Agriculture and Agri-Food Canada

About: Agriculture and Agri-Food Canada is a facility organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Population & Soil water. The organization has 10921 authors who have published 21332 publications receiving 748193 citations. The organization is also known as: Department of Agriculture and Agri-Food.

Tillage, crop residue and N fertilizer effects on crop yield, nutrient uptake, soil quality and nitrous oxide gas emissions in a second 4-yr rotation cycle

Abstract: An 8-yr (1998–2005) field experiment was conducted on a Gray Luvisol (Boralf) soil near Star City, Saskatchewan, Canada, to determine the effects of tillage (no-tillage – NT and conventional tillage – CT), straw management (straw retained – R and straw not retained – NR) and N fertilizer (0, 40, 80 and 120 kg N ha −1 , except no N to pea ( Pisum sativum L.) phase of the rotation) on seed and straw yield, mass of N and C in crop, organic C and N, inorganic N and aggregation in soil, and nitrous oxide (N 2 O) emissions for a second 4-yr rotation cycle (2002–2005). The plots were seeded to barley ( Hordeum vulgare L.) in 2002, pea in 2003, wheat ( Triticum aestivum L.) in 2004 and canola ( Brassica napus L.) in 2005. Seed, straw and chaff yield, root mass, and mass of N and C in crop increased with increasing N rate for barley in 2002, wheat in 2004 and canola in 2005. No-till produced greater seed (by 51%), straw (23%) and chaff (13%) yield of barley than CT in 2002, but seed yield for wheat in 2004, and seed and straw yield for canola in 2005 were greater under CT than NT. Straw retention increased seed (by 62%), straw (by 43%) and chaff (by 12%) yield, and root mass (by 11%) compared to straw removal for barley in 2002, wheat in 2004, and seed and straw yield for pea in 2003. No-till resulted in greater mass of N in seed, and mass of C in seed, straw, chaff and root than CT for barley in 2002, but mass of N and C were greater under CT than NT for wheat in 2004 and for canola in 2005 in many cases. Straw retention had greater mass of N and C in seed, straw, chaff and root in most cases compared to straw removal for barley in 2002, pea in 2003 and wheat in 2004. Soil moisture content in spring was higher under NT than CT and with R than NR in the 0–15 cm depth, with the highest moisture content in the NT + R treatment in many cases. After eight crop seasons, tillage and straw management had no effect on total organic C (TOC) and N (TON) in the 0–15 cm soil, but light fraction organic C (LFOC) and N (LFON), respectively, were greater by 1.275 Mg C ha −1 and 0.031 Mg N ha −1 with R than NR, and also greater by 0.563 Mg C ha −1 and 0.044 Mg N ha −1 under NT than CT. There was no effect of tillage, straw and N fertilization on the NH 4 -N in soil in most cases, but R treatment had higher NO 3 -N concentration in the 0–15 cm soil than NR. The NO 3 -N concentration in the 0–15, 15–30 and 30–60 cm soil layers increased (though small) with increasing N rate. The R treatment had 6.7% lower proportion of fine ( 38.0 mm) dry aggregates, and 4.5 mm larger mean weight diameter (MWD) compared to NR treatment. This suggests a lower potential for soil erosion when crop residues are retained. There was no beneficial effect of elimination of tillage on soil aggregation. The amount of N lost as N 2 O was higher from N-fertilized (580 g N ha −1 ) than from zero-N (155 g N ha −1 ) plots, and also higher in CT (398 g N ha −1 ) than NT (340 g N ha −1 ) in some cases. In conclusion, retaining crop residues along with no-tillage improved some soil properties and may also be better for the environment and the sustainability of high crop production. Nitrogen fertilization improved crop production and some soil quality attributes, but also increased the potential for NO 3 -N leaching and N 2 O-N emissions, especially when applied in excess of crop requirements.

Genome-Wide Analysis of Ethylene-Responsive Element Binding Factor-Associated Amphiphilic Repression Motif-Containing Transcriptional Regulators in Arabidopsis

Abstract: The ethylene-responsive element binding factor-associated amphiphilic repression (EAR) motif is a transcriptional regulatory motif identified in members of the ethylene-responsive element binding factor, C2H2, and auxin/indole-3-acetic acid families of transcriptional regulators. Sequence comparison of the core EAR motif sites from these proteins revealed two distinct conservation patterns: LxLxL and DLNxxP. Proteins containing these motifs play key roles in diverse biological functions by negatively regulating genes involved in developmental, hormonal, and stress signaling pathways. Through a genome-wide bioinformatics analysis, we have identified the complete repertoire of the EAR repressome in Arabidopsis (Arabidopsis thaliana) comprising 219 proteins belonging to 21 different transcriptional regulator families. Approximately 72% of these proteins contain a LxLxL type of EAR motif, 22% contain a DLNxxP type of EAR motif, and the remaining 6% have a motif where LxLxL and DLNxxP are overlapping. Published in vitro and in planta investigations support approximately 40% of these proteins functioning as negative regulators of gene expression. Comparative sequence analysis of EAR motif sites and adjoining regions has identified additional preferred residues and potential posttranslational modification sites that may influence the functionality of the EAR motif. Homology searches against protein databases of poplar (Populus trichocarpa), grapevine (Vitis vinifera), rice (Oryza sativa), and sorghum (Sorghum bicolor) revealed that the EAR motif is conserved across these diverse plant species. This genome-wide analysis represents the most extensive survey of EAR motif-containing proteins in Arabidopsis to date and provides a resource enabling investigations into their biological roles and the mechanism of EAR motif-mediated transcriptional regulation.

An Integrated Biplot Analysis System for Displaying, Interpreting, and Exploring Genotype × Environment Interaction

Abstract: Multienvironment trials (MET) generate two types of two-way data: genotype x environment data for a target trait and genotype x trait data in individual or across environments. These data can be visually analyzed by a GGE biplot and a genotype X trait biplot, respectively. This paper describes a third type of biplot, the covariate-effect biplot, and illustrates its tandem use with the other biplots to achieve a fuller understanding of MET data. The covariate-effect biplot is generated on the basis of an explanatory trait × environment two-way table consisting of correlation coefficients between the target trait (e.g., yield) and each of the other traits in each of the environments. This biplot displays the yield-trait relations in individual environments and addresses whether and how the genotype X environment interactions (GE) for yield can be explored by indirect selection for the other traits. These other traits are treated as genetic covariables and can be replaced by other genetic covariables such as genetic markers, QTL, or genes. The biplot methodology was demonstrated by MET data of barley (Hordeum vulgare L.) conducted across North America. Both the GGE biplot and the covariate-effect biplot showed that the environments fell into two (eastern vs. western) megaenvironments. The covariate-effect pattern explained 81% of the GGE pattern, suggesting that the GE pattern for yield can be effectively explored by indirect selection for these traits. Specifically, barley yield can be improved by selecting for larger kernel weight, earlier heading, and better lodging resistance in the eastern megaenvironment. In contrast, the yield-frait relationship in the western megaenvironment was highly variable, and yield improvement can be achieved only by selecting for yield per se across environments. We suggest that the GGE biplot, the genotype × trait biplot, and the covariate-effect biplot be used jointly to better understand and more fully explore MET data.