Engineering topics

Moller, Christopher A.

Publications and source records attributed to Moller, Christopher A..

6 records

DOE OSTI2023

Similar photosynthetic but different yield responses of C 3 and C 4 crops to elevated O 3

The deleterious effects of ozone (O 3 ) pollution on crop physiology, yield, and productivity are widely acknowledged. It has also been assumed that C 4 crops with a carbon concentrating mechanism and greater water use efficiency are less sensitive to O 3 pollution than C 3 crops. This assumption has not been widely tested. Therefore, we compiled 46 journal articles and unpublished datasets that reported leaf photosynthetic and biochemical traits, plant biomass, and yield in five C 3 crops (chickpea, rice, snap bean, soybean, and wheat) and four C 4 crops (sorghum, maize, Miscanthus × giganteus , and switchgrass) grown under ambient and elevated O 3 concentration ([O 3 ]) in the field at free-air O 3 concentration enrichment (O 3 -FACE) facilities over the past 20 y. When normalized by O 3 exposure, C 3 and C 4 crops showed a similar response of leaf photosynthesis, but the reduction in chlorophyll content, fluorescence, and yield was greater in C 3 crops compared with C 4 crops. Additionally, inbred and hybrid lines of rice and maize showed different sensitivities to O 3 exposure. This study quantitatively demonstrates that C 4 crops respond less to elevated [O 3 ] than C 3 crops. This understanding could help maintain cropland productivity in an increasingly polluted atmosphere.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2023

Similar photosynthetic, but different yield responses of C3 and C4 crops to elevated O3

This dataset contains leaf photosynthetic and biochemical traits, plant biomass, and yield in five C3 crops (chickpea, rice, snap bean, soybean, wheat) and four C4 crops (sorghum, maize, Miscanthus × giganteus, switchgrass) grown under ambient and elevated O3 concentration ([O3]) in the field at free-air O3 concentration enrichment (O3-FACE) facilities over the past 20 years.

C3 and C4 crops↗

DOE OSTI2022

The leaf economics spectrum of triploid and tetraploid C 4 grass Miscanthus x giganteus

Abstract The leaf economics spectrum (LES) describes multivariate correlations in leaf structural, physiological and chemical traits, originally based on diverse C 3 species grown under natural ecosystems. However, the specific contribution of C 4 species to the global LES is studied less widely. C 4 species have a CO 2 concentrating mechanism which drives high rates of photosynthesis and improves resource use efficiency, thus potentially pushing them towards the edge of the LES. Here, we measured foliage morphology, structure, photosynthesis, and nutrient content for hundreds of genotypes of the C 4 grass Miscanthus × giganteus grown in two common gardens over two seasons. We show substantial trait variations across M .× giganteus genotypes and robust genotypic trait relationships. Compared to the global LES, M .× giganteus genotypes had higher photosynthetic rates, lower stomatal conductance, and less nitrogen content, indicating greater water and photosynthetic nitrogen use efficiency in the C 4 species. Additionally, tetraploid genotypes produced thicker leaves with greater leaf mass per area and lower leaf density than triploid genotypes. By expanding the LES relationships across C 3 species to include C 4 crops, these findings highlight that M .× giganteus occupies the boundary of the global LES and suggest the potential for ploidy to alter LES traits.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2022

Testing unified theories for ozone response in C 4 species

Abstract There is tremendous interspecific variability in O 3 sensitivity among C 3 species, but variation among C 4 species has been less clearly documented. It is also unclear whether stomatal conductance and leaf structure such as leaf mass per area (LMA) determine the variation in sensitivity to O 3 across species. In this study, we investigated leaf morphological, chemical, and photosynthetic responses of 22 genotypes of four C 4 bioenergy species (switchgrass, sorghum, maize, and miscanthus) to elevated O 3 in side‐by‐side field experiments using free‐air O 3 concentration enrichment (FACE). The C 4 species varied largely in leaf morphology, physiology, and nutrient composition. Elevated O 3 did not alter leaf morphology, nutrient content, stomatal conductance, chlorophyll fluorescence, and respiration in most genotypes but reduced net CO 2 assimilation in maize and photosynthetic capacity in sorghum and maize. Species with lower LMA and higher stomatal conductance tended to show greater losses in photosynthetic rate and capacity in elevated O 3 compared with species with higher LMA and lower stomatal conductance. Stomatal conductance was the strongest determinant of leaf photosynthetic rate and capacity. The response of both area‐ and mass‐based leaf photosynthetic rate and capacity to elevated O 3 were not affected by LMA directly but negatively influenced by LMA indirectly through stomatal conductance. These results demonstrate that there is significant variation in O 3 sensitivity among C 4 species with maize and sorghum showing greater sensitivity of photosynthesis to O 3 than switchgrass and miscanthus. Interspecific variation in O 3 sensitivity was determined by direct effects of stomatal conductance and indirect effects of LMA. This is the first study to provide a test of unifying theories explaining variation in O 3 sensitivity in C 4 bioenergy grasses. These findings advance understanding of O 3 tolerance in C 4 grasses and could aid in optimal placement of diverse C 4 bioenergy feedstock across a polluted landscape.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2022

Testing unified theories for ozone response in C4 species

Twenty-two genotypes of C4 species grown under ambient and elevated O3 concentration were studied at the SoyFACE (40°02’N, 88°14’W) in 2019. This dataset contains leaf morphology, photosynthesis and nutrient contents measured at three time points. The results of CO2 response curves are also included.

C4↗

DOE OSTI2021

Bioenergy sorghum maintains photosynthetic capacity in elevated ozone concentrations

Abstract Elevated tropospheric ozone concentration (O 3 ) significantly reduces photosynthesis and productivity in several C 4 crops including maize, switchgrass and sugarcane. However, it is unknown how O 3 affects plant growth, development and productivity in sorghum ( Sorghum bicolor L.), an emerging C 4 bioenergy crop. Here, we investigated the effects of elevated O 3 on photosynthesis, biomass and nutrient composition of a number of sorghum genotypes over two seasons in the field using free‐air concentration enrichment (FACE), and in growth chambers. We also tested if elevated O 3 altered the relationship between stomatal conductance and environmental conditions using two common stomatal conductance models. Sorghum genotypes showed significant variability in plant functional traits, including photosynthetic capacity, leaf N content and specific leaf area, but responded similarly to O 3 . At the FACE experiment, elevated O 3 did not alter net CO 2 assimilation ( A ), stomatal conductance ( g s ), stomatal sensitivity to the environment, chlorophyll fluorescence and plant biomass, but led to reductions in the maximum carboxylation capacity of phosphoenolpyruvate and increased stomatal limitation to A in both years. These findings suggest that bioenergy sorghum is tolerant to O 3 and could be used to enhance biomass productivity in O 3 polluted regions.

09 BIOMASS FUELS↗