Density response of maize canopy architecture in adapted and unadapted synthetic populations

ABSTRACT Since the 1950\u27s, the average maize grain yield, on a per unit area basis, has risen exponentially and without a pause. Associated with this increase have been changes in shoot morphology which permit more light penetration into the canopy. Changes in plant traits including plant height, leaf number, individual leaf area, vertical leaf angle, tassel size and weight, and leaf area density distribution along the main stem have been reported in the literature; however, the response of canopy components to changes in plant density has not been examined in closed populations and at today\u27s densities. The objective of this study was to: (i) analyze canopy traits (leaf angle / leaf area) to determine how canopy architecture has changed; (ii) determine if canopy architecture interacted with density either directly or indirectly. Materials from unselected base populations, Iowa Stiff Stalk Synthetic (BSSS) and Iowa Corn Borer Synthetic no.1, were compared to the most advanced cycles of selection at four locations near Ames, Carroll, Crawfordsville, and Keystone, IA, in 2011. Populations were compared at six densities ranging from 3.0 to 9.5 plants m-1. Each breeding population by density combination was replicated once at each location and arranged in a split plot design. Increased densities resulted in reduced numbers of total nodes, lower ear height, shorter plant stature, smaller tassels, more upright leaf angles with smaller leaf areas at the top sector of the canopy and more horizontal leaf angles with larger leaf areas lower in the canopy. More importantly, the shape of the canopy was affected by plant height, ear height, node of attachment of the ear, and density

SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study

Background: Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. Methods: The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18-49, 50-69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. Results: NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351; best case 196, worst case 816) or non-cancer surgery (733; best case 407, worst case 1664). Both exceeded the NNV in the general population (1840; best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year. Conclusion: As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population