Applications for MINI-PAM-II: Porometer Configuration
Porometers are well established tools in plant research, used to measure stomatal conductance. However, the MINI-PAM-II/POROMETER takes your research a step further. Not only does it provide fast and accurate measurements of stomatal aperture, but it also allows detailed observation of stomatal movement over time. See some of the versatility of the applications in the experiments below: quick measurements on different plant leaves and differences induced by sun and shade growth, stomatal movement during an induction curve, and two different monitoring experiments. Whether you're investigating short-term responses or long-term changes, the MINI-PAM-II/POROMETER is your ideal companion.
Fast assessment of porometer data:
The MINI-PAM-II/POROMETER provides information on e.g. evaporation rate, VPD and stomatal conductance of the measured leaves. Measurements are easy to perform and provide accurate results within a typical sample measurement time of 15-30 seconds.
Fig.1: Recording of porometer measurements on a variety of leaves
To show typical measuring sequence, the datapoints were recorded every second using the WinControl-3 software. The dot circled in red marks a manual measurement triggering an additional saturation pulse analysis.
To optimize the workflow, the stability assessment can be performed automatically by the device. The change in conductance is then evaluated and the measurement is automatically triggered as soon as the stability criteria are met. The stability criteria are preset but can be customized to suit the individual requirements.
The stability criteria can be applied to both types of data acquisition: either porometer data only or the combination of SAT pulse analysis and porometer data acquisition. The latter was used for the analysis on shaded-grown (Fig.2A) vs. sun-exposed (Fig.2B) Viburnum rhytidophyllum leaves.
Fig.2: Measurements on shade-grown leaves (A) vs. sun-exposed-grown leaves (B)
Fig.3: Stomatal conductance (blue) and Y(II) (green) of shade-grown vs. sun-exposed-grown leaves
These differently grown leaves show many differences in parameter of porometer and chlorophyll fluorescence analysis. Fig.3 shows as an example the results of stomatal conductance (gs) and Y(II).
Particularly interesting for field measurements: the Porometer logs GPS, leaf solid angle of the surface normal and the incident vector of sunlight with each dataset so that the sample´s geographical context can be documented precisely.
Porometer and chlorophyll fluorescence protocols:
But the MINI-PAM-II/POROMETER offers even more. This porometer allows MINI-PAM-II protocols to be combined with porometer data, adding an important aspect of gas exchange to these established tools for chlorophyll fluorescence analysis. This facilitates the measurement of evaporation, VPD, stomatal conductance and stomatal movement e.g. during light curves or induction curves. Fig.4, shows stomal movement during an induction curve measured on a Taraxacum leaf.
The MINI-PAM-II/POROMETER can be operated with both MINI-PAM-II versions. Depending on the version, the actinic illumination is provided with red or blue actinic light.
If you prefer a more flexible choice of light colors, you can use the External LED Source 2054-L for the actinic lighting with red, green, blue or white light, or mixtures of these four light qualities like it was done in this experiment:
Fig.4: Induction curve, Taraxacum leaf 10% blue, 10% green, 10% red, 70% white actinic light
This is a screenshot of Taraxacum two-step induction curve with 10% blue, 10% green 10% red and 70% white at 190 µmol m-2 s-1, then 380 µmol m-2 s-1. Showing mainly the first part of this two-stage induction curve indicating Y(II) (green), PAR (yellow), ETR (red), NPQ (light blue) and stomatal conductance (dark blue). The Y-axis scaling refers to the stomatal conductance in mmol m-2 s-1.
MINI-PAM-II/Porometer used for monitoring:
A new clock feature the "Yield + Poro Only" gives the ability to trigger a saturation pulse, followed by a sequence of porometer-only measurements. This clock item is ideal for monitoring purposes if you want detailed information about stomatal conductance but less frequent saturation pulse measurements. In stand-alone operation, just supplied with some extra power, the MINI-PAM-II with porometer can monitor your sample for several days. You can capture PS(II) photosynthesis and the dynamics of stomata and their adaptation to changing conditions in a detailed and continuous manner as you can see here in two monitoring experiments:
1. Diurnal and Nocturnal monitoring of a Kalanchoe laxiflora leaf:
Fig.5: Stomatal conductance and ETR of Kalanchoe laxiflora during 4 days and nights of monitoring
The plant was cultivated under a 12-hour light (680 µmol m⁻² s⁻¹) and 12-hour dark cycle. As is typical for CAM plants, the porometer determines stomatal opening at night. As long as the plant was adequately watered, stomatal opening also occurred during the second half of the day e.g. to maintain photosynthetic efficiency. Initially well-watered, the data clearly show a decline in stomatal aperture during the second half of the day over the first three days. Following irrigation on the fourth day, there is a marked increase in nocturnal stomatal opening compared to the previous three nights.
Fig.6: MINI-PAM-II/POROMETER monitoring a Kalanchoe laxiflora leaf
2. Six-day monitoring experiment of a tomato leaf grown a small glasshouse.
Fig.7: Stomatal conductance (blue), PAR (yellow), CO2 (grey), ETR (red) and Temp. (brown), six-day monitoring of a tomato leaf.
In this experiment the instrument executed porometer and chlorophyll fluorescence measurements every half hour for monitoring a tomato leaf continuously for six days inside a small greenhouse. The figure displays some of the comprehensive data collected during this period. Daily cycles were well measured, and you can see the performance of the leaf under the fluctuating light conditions throughout the day.
The MINI-PAM-II/POROMETER allows for the simultaneous recording of environmental parameters, such as the CO₂ concentration within the greenhouse. Shown in grey is the CO2 concentration inside the greenhouse. It exhibits significant fluctuations with peak concentrations of more than 750 ppm CO2 during the day.
In accordance with M.A.Caird et al. (Funct Plant Biol. 2007 Apr;34(3):172-177. doi: 10.1071/FP06264) the tomato leaf measured in this experiment did not fully close the stomata and showed significant transpirational water loss throughout the night.
Experience precision and flexibility research with the MINI-PAM-II/Porometer.