasibility of ranking cultivars based on either, or both, AWC and AC. Field trials were undertaken in 2001 and 2002 to determine cultivar competitive ability for 29 barley cultivars commonly grown on the Canadian prairies. Cultivars were selected from semidwarf and full height, hulled and hull-less, 2- and 6-row, and feed and malt classes. Yield loss ranged from 6 to 79% while weed seed return ranged from 10 to 83% of gross yield. As a class, semidwarf and hull-less cultivars were less competitive than full height and hulled cultivars, respectively. However, considerable variation existed within these classes, and an absolute relationship between class membership and competitive ability did not exist. Ability to withstand competition was significantly correlated with ability to compete, but correlation coefficients were not strong enough to attempt reliable co-selection within a breeding program. Ability to compete was a more consistent measure of competitive ability than AWC. Ranking barley cultivar competitive ability would make it a valuable IWM tool for farmers and extension personnel.

Tillage practices may affect the active fraction of soil organic N. As part of a national project to examine soil management and environmental controls on the active fraction of organic N, this study examined the effects of no‐till (NT) and conventional tillage (CT) systems on the quantity of potentially mineralizable soil N (N 0 ) and mineralizable N pools, and the potential to detect changes in these pools using N availability indices. Preplant soil samples from the top 15 cm were collected from four long‐term tillage experiments at Swift Current, SK; Woodslee, ON; L'Acadie, QC; and Agassiz, BC. Potentially mineralizable N was determined by aerobic incubation at 25°C and periodic leaching for 24 wk. The N 0 was greater under NT than under CT, but only at Swift Current. The labile and intermediate mineralizable N pools were significantly higher under NT than under CT at three of the four sites. The stable mineralizable N pool and the mineralization rate coefficient ( k ) were greater under NT than under CT at only one of the four sites. Adoption of NT influenced the quality of the active organic N fraction at three sites, as indicated by an increased proportion of mineralizable N in the more labile N pools. Among tested indices of N availability, KCl‐extractable NH 4 –N, NaOH‐extractable N, Illinois Soil N Test, phosphate‐borate buffer extractable N, and particulate organic C were most sensitive to tillage‐induced changes in the active organic N fraction. Tillage‐induced changes in the size and quality of the active organic N fraction may influence soil N supply and should be considered in optimizing fertilizer N management.

Soil N mineralization is an important N contributor to crop uptake; however, the soil and climatic controls on soil mineralizable N are poorly understood. Soil samples from 56 sites across Canada were used to determine the potential to predict the size of mineralizable N pools through simple soil properties and through simple climatic indices and the re_clim indices. Mineralizable N was determined using a 24‐wk aerobic incubation at 25°C. Potentially mineralizable N (N 0 ) was estimated by curve fitting using N mineralized from 2 to 24 wk, and Pool I, a labile mineralizable N pool, was determined as the N mineralized in the first 2‐wk period. Soil properties were relatively effective predictors of N 0 with soil organic N (SON) and sand explaining 40 and 34% of the variability, respectively. Particulate organic matter N (POM‐N) and pH explained 18 and 25%, respectively, of the variability in Pool I. Simple climate normals were generally poor predictors of pool size except for potential evapotranspiration (PET), which predicted 24% of the variability in Pool I. The re_clim indices, normally applied to the activity of soil decomposers and applied here for the first time to explain soil mineralizable N pool size variability, performed better than simple climate indices and explained up to 26% of the variation in N 0 By including soil and climatic parameters in a multiple regression model, it was possible to explain about 63 and 40% of the variability in N 0 and Pool I, respectively, across a wide range of arable soils in Canada.

Abstract Traditionally, the oat crop ( Avena sativa ) has been neglected in a number of respects, cultivated in cropping areas not optimal for wheat, barley or maize. In recent years the interest in oats has increased, particularly because of its dietary benefits and therapeutic potential for human health. The uniqueness and advantages of naked oats over other popular cereals, due to its potentially valuable nutritional composition, have been well studied and reported, opening new market “niches” for oats. Despite the well‐documented benefits, the status of the oat crop is still fragile, due to many reasons. The area cultivated for the oat crop is much less compared with other cereals, and therefore commercial efforts in oat breeding are less. Oat groat yield is lower than other cereals such as wheat and the nutritious uniqueness has not been reflected in agreeable market prices. The same price still exists for both naked and conventional/covered oats in the world grain market. The absence of visible market competitiveness, and some of the oat biological drawbacks, including low grain yield, keeps the oat crop as a lower profitability minor crop. This review is intended to analyse and summarise main achievements and challenges in oat genetics, agronomy and phytopathology to find possible ways of oat improvement and future perspectives for oat breeding.