Lengthening of maize maturity time is not a widespread climate change adaptation strategy in the US Midwest

Increasing temperatures in the US Midwest are projected to reduce maize yields because warmer temperatures hasten reproductive development and, as a result, shorten the grain fill period. However, there is widespread expectation that farmers will mitigate projected yield losses by planting longer season hybrids that lengthen the grain fill period. Here, we ask: (a) how current hybrid maturity length relates to thermal availability of the local climate, and (b) if farmers are shifting to longer season hybrids in response to a warming climate. To address these questions, we used county‐level Pioneer brand hybrid sales (Corteva Agriscience) across 17 years and 650 counties in 10 Midwest states (IA, IL, IN, MI, MN, MO, ND, OH, SD, and WI). Northern counties were shown to select hybrid maturities with growing degree day (GDD°C) requirements more closely related to the environmentally available GDD compared to central and southern counties. This measure, termed “thermal overlap,” ranged from complete 106% in northern counties to a mere 63% in southern counties. The relationship between thermal overlap and latitude was fit using split‐line regression and a breakpoint of 42.8°N was identified. Over the 17‐years, hybrid maturities shortened across the majority of the Midwest with only a minority of counties lengthening in select northern and southern areas. The annual change in maturity ranged from −5.4 to 4.1 GDD year−1 with a median of −0.9 GDD year−1. The shortening of hybrid maturity contrasts with widespread expectations of hybrid maturity aligning with magnitude of warming. Factors other than thermal availability appear to more strongly impact farmer decision‐making such as the benefit of shorter maturity hybrids on grain drying costs, direct delivery to ethanol biorefineries, field operability, labor constraints, and crop genetics availability. Prediction of hybrid choice under future climate scenarios must include climatic factors, physiological‐genetic attributes, socio‐economic, and operational constraints

Fungicide, Insecticide, and Foliar Fertilizer Effect on Soybean Yield, Seed Composition, and Canopy Retention

Soybean [Glycine max (L.) Merr.] yield has increased over time through the introduction of new varieties and improved agronomic practices. However, seed protein concentration has decreased. We conducted field studies in 2018 and 2019 to investigate the effects of fungicide, insecticide, and foliar fertilizer application on grain yield and seed quality in two soybean maturity groups (MG). In‐season treatments targeted nutrient availability and soybean canopy duration during the seed‐filling period by fungicide, insecticide, or foliar fertilizer application at the onset of this period. Biomass samples were collected at R5, R6, and R7 and partitioned into plant parts. Year, location, and MG often influenced yield and seed composition, but foliar fungicide, insecticide, or fertilizer application had no impact on these parameters

Stacked crop rotations and cultural practices for canola and flax yield and quality

Canola (Brassica napus L.) and flax (Linum usitatissimum L.) are important oilseed crops, but improved management practices to enhance their yields and quality are needed. We studied the effect of stacked versus alternate‐year crop rotations and traditional versus improved cultural practices on canola and flax growth, seed yield, oil concentration, and N‐use efficiency from 2006 to 2011 in the northern Great Plains, USA. Stacked rotations were durum (Triticum turgidum L.)‐durum‐canola‐pea (Pisum sativum L.) (DDCP) and durum‐durum‐flax‐pea (DDFP). Alternate‐year rotations were durum‐canola‐durum‐pea (DCDP) and durum‐flax‐durum‐pea (DFDP). The traditional cultural practice included a combination of conventional tillage, recommended seed rate, broadcast N fertilization, and reduced stubble height. The improved cultural practice included a combination of no‐tillage, increased seed rate, banded N fertilization, and increased stubble height. Canola stand count was 36–123% greater with the improved than the traditional cultural practice in 2006, 2009, 2010, and 2011. Canola pod number and oil concentration were 3–36% greater in the improved than the traditional practice in 2007 and 2010, but trends reversed by 5–19% in 2008. Flax stand count was 28% greater with DFDP than DDFP in 2007 and 56% greater in the improved than the traditional practice in 2010. Flax pod number, seed weight, seed yield, N content, N‐use efficiency, and N‐removal index varied with crop rotations, cultural practices, and years. Canola growth and oil concentration increased with the improved cultural practice as well as flax growth, yield, and quality enhanced with alternate‐year crop rotation and the improved cultural practice in wet years

Monitoring Soil Quality to Assess the Sustainability of Harvesting Corn Stover

Harvesting feedstock for biofuel production must not degrade soil, water, or air resources. Our objective is to provide an overview of field research being conducted to quantify effects of harvesting corn (Zea mays L.) stover as a bioenergy feedstock. Coordinated field studies are being conducted near Ames, IA; St. Paul and Morris, MN; Mead, NE; University Park, PA; Florence, SC; and Brookings, SD., as part of the USDA-ARS Renewable Energy Assessment Project (REAP). A baseline soil quality assessment was made using the Soil Management Assessment Framework (SMAF). Corn grain and residue yield for two different stover harvest rates (∼50% and ∼90%) are being measured. Available soil data remains quite limited but sufficient for an initial SMAF analysis that confirms total organic carbon (TOC) is a soil quality indicator that needs to be closely monitored closely to quantify crop residue removal effects. Overall, grain yields averaged 9.7 and 11.7 Mg ha−1 (155 and 186 bu acre−1) in 2008 and 2009, values that are consistent with national averages for both years. The average amount of stover collected for the 50% treatment was 2.6 and 4.2 Mg ha−1 for 2008 and 2009, while the 90% treatment resulted in an average removal of 5.4 and 7.4 Mg ha−1, respectively. Based on a recent literature review, both stover harvest scenarios could result in a gradual decline in TOC. However, the literature value has a large standard error, so continuation of this long-term multi-location study for several years is warranted

Quality Protein Maize Germplasm Characterized for Amino Acid Profiles and Endosperm Opacity

Quality protein maize (QPM) is improved over normal (non-QPM) maize in grain concentrations of the essential amino acids lysine and tryptophan. Quality protein maize has a long history as tropical adapted germplasm, but little effort has been made to incorporate temperate or sub-tropical germplasm for temperate adaptation and interactions between different modifier loci in these backgrounds are poorly understood. A design-II mating scheme including new temperate and subtropical lines produced 69 hybrids. Large hybrid genetic variation components resulted in substantial broad-sense heritability H2 estimates, specifically tryptophan (0.46) and endosperm opacity (0.82). A microbial assay for amino acid estimation proved robust across diverse environments with minimal genotype × environment (G×E) effects. Endosperm opacity had no G×E effects across both Texas and Iowa locations demonstrating stability for this trait. Endosperm opacity primarily followed an additive, midparent trend, with a few hybrids deviating from the trend (36%) suggesting a complex nature of multiple modifier loci across diverse germplasm. The top QPM hybrid outperformed the top commercial hybrid by 35 and 30% for lysine and tryptophan as a proportion of grain, respectively. QPM line Tx832 was a parent of top hybrids for lysine and tryptophan, and the highest noncommercial hybrids for methionine. Minimal correlations with yield and other traits suggest that future breeding should result in QPM hybrids with increasingly competitive yields

Soybean yield and crop stage response to planting date and cultivar maturity in Iowa, USA

Soybean [Glycine max (L.) Merr.] planting date and maturity group are important agronomic decisions. This study quantified how maturity group selection and later than optimal planting dates affected grain yield and crop development across Iowa, US. Field experiments were conducted in seven locations between 2014 and 2016. Cultivar maturities ranged from 2.2 to 3.7 MG and planting dates targeted for 20-day intervals from early May to early July. Soybean grain yield ranged from 0.27 to 7.54 Mg ha-1. Cultivar maturity had little to no effect on grain yield at 4 of 7 sites while planting date was significant at all sites (p\u3c0.001) and the planting date and cultivar maturity interaction was not significant. As planting date was delayed, the VE- R3 and R3-R7 periods were each shortened by up to 15-20 days. The shorter growing period resulted in less radiation and growing degree day accumulation. A exponential-plateau relationship between relative yield and GDD was evident for the VE-R3 phase, with a plateau at 700oC days. A linear relationship between yield and GDD was evident from R3-R7, suggesting greater yield with more accumulated GDD. The opposite relationships were found for photoperiod which had a linear relationship for the VE-R3 and curvilinear for the R3-R7 phases. These results showed that yield potential would be maximized by planting before 20 May. We concluded that planting earlier in the spring was a better management practice than maturity selection to maximize yield and the R3-R7 period duration was critical in determining potential yield

Primed acclimation of cultivated peanut (Arachis hypogaea L.) through the use of deficit irrigation timed to crop developmental periods

Water-deficits and high temperatures are the predominant factors limiting peanut production across the U.S., either because of regional aridity or untimely rainfall events during crucial crop developmental periods. In the southern High Plains of west Texas and eastern New Mexico, low average annual rainfall (450. mm) and high evaporative demand necessitates the use of significant irrigation in production systems. In this west Texas study, the primary objective was to develop irrigation schemes that maximized peanut yield and grade while reducing overall water consumption. Therefore, a large-scale field experiment was established in 2005 and 2006 that utilized 15 treatment combinations of differing rates of irrigation (50, 75, and 100% of grower applied irrigation) applied at different periods of peanut development (early, middle, and late season). Precipitation patterns and ambient temperatures showed greater stress levels in 2006 which likely reduced yields across all treatments in comparison to 2005. Yields were reduced 26 (2005) and 10% (2006) in the lowest irrigation treatment (50% full season) compared with full irrigation (100% full season); but early-season water deficit (50 and 75% in the first 45. days after planting) followed by 100% irrigation in the mid- and late-seasons were successful at sustaining yield and/or crop value. Root growth was significantly enhanced at 50% irrigation compared with 100% irrigation, through greater root length, diameter, surface area, and depth, suggesting greater access to water during mid- and late-season periods. These results suggest that early to mid-season deficit irrigation has the potential to maintain peanut yield without altering quality, and to substantially reduce water use in this semi-arid environment

Análisis sistémico de las externalidades del mercado de bioetanol

Trabajo de investigaciónEn Colombia a partir de la resolución 40108 de 2018, se aumentó el porcentaje de mezcla del combustibles llegando a un 10% (90% combustibles fósiles 10% biocombustibles), actualmente para suplir esta demanda, las productoras de bioetanol requieren emplear al 100% su capacidad instalada, mejorar sus prácticas de cultivo de caña de azúcar y hacer uso de nuevas hectáreas, por tanto, el presente trabajo de grado tiene como objetivo realizar un análisis sistémico de las externalidades del mercado de bioetanol.INTRODUCCIÓN 1. Formulación del trabajo 2. Marco referencial 3. Diagrama propuesto 4. Conclusiones generales BibliografiaPregradoEconomist