contents

Research

THE FINALIZED PROJECT "CLIMAGRI" ON CLIMATE CHANGE AND AGRICULTURE

SUB-PROJECT 3
Drought, desertification and management of water resources

TOPIC 3.5
The Impact of Climatic Change on the Agricultural System: Research of Drought Tolerance Indicators

RESEARCH COORDINATOR
Enrico Brugnoli
Agroforestry Institute (IAS-National Research Council)


PURPOSE OF THE RESEARCH
The main objective of the research consists in the study and identification of indicators of tolerance to environmental stress, in particular to drought and high temperatures, in order to design forecasting models of agrarian productivity in environments characterized by different water availability or deficit of vapour saturation. To this purpose, we will verify the relationships existing between isotopic compositions 13C/12C e 18O/16O, the efficiency of water use, and the conductance of crops and productivity to obtain an initial calibration to use for successive research.

The influence of temperature and water availability on various phenological phases and on their duration and the verification of the existing relationships among intensities of water stress, photosynthesis activity, length and weight of epigeal apparatus, leaf areas indices (LAI) and relative growth rate (RGR) (Gratani, 1996), allow for the formulation of hypotheses on the efficiency of use of resources, on capacity on productivity and on resistance of natural species and crops. These relationships will be verified on spontaneous and cultivated species in different sites for climatic conditions and for degree of aridity, and in controlled conditions (high water stress, high radiation, high temperature, high CO2). The data obtained of isotopic compositions will be correlated with the gradients of aridity and agricultural productivity of different species in the same and in different areas.

This approach will allow for the characterizing of some scenarios in different degrees of aridity and vulnerability and, at the same time, provide an index for the classification of species and cultivars according to drought tolerance. It is considered capable of pinpointing functional and structural indices that may be used to monitoring. Further, an analysis will be carried out on a series of phenological, structural and physiological data relative to cultivated species, such as cereals and natural species, for instance some Mediterranean evergreens, already in the hands of the Department of Vegetal Biology and the available meteorological data at Central Office of Crop Ecology (UCEA).


THE RESEARCH GOALS
The data obtained during the three years of the project will be used in order to formulate forecasting models on productivity and to describe some scenarios on drought and/aridity. Further, synthetic indices will be refined to describe drought tolerance in species and genotypes of cultivated plants, through isotopic discrimination, the velocity of photosynthesis and phenological analysis. The results of the present research proposal will be extremely important from the technico-scientific point of view because they will allow for predicting variations in productivity of the main agricultural species and in characteristic environments.

The use of stable isotopes as indicators of tolerance/resistance to drought will permit a definition of a methodology for classifying species and genotypes in accordance to water use, productivity and photosynthetic efficiency in selected environments along a natural gradient of aridity. Further, the quantitative analysis of phenological stages in relation to different conditions of water stress and temperature represent a valid method for evaluating the productive capacity of the species and their adaptability. In these environments, it will be particularly relevant to study the relationships among phenology and 13C/12C as they have been verified up until now in controlled conditions (Brugnoli and Farquhar, 1999).

The velocity of photosynthesis, which varies during the different phenophases and in response to stress factors, can be used as an index of biomass production. For example, it will be possible to evaluate the variations of productivity of important species (for example, cereals) in certain characteristic scenarios identifying the species and the cultivars at risk and their adaptive capacity. It is expected that the species characterized by a major adaptability can remain in the areas of major aridity, also in consideration of the predicted climatic change. Therefore, in the final analysis, the obtained data of the following research proposal could be used in order to individuate the species and genotypes capable of adapting themselves to live and produce in environments that are characterized by contrasting climatic conditions valorizing such environments and permitting them to be used efficiently, with notable economic/social effects on the territory under study. Moreover, forecasting models on desertification and vulnerability of species and environment will be formulated.


DESCRIPTION OF THE THREE-YEAR RESEARCH

THE FIRST YEAR
In the first year of the project will be characterized the experimental sites under study through determining isotopic composition, 13C/12C e 18O/16O of the selecting species (cultivated and natural) and of atmospheric CO2 that will be collected annually in such environments in order to obtain initial calibrations as discussed. The phenological, net photosynthesis, and water potential and transpiration efficiency analyses, the determination of LAI and RGR of spontaneous and cultivated species in the field, will all be measured to show the existing relationship among climatic parameters and phenological phases and to evaluate the importance of different parameters in determining the duration of phenophases.


THE SECOND YEAR
In the second year, the results of the isotopic composition of various organs and photosynthetic products will be obtained (for example, sucrose and starch) in cereals and in Mediterranean species in experimental sites under study. We will obtain other data on phenological response to water stress, to high radiation and to high temperature, factors that determine damage to the photosynthetic apparatus and therefore reduce productivity.


THE THIRD YEAR
In the third year, the finalized model will be completed to ascertain the importance of factors (temperature, water availability, radiation), greatly involved in the growth process, in the amplification of phenological phases and photosynthesis activity of the species under consideration.


INNOVATIVE ASPECTS
The information obtained from data of isotopic composition of carbon and oxygen on different organs and photosynthetic metabolism associated with phenological data, from photosynthesis, water potential, efficiency of transpiration, of Leaf Area Index (LAI) and RGR, will allow for the individuating of indicators of aridity and drought tolerance to be reproduced and compared within different environments under study.

These indicators will be used to describe different scenarios according to climatic changes and to parameterize their vulnerability in relation to aridity and desertification. In particular, the use of stable isotopes represents a methodology capable of supplying information on photosynthetic efficiency and on plant-environment interaction, integrated according to different temporal scales. Such analytical techniques are highly reproducible with analysis time and costs, which are relatively limited, in respect to other investigative techniques. They enable the obtaining of easy-to-compare indicators of drought tolerance among environments under study.

By analysing these parameters, one may classify structural and functional indices of the species concerned that can be used for monitoring water stress. It will then be possible to design a model in response to the analysed species at stress conditions, evaluating variations in vegetative activity in various conditions of temperature and water availability, and to define their adaptive capacity, resulting from the interaction among genetic variability and individual tolerance. Both the methodology used and the topic studied are innovative because they have never before been used in forecasting climatic changes to the agricultural system and, in particular, to the Italian environment. These analyses will reap important results in predicting future scenarios in the agricultural sector and of the influences of climatic changes.


TECHNICO-SCIENTIFIC/SOCIO-ECONOMICAL EFFECTS
The results of the present research proposal could have great importance from the technico-scientific point of view because they allow for the prediction of variations of productivity in main agrarian species and in characteristic environments.

The use of stable isotopes as indicators of tolerance/resistance to drought will allow for the defining of a methodology to classify species and genotypes according to efficiency of water usage, productivity and photosynthesis efficiency in selected environments along natural gradient of aridity. Further, the quantitative analysis of the phenological stages in relation to different conditions of water and temperature stress represent a valid method of evaluating the productive capacity of the species and their adaptability. In this environment, it will be particularly relative to study the relationship between phenology and 13C/12C according to how they have been verified up until now in controlled conditions (Brugnoli and Farquhar 1999).

The velocity of photosynthesis, which varied during the course of different phenophases and in respect to stress factors, can be used as indices of biomass production. For example, it will be possible to evaluate the variations of productivity of important species (for example, cereals) in certain characteristic scenarios identifying the species and the cultivars at risk and their adaptive capacity. It is expected the species characterized by a major adaptability can remain in the area of major aridity also in consideration of the predicted climatic change. Therefore, in the final analysis, the obtained data from the following research proposal could be used to identify the species and genotypes capable of adapting themselves to live and produce in environments that are characterized by contrasting climatic conditions. Such an analysis will enhance such environments and allow them to be efficiently used, with notable economical/social effects on the territory under study. Further, forecasting models will be formulated on desertification and vulnerability of species and environments.


ESSENTIAL BIBLIOGRAPHY
  • Augusti, A., Lauteri, M., Spaccino, L. & Brugnoli, E. 1999. Short- and long-term responses of carbon isotope discrimination and photosynthetic energy dissipation to elevated CO2 concentration. In Raschi A. & Miglietta F. (eds.) CO2 springs as a model to study the impact of elevated CO2 on plants. (in press).
  • Brugnoli, E., Cona A. & Lauteri M. 1994. Xanthophyll cycle components and capacity for non-radiative energy dissipation in sun and shade leaves of Ligustrum ovalifolium exposed to conditions limiting photosynthesis. Photosynthesis Research, 41:451-463.
  • Brugnoli, E., Scartazza A., Lauteri, M., Monteverdi, M.C. & Maguas C. 1998. Carbon isotope discrimination in structural and non-structural carbohydrates in relation to productivity and adaptation to unfavorable conditions. In Griffiths H (ed.) Stable Isotopes: Integration of biological, ecological and geochemical processes. BIOS, Oxford, pp. 133-146.
  • Brugnoli, E., Scartazza A., De Tullio, M.C., Monteverdi, M.C., Lauteri, M. & Augusti A. 1998. Zeaxanthin and non-photochemical quenching in sun and shade leaves of C3 and C4 plants. Physiologia Plantarum, 104: 727-734.
  • Brugnoli, E. & Farquhar, G.D. 1999. Photosynthetic fractionation of carbon isotopes. In: Govindjee (editor-in-Chief) Advances in Photosynthesis. Leegood R.C., Sharkey T.D. and von Caemmerer, S. (eds.) Photosynthesis: physiology and metabolism. Kluwer Academic Publishers, (in press).
  • Loggioni, B., Scartazza, A., Brugnoli, E. & Navari-Izzo, F. 1999. Antioxidative defence system, pigment composition, and photosynthetic efficiency in two wheat cultivars subjected to drought. Plant Physiology, 119: 1091-1099.
  • Lauteri, M., Scartazza, A., Guido, C. & Brugnoli, E. 1997. Genetic variation in photosynthetic capacity, carbon isotope discrimination and mesophyll conductance in provenances of Castanea sativa adapted to different environments. Functional Ecology, 11: 675-683.
  • Scartazza, A., Lauteri, M., Guido, M.C. & Brugnoli, E. 1998. Carbon isotope discrimination in leaf and stem sugars, water-use efficiency and mesophyll conductance during different developmental stages in rice subjected to drought. Aust. J. Plant Physiol. 25: 489-498











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