As droughts become longer and more intense, impacts on terrestrial primary productivity are expected to increase progressively. Yet, some ecosystems appear to acclimate to multiyear drought, with constant or diminishing reductions in productivity as drought duration increases. We quantified the combined effects of drought duration and intensity on aboveground productivity in 74 grasslands and shrublands distributed globally. Ecosystem acclimation with multiyear drought was observed overall, except when droughts were extreme (i.e., ≤1-in-100-year likelihood of occurrence). Productivity losses after four consecutive years of extreme drought increased by ~2.5-fold compared with those of the first year. These results portend a foundational shift in ecosystem behavior if drought duration and intensity increase, from maintenance of reduced functioning over time to progressive and profound losses of productivity when droughts are extreme.

Intercropping, the growing of more than one crop at the same time within the same land area, could be a sustainable method of crop production in semiarid regions, which could increase biodiversity, and productivity and quality of crops compared to monocultures. This may be of significance under limited N, such as in organic agriculture, and could be an alternative to green manure. An organic study was conducted in the semiarid Canadian Prairie in drier than average years (2017–2018) to determine if intercropping legumes with non‐legumes could reduce weeds and increase grain yield and quality of crops at different seeding rate ratios. Intercrops examined were lentil ( Lens culinaris Medik.)–yellow mustard ( Sinapis alba L.), and field pea ( Pisum sativum L.)–oat ( Avena sativa L.), at three seeding rate ratios, and their respective monocultures. Weed density was lower in the pea–oat intercrop than the pea monoculture, while weed biomass was lower in the lentil–mustard intercrop than the lentil monoculture. Legumes, when intercropped even at monoculture ratios, had lower aboveground biomass and grain yield than their monocultures, with pea showing higher tolerance than lentil to competition with its companion. Total biomass and grain yield were accounted for mostly by the non‐legumes, which performed better than expected based on their seeding ratios. Mustard grown with lentil appeared to be more competitive than oat grown with pea. Grain weight of oat was higher in all intercrops with pea than in its monoculture, while grain protein of pea was higher when intercropped with oat than in its monoculture.

Abstract Background Genotype × environment interaction (GEI) slows genetic gains and complicates selection decisions in plant breeding programs. Forage breeding program seed sales often encompass large geographic regions to which the cultivars may not be adapted. An understanding of the extent of GEI in perennial, cool‐season forage grasses will facilitate improved selection decisions and end‐use in areas with harsh winters. Methods We evaluated the dry matter yield of nine meadow brome (Bromus biebersteinii Roemer & J. A. Schultes), nine orchardgrass (Dactylis glomerata L.), seven tall fescue (Lolium arundinaceum (Schreb.) Darbysh.), and 10 timothy (Phleum pratense L.) cultivars or breeding populations at seven high latitude and/or elevation locations in Canada and the United States from 2019 to 2021. Results For each of the species, we found significant differences among the genotypes for dry matter yield across environments and found significant levels of GEI. Using site regression analysis and GGE biplot visualizations, we then characterized the extent of the interactions in each species. Except for tall fescue, there was little evidence for the broad adaptation of genotypes across locations. Conclusions This research adds further evidence to the limitations of perennial, forage breeding programs to develop widely adapted cultivars and the need to maintain regional breeding efforts.

There has been a steady expansion in organic production in the Canadian Prairies because of higher consumer demand. Thus, increasing the sustainability of organic systems would be important. An organic trial was conducted in the semi-arid Prairies (2010-2015) with two tillage intensities (low vs. high) in a simplified [spring wheat (Triticum aestivum L.)-forage pea (Pisum sativum L.) green manure (GM)] and a diversified (spring wheat-oilseed-pulse-GM) rotation. In 2013-2015, the impact of these systems on root rot was examined on spring wheat, pulses, and GM crops. Several Fusarium spp. were more abundant in GM and pulses than spring wheat, suggesting that they could be a source of inoculum, especially of F. avenaceum (Fr.:Fr.) Sacc. (teleomorph Gibberella avenacea Cook), for Fusarium diseases in cereals including Fusarium head blight. Under different environments, tillage-rotation systems had an impact on root disease and fungal populations, some of which have biocontrol capabilities. There was no difference among systems for root rot in forage pea, while the low tillage-diversified rotation had the lowest root rot in spring wheat but was associated with more Fusarium spp. For all crops, most Fusaria were not associated with root rot severity. Cochliobolus sativus (Ito & Kurib.) Drechs. ex Dast. [anamorph Bipolaris sorokiniana (Sacc.) Shoemaker] accounted the most for root rot in spring wheat and was favored by intensive tillage and simplified rotations. The Shannon diversity index (H') of fungal species in spring wheat was higher in the diversified rotation under both tillage intensities than when spring wheat alternated with GM in the simplified rotation, especially under high tillage. In forage pea, H' was higher than in spring wheat, but did not differ among tillage-rotation systems.

Soil biota are critical drivers of plant growth, population dynamics, and community structure and thus have wide-ranging effects on ecosystem function. Interactions between plants and soil biota are complex, however, and can depend on the diversity and productivity of the plant community and environmental conditions. Plant-soil biota interactions may be especially important during stressful periods, such as drought, when plants can gain great benefits from beneficial biota but may be susceptible to antagonists. How soil biota respond to drought is also important and can influence plant growth following drought and leave legacies that affect future plant responses to soil biota and further drought. To explore how drought legacies and plant community context influence plant growth responses to soil biota and further drought, we collected soils from 12 grasslands varying in plant diversity and productivity where precipitation was experimentally reduced. We used these soils as inoculum in a growth chamber experiment testing how precipitation history (ambient or reduced) and soil biota (live or sterile soil inoculum) mediate plant growth and drought responses within an experimental plant community. We also tested whether these responses differed with the diversity and productivity of the community where the soil was collected. Plant growth responses to soil biota were positive when inoculated with soils from less diverse and productive plant communities and became negative as the diversity and productivity of the conditioning community increased. At low diversity, however, positive soil biota effects on plant growth were eliminated if precipitation had been reduced in the field, suggesting that diversity loss may heighten climate change sensitivity. Differences among species within the experimental community in their responses to soil biota and drought suggest that species benefitting from less drought sensitive soil biota may be able to compensate for some of this loss of productivity. Regardless of the plant species and soil origin, further drought eliminated any effects of soil biota on plant growth. Consequently, soil biota may be unable to buffer the effects of drought on primary productivity or other ecosystem functions as extreme events increase in frequency.

Costs of production and organic price premiums are defining factors influencing the economic viability of organic crop production systems. Different agronomic practices, such as crop rotation and tillage intensity, are known to affect the economic performance of the production systems. The aim of this study was to compare the impact of two crop rotation sequences (simplified and diversified) and two levels of tillage intensity (high and low) on the cost of production, gross return and gross margin of crops when grown under organic management in the semi-arid Brown soil zone of the Canadian Prairies. The 2-year simplified rotation sequence consisted of forage pea ( Pisum sativum L.) grown as a green manure followed by hard red spring wheat (HRSW) ( Triticum aestivum L.), while the 4-year diversified rotation sequence was forage pea green manure followed by flax ( Linum usitatissimum L.) or yellow mustard ( Sinapis alba L.), field pea or lentil ( Lens culinaris L.) and HRSW. Our hypothesis that a more diversified crop rotation would increase profitability over a traditional simplified crop rotation was supported by the findings. However, the findings did not support our hypothesis that reducing tillage intensity, and the combination of tillage reduction and diversified crop rotation through a synergetic response, would further enhance profitability. Analysis of the breakeven prices and breakeven yields for crops indicated the importance of adopting diversified crop rotations and choosing crops with high organic price premiums as means to maximize the long-term profitability of organic cropping systems.

Questions The relationships between biodiversity and ecosystem functioning (BEF) vary largely across natural ecosystems, with a unimodal, monotonous linear or no relationship. However, it remains unclear how BEF relationships vary under global change. Given future predicted changes in precipitation and nitrogen (N) deposition, it is crucial to determine how precipitation change and N deposition affect grassland biodiversity and productivity, and regulate their relationships. Location A Dry Mixed-Grass Prairie of western Canada. Methods We established a manipulative field experiment of increased precipitation (water addition with approximately 15% and 30% more monthly precipitation) and N addition (10 g/m(2)) using a randomized complete block design, including six treatments, each replicated five times (30 plots). We conducted vegetation sampling with a 1 m x 1 m quadrat in each plot from 2016 to 2017, to examine the individual and interactive effects of water and N addition on plant diversity, functional group composition, above- and below-ground productivity, and the diversity-productivity relationships. Results We found a positive linear diversity-above-ground biomass (AGB) relationship under increased precipitation, which was attributed to the water-induced increase in the abundance of forbs in the plant community, further promoting the positive effect of plant diversity on AGB. However, N addition caused a negative linear diversity-AGB relationship by increasing AGB and reducing plant diversity. The effects of N on diversity and productivity can be further strengthened under increased precipitation, which was due to the increase of C-3 rhizomatous grasses with high above- and below-ground biomass and the decrease of forbs with high richness. Conclusions Our results suggest that changes in functional group composition determine the plant species' diversity, productivity, and their relationships under increasing precipitation and N deposition, which has significant implications for understanding and modelling ecosystem productivity in the context of global change.

Many questions remain concerning the viability and productivity of seeding native legumes in the Canadian Prairies for forage production. Field research was conducted with four native legume species (Astragalus flexuosus, Dalea purpurea, Hedysarum boreale, and Vicia americana) to evaluate performance in Swift Current and Saskatoon, SK. The experimental design was a randomized complete block design with four replicates to evaluate legume–grass mixtures and monoculture performance, botanical composition, and effect of harvest dates (July and August) from 2016 to 2018. The native legume–grass mixtures performed differently at the sites, with greater foliar cover at Saskatoon but a greater proportion of legumes in mixtures at Swift Current. The mixtures had similar forage nutritive value as monoculture Bromus riparius, with legumes contributing 10% or less of the forage dry matter yield (DMY) at both sites. Astragalus flexuosus showed the greatest foliar cover and produced the greatest DMY in monoculture at both sites. Based on this study, native legumes would need to make up a larger proportion of forage dry matter yield to change the nutritional value of mixtures. In a subsequent seeding rate evaluation, the four legume species were planted at three seeding rates [300, 200, and 100 pure live seeds (PLS) per metre] and tested for DMY one year following establishment near Swift Current. Increasing seeding rates up to 300 PLS·m −1 corresponded with an increase in seedling density and foliar cover, but DMY was not affected. Additional research with A. flexuosus is needed to demonstrate its value as a forage.

Biodiversity drives ecosystem functioning across grassland ecosystems. However, few studies have examined how grazing intensity affects ecosystem multifunctionality (EMF) via its effects on plant diversity and soil microbial diversity in dry grasslands. We conducted a 12-year experiment manipulating sheep grazing intensity in a desert steppe of northern China. Through measuring plant species diversity, soil microbial diversity (bacteria diversity) and multiple ecosystem functions (i.e., aboveground net primary productivity, belowground biomass of plant community, temporal stability of ANPP, soil organic matter, moisture, available nitrogen and phosphorus, ecosystem respiration and gross ecosystem productivity), we aimed to understand how grazing intensity affected EMF via changing the diversity of plants and microbes. Our results showed that increasing grazing intensity significantly reduced EMF and most individual ecosystem functions, as well as the diversity of plants and microbes, while EMF and most individual functions were positively related to plant diversity and soil microbial diversity under all grazing intensities. In particular, soil microbial diversity in shallow soil layers (0-5 cm depth) had stronger positive correlations with plant diversity and EMF than in deeper soil layers. Furthermore, structural equation modeling (SEM) showed that grazing reduced EMF mainly via reducing plant diversity, rather than by reducing soil microbial diversity. Thus, plant diversity played a more important role in mediating the response of EMF to grazing disturbance. This study highlights the critical role of aboveand belowground diversity in mediating the response of EMF to grazing intensity, which has important implications for biodiversity conservation and sustainability in arid grasslands. (c) 2021 Elsevier B.V. All rights reserved.

Fungi play an essential role in regulating the functioning of terrestrial ecosystems and are sensitive to climate change factors. Climate change incidents, such as N deposition and altered precipitation, create abiotic stress regarding the water use efficiency of soil and nutrient limitation impacting the activity of soil fungi. This study aimed to examine the combined effects of N fertilization and altered precipitation on soil fungal diversity and composition in the desert steppe.

Intercropping with different crop species and different spatial patterns is suggested to lead to increased competition with weeds and reduced weed abundance and biomass. In this study, our objective was to explore the ability of multi-species annual forage crop mixtures to control weeds while providing productive forage. We utilized field and greenhouse trials to evaluate the impact of different crop mixtures and row spacing on weed control in the semi-arid Brown soil region of southwestern Saskatchewan, Canada. Seven different mixtures of up to eight annual forage crops were grown with row spacing of 15 or 30 cm in a replicated field trial. Weed abundance and biomass were significantly affected by crop species mixtures. Crop mixtures that contained radish and barley generally had higher weed suppression. Row spacing did not significantly impact weed abundance or biomass across the treatments. Results were similar over both years in spite of drastically different precipitation conditions. Forage production was significantly different between cropping mixtures in July in both years. The barley-radish mixture had the highest crop biomass in July, and this early crop production was linked to weed suppression because crop biomass had a significant effect on weed abundance and biomass in July, but not August. A greenhouse experiment was used to further evaluate the crops (i.e., barley and radish) that demonstrated the highest weed suppressive activity in the field trial. Crop identity and row spacing were both significant factors affecting weed and crop biomass production. Radish exhibited stronger control of common lamb's quarters (Chenopodium album) compared to barley, but the binary mixture of the two species produced the highest crop biomass and equivalent weed control compared to the radish monoculture. This research suggests that cropping with multiple species (particularly forage radish) may be an effective way to control weeds in semiarid environments.

Changes in nitrogen (N) and precipitation levels can substantially alter soil properties and plant growth, thereby altering soil microbial diversity and functionality. We used manipulated precipitation treatments (50% reduction, control, and plus 50%) and tested two N fertilization levels (control and plus 35 kg N ha−1 yr−1) from a 4-year field experiment to evaluate the effects on soil bacterial diversity, community composition, and N-cycle gene abundance. N additions significantly increased ammonia-oxidizing bacterial abundance (via AOB-amoA) but decreased denitrification genes (i.e., nirS and nosZ). Decreased precipitation significantly decreased the abundance of N-cycle genes (AOB-amoA, nirS, and nosZ), while increased precipitation conversely increased the abundance of these same genes. Decreased precipitation led to differences in the microbial community composition that favored drought resistance, indicating that plant-associated microbiomes may be able to modulate plant growth fitness in the context of extreme environmental conditions. N additions substantially altered soil bacterial communities, increasing the relative abundance of certain bacteria and of nitrification-related genes in a manner that depended on precipitation fluctuations. Differences in the bacterial community composition and N-cycle genes determined the functional response of a grassland ecosystem to decreased precipitation conditions, and therefore could affect the influence of N deposition on plant growth as well as the physical and chemical properties of the soil.

There is controversy over whether the addition of nitrogen (N) is the key to the rapid growth of Chinese rye grass Leymus chinensis (Trin.) Tzvel. in natural, semiarid grasslands. We investigated yearly impact of various N additions (0, 91, 183, and 274 kg N ha(-1)) on the relationships between nutrient traits (plant carbon [C], N, and phosphorous [P]), morphological traits (plant height, leaf number, leaf length, leaf width, stem length and stem diameter) and aboveground biomass in L. chinensis. Results showed that most of the growth characteristics of L. chinensis increased with N rate except for leaf number and stem length. Nitrogen addition increased aboveground biomass, plant height, leaf length and stem length of L. chinensis, which was related to high precipitation during the critical period for the growth of L. chinensis. Nitrogen addition increased the N concentration and N to P ratio of L. chinensis tissue, but decreased the C to N ratio in the leaf and stem of L. chinensis. Compared to the control, N addition increased C and N concentrations and the N to P ratio, but decreased P concentration and the C to N ratio.

In the Canadian Prairies, organic agriculture has traditionally relied on summer fallow and mechanical tillage for nutrient and pest management. More recently, there has been a substantial increase in the use of legume green manure, diversified crop rotations, and reduced tillage. The objectives of this study were to determine if diversified crop rotations and reduced tillage under organic management can maintain soil fertility and quality at adequate levels, keep weed populations at low levels, and foster healthy plants for sustainable and profitable production of annual crops. Earn 1.5 CEUs in Crop Management by reading this article and taking the quiz at https://www.certifiedcropadviser.org/education/classroom/classes/692 .

Core Ideas An organic field trial in the Brown soil zone examined tillage intensity in a simplified (wheat‐green manure) and a diversified (wheat‐oilseed‐pulse‐green manure) cropping system. Yield variation was explained more by precipitation and soil nitrate levels than by weed infestations. Wheat yields were higher under high than low tillage, and in the simplified than the diversified rotation. Protein concentration in wheat grain varied among years, and there was no negative association with yield. Based on observations in the wet years this trial was conducted, the low tillage treatment did not appear to be viable for more than a few years. Because of the increased consumer demand for organic products and expansion of organic production in the Canadian Prairies, development of organic cropping systems that help lower production costs and risks, while improving productivity and environmental sustainability is needed. A trial was conducted in the Brown soil zone (2010–2015) to examine tillage intensity (low vs. high) in a simplified (wheat [Triticum aestivum L.]‐green manure), and a diversified (wheat‐oilseed‐pulse‐green manure) cropping system. Above‐average precipitation in the years this trial was run resulted in high weed infestations and persistent increases in perennial weeds over time, especially under low tillage. Grain yield was highest at the beginning of the trial (2010 and 2011), and lowest in its final year (2015), which was drier than the rest. Yield variation was explained more by precipitation and soil nitrate levels than by weed infestations. Overall, wheat yields were higher under high than low tillage, and in the simplified than the diversified rotation. Over the duration of this trial, yields under low tillage averaged about three quarters of the yield in a nearby conventional zero‐till trial. Protein concentration in wheat grain varied among years, and there was no negative association with yield, which might be explained by the release of mineralized N throughout the growing season. Protein was similar or higher than the average for commercial conventional wheat in this area. Based on observations in the wet years this trial was conducted, the low tillage treatment did not appear to be viable for more than a few years.

Global climate change is expected to significantly influence soil respiration. When limited, rainfall and nitrogen (N) deposition strongly modify soil respiration in a broad range of biomes, but uncertainty remains with regards to the influence of the interactions of seasonal rainfall distribution and N deposition on soil respiration in an arid steppe. In the present study, we manipulated precipitation using V-shaped plexiglass gutters (minus 50%, control, and plus 50% treatments) and tested various N additions (control and plus 35 kg N ha(-1) yr(-1)) to evaluate their impact on soil respiration, measured using a Li-Cor 8100, in a desert steppe in China. Increased precipitation stimulated soil respiration by 26.1%, while decreased precipitation significantly reduced soil respiration by 10.8%. There was a significant increase in soil respiration under N addition at 11.5%. Statistical assessment of their interactions demonstrated that N supplementation strengthened the stimulation of soil respiration under increased precipitation, whereas decreased precipitation offset the positive impact of N addition and led to a reduction in soil respiration. Contrasting interannual precipitation patterns strongly influenced the temporal changes in soil respiration as well as its response to N addition, indicating that the desert steppe plant community was co-limited by water and N. Net primary productivity (aboveground and belowground) predominantly drove soil respiration under altered precipitation and N addition. As grasses are better equipped for water deficit due to their previous exposure to long periods without water, there could be a shift from forb to grass communities under drier conditions. These findings highlight the importance of assessing the differential impacts of plant traits and soil physiochemical properties on soil respiration under altered precipitation and N addition. (C) 2019 Published by Elsevier B.V.

Core Ideas A 6‐year organic field trial evaluated two tillage intensities (high and low) and two rotation sequences, simplified (wheat‐green manure) and diversified (wheat‐oilseed‐pulse‐green manure). Soil moisture and NO3‐N content were highest in the simplified rotation under high tillage. There were few soil P differences, although levels were higher for the low than high tillage in the simplified rotation. Reduced tillage intensity tended to increase soil organic C and decreased the percentage of erodible soil particles. Soil NO3‐N and PO4‐P content were also analyzed within the soil profile, down to 120 cm. During the past few decades, organic crop production in Canada and beyond has become increasingly widespread. In the Canadian Prairies, organic agriculture has traditionally relied on summer fallow and mechanical tillage for nutrient and pest management. More recently, there has been a substantial increase in the use of legume green manure, diversified crop rotations, and reduced tillage. Our objective was to determine if organic wheat (Triticum aestivum L.) production using diversified crop rotations and reduced tillage could optimize production while minimizing its environmental impact within the Brown soil zone of Western Canada. A 6‐yr (2010 to 2015) field study evaluated two tillage intensities (high and low), and two rotation sequences, simplified (wheat–green manure) and diversified (wheat–oilseed–pulse–green manure). Precipitation throughout the study period was substantially greater than the long‐term mean. Spring soil NO3−N and P content were highest in the first years of this trial. Soil moisture and NO3−N content were highest in the simplified rotation under high tillage. There were few soil P differences, although levels were higher for the low than high tillage in the simplified rotation. Reduced tillage intensity tended to increase soil organic C and decreased the percentage of erodible soil particles. These soil quality changes would result in an increase in the soil’s resistance to wind and water erosion, thus promoting environmental sustainability.

This wholly conceptual paper examines the breadth of literature on Market Entry Modes, a fundamentally important and strategic issue for managers in growing organisations of all sizes in all sectors. Key concepts and terms are defined and then a set of key Internationalisation Theories are systematically and critically reviewed, these being: the Transaction Cost Approach, Institutional Theory, the Eclectic Paradigm, the Uppsala Internationalisation Model and the Resource Based View. The final portion of the paper is integrative and highlights three key literature gaps as signposts for future work.

The desert steppe is a large component of the semi-arid grassland ecosystem in northern China, and provides significant resources for livestock production. However, overgrazing is regarded as one of main causes of its degradation and desertification over recent decades. Quantifying the direct and indirect effects of grazing disturbance on plant community productivity in the desert steppe ecosystem can provide insights into appropriate measures for the restoration of degraded grassland and biodiversity conservation. Here, we examine the effects of four grazing intensity treatments: no grazing (control), light grazing (LG), moderate grazing (MG) and heavy grazing (HG) on the plant community and soil nutrients with sheep grazing over 12 years in a desert steppe in Inner Mongolia, northern China. The results showed that increasing grazing intensity resulted in decreased species richness, Shannon-Wiener and Pielou's index, as well as above- and belowground biomass. Soil moisture, nitrogen, available potassium and soil organic carbon were not affected (P > 0.05) by grazing disturbance. In addition, grazing disturbance had a greater indirect effect on aboveground biomass via plant diversity. Consequently, plant diversity is a key indirect factor that determines community productivity in response to grazing disturbance. Reducing grazing pressure can contribute to maintaining relatively high species diversity and productivity in the desert steppe of northern China.

Recent advances in next generation sequencing technologies make genotyping-by-sequencing (GBS) more feasible for the molecular characterization of plant germplasm with complex and unsequenced genomes. This study represents the first preliminary effort using GBS to discover genome-wide genetic variants of northern wheatgrass (Elymus lanceolatus ssp. lanceolatus (Scribn. and J. G. Sm.) Gould) plants and to assess the genetic diversity present in four cultivated and six wild accessions. The effort generated the first novel set of genomic resources and 5659 single nucleotide polymorphism (SNP) markers for this tetraploid grass. The diversity analysis revealed 8.8% of SNP variation residing among the 10 accessions and 1.9% SNP variation present between cultivated and wild accessions. The Bayesian analysis identified three major clusters of the assayed samples, and the principal coordinates analysis revealed the genetic distinctness of the two accessions collected from Nevada and Wyoming. The flow cytometry analysis confirmed the tetraploid nature of some of the assayed samples and estimated the average genome size to be 9.3–9.4 Gb for this species. These findings are useful for the genetic improvement of this native grass species for forage production and rangeland reclamation. The findings are also encouraging for the broad application of genotyping-by-sequencing in the characterization of genome-wide genetic variability in non-model polyploid plants.