I'm not sure how well it might work with Casuraina equisetifolia because the leaves are so fine, but we've been having great success with fluorescence measurements in balsam fir needles in our lab.

For balsam fir we remove about 6 needles and lay them flat on some basic lab tape (white usually) sticky side up. That holds the needles from moving. These are dark acclimated with the clamps that we ordered for our meter, which have a slider to open and close a round opening. After dark acclimation we simply attach the clamp to our fluorescence meter. Very consistent measurements, both with each other and published literature values. We'll be releasing a manuscript regarding this in the next few months - though that's likely not helpful to you in the immediate future.

Our equipment came from Opti-sciences, which we ordered specifically because we were having trouble getting consistent measurements on needles.

We have measured fluorescence in pine needles. As soon as you gather them and lay them flat I believe you won't have any problem, even if there are some gaps. Check:

Kalaji, H.M.; et al, 2014. Frequently asked questions about in vivo chlorophyll fluorescence: practical issues. Photosynth Res 122:121–158

Thank you very much dear Oliet.

Thank you very much dear Mason T Macdonald for informative and quality measurement methodologies. 

Thanks

There is enough literature on both invitro and invivo fluorescence measurements in many species including Casuarina equisitifolia, as it helps to understand responses in plants.  In many photosynthesis advanced research laboratoris, this is routinely being carried out

Dear Munusamy Vivekanandan  Sir

Thank you very much.

Please refer this paper

http://download.springer.com/static/pdf/454/art%253A10.1023%252FA%253A1022618823538.pdf?auth66=1416817534_0f74797d1e2df3ad3f6ff9bd75f3e810&ext=.pdf

it can be measured with the classical PAM fluorometers like e.g. MINI-PAM from Walz in Germany, but it depends a Little on the Parameters you would like to get. In case the Chlorophyll content of the leafs is interesting for you would need a bündle of leaves covering the whole measuring area and determine Fo value (no linear relation between Fo and Chl. Content). Much easier is the determination of photosynthesis parameters – they are normally relative and thus do not depend on the leaf area visible in front of the detector fiber.

There is a paper about that principle using the Monitoring-PAM which can be found here:http://link.springer.com/article/10.1007%2Fs11120-008-9292-3. In Fig. you can see a similar application.

I would advise you to make clear what do you mean "needle type of leaves in casuarina". In fact, Casuarina has reduced leaves fused tightly with the stem. The leaves can be seen under a stereo microscope; they look like scales surrounding the stem. I think what do you call  "needle" is a stem or a stem surrounded with leafy tissues. In cross section one can easily identify what is stem and what is leaf. Otherwise you have to dissect the leaf tissues carefully if you want to measure any detail of the leaves. Otherwise, you get a mixture of results from stem and leaf chlorenhyma tissues; I am not sure they are exactly the same.

 On the other hand, using several sample pieces can cause dsitortions in the fluorescence values. In steady state fluorescence spectroscopy significant baseline distortion, interference ghost signals, light scattering, etc. can cause troubles when the pigment distribution is not equal in the illuminated sample window. I am sure the amplitude value (what you measure as F0) must be influenced by the geometry of your samples; can they be Casuarina stems, pine needles or any not flat samples.

Dear Dileswar,

the green needle-like twigs of Casuarina can easily be measured, I have used fluorometers on various conifers before. As others pointed out, it is perhaps good practice to gather a bunch of the leaf-like twigs in a single layer. If you're using a leaf clip holder (such as provided by hand-held instruments such as a MINI-PAM) then it is fairly easy to spread the twigs evenly over the measured area. Hope that helps!

This could very well be achieved. I have successfully measured flourescence in balsam fir needles. Although there are special fluorometers for the conifers, a regular flourometer that measure surfaces is sufficient. The key is to dislodge the needles and use them for measurement immediately before they dry out. The window of this time is under 15 minutes for balsam fir. You may want to do a mini-trial to discover this time limit with dislodged and intact needles. Once known, dislodge your needles and arrange them closely with no significant gaps on a mask tape. Make sure the tape is completely covered with the needle surface. We have to make sure we measure the correct side of the needle (adaxial or abaxial). Once you prepare the tape with needles arranged, the measurement is straight forward like any other leaf surface area. Care must be taken not to prepare the tape with needles if the measurements are taken immediately. Each flourometer will have a minimal suface area it can handle. We have to make sure our tape needle surface exceeds this requirement. It is advisable to play with this technique several times, before the actual experiment. Good luck.

Yes, it is possible to measure fluorescence of C. equisetifolia  needles using fluorimeter.  Many researchers have done this.  The measurement  is like invivo fluorescence.  The needle is not leaf and therefore the available area is minimal.  The fluorescence can  be  measured using different surface area and an average value can be taken

Thank you sir