The study of plant response to environmental stresses has developed rapidly during the past sever... more The study of plant response to environmental stresses has developed rapidly during the past several decades. Attention has increasingly been devoted to the biochemical, biophysical, and physiological processes involved in the changes in solute concentration and content of cells which occur in response to changes in the external water potential. One aspect of these changes is osmotic adjustment.
ABSTRACT The distribution of vegetation over the earth’s surface is controlled more by the availa... more ABSTRACT The distribution of vegetation over the earth’s surface is controlled more by the availability of water than by any other factor. Production of crops requires a reliable supply of water from either rainfall or irrigation. Increasingly agriculture, industry, and cities are competing for scarce water resources. Thus, there is great interest in developing technologies which would make it possible to use water of low quality, currently considered to be unsuitable for irrigation, such as water with high salt content. Such technologies would make it possible to raise crops on large areas where none can be raised now. Many important contributions have been made to the study of water use by crops. Although this information has helped in the planning of reservoir and canal sizes, the hope for breeding plants with lower requirements for water or for developing technologies that might make it possible to use water with a high salt content has not, as yet, been realized. Progress with improving water use efficiency of crops hinges on gathering the information needed to develop a theoretical framework for understanding and eventually manipulating mechanisms that influence uptake, use, and loss of water by plants. Once these mechanisms have been identified, and a better understanding of the plant as an integrated whole is gained, biotechnology may help in the development of more water use efficient plants. For the near term traditional methods of plant breeding must be relied upon, even though there is increasing evidence that for many crops the limits to improvement by this method are being approached. To break through this yield plateau, plant breeders, physiologists, and biochemists must work together to understand the stress response hierarchy. Plant performance under a variety of environmental stresses, including water, salinity and temperature stresses, has been evaluated at the molecular level, the cellular level, and the whole plant level. Unfortunately, large gaps of understanding remain because the goal of constructing a unified theory of plant response based on information drawn from such studies has not yet been attained. One approach which could be useful in achieving this goal would be to combine mathematical description of basic plant processes based on thermodynamic considerations, with experimental results obtained in trials using whole plants. The applicability of this approach for the study of whole plant processes as a basis for characterizing plant response to water and salinity stresses is examined. Keywords:plant growth–water potential–activation energy–osmotic adjustment–temperature
We developed a simple analytical model for carbon and nitrogen dynamics in soils. Description of ... more We developed a simple analytical model for carbon and nitrogen dynamics in soils. Description of the soil C and N dynamics focus on the total carbon residue function, R, defined as the fraction of original plant carbon input remaining in the soil as a function of time, and nitrogen concentration function, N, defined as the N concentration of the carbon residue as a function of R. A simple two-parameter function, R ؍ Exp(؊(kt) ␣ ), was used for total carbon residue function. N concentration of carbon residue is derived to be a linear function of R. We tested our model with data reported in the literature. The model parameters (k and ␣) were calculated from independently determined gross turnover time and 14 C age of soil organic carbon. Our model accurately predicts C and N dynamics in response to fertilization and manure application for time periods ranging from a few months to more than 150 years. (Soil Science 2001;166:431-440
ABSTRACT Remote optical techniques are well suited for obtaining representative average values fo... more ABSTRACT Remote optical techniques are well suited for obtaining representative average values for gas fluxes emanating from a semi-infinite flat surface. Unisearch, the Alberta Reserach Council and the University of Alberta have developed a technique and methodology for making such measurements using a near-IR tunable diode laser analyzer and a set of open path optics. The technqiue uses the LasIR to measure gas concentrations at two different heights along paths which folow the perimeter of a square, flat surface. The measurements are used to calculate a concentration gradient across the height difference. These values, along with air temperature, relative humidity, soil heat flux, net radiation and wind speed/direction data, are then used to calculate the average flux emanating from the surface by applying an integrated flux gradient analysis based on Monin-Obukhov similarity theory. This method was applied to measure fluxes of methane emanating from a 50m × 50m test agricultural plot after the application of manure. Plans are underway to extend the capability of the system to measure up to four different species simultaneously.
Re-establishment of self-sustaining ecosystems is a major challenge in the reclamation of land di... more Re-establishment of self-sustaining ecosystems is a major challenge in the reclamation of land disturbed by oil sands mining operation. We explored the possibility of using oil sands mining by-products as reclamation materials for the disturbed lands. A procedure to artificially aggregate soils or soil-like materials using oil sands mining by-products, namely, mature fine tails(MFT), composite tails(CT), and tail- ings sand (TS) was developed. A greenhouse experiment was conducted to evaluate plant performance on the artificially aggregated materials with different amount of peat moss as an amendment. Three plant species, AEC highlander wheatgrass (Elymus trachycaulus subsp. trachycaulus), Alpine Milkvetch (Astragalus alpinus L.), and saskatoon (Amelanchier alnifo- lia, smokey), were grown in seven different treatments. In the summer of 1997, a field experiment site was established to test the feasibility of reclaiming oil sands processing by-products. The aggregation procedure deve...
Partition of photosynthates between shoot and root in spring wheat (Triticum aestivum L.) as a fu... more Partition of photosynthates between shoot and root in spring wheat (Triticum aestivum L.) as a function of soil water potential and root temperature
We examined the roles of turgor potential and osmotic adjustment in plant growth by comparing the... more We examined the roles of turgor potential and osmotic adjustment in plant growth by comparing the growth of spring wheat {Triticum aestivum cv. Siete cerrors) and sudangrass (Sorghum vulgare var. Piper) seedlings In response to soil water and temperature stresses. The rates of leaf area expansion, leaf water potential and osmotic potential were measured at combinations of 5 soil water potentials ranging from-0.03 to-0.25 MPa and 6 soil temperatures ranging from 14 to 36°C. Spring wheat exhibited little osmotic adjustment while sudangrass exhibited a high degree of osmotic adjustment. However, the rate of leaf area growth for sudangrass was more sensitive to water stress than that of spring wheat. These results were used to evaluate the relationship between growth and turgor potential. The modified Arrhenius equation based on thermodynamic considerations of the growth process was evaluated. This equation obtains growth rate as a function of activation energy, enthalpy difference between active and inactive states of enzymes, base growth rate and optimum temperature. Analyses indicate that the modified Arrhenius equation is consistent with the Lockhart equation with a metabolically controlled cell wail extensibility.
Simulation models are widely used to make predictions of crop growth and yield, and soil carbon a... more Simulation models are widely used to make predictions of crop growth and yield, and soil carbon and nutrient dynamics under various agricultural practices and soil-climatic conditions. An analytical model of soil carbon and nutrient dynamics, K-model, was expanded to include a plant sub-model (K-Model-P). This allows for the prediction of short-and long-term crop growth, and soil carbon and nitrogen dynamics. The simulations for a short-term experiment (2 growing seasons) with three nitrogen application rates showed that K-Model-P correctly predicted the growth processes of above-ground plant biomass and grain yields. Predicted and measured daily accumulative biomass were significantly correlated, and differences were statistically insignificant. The simulation results for long-term experiments (70 years) of two crop rotations with three soil amendments showed that predicted and measured annual straw and grain yields were significantly correlated, with the differences of less than 13%. Annual crop straw and grain yields can be estimated by the model without significant errors. The agreement between the predicted daily growth and annual yields and experimental data illustrated that the K-Model-P can be used to produce reliable predictions for daily and annual crop growth.
ABSTRACT Mathematical description of plant processes based on thermodynamic considerations can be... more ABSTRACT Mathematical description of plant processes based on thermodynamic considerations can be used to describe the response of plants to water and temperature stresses. This study was initiated to explore this possibility. Leaf area, shoot dry mass, leaf water potential (ψ1), osmotic potential (π), and the rate of photosynthetic dry mass production (P t ) of spring wheat seedlings were determined at combinations of five soil water potentials from −0.03 to −0.25 MPa and seven root temperatures from 12 to 32 °C. The relative growth rates of leaf area and shoot dry mass and P t were fitted to a mathematical equation derived from thermodynamic considerations. A non-linear least-squares procedure was used with root temperature and ψ 1 as independent variables. These calculations yielded values of activation energy, optimum temperature, and base rates of photosynthesis and plant growth. Activation energies increased with decreasing ψ 1 for growth rates of leaf area and shoot dry mass and for P t . Increase of activation energy was greater for the growth rates than for photosynthesis, suggesting that growth was more sensitive to water stress than photosynthesis. The base rate, K 0 , which is the theoretical rate at zero activation energy, for the growth of leaf area and shoot dry mass increased linearly with turgor potential (ψ p ). However, K 0 was independent of ψ p for P t . We conclude that the rate of leaf expansion was proportional to ψ p and that the proportionality coefficient was affected by temperature and water stresses in a similar manner as P t was affected. Our analysis supports the proposition that plant cell extensibility is under metabolic control.
The study of plant response to environmental stresses has developed rapidly during the past sever... more The study of plant response to environmental stresses has developed rapidly during the past several decades. Attention has increasingly been devoted to the biochemical, biophysical, and physiological processes involved in the changes in solute concentration and content of cells which occur in response to changes in the external water potential. One aspect of these changes is osmotic adjustment.
ABSTRACT The distribution of vegetation over the earth’s surface is controlled more by the availa... more ABSTRACT The distribution of vegetation over the earth’s surface is controlled more by the availability of water than by any other factor. Production of crops requires a reliable supply of water from either rainfall or irrigation. Increasingly agriculture, industry, and cities are competing for scarce water resources. Thus, there is great interest in developing technologies which would make it possible to use water of low quality, currently considered to be unsuitable for irrigation, such as water with high salt content. Such technologies would make it possible to raise crops on large areas where none can be raised now. Many important contributions have been made to the study of water use by crops. Although this information has helped in the planning of reservoir and canal sizes, the hope for breeding plants with lower requirements for water or for developing technologies that might make it possible to use water with a high salt content has not, as yet, been realized. Progress with improving water use efficiency of crops hinges on gathering the information needed to develop a theoretical framework for understanding and eventually manipulating mechanisms that influence uptake, use, and loss of water by plants. Once these mechanisms have been identified, and a better understanding of the plant as an integrated whole is gained, biotechnology may help in the development of more water use efficient plants. For the near term traditional methods of plant breeding must be relied upon, even though there is increasing evidence that for many crops the limits to improvement by this method are being approached. To break through this yield plateau, plant breeders, physiologists, and biochemists must work together to understand the stress response hierarchy. Plant performance under a variety of environmental stresses, including water, salinity and temperature stresses, has been evaluated at the molecular level, the cellular level, and the whole plant level. Unfortunately, large gaps of understanding remain because the goal of constructing a unified theory of plant response based on information drawn from such studies has not yet been attained. One approach which could be useful in achieving this goal would be to combine mathematical description of basic plant processes based on thermodynamic considerations, with experimental results obtained in trials using whole plants. The applicability of this approach for the study of whole plant processes as a basis for characterizing plant response to water and salinity stresses is examined. Keywords:plant growth–water potential–activation energy–osmotic adjustment–temperature
We developed a simple analytical model for carbon and nitrogen dynamics in soils. Description of ... more We developed a simple analytical model for carbon and nitrogen dynamics in soils. Description of the soil C and N dynamics focus on the total carbon residue function, R, defined as the fraction of original plant carbon input remaining in the soil as a function of time, and nitrogen concentration function, N, defined as the N concentration of the carbon residue as a function of R. A simple two-parameter function, R ؍ Exp(؊(kt) ␣ ), was used for total carbon residue function. N concentration of carbon residue is derived to be a linear function of R. We tested our model with data reported in the literature. The model parameters (k and ␣) were calculated from independently determined gross turnover time and 14 C age of soil organic carbon. Our model accurately predicts C and N dynamics in response to fertilization and manure application for time periods ranging from a few months to more than 150 years. (Soil Science 2001;166:431-440
ABSTRACT Remote optical techniques are well suited for obtaining representative average values fo... more ABSTRACT Remote optical techniques are well suited for obtaining representative average values for gas fluxes emanating from a semi-infinite flat surface. Unisearch, the Alberta Reserach Council and the University of Alberta have developed a technique and methodology for making such measurements using a near-IR tunable diode laser analyzer and a set of open path optics. The technqiue uses the LasIR to measure gas concentrations at two different heights along paths which folow the perimeter of a square, flat surface. The measurements are used to calculate a concentration gradient across the height difference. These values, along with air temperature, relative humidity, soil heat flux, net radiation and wind speed/direction data, are then used to calculate the average flux emanating from the surface by applying an integrated flux gradient analysis based on Monin-Obukhov similarity theory. This method was applied to measure fluxes of methane emanating from a 50m × 50m test agricultural plot after the application of manure. Plans are underway to extend the capability of the system to measure up to four different species simultaneously.
Re-establishment of self-sustaining ecosystems is a major challenge in the reclamation of land di... more Re-establishment of self-sustaining ecosystems is a major challenge in the reclamation of land disturbed by oil sands mining operation. We explored the possibility of using oil sands mining by-products as reclamation materials for the disturbed lands. A procedure to artificially aggregate soils or soil-like materials using oil sands mining by-products, namely, mature fine tails(MFT), composite tails(CT), and tail- ings sand (TS) was developed. A greenhouse experiment was conducted to evaluate plant performance on the artificially aggregated materials with different amount of peat moss as an amendment. Three plant species, AEC highlander wheatgrass (Elymus trachycaulus subsp. trachycaulus), Alpine Milkvetch (Astragalus alpinus L.), and saskatoon (Amelanchier alnifo- lia, smokey), were grown in seven different treatments. In the summer of 1997, a field experiment site was established to test the feasibility of reclaiming oil sands processing by-products. The aggregation procedure deve...
Partition of photosynthates between shoot and root in spring wheat (Triticum aestivum L.) as a fu... more Partition of photosynthates between shoot and root in spring wheat (Triticum aestivum L.) as a function of soil water potential and root temperature
We examined the roles of turgor potential and osmotic adjustment in plant growth by comparing the... more We examined the roles of turgor potential and osmotic adjustment in plant growth by comparing the growth of spring wheat {Triticum aestivum cv. Siete cerrors) and sudangrass (Sorghum vulgare var. Piper) seedlings In response to soil water and temperature stresses. The rates of leaf area expansion, leaf water potential and osmotic potential were measured at combinations of 5 soil water potentials ranging from-0.03 to-0.25 MPa and 6 soil temperatures ranging from 14 to 36°C. Spring wheat exhibited little osmotic adjustment while sudangrass exhibited a high degree of osmotic adjustment. However, the rate of leaf area growth for sudangrass was more sensitive to water stress than that of spring wheat. These results were used to evaluate the relationship between growth and turgor potential. The modified Arrhenius equation based on thermodynamic considerations of the growth process was evaluated. This equation obtains growth rate as a function of activation energy, enthalpy difference between active and inactive states of enzymes, base growth rate and optimum temperature. Analyses indicate that the modified Arrhenius equation is consistent with the Lockhart equation with a metabolically controlled cell wail extensibility.
Simulation models are widely used to make predictions of crop growth and yield, and soil carbon a... more Simulation models are widely used to make predictions of crop growth and yield, and soil carbon and nutrient dynamics under various agricultural practices and soil-climatic conditions. An analytical model of soil carbon and nutrient dynamics, K-model, was expanded to include a plant sub-model (K-Model-P). This allows for the prediction of short-and long-term crop growth, and soil carbon and nitrogen dynamics. The simulations for a short-term experiment (2 growing seasons) with three nitrogen application rates showed that K-Model-P correctly predicted the growth processes of above-ground plant biomass and grain yields. Predicted and measured daily accumulative biomass were significantly correlated, and differences were statistically insignificant. The simulation results for long-term experiments (70 years) of two crop rotations with three soil amendments showed that predicted and measured annual straw and grain yields were significantly correlated, with the differences of less than 13%. Annual crop straw and grain yields can be estimated by the model without significant errors. The agreement between the predicted daily growth and annual yields and experimental data illustrated that the K-Model-P can be used to produce reliable predictions for daily and annual crop growth.
ABSTRACT Mathematical description of plant processes based on thermodynamic considerations can be... more ABSTRACT Mathematical description of plant processes based on thermodynamic considerations can be used to describe the response of plants to water and temperature stresses. This study was initiated to explore this possibility. Leaf area, shoot dry mass, leaf water potential (ψ1), osmotic potential (π), and the rate of photosynthetic dry mass production (P t ) of spring wheat seedlings were determined at combinations of five soil water potentials from −0.03 to −0.25 MPa and seven root temperatures from 12 to 32 °C. The relative growth rates of leaf area and shoot dry mass and P t were fitted to a mathematical equation derived from thermodynamic considerations. A non-linear least-squares procedure was used with root temperature and ψ 1 as independent variables. These calculations yielded values of activation energy, optimum temperature, and base rates of photosynthesis and plant growth. Activation energies increased with decreasing ψ 1 for growth rates of leaf area and shoot dry mass and for P t . Increase of activation energy was greater for the growth rates than for photosynthesis, suggesting that growth was more sensitive to water stress than photosynthesis. The base rate, K 0 , which is the theoretical rate at zero activation energy, for the growth of leaf area and shoot dry mass increased linearly with turgor potential (ψ p ). However, K 0 was independent of ψ p for P t . We conclude that the rate of leaf expansion was proportional to ψ p and that the proportionality coefficient was affected by temperature and water stresses in a similar manner as P t was affected. Our analysis supports the proposition that plant cell extensibility is under metabolic control.
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Papers by Yongsheng Feng