Seminarid

 


Seminar 19.06.2009

Teemad

Plant stress, emissions

Dr. Astrid Kännaste

Grid Computing: The Xgrid at Maaülikool

Dr. Steffen M. Noe
 


Seminar 24.04.2009

Teemad

The ins and outs of Metaphenomics

Dr. Hendrik Poorter

Looking for better methods in leaf water potential measurements

Water potential is probably the best single measure of the water status in plants (Spomer, 1985), and the pressure chamber has been considered good indicator of water potential in plants (Boyer, 1969; Scholander et al., 1964: Kaufmann, 1968a, b). The bulk elastic modulus (ε) of an individual leaf represents the ratio of the change in cell turgor (P) to that in the relative cell volume (ΔV/V) of the leaf [ε = ΔP/(ΔV/V)]. This parameter is obtained by the pressure-volume (P-V) technique (Tyree and Hammel, 1972, Cheung et al., 1976). ε determines how cell turgor decreases with loss of water in the leaf. The decrease in turgor connects directly with the decrease in leaf water potential, and produces the driving force for water flow in the soil-plant-atmosphere continuum (Saito et al., 2006). In this way, ε has a direct relationship with the water of the whole plant, and the effects on cells turgor can be seen during water stress period and recovery time.
Most of cases, plants are not in a optimal status, and traditionally, cut leaves and stems have been used in order to measure P-V curves. From those materials, consider that P-V curve starts on 100% hydration seems wrong, because the maximum hydration potential of the leaf only can be reached with a re-hydration time. In this experiment, three methods of re-hydration of leaves is proposed in order to measure P-V curves and calculate the bulk elastic modulus.
Leaves from laboratory-grown Citrus, Quercus and Populus are being measured with those three methods, and a water stress period and recovery time will be applied to Citrus and Quercus trees.

Miguel Portillo Estrada
 


Seminar 27.03.2009

Teemad

Using alternative carbon source for isoprene emission.

Zhihong Sun

 


Seminar 27.02.2009

Teemad

Polymerase chain reaction(PCR) and it's application.

Leila Pazouki

 


Seminar 25-26.11.2008

Teemad

Discussions of the work and experiments for 2009

TBA (Ülo Niinemts, 26.)

Resource management and safety regulation in the laboratory (Lucian O. Copolovici, 25.)

Some thoughts about work (Steffen M. Noe, 25.)

PhD presentations

In silico study of isoprene synthase based on database (Leila Pazouki, 25.)
Work reports and experiment introduction (Zhihong Sun, 25.)
Introduction to the experiments of my PhD studies (Miguel Portillo, 25.)
Internal conductance as depending on leaf inner sructure (Tiina Tosens, 26.)
A brief overview of my doctoral thesis (Lea Halik, 26.)
Respiration and starch degradation in leaves of Arabidopsis (Hiie Ivanova, 26.)


 


Seminar 25.04.2008

Teemad

Plant leaf respiration at high temperature.

Hiie Ivanova

PhD students Sun Zhihong and Leila Pazouki will introduce their former work.
 


Seminar 28-29.03.2008

Teemad

Some results from the CO2 experiment

We run experiments where we investigate the relationship between CO2 concentration and Isoprene emission from Poplar trees. An automatic cuevette system, where we can manipulate CO2 concentration is used for that experiment. This talk will present some results, but also introduces the measurement system, the theory behind a possible regulation of the isoprene synthesis pathway on a cellular level.

Steffen M. Noe

Responses of optical reflectance indices to experimental warming and drought in European shrublands along a North-South climatic gradient

Lea Hallik

Plant tissue culture

Rael Vardia
 


Seminar 25.01.2008

Teema

Photosynthesis capacity as depending on leaf structure and internal gas exchange resistance in Populus tremula

This study demonstrates that the rates of leaf photosynthesis are particularly sensitive to developmental and stress induced changes in internal mesophyll resistance to CO2.
Increases in leaf area during leaf ontogeny imply a greater area for interception of radiation energy and photosynthesis while increases in leaf thickness imply more photosynthetic mesophyll per unit leaf area. However thicker leaves also imply a longer diffusional pathway for CO2. Our study further indicates that the values of leaf anatomical parameters are strongly modified by various environmental factors, even though the general environmental pattern is maintained also in stressed plants. Environmental stresses primely modify leaf photosynthetic potentials due to changes in leaf area but due to enhanced internal diffusional resistance.

Tiina Tosens

22.04.2009

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