ALBERT

Description: Ecological functioning of the intensive, homogeneous agroecosystems in the Chippewa River Watershed (CRW), MN, USA, can be improved by reducing soil erosion, runoff, and nutrient leaching. These ecosystem services can be achieved through increased perennials in crop rotations to diversify land use and sustain carbon sequestration. We calibrated, validated, and used APSIM software to simulate the effect of 100 yrs each of historical and future climate change scenario (IPCC-A2) on biophysical processes in representative soil types of the predominant farming systems in CRW. The interrelationships between crop rotations, soil types, climate variables, and ecosystem services indicated that not all objectives of sustainable agro-ecosystem are compatible, and tradeoffs among them are necessary. Site-specific and diversified crop rotations that comply with the environmental constraints of climate and soils could lead to more efficient implementation of strategies to improve ecosystem services in the watershed if current management practices of high external inputs and tillage persisted.

Description: Farmers' decision to adopt new management or production system depends on production risk. Grain yield data was used to assess production risk in a field experiment composed of two cropping systems (CNV and ORG), each with eight subsystems (two levels each of crop rotation (2-yr and 4-yr), tillage management (conventional, CT and strip, ST), and fertilizer input (fertilized, YF and non-fertilized, NF)). Statistical moments, cumulative yield (CY), temporal yield variance (TYV) and coefficient of variation (CV) were used to assess the risk associated with adopting combinations of new management practices in CNV and ORG. The mean-variance-skewness (M-V-S) statistics derived from yield data separated all 16 subsystems into three clusters. Both cropping systems and clustered subsystems differed as to their ability to maintain a constant yield over years, displayed different yield cumulative probabilities, exhibited significant and different M-V-S relationships, and differed as to the reliability of estimating TYV as a function of CY. Results indicated that differences in management among cropping systems and subsystems contributed differently to the goal of achieving yield potential as estimated by the cumulative density function, and that certain low-input management practices caused a positive shift in yield distribution, and may lower TYV and reduce production risk.

Description: Ecological functioning of the intensive, homogeneous agroecosystems in the Chippewa River Watershed (CRW), MN, USA, can be improved by reducing soil erosion, runoff, and nutrient leaching. These ecosystem services can be achieved through increased perennials in crop rotations to diversify land use and sustain carbon sequestration. We calibrated, validated, and used APSIM software to simulate the effect of 100 yrs each of historical and future climate change scenario (IPCC-A2) on biophysical processes in representative soil types of the predominant farming systems in CRW. The interrelationships between crop rotations, soil types, climate variables, and ecosystem services indicated that not all objectives of sustainable agro-ecosystem are compatible, and tradeoffs among them are necessary. Site-specific and diversified crop rotations that comply with the environmental constraints of climate and soils could lead to more efficient implementation of strategies to improve ecosystem services in the watershed if current management practices of high external inputs and tillage persisted.

Description: Agronomy, Vol. 8, Pages 139: Statistical Modeling of Phenotypic Plasticity under Abiotic Stress in Triticum durum L. and Triticum aestivum L. Genotypes Agronomy doi: 10.3390/agronomy8080139 Authors: Abdullah A. Jaradat Future challenges to the role of durum and bread wheat in global food security will be shaped by their potential to produce larger yields and better nutritional quality, while increasingly adapting to multiple biotic and abiotic stresses in the view of global climate change. There is a dearth of information on comparative assessment of phenotypic plasticity in both wheat species under long-term multiple abiotic stresses. Phenotypic plasticities of two durum and bread wheat genotypes were assessed under increasing abiotic and edaphic stresses for six years. Combinations of normal and reduced length of growing season and population density, with or without rotation, generated increasing levels of competition for resources and impacted phenotypic plasticity of several plant and yield attributes, including protein and micronutrients contents. All the phenotypic plasticity (PPs) estimates, except for the C:N ratio in both genotypes and grain protein content in T. aestivum genotype, were impacted by abiotic stresses during the second stress phase (PS II) compared with the first (PS I); whereas, covariate effects were limited to a few PPs (e.g., biomass, population density, fertile tillers, grain yield, and grain protein content). Discrimination between factor levels decreased from abiotic phases > growth stages > stress treatments and provided selection criteria of trait combinations that can be positively resilient under abiotic stress (e.g., spike harvest and fertility indices combined with biomass and grain yield in both genotypes). Validation and confirmatory factor models and multiway cluster analyses revealed major differences in phenotypic plasticities between wheat genotypes that can be attributed to differences in ploidy level, length of domestication history, or constitutive differences in resources allocation. Discriminant analyses helped to identify genotypic differences or similarities in the level of trait decoupling in relation to the strength of their correlation and heritability estimates. This information is useful in targeted improvement of traits directly contributing to micronutrient densities, yield components, and yield. New wheat ideotype(s) can be designed for larger grain yield potential under abiotic stress by manipulating yield components that affect kernels m−2 (e.g., number of tillers, number of florets per spikelet, and eventually spike fertility and harvest indices) without impacting nutrient densities and kernel weight, thus raising harvest index beyond its current maximum.

Description: Ecological functioning of the intensive, homogeneous agroecosystems in the Chippewa River Watershed (CRW), MN, USA, can be improved by reducing soil erosion, runoff, and nutrient leaching. These ecosystem services can be achieved through increased perennials in crop rotations to diversify land use and sustain carbon sequestration. We calibrated, validated, and used APSIM software to simulate the effect of 100 yrs each of historical and future climate change scenario (IPCC-A2) on biophysical processes in representative soil types of the predominant farming systems in CRW. The interrelationships between crop rotations, soil types, climate variables, and ecosystem services indicated that not all objectives of sustainable agro-ecosystem are compatible, and tradeoffs among them are necessary. Site-specific and diversified crop rotations that comply with the environmental constraints of climate and soils could lead to more efficient implementation of strategies to improve ecosystem services in the watershed if current management practices of high external inputs and tillage persisted.

Description: Ecological functioning of the intensive, homogeneous agroecosystems in the Chippewa River Watershed (CRW), MN, USA, can be improved by reducing soil erosion, runoff, and nutrient leaching. These ecosystem services can be achieved through increased perennials in crop rotations to diversify land use and sustain carbon sequestration. We calibrated, validated, and used APSIM software to simulate the effect of 100 yrs each of historical and future climate change scenario (IPCC-A2) on biophysical processes in representative soil types of the predominant farming systems in CRW. The interrelationships between crop rotations, soil types, climate variables, and ecosystem services indicated that not all objectives of sustainable agro-ecosystem are compatible, and tradeoffs among them are necessary. Site-specific and diversified crop rotations that comply with the environmental constraints of climate and soils could lead to more efficient implementation of strategies to improve ecosystem services in the watershed if current management practices of high external inputs and tillage persisted.

Description: Ecological functioning of the intensive, homogeneous agroecosystems in the Chippewa River Watershed (CRW), MN, USA, can be improved by reducing soil erosion, runoff, and nutrient leaching. These ecosystem services can be achieved through increased perennials in crop rotations to diversify land use and sustain carbon sequestration. We calibrated, validated, and used APSIM software to simulate the effect of 100 yrs each of historical and future climate change scenario (IPCC-A2) on biophysical processes in representative soil types of the predominant farming systems in CRW. The interrelationships between crop rotations, soil types, climate variables, and ecosystem services indicated that not all objectives of sustainable agro-ecosystem are compatible, and tradeoffs among them are necessary. Site-specific and diversified crop rotations that comply with the environmental constraints of climate and soils could lead to more efficient implementation of strategies to improve ecosystem services in the watershed if current management practices of high external inputs and tillage persisted.

Description: Guidelines are needed to develop proper statistical analyses procedures and select appropriate models of covariance structures in response to expected temporal variation in long-term experiments. Cumulative yield, its temporal variance, and coefficient of variation were used in estimating and describing covariance structures in conventional and organic cropping systems of a long-term field experiment in a randomized complete block design. An 8-year database on 16 treatments (conventional and organic cropping systems, crop rotations, and tillage) was subjected to geostatistical, covariance structure, variance components, and repeated measures multivariate analyses using six covariance models under restricted maximum likelihood. Differential buildup of the cumulative effects due to crop rotations being repeated over time was demonstrated by decreasing structured and unstructured variances and increasing range estimates in the geostatistical analyses. The magnitude and direction of relationships between cumulative yield and its temporal variance, and coefficient of variation shaped the covariance structures of both cropping systems, crop rotations, and phases within crop rotations and resulted in significant deviations of organic management practices from their conventional counterparts. The unstructured covariance model was the best to fit most factor-variable combinations; it was the most flexible, but most costly in terms of computation time and number of estimated parameters.