2.Investigators:

GUTMAN, Mari
Migal - Galilee Technological Center, Kiriat Shmona 10200, Israel Fax: 972- 6-944980.
E-mail: mgutman@Migal.co.Il

3. Specific Objectives

I. Evaluate biomass partitioning in annual and perennial grasses in response to levels of simulated grazing.

II. Conduct simulation experiments to evaluate plant production responses to alternative management decisions.

III. Develop decision rules for grazing management based upon forage plant biology and system function to optimize sustained yield of leaf material, relative to root mass and reproductive structures.

4. Technical discussion

Native or domestic forage is the most cost effective feed source for ruminants production. Management of forage production and utilization on ranges and pastures to achieve sustained productivity and profitability requires sound management decisions. These decisions must be supported by knowledge of forage plant biology and system function.

A static optimum management solution does not exist because both environmental and economic components of the system are highly variable through time. Consequently, management prescriptions must be sufficiently flexible to accommodate a variety of inputs on various time scales.

For nine consecutive years (1987-1995) an American - Israeli team developed a system to measure the impact of plant manipulation on herbage production. The trials were conducted under controlled grazing conditions with animals (cattle in our case) or by simulation of grazing by clipping plants raised in containers. We propose to apply this acquired knowledge on rangelands grasses species in order to determine the pertinent data needed to improve management in these rangelands.

Empirical field research cannot provide sufficiently diverse information to address all of the potential managerial scenarios encountered. Simulation modeling is a proven tool for investigating system function and developing decision criteria for management; however, effective models require experimental data for parameterization and validation.

The potential for managerial manipulation could be evaluated in l annual and perennial species utilizing destructive harvests and controlled grazing trials.

Results from these experiments will be used to parameterize biomass partitioning between reproductive and vegetative growth sub- models to be incorporated into an existing forage growth model for economically important annual and perennial grasses.

Research in Israel

The research will be carried out on mixed annual-perennial grasslands in Galilee, where the Karei-Deshe experimental range is located. Considerable quantitative information on the environment, plants and animals is available from previous research at this location.

Two species have been chosen for investigation. Hordeum bulbosum, is an erect perennial grass, which regenerates annually and reproduces asexually from bulbs just below the surface, but also produces abundant seeds in certain conditions. It is a major dominant in ungrazed conditions and in a wide range of grazing pressures. Avena sterilis, a tall, large-seeded annual grass represents the group of wild cereal grasses (including also wild barley and oat) which are abundant and locally dominant in lightly grazed areas.

The research plan consists of the following components:

A). Controlled experiments evaluating the effects of defoliation frequency and intensity on biomass partitioning between vegetative and reproductive (spike and bulb) structures. The experiments will be carried out on containerized plants of Avena sterilis (grown from seeds), in environmental conditions (soil type, weather, plant density) comparable to those encountered under field conditions. A factorial design with 2-3 clipping heights x 2-3 clipping frequencies and a suitable number of replicates will be used. The experiment will be repeated in year two; in the second year the design may be modified according to results and lessons obtained from the first year. Growth will be evaluated by morphological units (numbers of vegetative tillers, leaves, reproductive culms, mature spikes, spikelets, bulbs) and biomass of the various components. Numbers of above-ground units and biomass of clipped parts will be monitored during the growing season. Below-ground units and biomass of all parts will be determined at the end of the growing season.

B) Development and parameterization of a biomass partitioning model. The hypotheses presented above and evidence from literature will be used to formulate a model to partition growth between vegetative and reproductive structures in annual and perennial (bulb-forming) grasses, in relation to defoliation. Results from the controlled experiments will be used to check, refine or modify (as necessary) the model and to estimate its parameters for an annual and a perennial grass.

C) Evaluation of biomass partitioning under different grazing regimes. This will be carried out in a grazing trial with cattle on natural rangeland at Karei-Deshe, with two grazing systems (continuous and deferred) x two stocking rates x two fields, and an exclosure protected from grazing during the growing season. Random samples of Avena sterilis plants from populations in various fields will be collected at 3-4 times during the growing season. Numbers and biomass of vegetative and reproductive (above- and belowground) units will be determined. The results will be compared with results from the clipping experiments and with predictions of the model for clipping regimes characteristic of the different grazing treatments.
 
 

5. Innovation. The understanding of biomass partitioning into vegetative and sexual reproduction is largely theoretical. Few, if any, major efforts have attempted to transfer information concerning biomass partitioning from the level of the individual plant to application in agricultural systems.

Development and parameterization of the biomass partitioning model including responses to defoliation and environmental variables will be a significant step towards the development of models that can realistically simulate environment-plant-animal interactions. While these processes have frequently been described, they have not been integrated into a quantitative model applicable to agricultural systems. These activities may potentially define an innovative modeling protocol by integrating mechanistic plant level responses into the analysis of managerial decisions at the agricultural system level. This study should produce basic physiological data that will have considerable scientific value beyond its utility for management of forage crops and range plants.

6. Relevance. Grazing management strategies based on a sound understanding of forage plant biology may represent a cost effective means of optimizing production and utilization of high quality forage. Increased leaf production, at the expense of root mass or high fiber components (culms or stems), may be achieved by manipulating biomass partitioning among roots, leaves and reproductive

structures. An approach incorporating both experimental data and simulation modeling will facilitate the integration of data from diverse studies into a unified theory for biomass partitioning. Experimentation in vegetation as diverse as the Mediterranean grasslands of Israel and grasslands of Slovakia will provide a rigorous test of the proposed concepts. If the concepts are proven successful in these environments they should be applicable to forage systems throughout the world.

7. Capacity strengthened. Very few experiments concerning responses to grasses to grazing have been conducted in Slovakia, the proposed research will provide the tools to develop a relatively simple method to obtain relevant data to substainlable pasture management.

8. Collaboration. During the past years in international congresses and during a visit to Slovakia Dr. Mario Gutman get acquitted with characteristics and needs of research in Slovakia. The experience acquired during the years of joint USA Israeli research could be easily transferred to Slovakia.

9. Budget

Detailed Israel Budget (US$)

ABSTRACT

Native or domestic forage is the most cost effective feed source for beef cattle and dairy production. Management practices that

initiate forage production earlier in the season or extend the growth period can significantly reduce production costs. Production efficiency

of a forage base can be enhanced by increasing total production with the addition of cultural inputs (i.e. fertilizer, irrigation, improved plant

materials) and/or by increasing the quality of forage production. Since forage production in many grazed systems is constrained by environmental limitations which are difficult to mitigate in a cost effective manner, we propose to investigate the manipulation of biomass partitioning to improve forage quality and increase production efficiency. The potential for managerially manipulating biomass partitioning to root:shoot:reproductive growth will be evaluated in several annual and perennial species utilizing destructive harvests and the stable carbon isotope C-13 in controlled environment conditions. Results from these experiments will be used to parameterize a biomass partitioning sub-model to be incorporated into an existing forage growth model for economically important annual and perennial grasses. Managerial alternatives to potentially enhance the quality of forage production within a range of environmental constraints will be evaluated with the simulation model. Increased knowledge of the effects of defoliation and its interactions with water and nitrogen availability on biomass partitioning will contribute to the development of more efficient management practices.

D.1.TITLE: BIOMASS PARTITIONING IN GRASSES SUBJECTED TO DEFOLIATION: THE KEY TO INCREASING PRODUCTION

EFFICIENCY IN GRAZED SYSTEMS

D.2. DESCRIPTION OF PROBLEM:

Native or domestic forage is the most cost effective feed source for beef cattle and dairy production. Management practices that initiate forage production earlier in the season or extend the growth period can reduce production costs significantly. Production efficiency from a forage base can be enhanced by increasing total production with additional cultural inputs (i.e. fertilizer, irrigation, improved plant

materials) or by increasing the quality rather than quantity of forage production. Since forage production in many grazed systems is constrained by environmental limitations which are difficult to mitigate cost effectively, the latter alternative would appear to be the most

feasible. This approach requires the integration of process level research governing biomass partitioning at the individual plant level with biological and managerial responses of agricultural systems.

Management of forage production and utilization on ranges and pastures to achieve sustained productivity and profitability requires

sound management decisions. These decisions must be supported by knowledge of forage plant biology and system function. A static

optimum management solution does not exist because both environmental and economic components of the system are highly variable through time. Consequently, management prescriptions must be sufficiently flexible to accommodate a variety of inputs on various time scales. Empirical field research cannot provide sufficiently diverse information to address all of the potential managerial scenarios encountered. Simulation modelling is a proven tool for investigating system function and developing decision criteria for management; however, effective models require experimental data for parameterization and validation.

Even though several plant growth models have been constructed and validated, they do not adequately simulate biomass partitioning

in variable environments and management systems (Johnson and Thornley 1983, Coughenour et al. 1984, Johnson and Parsons 1985, Brown et al. 1986, Spek and Van Oijen 1988, Bachelet et al. 1989). A theoretical model of shoot:root partitioning under optimal growth conditions has been presented (Johnson and Thornley 1987). Unfortunately, the theoretical model does not generate realistic simulations under suboptimal growth conditions frequently encountered in field situations. Thus, additional experimental data will be required for model parameterization under conditions of less than optimal growth (i.e. defoliation and abiotic stresses). The lack of experimental work utilizing partitioning models suggests that an integrated experimental/ theoretical approach focusing on biomass partitioning would be timely and productive.

Quantitative information is required in two essential areas to successfully predict biomass partitioning in grazed systems: firstly,

partitioning between roots and shoots and secondly, between vegetative and reproductive structures. Grazing can exert a major influence on both processes by regulating the demand for resources in either shoots or roots (sink strength) and the availability and commitment of

meristems to vegetative or reproductive growth. Grazing may enthe proportion of quality forage (i.e. leaves) by increasing the sink strength of shoots and limiting the number of reproductive tillers. However, the impact of both processes on plant growth must be sufficiently understood to minimize the probability of decreasing sustained production by restricting root growth or reducing the establishment of new individuals within a population. The problem of quantifying biomass partitioning within plant growth is one of the most important and difficult problems in plant physiology and crop production.

D.3. OBJECTIVES:

Hypotheses

Biomass partitioning to shoots, roots and reproductive structures of grasses follows an optimum strategy to maximize reproductive

potential (fitness) and acquire the most limiting resource(s). Although both processes may potentially optimize total biomass production within the constraints of resource availability, allocation priorities may limit production of quality forage (i.e. leaves). Several corollary hypotheses follow.

Shoot:Root Biomass Partitioning

1. Biomass partitioning to shoot decreases (relative to root) as the interval between defoliations increases, and as severity of water or nitrogen limitations intensify.

2. Biomass partitioning among shoots, roots and reproductive structures in response to defoliation and environmental stresses is genetically

regulated and therefore displays a large degree of interspecific variation within annual and perennial grass species.

Vegetative:Reproductive Partitioning

1. Biomass partitioning to reproductive (or storage) structures increases at the point when complete plant cover (plant bases shaded) and

maximum absolute growth rate have been attained; differentiation of reproductive meristems will begin prior to this time and will continue as long as the existing sinks do not exhaust the available assimilates.

2. Defoliation prior to or during this stage of development will stimulate continued vegetative growth of existing tillers and the initiation of new tillers while reducing growth of existing reproductive structures and delaying differentiation of additional ones.

3. Removal of existing reproductive structures from annual species will result in increased partitioning to remaining culms and inflorescences;

whereas, in perennial species, removal of reproductive structures will result in increased partitioning belowground (roots, bulbs and rhizomes).

The practical corollary of these hypotheses is that production of high quality forage from native and domestic forage crops can be

increased substantially. More precise decision rules for grazing, irrigation and fertilization can potentially manipulate forage plants to produce more leaf and less culm, thus enhancing forage quality without additional resources to promote total growth.

Specific Objectives

1. Evaluate biomass and carbon partitioning in several annual and perennial grasses in response to levels of simulated grazing, irrigation and nitrogen fertilization.

2. Develop and parameterize models for shoot:root:reproductive biomass partitioning using experimental data.

3. Link biomass partitioning models with existing plant growth models.

4. Validate simulation models using data from controlled environment studies.

5. Conduct simulation experiments to evaluate plant production responses to alternative management decisions.

6. Develop decision rules for grazing management, irrigation and N fertilization, based upon forage plant biology and system function to

optimize sustained yield of leaf material, relative to root mass and reproductive structures.

D.4. BACKGROUND:

Shoot-root partitioning

Root:shoot relationships have been investigated in numerous grass species beginning with the seminal work of Troughton (1960).

Partitioning between these two components is strongly influenced by environmental parameters in the soil-plant system. Root:shoot ratios are inversely related to the availability of soil water, nitrogen and phosphorus and the occurrence of optimal temperatures (Davidson 1969, Gales1979). Conversely, low levels of irradiance shift the balance of growth in favor of shoots. These shifts in biomass partitioning have been viewed as adaptations to maintain a functional equilibrium within changing environments. The ratio of carbon:nitrogen availability within the plant has long been viewed as the physiological basis governing the partitioning of biomass between root and shoot systems (Troughton 1960, Reynolds and Thornley 1982, Agren and Ingestad 1987).

Biomass partitioning between roots and shoots displays a high degree of interspecific variation indicating that it is a genetically

determined trait. Perennial grasses allocate approximately equivalent amounts of carbon to apical, lateral (new tiller primordia) and root

meristems, while the apical or terminal meristem serves as the predominant sink in annual species (Ryle 1970). However, Parsons and Robson (1981) found carbon allocation to the root system did not exceed 15% of the currently assimilated carbon in established plants of Lolium

perenne. The stem or culm may be a weaker sink in perennial than annual grasses with a large amount of resources allocated to new tillers

in perennial species (Clemence and Hebblethwaite 1984). However, the formation of reproductive tillers in perennial species induces an

abrupt, but short lived shift in allocation to culms and inflorescences (Ryle 1970, Parsons and Robson 1981). The degree of environmental

stress and disturbance influences the life history strategy of plants and significantly affects the degree of root-shoot partitioning (Hunt et al.

1987).

The amount of carbon allocated to the root system of grasses is quite small in relation to the large amount of root mass produced.

The greater longevity and consequently, slower turnover of roots in comparison with leaves may provide a partial explanation. The active

life of a root may range from 5 to 24 months depending on species and environment (Weaver and Zink 1946, Garwood 1967), while leaf

longevity ranges from 1 to 4 months depending upon the species and season of initiation (Grant et al. 1983, Chapman et al. 1984). In addition, no reliable, rapid technique is available for determining which portion of the total root mass is physiologically active.

Defoliation affects biomass and carbon partitioning by increasing the proportion remaining aboveground to reestablish photosynthetic

tissues (Ryle and Powell 1975, Detling et al. 1979). Flexibility in carbon allocation may increase grazing tolerance by increasing the rate of

leaf replacement. For example, Agropyron desertorum, known to be more grazing tolerant than Agropyron spicatum, exhibits a greater

capacity to reallocate carbon to reestablish photosynthetic tissues following the activation and development of axillary buds while temporarily decreasing partitioning belowground (Caldwell et al. 1981, Richards 1984, Mueller and Richards 1986). These data indicate that a short-term cessation or reduction in root growth is not necessarily detrimental to the leaf replacement potential or competitive ability of grazed plants.

Vegetative:reproductive partitioning

Since plants obtain a finite amount of resources from the environment, it is generally assumed that allocation to one priority may

occur at the expense other priorities. Resource allocation to vegetative and sexual reproduction has been viewed in a competitive manner

for several decades (Law 1979, Abrahamson 1980, Loehle 1987). Although data exist to substantiate this perspective, it is inconclusive. Cases have been observed where the occurrence of sexual reproduction did not reduce vegetative reproduction (Horvitz and Schemske 1988) or

where only vegetative growth, but not total growth, was reduced (Reekie and Bazzaz 1987). Sexual reproduction may not directly compete with vegetative reproduction as previously thought because the culm and inflorescence can assimilate carbon and the photosynthetic rate of nonreproductive tissue may increase in response to an increase in sink strength induced by reproduction (Cet al. 1981, Reekie and Bazzaz 1987).

It has long been recognized that the amount of resources allocated to reproduction varies with the life history strategy of specific

plant species. The portion of biomass partitioned to sexual reproduction in herbaceous perennials varies between 1.5 and 70% (Abrahamson

1980). The annual grass Aristida oligantha allocated 15% of its biomass and 28% of its nitrogen to reproduction, while the perennials

Schizachyrum scoparium, Andropogon gerardii and Sorgastrum nutans allocated less than 3% of their biomass and 5% of their nitrogen to

sexual reproduction. Culms were not included in these estimates of reproductive effort; their inclusion would greatly increase these values.

Reproductive culms comprise a majority of shoot biomass in temperate bunchgrass species in the latter portion of the growing season (Hyder

and Sneva 1963, Caldwell et al. 1981). Culms possess low nutritional value and interfere with animal access to the higher quality forage (Willms et al. 1980, Norton and Johnson 1983).

Numerous biotic and abiotic factors influence the proportion vegetative and sexual reproduction (Abrahamson 1980). Competition

or plant density and grazing are perhaps the two most important considerations under managerial control. Grazing reduces allocation to

sexual reproduction by removing the rudimentary inflorescences or reducing photosynthetic surfaces, thus limiting the availability of carbon (Hill and Watkin 1975, Caldwell et al. 1981, Butler and Briske 1988). Grazing exerts a strong indirect influence on sexual reproduction by influencing tiller density and age class distribution. Lenient grazing early in the season can increase the number of tillers which may potentially become reproductive later in the year (Knight 1970). However, if grazing becomes too severe or continues too late into the season, the number of reproductive tillers will diminish. Tillers which become reproductive early in the season produce the largest inflorescences with greatest seed weight (Lambert and Jewiss 1970, Hill and Watkin 1975).

The developmental biology of Hordeum bulbosum, including the effects of photoperiod and temperature on flowering and dormancy,

has been studied in detail (Koller and Highkin 1960, Ofir et al. 1967, Ofir and Koller 1972, 1974, Ofir 1981). Frequently, cessation of tillering,

spike differentiation, bulb thickening and dormancy of axillary buds within an individual shoot are closely synchronized. Vernalization and

photoperiod treatments modify the absolute timing of these events, and in some conditions their relative timing and intensity (e.g. bulb formation before flowering). These results indicate that the plant has considerable plasticity in allocation and developmental processes. These responses to external stimuli presumably increase fitness. These factors may also operate in response to grazing and defoliation.

Developmental Morphology

The developmental morphology of grasses following defoliation is reasonably well documented, but the application of this information to forage based agricultural systems has been limited (see Hyder and Sneva 1963 as a notable exception). Floral induction marks the transition of the apical meristem from a structure producing leaf primordia to a rudimentary inflorescence (Booysen et al. 1963). Floral

induction is triggered by a photoperiodic response when an individual tiller has surpassed a juvenile growth period. At this stage of development, leaf primordia are no longer differentiated, halting vegetative growth. Contrastingly, axillary bud differentiation is accelerated initiating the process of spikelet formation. Defoliation must remove the rudimentary inflorescence below the uppermost node to prevent further culm elongation (Cook and Stoddart 1953, Hyder and Sneva 1963). Culm elongation will continue even if all leaves have been removed prior to elongation or if the inflorescence has been partially or totally removed while the uppermost node remains intact. In species having strong apical dominance, growth following removal of the terminal meristem is delayed by the time required for expansion of axillary buds leading to the recommendation that species with a high percentage of culmed shoots are most effectively harvested at periodic intervals rather than continuously (Branson 1953, Hyder and Sneva 1963).

The concept of apical dominance is assumed to regulate tiller development in both annual and perennial species (Leopold 1949).

Apical dominance was conferred by expanding leaves in vegetative ryegrass tillers and by either the inflorescence or elongating culm in

reproductive tillers (Laidlaw and Berrie 1974). However, increased tiller recruitment has been observed to occur following grazing even though apical meristems were not removed (Butler and Briske 1988). Conversely, removal of apical meristems from tillers of crested wheatgrass did not always result in accelerated tiller recruitment (Olson and Richards 1988). Light quality, presumably mediated by phytochrome, has recently been observed to control axillary bud expansion in both annual and perennial species (Deregibus et al. 1985, Casal et al. 1986, Kasperbauer and Karlen 1986). A decrease in the ratio of red:far-red radiation associated with increasing canopy development may signal the diminishing availability of resources and suppress additional tiller recruitment (Deregibus et al. 1985, Simon and Lemaire 1987). Partial removal of the plant canopy by grazing would increase the ratio of red:far-red radiation and promote tillering. The versatility of phytochrome as a mechanism regulating tiller recruitment is yet to be proven, but the direct inhibition of apical dominance presented by Leopold (1949) is overly restrictive.

Root growth and function is dependent upon energy provided by photosynthesis. The suppression of root growth is generally

proportional to the intensity and frequency of defoliation (Crider 1955, Cook et al. 1958, Youngner 1972). Cessation of root growth has been

observed to occur within hours of defoliation (Davidson and Milthorpe 1966, Hodgkinson and Baas Becking 1977). Root growth cessation

affects both lateral and vertical development of root systems (Schuster 1964, Smoliak et al. 1972) as well as detrimentally influencing root

initiation, diameter, branching and total production (Biswell and Weaver 1933, Jameson 1963, Evans 1973, Carman and Briske 1982, Richards

1984). Root mortality has also been observed to dramatically increase following defoliation (Weaver and Zink 1946, Troughton 1981,

Hodgkinson and Baas Becking 1977). The sum of these responses serves to reduce the total absorptive surfaces and soil volume explored

for water and nutrients.

Simulation models

Numerous plant growth models have been constructed to meet specific objectives. Consequently, each of the models differ in their

respective strengths and weaknesses. Coughenour et al. (1984) developed a simulation model of perennial graminoid growth that united morphometric traits with physiological processes. It contained a shoot density submodel that simulated vegetative production, a carbon

submodel that simulated assimilation and allocation, and a nitrogen submodel that simulated uptake and allocation. This model did not

consider situations involving nutrient or water limitations or herbivory. The vegetative crop growth model developed for Lolium perenne

considered grazing by livestock, but was restricted to the vegetative growth phase and did not address carbon allocation in nutrient or water

limited environments (Johnson and Thornley 1983, Johnson and Parsons 1985). A model of intraseasonal carbon and nitrogen dynamics of blue

grama considered carbon and nitrogen allocation in variable environments and grazing (Bachelet et al. 1989); however, it did not address morphometric characteristics or nutritional aspects of forage quality. Although grazing was considered, the grazing interface was not

adequately developed. Numerous crop growth models do not address the problem of growth partitioning (Brown et al. 1986).

Thornley's (1977) mathematical consideration of the physiological processes involved in growth and maintenance respiration

provides a conceptual basis for selecting the appropriate state variables for simulation of crop growth. Based on these concepts, a model to partition growth between shoots and roots was developed, but not validated (Johnson 1985, Johnson and Thornley 1987). The model utilizes carbon:nitrogen ratios as the basis for growth partitioning. Under conditions involving restrictions to water or nutrient availability, the model must be parameterized using experimental data. There is a need to integrate the theoretical concepts of growth partitioning with the physiological information concerning plant growth to develop more realistic plant growth simulation models. This linkage is essential to the

development of a plant growth model that can be truly interactive in forage-based livestock production systems.

D.5. RATIONALE AND SIGNIFICANCE:

The production potential of many forage-based animal production systems is constrained by climatic variables beyond managerial control. Life history strategies of many species adapted to these environments determines that a large portion of biomass exists belowground in perennials or is allocated to reproductive tillers and seed production in annuals. This provides the impetus for optimizing the production and harvest of highly digestible forage. Grazing management strategies based on a sound understanding of forage plant biology may represent a cost effective means of optimizing production and utilization of high quality forage. Increased leaf production, at the expense of root mass or high fiber components (culms or stems), may be achieved by manipulating biomass partitioning among roots, leaves and reproductive

structures.

Currently, a large amount of information exists describing biomass partitioning between roots and shoots of grasses, while our understanding of biomass partitioning into vegetative and sexual reproduction is largely theoretical. Few, if any, major efforts have attempted to transfer information concerning biomass partitioning from the level of the individual plant to application in agricultural systems. An approach incorporating both experimental data and simulation modelling will facilitate the integration of data from diverse studies into a unified theory for biomass partitioning. Experimentation in vegetation as diverse as the Mediterranean grasslands of Israel and tallgrass prairie of south central U.S. will provide a rigorous test of the proposed concepts. If the concepts are proven successful in these environments they should be applicable to forage systems throughout the world.

D.6. DESCRIPTION OF THE RESEARCH PLAN:

Israel

The research will be carried out on mixed annual-perennial grasslands in Galilee, where the Karei-Deshe experimental range is

located. Considerable quantitative information on the environment, plants and animals is available from previous research at this location.

Two species have been chosen for investigation. Hordeum bulbosum, is an erect perennial grass, which regenerates annually and reproduces

asexually from bulbs just below the surface, but also produces abundant seeds in certain conditions. It is a major dominant in ungrazed conditions and in a wide range of grazing pressures. Triticum dicoccoides (wild emmer wheat), a tall, large-seeded annual grass represents the group of wild cereal grasses (including also wild barley and oat) which are abundant and locally dominant in lightly grazed areas.

The research plan consists of the following components:

1. Controlled experiments evaluating the effects of defoliation frequency and intensity on biomass partitioning between vegetative

and reproductive (spike and bulb) structures. The experiments will be carried out on containerized plants of Hordeum bulbosum (grown from

bulbs) and of Triticum dicoccoides (grown from seeds), in environmental conditions (soil type, weather, plant density) comparable to those encountered under field conditions. A factorial design with 2-3 clipping heights x 2-3 clipping frequencies and a suitable number of replicates will be used. The experiment will be repeated in year two; in the second year the design may be modified according to results and lessons obtained the first year. Growth will be evaluated by morphological units (numbers of vegetative tillers, leaves, reproductive culms, mature spikes, spikelets, bulbs) and biomass of the various components. Numbers of aboveground units and biomass of clipped parts will be monitored during the growing season. Belowground units and biomass of all parts will be determined at the end of the growing season.

2. Development and parameterization of a biomass partitioning model. The hypotheses presented above and evidence from

literature will be used to formulate a model to partition growth between vegetative and reproductive structures in annual and perennial (bulb-forming) grasses, in relation to defoliation. Results from the controlled experiments will be used to check, refine or modify (as necessary) the model and to estimate its parameters for an annual and a perennial grass.

3. Evaluation of biomass partitioning under different grazing regimes. This will be carried out in a grazing trial with cattle on natural

rangeland at Karei-Deshe, with two grazing systems (continuous and deferred) x two stocking rates x two fields, and an exclosure protected

from grazing during the growing season. Random samples of Hordeum bulbosum and Triticum dicoccoides plants from populations in various

fields will be collected at 3-4 times during the growing season. Numbers and biomass of vegetative and reproductive (above- and

belowground) units will be determined. The results will be compared with results from the clipping experiments and with predictions of the

model for clipping regimes characteristic of the different grazing treatments.

Dr. Gutman will be responsible for conducting the grazing trials and will assist in the controlled growth experiments. Professor Noy-Meir will be responsible for the controlled growth experiments and model development and utilization.

USA

Biomass partitioning and carbon allocation will be investigated in a series of controlled experiments to evaluate the proposed

hypothesis and provide suitable data for parameterization of a biomass partitioning submodel. The submodel will be incorporated into a forage

dynamics model developed in a previous BARD project (Blackburn and Kothmann 1989).

Biomass and carbon partitioning experiments will be conducted in a completely random factorial design with adequate replications.

Containerized plants will be used to facilitate complete recovery of plant root systems. Treatments will consist of two defoliation frequencies

and intensities, a high and low soil nitrogen regime, and a high and low watering regime. Model parameterization and validation will be

conducted with two grass species, a C3 annual (wheats, Triticum aestivum) and a C4 perennial (kleingrass, Panicum coloratum) to complementwork by Israeli investigators. To evaluate the broader applicability of these hypotheses and the potential for interspecific variation in allocation patterns in response to defoliation, two additional native forage grasses will be investigated. Schizachyrium scoparium is a C4 buchgrass which decreases in response to intensive grazing, while Stipa leucothrica, a C3 bunchgrass, generally increases in abundance.

Crowns of the perennial species will be transplanted while seed of the annual will be planted into pots during the fall. The number

of tillers per pot will be equalized at the time of transplanting in the perennials and following germination of the annual. Plants will be

defoliated to remove 50 or 80% of the shoot mass at 4 or 8 wk intervals. The study will extend for one complete year for the perennials and

from October through May for the annual, which will include one complete growth cycle for all species. A portion of the plawill be

harvested at four times during the investigation and separated into root, culm and sheath, lamina and inflorescence. The number and size of morphological units for each plant will be measured prior to clipping and at the final harvest. Analyses will include dry weight and total carbon and nitrogen for each fraction. A stable isotope of carbon, carbon-13, will be introduced into the leaves of each of the species to

mechanistically evaluate the magnitudes and patterns of carbon allocation among the various plant fractions in response to the various

treatments. This technique has proven successful with several plant species in previous investigations (Mordacq et al. 1986).

Dr. Kothmann will serve as PI and will be responsible for the development and utilization of the model and coordination with the

Israeli research. Dr. Briske will conduct the controlled growth experiments and collaborate in model development. Dr. Boutton will be

responsible for the carbon-13 work and sample analysis.

D.7. TIME SCHEDULE OF THE WORK PLAN:

Israel Time Schedule

1990-91

Initiate first clipping experiment; develop biomass partitioning model and conduct first year of grazing trial.

1991-92

Conduct second (possibly modified) clipping experiment; refine and parameterize biomass partitioning model; run simulation

experiments with the model under different clipping and grazing regimes and complete second year of evaluation under grazing.

1992-93

Further development and evaluation of the biomass partitioning model and complementary field measurements; incorporate elements

of the partitioning model developed by U.S. scientists into the model; conduct simulation experiments with combined model.

Develop conclusions for grazing management decisions.

USA Time Schedule

1990-91

Conduct biomass and carbon-13 partitioning experiments.

1991-92

Complete biomass partitioning and tracer experiments, analyze samples and data. Develop biomass partitioning model in

collaboration with Israeli scientists and integrate it into the plant growth model.

1992-93

Validate plant growth model with C allocation data. Utilize the model to evaluate the potential impact of alternative management

strategies on forage production.

D.8. DESCRIPTION AND CONTRIBUTION OF EXPECTED RESULTS:

Scientific

Development and parameterization of the biomass partitioning model including responses to defoliation and environmental variables will be a significant step towards the development of models that can realistically simulate environment-plant-animal interactions. While these processes have frequently been described, they have not been integrated into a quantitative model applicable to agricultural systems. These activities may potentially define an innovative modelling protocol by integrating mechanistic plant level responses into the analysis of

managerial decisions at the agricultural system level. This study should produce basic physiological data that will have considerable scientific

value beyond its utility for management of forage crops and range plants.

Agricultural and Economic

Root:shoot partitioning of photoassimilate is an important problem in many areas of crop production. The stability and productivity of ranges and pastures is affected by allocation patterns of species in response to environmental variables and grazing severity. Grazing and

environmental impacts have significant cumulative effects that are frequently difficult to predict and manage. An improved understanding of environment-plant-animal interactions will provide a basis for more effective management of both tame and native pastures. This research

also has important implications for plant breeding and selection. It will provide quantitative criteria for the selection of plant materials that may contribute to greater production efficiency in grazed systems.

D.9. FACILITIES AND EQUIPMENT:

Israel

- Karei-Deshe Experimental Range Station, experimental pastures and livestock with infrastructure for research support

- Vehicle for field work

- Field laboratory with basic equipment for plant measurements

- Olivetti M24 micro-computer

USA

Adequate facilities and equipment are available for all phases of the proposed research.

- Three 4.5 m2 controlled environment chambers with high intensity light banks

- Stable isotope laboratory equipped with two isotope ratio mass spectrometers and associated sample preparation equipment

- Equipment for monitoring physiological responses of vegetation (null balance diffusion porometer, pressure chamber, leaf area

meter) and routine dry lab facilities

- Analytical laboratory for nutrition analyses
 
 

- Computers

. PC-XT - 20 Meghard disk

. IBM-AT - 60 Meghard disk, Tape drive
 
 

. AT&T 6386 WGS - 4MB RAM

135 MB Harddisk

Tape drive

. IBM 3090 Mainframe

- Software

. Fortran . Wordperfect 5.0

. PC-SAS . Unix Development System

. Quatro . Reflex 2.0
 
 

D.10. RELEVANT BIBLIOGRAPHY ON RESEARCH AREA:

Abrahamson, W.G. 1980. Demography and vegetative reproduction. in Demography and Evolution in Plant Populations. O.T. Solbrig (ed.)

University of California Press Botanical Monographs Vol. 15.

Agren, G.I. and T. Ingestad. 1987. Root:shoot ratio as a balance between nitrogen productivity and photosynthesis. Plant, Cell and Environ.

10:579-586.

Bachelet, D., H.W. Hunt and J.K. Detling. 1989. A simulation model of intraseasonal carbon and nitrogen dynamics of blue grama swards as

influenced by above- and belowground grazing. Ecol. Modelling 44:231-252.

Biswell, H.A. and J.E. Weaver. 1933. Effect of frequent clipping on the development of roots and tops of grasses in prairie sod. Ecology 14:368-

390.

Blackburn, H.D. and M.M. Kothmann. 1989. A forage dynamics model for use in range or pasture environments. Grass and Forage Sci. 44:(in

press).

Booysen, P. de V., N.M. Tainton and J.D. Scott. 1963. Shoot-apex development in grasses and its importance in grassland management. Herb.

Abs. 33:209-213.

Branson, F.A. 1953. Two new factors affecting resistance of grasses to grazing. J. Range Manage. 6:165-171.

Brown, W.F., L.E. Moser and T.J. Klopfenstein. 1986. Development and validation of a dynamic model of growth and quality for cool season

grasses. Agric. Syst. 20:37-52.

Butler, J.L. and D.D. Briske. 1988. Population structure and tiller demography of the bunchgrass Schizachyrium scoparium in response to

herbivory. Oikos 51:306-312.

Caldwell, M.M., J.H. Richards, D.A. Johnson, R.S. Nowak and R.S. Dzurec. 1981. Coping with herbivory: Photosynthetic capacity and resource

allocation in two semiarid Agropyron bunchgrasses. Oecologia (Berl) 50:14-24.

Carman, J.G. and D.D. Briske. 1982. Root initiation and root and leaf elongation of dependent little bluestem tillers following defoliation. Agron.

J. 74:432-435.

Casal, J.J., R.A. Sanchez and V.A. Deregibus. 1986. The effect of plant density on tillering: the involvement of R/FR ratio and the proportion

of radiation intercepted per plant. Environ. Exp. Bot. 26:365-371.

Chapman, D.F., D.A. Clark, C.A. Land and N. Dymock. 1984. Leaf and tiller or stolon death of Lolium perenne, Agrostis spp., and Trifolium

repens in set-stocked and rotationally grazed hill pastures. N.Z. J. Agri. Res. 27:303-312.

Clemence, T.G.A. and P.D. Hebblethwaite. 1984. An appraisal of ear, leaf and stem 14CO2 assimilation, 14C- assimilate distribution and growth

in a reproductive seed crop of amenity Lolium perenne. Ann. Appl. Biol. 105:319-327.

Cook, C.W. and L.A. Stoddart. 1953. Some growth responses of crested wheatgrass following herbage removal. J. Range Manage. 6:267-.

Cook, C.W., L.A. Stoddart and F.E. Kinsinger. 1958. Responses of crested wheatgrass to various clipping treatments. Ecol. Mon. 28:237-272.

Coughenour, M.B., S.J. McNaughton and L.L. Wallace. 1984. Modelling primary production of perennial graminoids- Uniting physiological

processes and morphometric traits. Ecol. Modelling. 23:101-134.

Crider, F.J. 1955. Root-growth stoppage resulting from defoliation of grass. U.S.D.A. Tech. Bul. 1102.

Davidson, J.L. 1969. Effects of soil nutrients and moisture on root/shoot ratios in Lolium perenne L. and Trifolium repens L. Ann. Bot. 33:571-577.

Davidson, J.L. and J.L. Milthorpe. 1966. The effects of defoliation on the carbon balance in Dactylis glomerata. Ann. Bot. 30:185-198.

Deregibus, V.A., R.A. Sanchez, J.J. Casal and M.J. Trlica. 1985. Tillering responses to enrichment of red light beneath the canopy in a humid

natural grassland. J. App. Ecol. 22:199-206.

Detling, J.K., M.I. Dyer and D.T. Winn. 1979. Net photosynthesis, root respiration, and regrowth of Bouteloua gracilis following simulated

grazing. Oecologia (Berl.) 41:127-134.

Evans, P.S. 1973. The effect of repeated defoliation to three different levels on root growth of five pasture species. N.Z. J. Agri. Res. 16:31-34.

Gales, K. 1979. Effects of water supply on partitioning of dry matter between roots and shoots in Lolium perenne. J. App. Ecol. 16:863-877.

Garwood, E.A. 1967. Seasonal variation in appearance and growth of grass roots. J. Br. Grassl. Soc. 22:121-130.

Grant, S.A., G.T. Barthram, L. Torvell, J. King and H.K. Smith. 1983. Sward management, lamina turnover and tiller population density in

continuously stocked Lolium perenne dominated swards. Grasses and Forage Sci. 38:333-344.

Hill, M.J. and B.R. Watkin. 1975. Seed production studies on perennial ryegrass, timothy and prairie grass. 1. Effect of tiller age on tiller

survival, ear emergence and seedhead components. J. Br. Grassl. Soc. 30:63-71.

Hodgkinson, K.C. and H.G. Baas Becking. 1977. Effect of defoliation on root growth of some arid zone perennial plants. Aust. J. Agric. Res.

29:31-42.

Horvitz, C.C. and D.W. Schemske. 1988. Demographic cost of reproduction in a neotropical herb: an experimental field study. Ecology 69:1741-

1745.

Hunt, R., A.O. Nicholls and S.A. Fathy. 1987. Growth and root-shoot partitioning in eighteen British grasses. Oikos 50:53-59.

Hyder, D.N. and F.A. Sneva. 1963. Morphological and physiological factors affecting the grazing management of crested wheatgrass. Crop

Sci. 3:267-271.

Jameson, D.A. 1963. Responses of individual plants to harvesting. Bot. Rev. 29:532-594.

Johnson, I.R. 1985. A model of the partitioning of growth between the shoots and roots of vegetative plants. Annals of Botany. 55:421-431.

Johnson, I.R. and A.J. Parsons. 1985. A theoretical analysis of grass growth under grazing. J. Theo. Biol. 112: 345-367.

Johnson, I.R. and J.H.M. Thornley. 1983. Vegetative crop growth model incorporating leaf area expansion and senescence, and applied to grass.

Plant, Cell Environ. 6:721-729.

Johnson, I.R. and J.H.M. Thornley. 1987. A model of shoot:root partitioning with optimal growth. Ann. Bot 60:133-142.

Kasperbauer, M.J. and D.L. Karlen. 1986. Light-mediated bioregulation of tillering and photosynthate partitioning in wheat. Physiol. Plant 66:159-

163.

Knight, R. 1970. The effects of plant density and frequency of cutting on the growth of cocksfoot (Dactylis glomerata L.) 1. The production of

vegetative and reproductive tillers. Aust. J. Agric. Res. 21:9-17.

Koller, D. and H.R. Highkin. 1960. Environmental control of reproductive development in Hordeum bulbosum, a perennial grass. Amer. J. Bot.

47:843-847.

Laidlaw, A.S. and A.M.M. Berrie. 1974. The influence of expanding leaves and the reproductive stem apex on apical dominance in Lolium

multiflorum. Ann. Appl. Biol. 78:75-82.

Lambert,D.A. and O.R. Jewiss. 1970. The position in the plant and the date of origin of tillers which produce inflorescences. J. Br. Grassl. Soc.

25:107-112.

Law, R. 1979. The cost of reproduction in annual meadow grass. Am. Nat. 113:3-16.

Leopold, A.C. 1949. The control of tillering in grasses by auxin. Amer. J. Bot. 36:437-440.

Loehle, C. 1987. Partitioning of reproductive effort in clonal plants: a benefit-cost model. Oikos. 49:199-208.

Mordacq, L., M. Mousseau and E. Deleens. 1986. A 13C method of estimation of carbon allocation to roots in a young chestnut coppice. Plant,

Cell and Environ. 9:735-739.

Mueller, R.J. and J.H. Richards. 1986. Morphological analysis of tillering in Agropyron spicatum and Agropyron desertorum. Ann. Bot. 58:911-921.

Norton, B.E. and P.S. Johnson. 1983. Pattern of defoliation by cattle grazing crested wheatgrass pastures. in: Smith, J.A. and Hayes. V.W. (eds).

Proc. XIV Int. Grassland Congress. Westview Press, Boulder, CO. pp 462-464

Ofir, M. 1981. Effects of induction level on morphogenetic aspects of summer dormancy and flowering in Hordeum bulbosum L. Israel J. Bot.

30:173-180.

Ofir, M. and D. Koller. 1972. A kinetic analysis of the relationships between flowering and the initiation of the dormant state in Hordeum

bulbosum - a perennial grass. Israel J. Bot. 21:21-34.

Ofir, M. and D. Koller. 1974. Relationships between thermoinduction and photo-induction in Hordeum bulbosum L., a perennial grass. Aust.

J. Plant Physiol. 1:259-270.

Ofir, M., D. Koller and M Negbi. 1967. Studies on the physiology of regeneration buds of Hordeum bulbosum. Bot. Gaz. 128:25-34.

Olson, B.E. and J.H. Richards. 1988. Annual replacement of the tillers of Agropyron desertorum following grazing. Oecologia (Berl.)76:1-6.

Parsons, A.J. and M.J. Robson. 1981. Seasonal changes in the physiology of S24 perennial ryegrass(Lolium perenne L.) 3. Partition of assimilates

between root and shoot during the transition from vegetative to reproductive growth. Ann. Bot. 48:733-744.

Reekie, E.G. and F.A. Bazzaz. 1987. Reproductive effort in plants. 3. Effect of reproduction on vegetative activity. Am. Nat. 129:907-919.

Reynolds, J.F. and J.H.M. Thornley. 1982. A shoot:root partitioning model. Ann. Bot. 49:585-597.

Richards, J.H. 1984. Root growth response to defoliation in two Agropyron bunchgrasses: field observations with an improved root periscope.

Oecologia (Berl). 64:21-25.

Ryle, G.J.A. 1970. Partition of assimilates in an annual and perennial grass. J. Appl. Ecol. 7:217-227.

Ryle, G.J. and C.E. Powell. 1975. Defoliation and regrowth in the graminaceous plant: the role of current assimilate. Ann. Bot. 39:297-310.

Schuster, J.L. 1964. Root development of native plants under three grazing intensities. Ecology 45:63-70.

Simon, J.C. and G. Lemaire. 1987. Tillering and leaf area index in grasses in the vegetative phase. Grass Forage Sci. 72:373-380.

Smoliak, S., J.F. Dormaar and A. Johnston. 1972. Long-term grazing effects on Stipa-Bouteloua soils. J. Range Manage. 25:246-250.

Spek, L. and M. Van Oijen. 1988. A simulation model of root and shoot growth at different levels of nitrogen availability. pp 115-121 in: Structural

and Functional Aspects of Transport in Roots, B.C. Loughman et al. Eds. Kluwer Academic Publ.

Thornley, J.H.M. 1977. Growth, maintenance and respiration: a re-interpretation. Ann. Bot. 41:1191-1203.

Troughton, A. 1960. Further studies on the relationship between shoot and root systems of grasses. J. Br. Grassl. Soc. 15:41-47.

Troughton, A. 1981. Length of life of grass roots. Grass Forage Sci. 36:117-120.

Weaver, J.E. and E. Zink. 1946. Length of life of roots of ten species of perennial range and pasture grasses. Plant Physiol. 21:201-217.

Willms, W., A.W. Bailey and A. McLean. 1980. Effect of burning or clipping Agropyron spicatum in the autumn on the spring foraging behavior

of mule deer and cattle. J. Appl. Ecol. 17:69-84.

Youngner, V.B. 1972. Physiology of defoliation and regrowth. in: Youngner, V.B. and McKell, C.M. (eds). The Biology and Utilization of Grasses.

Academic Press, New Y. pp 292-303.
 
 

E. COOPERATION:

Four of the scientists from US and Israel are completing a 3-year BARD project focused on the effects of early-season grazing on forage production and utilization. This project included visits by both Israel scientists to the U.S., and one visit by the U.S. PI to Israel. There has been regular and extensive communication including sharing of data and models. Forage dynamics models have been developed and linked with diet selection and animal production models. These research efforts lead to the identification of biomass allocation as the critical element for the development of plant growth models that could simulate the interactions of photosynthesis and respiration with defoliation and environment to produce a robust plant growth model.

During this project both Israeli scientists will visit Texas A&M University and the U.S. PI will visit Israel. Close communication will

be maintained throughout the planning, execution, and analysis phases of the proposed investigations. Collaborative efforts are planned for

the development and evaluation of the models.

F.BUDGET SUMMARY:

Detailed Israel Budget
 
 

YEAR 1 YEAR 2 YEAR 3 TOTAL

ARO HUJ ARO HUJ ARO HUJ ARO HUJ

PERSONNEL SERVICES 15000 7200 14000 9600 10000 9600 39000 26400

EQUIPMENT 3000 4000 3000 2000 - - 6000 6000

OPERATING EXPENSES 4000 700 4000 700 6000 700 14000 2100

FOREIGN TRAVEL - - 3000 - - - 3000

TOTAL EXPENSES 22000 11900 24000 12300 16000 10300 62000 34500

OVERHEAD 25% 5500 3000 6000 3100 4000 2600 15500 8700

TOTAL BUDGET 27500 14900 30000 15400 20000 12900 77500 43200

TOTAL BUDGET ISRAEL 42400 45400 32900 120700
 
 

Budget Justification Israel

PERSONNEL SERVICES:

ARO: 50% Technician for 3 years (Grazing trial + controlled experiment) 50% Technician for year 1 and 2 (Controlled

experiment)

HUJ: 30-40% Computer programmer for 3 years (Modelling + data analysis)

EQUIPMENT:

ARO: 1 electric balance, lap-top computer

HUJ: 1 Microcomputer, 1 Plotter

OPERATING EXPENSES:

ARO: Year 1 - Supplies and installations for controlled experiment. All years - Local travel, supplies

HUJ: Local travel, computer supplies

FOREIGN TRAVEL:

ARO: Visit Dr. Gutman to US in year 2
 
 

Budget Detail U.S.A. Project RF-89-1111

Proposed Budget Period: 6/1/90 - 5/31/93

YEAR 1 YEAR 2 YEAR 3 TOTAL

1. Personnel Services

Salaries and Wages

Principal Investigator

M.M. Kothmann

10% Time, 12 Calendar Months/Year NC NC NC NC
 
 

Co-Investigator

D.D. Briske

10% Time, 12 Calendar Months/Year NC NC NC NC

Cooperator

T. Boutton

5% Time, 12 Calendar Months/Year NC NC NC NC

Research Assistants

2 @ To Be Named

50% Time, 12 Calendar Months/Year 9300 9800 10250 29350

Computer Programmer/Modeller

To Be Named

25% Time, 12 Calendar Months Yrs 2&3 0 7500 8000 15500

Laboratory Technician

To Be Named

15% Time, 12 Calendar Months Yrs 1&2 2930 3080 0 6010

10% Time, 12 Calendar Months Year 3 0 0 2150 2150

Student Worker

To Be Named

Hourly As Needed 2000 2000 1750 5750

Subtotal Salaries & Wages 14230 22380 22150 58760
 
 

Fringe Benefits

(FICA and Insurance)

@ 26% and 15% of Salaries

and Wages 2457 4521 4439 11417

Total Personnel Services 16687 26901 26589 70177
 
 

2. Non-Expendable Equipment 0 0 0 0

3. Operating Costs

In-Country Travel

Travel from College Station, TX to

Destinations to be Determined to

Attend Scientific Meetings (2 Persons) 1000 1500 1500 4000

Computer Services 500 500 1000 2000

Supplies 6000 4000 2000 12000

Sample Analysis 6000 6000 0 12000

Publication Costs 0 0 1000 1000

Total Operating Costs 13500 12000 5500 31000

4. Foreign Travel

Travel to Israel to Confer

for M.M. Kothmann 2500 0 0 2500

Total Foreign Travel 2500 0 0 2500

5. Total Direct Costs 32687 38901 32089 103677

6. Overhead or Indirect Expenses

@ 25% of Total Direct Costs

($32,687; $38,901; $32,089) 8173 9726 8022 25920

7. Total Costs 40860 48627 40111 129597
 
 
 
 
 
 

The sponsor will not use nor permit others to use the names of Texas A&M Research Foundation or The Texas A&M University

System or any abbreviations or trademark in any publicity, advertising or other public presentation which directly or indirectly implies

endorsement of any product or service.
 
 
 
 

Budget Justification USA

PERSONNEL SERVICES:

One Ph.D. level Research Assistant will be employed to help conduct controlled experiments, including C-13 studies. A computer

programmer will be hired (25% part-time) to assist in coding and utilzing the model. The laboratory technician will assist in

chemical analysis of samples. The student worker will assist part-time with the research.

EQUIPMENT:

No additional equipment will be required.

OPERATING EXPENSES:

Local travel includes participation in national professional society meetings each year to report research results. costs

for this study will be low because most of the work can be done on the 286 and 386 Personal Computers. Supplies will be required

for the controlled growth experiments. Sample analysis is for operation of the Mass spectrometer and wet chemistry analysis.

FOREIGN TRAVEL:

During year 1, Dr. Kothmann will visit Israel to coordinate study plans and collaborate on model design and development.

G. OTHER RESEARCH GRANTS

This proposal has not been submitted to any other agency for funding. Base funding from Texas Agricultural Experiment Station

will provide the investigators salaries and supporting research infrastructure.