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.

The interplay between atrial fibrillation and heart failure on long-term mortality and length of stay: Insights from the, United Kingdom ACALM registry.

BACKGROUND: There is concern that the development of heart failure and atrial fibrillation has a detrimental influence on clinical outcomes. The aim of this study was to assess all-cause mortality and length of hospital stay in patients with chronic and new-onset concomitant AF and HF. METHODS: Using the ACALM registry, we analysed adults hospitalised between 2000 and 2013 with AF and HF and assessed prevalence, mortality and length of hospital stay. Patients with HF and/or AF at baseline (study-entry) were compared with patients who developed new-onset disease during follow-up. RESULTS: Of 929,552 patients, 31,695 (3.4%) were in AF without HF, 20,768 (2.2%) had HF in sinus rhythm, and 10,992 (1.2%) had HF in AF. Patients with HF in AF had the greatest all-cause mortality (70.8%), followed by HF in sinus rhythm (64.1%) and AF alone (45.1%, p<0.0001). Patients that developed new-onset AF, HF or both had significantly worse mortality (58.5%, 70.7% and 74.8% respectively) compared to those already with the condition at baseline (48.5%, 63.7% and 67.2% respectively, p<0.0001). Patients with HF in AF had the longest length of hospital stay (9.41days, 95% CI 8.90-9.92), followed by HF in sinus rhythm (7.67, 95% CI 7.34-8.00) and AF alone (6.05, 95% CI 5.78-6.31). CONCLUSIONS: Patients with HF in AF are at a greater risk of mortality and longer hospital stay compared to patients without the combination. New-onset AF or HF is associated with significantly worse prognosis than long-standing disease.