Growth, productivity, and utilization of kenaf (Hibiscus cannabinus L.): A promising fiber and fuel crop for Iowa

Producing natural fibers to replace finite synthetic fibers is a good strategy to move from a petroleum-based society to a bioeconomy. Kenaf (Hibiscus cannabinus L.) has been identified as a promising multi-purpose crop that could have potential to grow in the Midwest. It is critical to determine the varieties and management practices that are optimal to produce high quantity and quality of kenaf fibers in Iowa, where corn and soybean are prevalent. Information regarding its potential for biofuel is scarce and requires to be investigated. Finally, consequences of including kenaf in traditional cropping systems on soil quality need to be studied in this area of the U.S. In the first study (Chapter 2), we demonstrated that ‘Tainung 2’ and ‘Whitten’ were the most promising in Iowa. Also, when its biomass was pyrolyzed, kenaf could have potential in the production of levoglucosan that can be further upgraded into ethanol. Our second study (Chapter 3) showed that it exists an optimal combination of management practices that influenced kenaf productivity and morphology. In the third study (Chapter 4), we found that N fertilization does not have any influence on kenaf stem production. However, N and other agricultural practices did influence morphology and composition. Our fourth study (Chapter 5) investigated kenaf productivity in Iowa and Kentucky. The results showed that Kentucky has more potential than Iowa, but that kenaf production in Iowa was less variable than in Kentucky. Finally, in our fifth study (Chapter 6), we developed a model in APSIM for kenaf, which was used to analyze the effects of kenaf inclusion in corn-soybean systems on soil quality. Overall, this work showed that kenaf could be a promising alternative crop in Iowa

Ecophysiological Responses of Tall Fescue Genotypes to Endophyte Infection and Climate Change

Tall fescue is a widely used forage grass in the eastern USA and can form a symbiosis with a fungal endophyte, which can be beneficial for the plant but can cause livestock health issues. Little is known regarding the symbiotic response to predicted climate change. To address this knowledge gap, I analyzed tall fescue variety trial data collected throughout the U.S., exploring relationships between climate variables and yield for two different fescue cultivars that were either endophyte-free or infected. This study showed no endophyte or cultivar effect on fescue yield, but identified temperature, precipitation and location as significant predictors of yield, suggesting that local conditions were more important than endophyte presence or fescue genotype for this dataset. Using a field experiment located in central Kentucky, I quantified the ecophysiological responses of four tall fescue genotypes to endophyte presence, elevated temperature and increased growing season precipitation. In this study, tall fescue genotype was as important as endophyte presence in determining ecophysiological responses to climate change treatments. My thesis illustrates that tall fescue response to climate change will depend on host genetics, the presence and genetics of the fungal endophyte symbiont, and the specific changes to the environment experienced at a site

Yield, Morphology, Composition, and Quantity and Quality of Pyrolysis Products from Kenaf Grown in Iowa

In a world where efforts are made to become more and more independent from our petroleum economy, agriculture represents one solution to turn our society toward a bioeconomy. Kenaf (Hibiscus cannabinus) is a warm season herbaceous plant mostly used as a fiber-crop in the textile and pulp industry, but also has potential for lignocellulosic bioenergy considering the characteristics of its bast and core fibers. Midwest studies on growth and use of kenaf have been scant; however, kenaf may be promising for Iowa. Eight kenaf varieties were established in Boone County, IA between 2004 and 2007, evaluated, and compared for their production potential in the Midwest. More specifically, our questions were 1) how do kenaf varieties perform in Iowa for yield? 2) how does fiber morphology and quality differ among varieties? and 3) how does kenaf (bast and core) compare with corn and pine fiber for fuel potential from micro-pyrolysis? The results show that Tainung 2 and Whitten were the most productive varieties in Central Iowa. Variety influenced morphology and fiber composition, but each variety was different. Stem diameter, leaf:stem ratio and core:bast ratio was dependent on the year, whereas stem length was greater for Tainung 2 and core:bast ratio was greater for both varieties. Core components were sensitive to climate conditions (year) whereas bast components were more affected by genetic variability for fiber composition. Overall, Tainung 2 and Whitten would be the most promising cultivars for Central Iowa and could likely be used to diversify the Iowa agriculture

Variety Trial and Pyrolysis Potential on Kenaf Grown in Iowa

Kenaf (Hibiscus cannabinus L.) is a warm-season, herbaceous plant mostly used as a fiber-crop in the textile and pulp industry, but also has potential for lignocellulosic bioenergy. Midwest studies on growth and use of kenaf have been scant; however, kenaf may have potential as an alternative crop for Iowa and the Midwest. Seven kenaf varieties were grown in Boone County, IA between 2004 and 2007 and evaluated for their production potential in the Midwest. More specifically, our questions were: 1) how do kenaf varieties perform in Iowa for yield?, 2) how does fiber morphology and quality differ among varieties and among core and bast fiber?, and 3) what potential does kenaf (bast and core) have for producing fuel using fast pyrolysis? The results show that Tainung 2 was the most productive variety in Central Iowa over multiple years. With regards to its chemical composition, bast kenaf had 8% more cellulose and 23% less hemicellulose than the core but it varied among varieties. Also, regardless of variety, core had in average more 40% lignin than bast. In general, core components were sensitive to climate conditions (year) whereas bast components were more affected by genetic variability for fiber composition. Similar to the plant morphology, the chemical composition determined by micro-pyrolysis showed that there are significant differences among varieties and between bast and core fiber. Overall, Tainung 2 would be the most promising cultivar for Central Iowa and could be grown to diversify Iowa agriculture and provide alternative feedstock to the biofuel industry

Optimal Agricultural Practices for Growing Kenaf in Iowa

Replacing petroleum-based materials with renewable materials is of critical importance as we transition to a vigorous bioeconomy. The use of natural fibers derived from plants like kenaf (Hibiscus cannabinus L.), an annual herbaceous multi-purpose fiber crop, represents one way to address the economic and environmental problems associated with the use of synthetics. Although kenaf is adapted to subtropical areas and can be grown in temperate areas where corn is adapted, very few kenaf studies have been conducted in the Midwest, especially in Iowa, where kenaf could be a promising crop, if properly grown. This study focused on investigating planting date, seeding density, row spacing, and nitrogen fertility effects on fiber quantity and quality of kenaf in Iowa. A first experiment was conducted in 2004, 2005 and 2006 and was planted in a randomized complete block with split plots in early May, late May and early June at 20, 38 and 76 cm-rows using 185328, 277993, 370657 seed/ha and 0 or 168 kg/ha of nitrogen. A similar experiment was performed in 2014 using this time two kenaf cultivars planted at 38 or 76 cm-rows at 247105 or 370657 seed/ha and receiving 0, 56, 112, 168 and 224 kg/ha of nitrogen. Yield, biweekly stem height and diameter, bast and core ratio and fiber composition were measured. The results show that it is better to plant kenaf in early or late May and that seeding rate and row spacing may be important considerations relative to kenaf end use because more crowded plants produce smaller stem diameters, richer in core fibers. Also, adding nitrogen was beneficial to kenaf but the response was year, season and variety dependent and could be used to manage crop composition. Overall, kenaf could be relatively easy to grow in Iowa and could bring diversity to its agriculture and industry

Optimal Agricultural Practices for Growing Kenaf in Iowa

The demand for natural fibers is increasing worldwide due to a growing interest in using renewable sources in place of those derived from petrochemicals. Kenaf (Hibiscus cannabinus L.) is a promising biorenewable resource for natural fibers that has rarely been grown in the Midwest. Literature is abundant about effects of management practices on kenaf productivity and fiber yield, but few studies have evaluated their interactions. The objectives of this study were to: 1) determine management practices leading to optimal kenaf and fiber yield; 2) evaluate stem height, basal diameter, and leaf area index (LAI) over the growing season; and 3) assess the influence of the management practices on fiber (bast, core) composition, and C, N, and ash quantity. Cultivars ‘Tainung 2’ and ‘Whitten’ were planted at 247,000 and 371,000 seed ha-1, in 38-cm and 76-cm rows, received 0, 56, 112, 168, or 224 kg ha-1 N in Central Iowa in 2014 and 2015. Stem DM yield, core and bast ratio, lignocellulose concentration, total ash, and carbon and nitrogen ratio were determined at the harvest, and stem height, basal diameter, and LAI were measured during the growing season of each year. The most striking result was that N fertilization did not increase stem DM yield, regardless to how much N was applied. However, we found that N effects were often observed for cell wall composition and ash concentration, and that the implications of these observations were directly related to kenaf end-use products. Moreover, we demonstrated that Tainung 2 and Whitten respond differently, depending on the management practices used. Overall, this study brought new evidence that kenaf could be successfully grown in Iowa, and that it is a promising multi-purpose crop for the region

Kenaf Productivity and Morphology. When Grown in Iowa and in Kentucky. Poster Number

Natural fibers are a promising alternative to synthetic fibers for reinforcing plastic or other composite materials, or fuel purposes. Kenaf (Hibiscus cannabinus L.), a fiber crop is grown to a limited extent in the U.S. predominantly in the Southern states. Producing kenaf in the Midwestern U.S. could provide a local source of these fibers for use in a number of manufactured products and potentially for use as a biofuel feedstock. The objectives of this study were to: 1) compare the productivity and the morphology of kenaf cultivars ‘Tainung 2’ and ‘Whitten’ when grown in Iowa and Kentucky and harvested after the first killing frost; 2) assess kenaf growth over the growing season; and 3) determine management (variety and seed density) effects on kenaf productivity and morphology. When grown in Kentucky in 2014, Tainung 2 yielded 24 Mg ha-1 whereas Whitten had a yield of 19 Mg ha-1. In contrast, kenaf grown in Iowa showed a yield of 8 Mg ha-1. In 2015, kenaf grown in Iowa and Kentucky had similar yield of 12.6 Mg ha-1 on average. When grown in Iowa, kenaf response to variety and seed density was more stable over time than in Kentucky. Therefore, a producer in Kentucky could influence kenaf productivity by changing management practices and variety. Tainung 2 was in general more sensitive to location and to seed density than Whitten. In 2015, Tainung 2 planted at a denser population produced 30% greater biomass than for Whitten and other seed densities. Whitten performed similarly across locations and seed densities. Growing Tainung 2 in Kentucky produced plants with 16% more core fiber than in Iowa, but using that same variety in Iowa would result in higher bast production. Overall, kenaf production is very feasible in Kentucky and Iowa but Kentucky has greater yield potential

Kenaf productivity and morphology, when grown in Iowa and in Kentucky

Kenaf (Hibiscus cannabinus L.), mostly produced in China and India, is grown to a limited extent in the U.S., although this natural fiber can be a promising alternative to synthetic fibers for reinforcing plastic or other composite materials, or fuel purposes. Producing kenaf in the Midwestern U.S. could provide a local source of this fiber for use in a number of manufactured products and potentially for use as a biofuel feedstock. The objectives of this study were to: 1) compare the productivity and the morphology of kenaf cultivars ‘Tainung 2’ and ‘Whitten’ when grown in Iowa and Kentucky and harvested after the first killing frost; 2) assess kenaf growth over the growing season; and 3) determine management (variety and seed density) effects on kenaf productivity and morphology. In 2014 and 2015, varieties ‘Tainung 2’ and ‘Whitten’ were grown at 185300 and 370700 seed/ha in Iowa and in Kentucky. Stem and leaf biomass, plant population, core:bast ratio, stem height and diameter, leaf area index (LAI), and nitrogen concentration were measured during 6 in-season harvests and at the final harvest. Results showed that, ‘Tainung 2’ and ‘Whitten’ grown in Kentucky in 2014 yielded 24 and 19 Mg/ha, respectively, whereas both cultivars reached a final yield of 8 Mg/ha in Iowa. However, in 2015, final yields were similar for both locations (12.6 Mg/ha on average). It was found that variety and seed density treatment effects were starting to be observed during the growing season, and that, when grown in Iowa, kenaf response to treatments was less variable over time than in Kentucky. With respect to fiber production, growing ‘Tainung 2’ in Kentucky produced plants with 16% more core fiber than in Iowa, but using that same variety in Iowa would result in higher bast production. Therefore, a producer in Kentucky could influence kenaf productivity by changing management practices and variety. Overall, kenaf production is very feasible in Kentucky and Iowa, but Kentucky has greater yield potential

Amodal Atypical Neural Oscillatory Activity in Dyslexia: A Cross-Linguistic Perspective

First Published December 21, 2016It has been proposed that atypical neural oscillations in both the auditory and the visual modalities could explain why some individuals fail to learn to read and suffer from developmental dyslexia. However, the role of specific oscillatory mechanisms in reading acquisition is still under debate. In this article, we take a cross-linguistic approach and argue that both the phonological and orthographic specifics of a language (e.g., linguistic rhythm, orthographic depth) shape the oscillatory activity thought to contribute to reading development. The proposed theoretical framework should allow future research to test cross-linguistic hypotheses that will shed light on the heterogeneity of auditory and visual disorders and their underlying brain dysfunction(s) in developmental dyslexia, and inform clinical practice by helping us to diagnose dyslexia across languages.This research was funded by the European Research Council (ERC Advanced Grant, BILITERACY Project, to M.C.), and the Spanish government (Plan Nacional-PSI2012-32128 and PSI2015-65338-P to M.L., Plan Nacional-PSI2012-32350 and PSI2015-65694-P to N.M., and Plan Nacional-PSI2015-67353-R to M.C.). The Basque Center on Brain Cognition and Language acknowledges funding from Ayuda Centro de Excelencia Severo Ochoa SEV-2015-0490

Point Mutations of Two Arginine Residues in the Streptomyces R61 Dd-Peptidase

peer reviewedIncubation of the exocellular DD-carboxypeptidase/transpeptidase of Streptomyces R61 with phenylglyoxal resulted in a time-dependent decrease in the enzyme activity. This inactivation was demonstrated to be due to modification of the Arg-99 side chain. In consequence, the role of that residue was investigated by site-directed mutagenesis. Mutation of Arg-99 into leucine appeared to be highly detrimental to enzyme stability, reflecting a determining structural role for this residue. The conserved Arg-103 residue was also substituted by using site-directed mutagenesis. The modification to a serine residue yielded a stable enzyme, the catalytic properties of which were similar to those of the wild-type enzyme. Thus Arg-103, although strictly conserved or replaced by a lysine residue in most of the active-site penicillin-recognizing proteins, did not appear to fulfil any essential role in either the enzyme activity or structure