Jeffrey Weidenhamer | Ashland University (original) (raw)

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Papers by Jeffrey Weidenhamer

Abstracts of Papers of The American Chemical Society, 2002

Plant and Soil, 2021

Integrated weed management in commercial wheat production is urgently needed due to increasing he... more Integrated weed management in commercial wheat production is urgently needed due to increasing herbicide resistance and production costs. Benzoxazinoids (BXs), which include benzoxazinones and benzoxazolinones, are unique bioactive metabolites produced by certain members of the Poaceae including maize, wheat, rye and some dicots. BXs play important roles in plant defence and are causal agents of allelopathic interference. We investigated the role of genetics, environment and crop growth stage on BX abundance in the roots and rhizoplane of selected commercial wheat cultivars, and quantified their microbial transformation products (aminophenoxazinones) in roots and rhizosphere soils. Cultivar trials of competitive wheat (Triticum aestivum L.) genotypes were conducted in two moderate to low rainfall (449–572 mm) locations in southeastern Australia in 2015 and 2016. Replicated shoot, root, rhizoplane, and rhizosphere soil samples were collected for metabolic profiling at selected crop phenological stages, extracted and further analysed for known benzoxazinoid metabolites by liquid chromatography coupled with high resolution mass spectrometry. Fifteen BXs and related microbially derived aminophenoxazinones were detected in wheat shoots, roots, rhizoplanes and rhizosphere soils in both years and locations. MBOA, HMBOA and HMBOA-Glc were the three most abundant BX metabolites in wheat tissues, with the heritage cultivar Federation producing the highest levels of MBOA. The phytotoxic aminophenoxazinones APO and AMPO were the most abundant BX microbial transformation products and were detected in wheat roots, rhizoplanes and rhizospheres. Abundance varied with cultivar, growth stage, location and year. Microbially-produced aminophenoxazinones generated from both heritage and modern wheat root exudates were detected and quantified in rhizosphere soils, with abundance dependent on cultivar, growth stage, and season. Concentrations of microbial metabolites APO, AMPO, and AAPO were higher in the rhizosphere of young wheat seedlings in contrast to that of mature plants suggesting that phenoxazinone production was upregulated early in the season. Our findings demonstrate that BX metabolites at all life stages of wheat potentially undergo rapid biotransformation to aminophenoxazinones under field conditions, resulting in ecologically relevant concentrations sufficient for weed suppression by certain wheat cultivars.

In 2014–2016, replicated field trials were performed to evaluate mechanisms of weed suppression i... more In 2014–2016, replicated field trials were performed to evaluate mechanisms of weed suppression in Australian canola genotypes in moderate to low rainfall zones at Wagga Wagga (572 mm) and Condobolin (449 mm) NSW, respectively. In 2015–2016, a split plot design with and without trifluralin as the main plot and cultivar as the sub plot was employed for trials; in this experiment 8 cultivars including hybrid and open-pollinated cultivars were assessed. At each site, crop and weed growth were monitored at various phenological stages including early season, vegetative, grain-filling, harvest and post-harvest. Certain cultivars exhibiting early vigour and also the ability to intercept light due to leaf canopy structure were associated with increased suppression of in-crop weed growth in canola trials; in addition, improved post-harvest weed suppression was associated with the presence of remaining crop residues after harvest. Cultivars GT-50, Hyola 600RR and Hyola 50 were Field evaluatio...

In 2014 and 2015, replicated field trials were performed at commercial paddocks in moderate to lo... more In 2014 and 2015, replicated field trials were performed at commercial paddocks in moderate to low rainfall zones at Wagga Wagga and Condobolin NSW, respectively. In 2014, a total of 11 winter wheat cultivars (Triticum aestivum L.) representing four major breeding family lines grown in Australia were evaluated with 13 cultivars assessed in 2015. At each site, crop and/or weed growth were monitored at various stages of growth: early season (tillering), vegetative, grain filling, harvest and post-harvest. Significant differences between wheat cultivar and location were observed for crop biomass, early vigour, leaf area index (LAI), weed number, weed biomass, canopy architecture and yield in both 2014 and 2015. Differences in weed suppression were largely impacted by crop architecture and phenology early in the growing season. Cultivar competitive traits were also influenced by both genotype and environmental factors, as shown by clear differences in cultivar performance, yield and wee...

Replicated and randomised wheat (Triticum aestivum L.) cultivar trials were conducted in moderate... more Replicated and randomised wheat (Triticum aestivum L.) cultivar trials were conducted in moderate to low rainfall zones at Wagga Wagga and Condobolin NSW, respectively in 2014 to 2016. At each experimental site, crop and/or weed growth were monitored at selected growth stages including tillering, vegetative, grain filling, harvest and after crop harvest. In addition, shoots, roots, rhizoplane and bulk rhizosphere soil samples were collected. All shoot and root samples were extracted in methanol using Buchi automated high pressure extractor, while soil samples were extracted using a rotary shaker. Extracts were profiled for unique secondary plant products acting as allelochemicals for weed suppression, specifically benzoxazinoids (BXs), using liquid chromatograph coupled to a triple quadrupole mass spectrometer (UPLC-MS QQQ). In addition, non-targeted metabolomics analysis was performed to evaluate relative abundance of diverse metabolites using a quadrupole time-of-flight mass spect...

Integrated weed management for sustainable agriculture, 2017

Due to the rise of herbicide resistance, diverse weed management tools are required to ensure sus... more Due to the rise of herbicide resistance, diverse weed management tools are required to ensure sustainable weed control. This chapter focuses on competitive cereal crops and cultural strategies for weed management, including the use of weed-suppressive cultivars, post-harvest crop residues, and cover crops for management of the weed seedbank and eventual weed suppression. It also addresses factors influencing the effect of allelopathy on weeds, including soil and environmental conditions which limit or intensify the efficacy of allelochemicals. The response of some weeds to secondary metabolites released by living cereal crops and/or crop residues (selectivity) is also reviewed. Finally, recommendations are given for future research, aiming to address the knowledge gap regarding the fate of these compounds in the environment and their role in important physiological processes in both plants and microbes in the soil rhizosphere.

Agronomy, 2020

Herbicide resistance in weeds restricts control options, thereby escalating economic loss and thr... more Herbicide resistance in weeds restricts control options, thereby escalating economic loss and threatening agricultural sustainability in cereal production. Field evaluation of the crop performance, competitive traits, and consequent weed suppressive potential of 13 commercial winter wheat (Triticum aestivum L.) cultivars was performed in central NSW Australia with a focus on the evaluation and modelling of above-ground interactions. In 2015 and 2016, replicated field trials were established with genetically diverse commercial wheat genotypes under moderate to low rainfall conditions in Wagga Wagga (572 mm) and Condobolin (437 mm) New South Wales, respectively. The heritage cultivar Federation and a commercial cultivar of winter cereal rye (Secale cereale L.) were included as known weed-suppressive controls. Crop and weed growth, as well as early vigour, leaf area index, and photosynthetically active radiation, were monitored at various crop phenological stages including early growth...

Abstracts of Papers of The American Chemical Society, 2002

Plant and Soil, 2021

Integrated weed management in commercial wheat production is urgently needed due to increasing he... more Integrated weed management in commercial wheat production is urgently needed due to increasing herbicide resistance and production costs. Benzoxazinoids (BXs), which include benzoxazinones and benzoxazolinones, are unique bioactive metabolites produced by certain members of the Poaceae including maize, wheat, rye and some dicots. BXs play important roles in plant defence and are causal agents of allelopathic interference. We investigated the role of genetics, environment and crop growth stage on BX abundance in the roots and rhizoplane of selected commercial wheat cultivars, and quantified their microbial transformation products (aminophenoxazinones) in roots and rhizosphere soils. Cultivar trials of competitive wheat (Triticum aestivum L.) genotypes were conducted in two moderate to low rainfall (449–572 mm) locations in southeastern Australia in 2015 and 2016. Replicated shoot, root, rhizoplane, and rhizosphere soil samples were collected for metabolic profiling at selected crop phenological stages, extracted and further analysed for known benzoxazinoid metabolites by liquid chromatography coupled with high resolution mass spectrometry. Fifteen BXs and related microbially derived aminophenoxazinones were detected in wheat shoots, roots, rhizoplanes and rhizosphere soils in both years and locations. MBOA, HMBOA and HMBOA-Glc were the three most abundant BX metabolites in wheat tissues, with the heritage cultivar Federation producing the highest levels of MBOA. The phytotoxic aminophenoxazinones APO and AMPO were the most abundant BX microbial transformation products and were detected in wheat roots, rhizoplanes and rhizospheres. Abundance varied with cultivar, growth stage, location and year. Microbially-produced aminophenoxazinones generated from both heritage and modern wheat root exudates were detected and quantified in rhizosphere soils, with abundance dependent on cultivar, growth stage, and season. Concentrations of microbial metabolites APO, AMPO, and AAPO were higher in the rhizosphere of young wheat seedlings in contrast to that of mature plants suggesting that phenoxazinone production was upregulated early in the season. Our findings demonstrate that BX metabolites at all life stages of wheat potentially undergo rapid biotransformation to aminophenoxazinones under field conditions, resulting in ecologically relevant concentrations sufficient for weed suppression by certain wheat cultivars.

In 2014–2016, replicated field trials were performed to evaluate mechanisms of weed suppression i... more In 2014–2016, replicated field trials were performed to evaluate mechanisms of weed suppression in Australian canola genotypes in moderate to low rainfall zones at Wagga Wagga (572 mm) and Condobolin (449 mm) NSW, respectively. In 2015–2016, a split plot design with and without trifluralin as the main plot and cultivar as the sub plot was employed for trials; in this experiment 8 cultivars including hybrid and open-pollinated cultivars were assessed. At each site, crop and weed growth were monitored at various phenological stages including early season, vegetative, grain-filling, harvest and post-harvest. Certain cultivars exhibiting early vigour and also the ability to intercept light due to leaf canopy structure were associated with increased suppression of in-crop weed growth in canola trials; in addition, improved post-harvest weed suppression was associated with the presence of remaining crop residues after harvest. Cultivars GT-50, Hyola 600RR and Hyola 50 were Field evaluatio...

In 2014 and 2015, replicated field trials were performed at commercial paddocks in moderate to lo... more In 2014 and 2015, replicated field trials were performed at commercial paddocks in moderate to low rainfall zones at Wagga Wagga and Condobolin NSW, respectively. In 2014, a total of 11 winter wheat cultivars (Triticum aestivum L.) representing four major breeding family lines grown in Australia were evaluated with 13 cultivars assessed in 2015. At each site, crop and/or weed growth were monitored at various stages of growth: early season (tillering), vegetative, grain filling, harvest and post-harvest. Significant differences between wheat cultivar and location were observed for crop biomass, early vigour, leaf area index (LAI), weed number, weed biomass, canopy architecture and yield in both 2014 and 2015. Differences in weed suppression were largely impacted by crop architecture and phenology early in the growing season. Cultivar competitive traits were also influenced by both genotype and environmental factors, as shown by clear differences in cultivar performance, yield and wee...

Replicated and randomised wheat (Triticum aestivum L.) cultivar trials were conducted in moderate... more Replicated and randomised wheat (Triticum aestivum L.) cultivar trials were conducted in moderate to low rainfall zones at Wagga Wagga and Condobolin NSW, respectively in 2014 to 2016. At each experimental site, crop and/or weed growth were monitored at selected growth stages including tillering, vegetative, grain filling, harvest and after crop harvest. In addition, shoots, roots, rhizoplane and bulk rhizosphere soil samples were collected. All shoot and root samples were extracted in methanol using Buchi automated high pressure extractor, while soil samples were extracted using a rotary shaker. Extracts were profiled for unique secondary plant products acting as allelochemicals for weed suppression, specifically benzoxazinoids (BXs), using liquid chromatograph coupled to a triple quadrupole mass spectrometer (UPLC-MS QQQ). In addition, non-targeted metabolomics analysis was performed to evaluate relative abundance of diverse metabolites using a quadrupole time-of-flight mass spect...

Integrated weed management for sustainable agriculture, 2017

Due to the rise of herbicide resistance, diverse weed management tools are required to ensure sus... more Due to the rise of herbicide resistance, diverse weed management tools are required to ensure sustainable weed control. This chapter focuses on competitive cereal crops and cultural strategies for weed management, including the use of weed-suppressive cultivars, post-harvest crop residues, and cover crops for management of the weed seedbank and eventual weed suppression. It also addresses factors influencing the effect of allelopathy on weeds, including soil and environmental conditions which limit or intensify the efficacy of allelochemicals. The response of some weeds to secondary metabolites released by living cereal crops and/or crop residues (selectivity) is also reviewed. Finally, recommendations are given for future research, aiming to address the knowledge gap regarding the fate of these compounds in the environment and their role in important physiological processes in both plants and microbes in the soil rhizosphere.

Agronomy, 2020

Herbicide resistance in weeds restricts control options, thereby escalating economic loss and thr... more Herbicide resistance in weeds restricts control options, thereby escalating economic loss and threatening agricultural sustainability in cereal production. Field evaluation of the crop performance, competitive traits, and consequent weed suppressive potential of 13 commercial winter wheat (Triticum aestivum L.) cultivars was performed in central NSW Australia with a focus on the evaluation and modelling of above-ground interactions. In 2015 and 2016, replicated field trials were established with genetically diverse commercial wheat genotypes under moderate to low rainfall conditions in Wagga Wagga (572 mm) and Condobolin (437 mm) New South Wales, respectively. The heritage cultivar Federation and a commercial cultivar of winter cereal rye (Secale cereale L.) were included as known weed-suppressive controls. Crop and weed growth, as well as early vigour, leaf area index, and photosynthetically active radiation, were monitored at various crop phenological stages including early growth...