Expansion Of Soybean Cultivation Research Articles

Identification of New Isolates of Phytophthora sojae and Selection of Resistant Soybean Genotypes.

Phytophthora root and stem rot (PRR), caused by Phytophthora sojae, can occur at any growth stage under poorly drained and humid conditions. The expansion of soybean cultivation in South Korean paddy fields has increased the frequency of PRR outbreaks. This study aimed to identify four P. sojae isolates newly collected from domestic fields and evaluate race-specific resistance using the hypocotyl inoculation technique. The four isolates exhibited various pathotypes, with GJ3053 exhibiting the highest virulence complexity. Two isolates, GJ3053 and AD3617, were screened from 205 soybeans, and 182 and 190 genotypes (88.8 and 92.7%, respectively) were susceptible to each isolate. Among these accessions, five genotypes resistant to both isolates were selected. These promising genotypes are candidates for the development of resistant soybean cultivars that can effectively control PRR through gene stacking.

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Soybean (Glycine Max), as an important oil crop, was rarely planted in low latitudes due to its poor latitude adaptability. The E6 recessive allele plays a key role in the expansion of soybean cultivation into the lower latitudes of Brazil. In this issue, Fang et al. (995–1003) report that e6PG is a loss‐of‐function allele long juvenile gene J, which was mutagenized by a natural transposon insertion.

Tensions around Land Tenure in Argentina’s Agrarian Periphery: Scales and Multiple Temporalities of Capitalism in Santiago del Estero, Argentina

This article contributes to discussions on capitalist transformation and impact on peripheral agriculture by focusing on the province of Santiago del Estero in northern Argentina. The concept of land grabbing is useful for qualitative analysis of the recent dynamics in the land market in this peripheral territory, where the concentration of land for agrarian use is historical but has accelerated in recent decades with the expansion of soybean cultivation. Tensions between capitalist and noncapitalist actors have been taking place within the current crisis of the world capitalist system and its expansion to marginal lands, often occupied by peasant producers with precarious tenure and different logics to that of market capitalism. The province’s history is characterized by processes of different temporalities and scales of limited capitalist transformation, agrarian land concentration, and exploitation of local populations. This article seeks to understand the overlaps and tensions in these processes.

Phenotypic Analysis of Major Agronomic Traits in 1008 RILs from a Diallel of Early European Soybean Varieties

Soybean [Glycine max (L.) Merr.] is the most important leguminous crop worldwide, but Europe is currently heavily dependent on soybean imports. A prerequisite for further expansion of soybean cultivation in Europe is the improvement of cultivars by breeding. In our study, 1008 F5:8 recombinant inbred lines derived from an incomplete half‐diallel cross of five early‐maturing European soybean varieties were evaluated in multilocation field trials for grain yield, thousand‐kernel weight, plant height, protein content, and oil content. We observed significant genotypic variances, high heritabilities (h2 > 0.7), and transgressive segregation for all traits. Our results further revealed complex relationships between grain yield, plant height, and maturity, but nevertheless indicated that breeding of adapted and high‐yielding varieties is feasible. By contrast, protein and oil content were not affected by maturity but were highly negatively correlated (r ∼ −0.9). Our results suggest that, to maximize protein yield, the maximization of grain yield appears to be the most promising strategy for soybeans for feeding purposes, while the selection of lines with very high protein content may be advantageous for food‐grade varieties, especially for tofu production. Taken together, our results on the available phenotypic variation, variance components, heritabilities, and trait correlations can expedite soybean breeding targeted at Central Europe.

Cold Stress Tolerance during Early Growth Stages of Naturalized Helianthus petiolaris Populations

AbstractIn the last 10 years the sunflower crop area of Argentina has shifted towards the Southwest as a result of the expansion of soybean cultivation. Early sowings require greater tolerance to low temperatures in order to optimize the use of water resources by the crop, especially in the seedling stage, when cold stress limits growth and productivity.Helianthus petiolarisis a wild genetic resource that has contributed to the production of sunflower cultivars. The goal of this study was to evaluate the tolerance to low temperatures inH. petiolarisplants. Morphological traits (plant height, leaf width and leaf length) and physiological traits (electrolyte leakage, chlorophyll content, and glucose content) were compared in eight accessions having an early germination in the field and one with normal life cycle. Acclimated and non-acclimated plants were subjected to cold stress followed by a recovery period. Physiological traits during early growth stages showed differences in cold tolerance and for acclimation ability between accessions, suggesting the existence of heritable components. Four accessions were the most cold-tolerant among the studied populations, suggesting a natural adaptation related to the geographical site. Results point out thatH. petiolarisis a useful genetic resource to contribute to sunflower breeding in the search of cold tolerant cultivars.

On the margins of soy farms: traditional populations and selective environmental policies in the Brazilian Cerrado

In the Cerrado, the expansion of soybean cultivation since the 1990s has coincided with the strengthening of environmental regulations. We analyze how the two main environmental policies – Protected Areas and the Forest Code – have played out at the ground level in western Bahia state. These policies in Cerrado have not been designed to curb the expansion of this agricultural frontier. These norms have, on the contrary, accommodated this expansion because the way environmental managers selectively choose environmental problems and publicize them through specific information systems depreciates traditional fire-dependent production systems. These ‘politics of selection’ are likely to increase competition for resources in the margins of soybean agriculture, which is where traditional populations have now become confined.

Multi-Season Regional Analysis of Multi-Species Occupancy: Implications for Bird Conservation in Agricultural Lands in East-Central Argentina.

Rapid expansion and intensification of agriculture create challenges for the conservation of biodiversity and associated ecosystem services. In Argentina, the total row crop planted area has increased in recent decades with the expansion of soybean cultivation, homogenizing the landscape. In 2003 we started the first long-term, large-scale bird monitoring program in agroecosystems of central Argentina, in portions of the Pampas and Espinal ecoregions. Using data from this program, we evaluated the effect of land use and cover extent on birds between 2003-2012, accounting for imperfect detection probabilities using a Bayesian hierarchical, multi-species and multi-season occupancy model. We tested predictions that species diversity is positively related to habitat heterogeneity, which in intensified agroecosystems is thought to be mediated by food availability; thus the extent of land use and cover is predicted to affect foraging guilds differently. We also infer about ecosystem services provisioning and inform management recommendations for conservation of birds. Overall our results support the predictions. Although many species within each guild responded differently to land use and native forest cover, we identified generalities for most trophic guilds. For example, granivorous gleaners, ground insectivores and omnivores responded negatively to high proportions of soybean, while insectivore gleaners and aerial foragers seemed more tolerant. Habitat heterogeneity would likely benefit most species in an intensified agroecosystem, and can be achieved with a diversity of crops, pastures, and natural areas within the landscape. Although most studied species are insectivores, potentially beneficial for pest control, some guilds such as ground insectivores are poorly represented, suggesting that agricultural intensification reduces ecological functions, which may be recovered through management. Continuation of the bird monitoring program will allow us to continue to inform for conservation of birds in agroecosystems, identify research needed to reduce key uncertainties, and anticipate the effects of changes in agriculture in central Argentina.

Differences in throughfall and net precipitation between soybean and transitional tropical forest in the southern Amazon, Brazil

The expansion of soybean cultivation into the Amazon in Brazil has potential hydrological effects at local to regional scales. To determine the impacts of soybean agriculture on hydrology, a comparison of net precipitation (throughfall, stemflow) in undisturbed tropical forest and soybean fields on the southern edge of the Amazon Basin in the state of Mato Grosso is needed. This study measured throughfall with troughs and stemflow with collar collectors during two rainy seasons. The results showed that in forest 91.6% of rainfall was collected as throughfall and 0.3% as stemflow, while in soybean fields with two-month old plants, 46.2% of rainfall was collected as throughfall and 9.0% as stemflow. Hence, interception of precipitation in soybean fields was far greater than in intact forests. Differences in throughfall, stemflow and net precipitation were found to be mainly associated with differences in plant structure and stem density in transitional forest and soybean cropland. Because rainfall interception in soybean fields is higher than previously believed and because both the area of cropland and the frequency of crop cycles (double cropping) are increasing rapidly, interception needs to be reconsidered in regional water balance models when consequences of land cover changes are analyzed in the Amazon soybean frontier region. Based on the continued expansion of soybean fields across the landscape and the finding that net precipitation is lower in soy agriculture, a reduction in water availability in the long term can be assumed.

Structure and composition of bacterial and fungal community in soil under soybean monoculture in the Brazilian Cerrado

Soybean is the most important oilseed cultivated in the world and Brazil is the second major producer. Expansion of soybean cultivation has direct and indirect impacts on natural habitats of high conservation value, such as the Brazilian savannas (Cerrado). In addition to deforestation, land conversion includes the use of fertilizers and pesticides and can lead to changes in the soil microbial communities. This study evaluated the soil bacterial and fungal communities and the microbial biomass C in a native Cerrado and in a similar no-tillage soybean monoculture area using PCR-DGGE and sequencing of bands. Compared to the native area, microbial biomass C was lower in the soybean area and cluster analysis indicated that the structure of soil microbial communities differed. 16S and 18S rDNA dendrograms analysis did not show differences between row and inter-row samples, but microbial biomass C values were higher in inter-rows during soybean fructification and harvest. The study pointed to different responses and alterations in bacterial and fungal communities due to soil cover changes (fallow x growth period) and crop development. These changes might be related to differences in the pattern of root exudates affecting the soil microbial community. Among the bands chosen for sequencing there was a predominance of actinobacteria, y-proteobacteria and ascomycetous divisions. Even under no-tillage management methods, the soil microbial community was affected due to changes in the soil cover and crop development, hence warning of the impacts caused by changes in land use.

Structure and composition of bacterial and fungal community in soil under soybean monoculture in the Brazilian Cerrado.

Soybean is the most important oilseed cultivated in the world and Brazil is the second major producer. Expansion of soybean cultivation has direct and indirect impacts on natural habitats of high conservation value, such as the Brazilian savannas (Cerrado). In addition to deforestation, land conversion includes the use of fertilizers and pesticides and can lead to changes in the soil microbial communities. This study evaluated the soil bacterial and fungal communities and the microbial biomass C in a native Cerrado and in a similar no-tillage soybean monoculture area using PCR-DGGE and sequencing of bands. Compared to the native area, microbial biomass C was lower in the soybean area and cluster analysis indicated that the structure of soil microbial communities differed. 16S and 18S rDNA dendrograms analysis did not show differences between row and inter-row samples, but microbial biomass C values were higher in inter-rows during soybean fructification and harvest. The study pointed to different responses and alterations in bacterial and fungal communities due to soil cover changes (fallow x growth period) and crop development. These changes might be related to differences in the pattern of root exudates affecting the soil microbial community. Among the bands chosen for sequencing there was a predominance of actinobacteria, γ-proteobacteria and ascomycetous divisions. Even under no-tillage management methods, the soil microbial community was affected due to changes in the soil cover and crop development, hence warning of the impacts caused by changes in land use.

More is less: agricultural impacts on the N cycle in Argentina

Human impact on nitrogen cycling, in particular the introduction of reactive nitrogen in terrestrial and aquatic ecosystems, can be examined at multiple scales, from the global impact on atmospheric chemistry to the impact of human activities on soil organic matter and fertility at the scale of square meters. Nevertheless, anthropogenic loading of nitrogen cycling in natural and managed ecosystems can be seen most directly at the regional scale, where concentrated human activity results in disruption of the nitrogen balance, with consequences for biogeochemical cycling and their interactions. Differences in land-use and agricultural practices between North and South America, and the importance of economic drivers that determine the fate of new reactive nitrogen demonstrate a contrasting picture of human impact on N cycling when the consequences are considered at the global vs. the regional scale. In particular, in the Pampa region of Argentina, the central agricultural zone of the country, the expansion of soybean cultivation in the last 20 years and the use of synthetic fertilizers have resulted in an influx of reactive nitrogen into these systems, with unexpected consequences for the nitrogen balance. A mass balance of nitrogen for soybean demonstrates that increased nitrogen inputs from biological fixation do not compensate for losses due to seed export, such that most areas under soybean cultivation are currently experiencing a substantive net loss of nitrogen. In addition, other crops that are currently being fertilized still show a net loss of nitrogen also due to the effect of primary exports from these agroecosystems. These simple models demonstrate that socioeconomic factors in large part drive the contrasting effects of anthropogenic impact on nitrogen cycling at global vs. regional scales. The future impact on nitrogen cycling in the Americas requires an integration of both ecological factors and socioeconomic drivers that will ultimately determine human disruption of the nitrogen cycle.

Impact of changing land use practices on nitrate export by the Mississippi River

The increased use of nitrogen fertilizer in the Mississippi River Basin since the 1950s has been blamed for declining water quality, the degradation of aquatic ecosystems and the growth of a seasonal hypoxic zone in the Gulf of Mexico. In this study, we use the IBIS terrestrial ecosystem model and the HYDRA aquatic transport model to examine how agricultural practices and climate influenced terrestrial and aquatic nitrogen cycling across the Mississippi Basin and the nitrate export to the Gulf. The modeling system accurately depicts the observed trends and interannual variability in nitrate export by the Mississippi River (r2 > 0.83), and several of the major tributaries, between 1960 and 1994. The challenge of simulating nitrate export from the central western sub‐basins highlights the key role of processes like denitrification. The simulations demonstrate that three factors led to the doubling of nitrate export by the Mississippi River since 1960: (1) an increase in fertilizer application rates, particularly on maize; (2) an increase in runoff across the basin; and (3) the expansion of soybean cultivation. By the early 1990s, fertilized crops may have accounted for almost 90% of the nitrate leached to the river system, despite representing only 20% of the watershed area. The majority of the nitrate exported to the Gulf appears to originate from “hot spots,” including a stretch of the “Corn Belt” across Iowa, Illinois, and Indiana. The relative contribution of such heavily fertilized lands, particularly those in close proximity to higher order streams, can be even greater during wet years.