| title: | Ontogenetic development of structural and functional characteristics of water relations and photosynthesis of leaves in temperate deciduous tree canopy |
|---|---|
| reg no: | ETF5305 |
| project type: | Estonian Science Foundation research grant |
| subject: |
1.5. Biophysics 1.14. Ecology 4.3. Sylviculture, Forestry |
| status: | completed |
| institution: | University of Tartu |
| head of project: | Anu Sõber |
| duration: | 01.01.2002 - 31.12.2005 |
| description: | Water uptake, storage and evaporation in the foliage depends on environmental conditions, but also on structure and function of leaves. Term "structure" means here quantity and size of structural elements (e.g. stomata or xylem elements) but also quantity of enzymatic apparatus in leaves and its distribution within the foliage. Mature leaves only have been studied in most cases. Less data have been published about the development of structural and functional characteristics of leaves and it can not be predicted, which stationary values these characteristics would achieve in different environmental conditions. The foliage of most temperate deciduous tree species is developing during short period of spring and early summer. This period is short to add significantly to annual summary gas-exchange of foliage, but we hypothesize that this short period would determine the maximal possible values of hydraulic conductance and gas exchange during current growing season. The aim of this project is to study the development of structural and functional characteristics of leaves (density and size of stomata, xylem elements and pit-membranes, contents of water, nitrogen, Rubisco and chlorophyll; hydraulic conductance, stomatal conductance and photosynthesis rate) during time-interval between bud-break and leaf maturation: (1) In mixed forest canopy of Järvselja (Estonia), where influence of light regime and species differences will be studied, (2) in growth chamber experiment (influence of soil water and nitrogen content) and (3) in "Aspen FACE" experiment (WI, USA), where development of leaf area and its distribution dependently on height and chlorophyll-Rubisco-nitrogen contents will be studied in young developing canopies under elevated CO2 and O3 concentrations. We hypothesize, that: (1) structural and functional characteristics which determine water-balance of leaves would develop in coordination of development of photosynthetic apparatus and increase in leaf nitrogen content, depending on the quantity and size of buds, on water and nitrogen availability, temperature and ABA concentration during bud-break and leaf development; (2) Leaves with high rate of nitrogen incorporation would develop big cells, nonsensitive (open) stomata, high hydraulic conductance and high water-content which can be regulated without stomatal closure. Leaves with low rate of nitrogen incorporation would develop small cells, sensitive stomata, low hydraulic conductance and low water content which would depend on stomata. |
| project group | ||||
|---|---|---|---|---|
| no | name | institution | position | |
| 1. | Krõõt Aasamaa | University of Tartu | PhD student | |
| 2. | Märt Rahi | Agricultural Univ | scientific secr | |
| 3. | Anu Sõber | University of Tartu, Institute of Botany and Ecology | senior researh associate | |