Transcript Laurenţiu Filipescu - Program IDEAS

ENVIRONMENTAL FRIENDLY FOLIAR
NUTRITIVE FLUIDS CHEMICAL STRESS
BY CHLOROPHYLL FLUORESCENCE
Aura Dana Ionita, Viorica Chitu, Emil Chitu,
Laurentiu Filipescu
Marina Cirjaliu-Murgea, Nicoleta Teodorut,
Department of Technology of Inorganic Substances and Environmental Protection
Faculty of Applied Chemistry and Material Science, University Politehnica of
Bucharest, Phone: (021)4023885, e-mail: [email protected]
ICDP Research Institute for Fruit Growing Pitesti – Maracineni
Romanian International Conference of Chemistry and Chemical Engineering,
RICCCE 16, Bucharest, 2009
PHOTOSYNTHESIS
Chlorophyll fluorescence is a non-invasive approach to energetics of the
photosystem II (PSII).
Light absorbed by chlorophyll from leaves is consumed in three
processes:
a) photosynthesis (photochemistry);
b) dissipation as heat;
c) re-emission as red fluorescence (Figure 1).
The total yield in energy adsorption is constant and subsumes the yields
of the all three processes.
Photochemistry (P) + Fluorescence (F) + Heat production (D) = 1
Figure 1: Absorption and emission spectrum of
chlorophyll a.
Consequently, the measurements of the yield of chlorophyll fluorescence
grant significant information about photosynthesis share in captured energy
consumption and heat losses by dissipation (Figure 2).
Figure 2. Transformation of light energy into chemically
fixed energy by charge separation at photosystem II
reaction centers
Light energy absorbed by photosystem II antenna pigments, (h • v)A, is
transfered by inductive resonance to the reaction center chlorophyll (P
680) which mediates reduction of an acceptor Q by a donor D;
At the donor side accumulation of positive charges leads to the
splitting of H2O;
At the acceptor side electrons are taken up by the plastoquinone
pool (PQ) from which they are transported via photosystem I to NADP
(NICOTINAMIDE ADENINE DINUCLEOTIDE PHOSPHATE) and eventually
into the Calvin cycle to reduce CO2 .
Minimum fluorescence level, (h • v)F, occurs at a minimum level
(O~level) for all centers being open (acceptor Q completely oxidized);
Maximum
reduction of Q.
fluorescence
level
is
reached
upon
complete
Schreiber, U., Chlorophyll fluorescence yield changes as a tool in plant, physiology I. The
measuring system Photosynthesis Research 4, 1983, p.361-373.
Principle of measurements
Each quantum of light absorbed by a chlorophyll
molecule rises an electron from the ground state to an
excited state.
Upon de-excitation from a chlorophyll a molecule
from excited state 1 to ground state, a small proportion (35% in vivo) of the excitation energy is dissipated as red
fluorescence.
The rest of de-excitation energy is discharge in:
 primarily photochemistry;
 secondarily in heat dissipation (enzymes
activation, transpiration, mineral transport, etc.).
Therefore, changes in the fluorescence yield reflect
changes in photochemical efficiency and heat dissipation
rate.
A typical measurement on a healthy leaf by the saturation pulse method
is shown in Figure 3 (Fracheboud, Y.,Using chlorophyll fluorescence to study
photosynthesis, www.ab.ipw.agrl.ethz.ch/~yfracheb/flex.htm).
Figure 3. Measurement of chlorophyll fluorescence
Steps:
 plant leaf is dark adapted for 20 minutes prior to the
measurement minimum (basic) chlorophyll fluorescence is
measured, Fo (QA, the first electron acceptor of PSII is fully
oxidazed);
 of a saturating flash (8000 mmol m-2 s-1 for 1 s) is applied and
the maximum value of chlorophyll fluorescence is measured, Fm
(QA, the first electron acceptor of PSII is fully reduced);
 constant illumination with actinic light produces a transient rise
in fluorescence yield, due to the lag phase before carbon fixation
(some carbon fixing enzymes are requiring light-activation); next
upon the onset of photochemical and heat dissipation processes,
fluorescence yield is quenched and reaches a steady state value
Ft;
 second saturation flash in the presence of actinic light,
produces the maximum fluorescence under actinic light, Fm’.
Thus, there were measured 4 parameters:
 Fm - maximum value of the chlorophyll fluorescence on the
dark adapted leaf (QA- fully reduced);
 Fo – minimum value of the chlorophyll fluorescence on the dark
adapted leaf (QA - fully oxidized);
 Fm’ - maximum value of the chlorophyll fluorescence on the
light adapted leaf (QA- fully reduced);
 Ft - minimum value of the chlorophyll fluorescence on the light
adapted leaf (QA - fully oxidized);
Fm > Fm’ ; Ft > Fo
All for parameters give information about the fractions of light energy
used for photosynthesis and for heat dissipation, respectively.
(Fm’ - Ft) indicates the photochemical part of fluorescence quenching
(Fm - Fm’) indicates the heat dissipation part of fluorescence quenching
The following computed parameters reflect some information about process occurring in
the plant leaf:
1. Photochemical quenching:
qP = (Fm’-Ft)/(Fm’-Fo)]
indicates the redox state of the primary electron acceptor of PSII QA.
2. Non-photochemical quenching:
qN = (Fm-Fm’)/(Fm-Fo) or NPQ = (Fm-Fm’)/Fm’]
indicates the energy dissipated as heat related to energization of the thylakoid membrane
due to lumen acidification.
3. Quantum yield of electron transfer at PSII (FPSII):
Y(II) = (Fm’-Ft)/Fm’
indicates the overall efficiency of PSII reaction centers in the light.
4. Ratio Fv’/Fm’ = (Fm’-Fo)/Fm’
indicates the efficiency of open reaction centers in light
Some other parameters may be computed to learn more about stress factors on
the energetic of leaf processes as happened when fertilizers or other chemicals are applied
on the foliar way.
In this paper, for the evaluation of the foliar nutritive products
effect on leaf photosynthesis process, there were used 2 parameters:
A. Fv/Fm = (Fm - Fo)/Fm
which is the maximum potential quantum efficiency of Photosystem II
(PSII) .
B. Y(II) = (Fm’-Ft)/Fm’
which is measuring the magnitude of effective quantum photosynthesis
yield under steady-state photosynthetic lighting conditions.
C. half-rise time of FM (T1/2)
which gives information about the effects
stressfactors on the photochemical reactions rate.
of
environmental
Last generation of fluorimeters provides much more complex
measurement. OJIP protocol involves the same parameters described
above, but the measurements are made by successive saturation flashes
at for levels of excitation with frequency modulated light at variable
intensity. This protocol allows computation of at least 30 parameters
describing qualitatively and quantitatively the yields of chlorophyll
fluorescence.
The raise in electron transport per reaction centre
ET0 / RC = M0 . (1 / VJ) . Phi_0)
which quantifies the flux of electrons beyond QA (see PS I) during the
initial fluorescence rise after actinic light impulse, was the choice for
describing the effects of the emulsified nutritive fluids.
M0 = 4 (F300 - F0) / (FM - F0)
VJ =(FJ - F0) / (FM - F0)
Phi_0 = 1 - VJ
EXPERIMENTAL SET UP
Foliar nutritive fluids
Emulsified foliar nutritive fluids transporting to the foliage
surface:
• variable NPK macronutrient formulas overcharged with mezzo
nutrients: (Nutrinaft A);
•
growth enhancers (Nutrinaft B);
•
micronutrients (Amokem);
•
fungicides (Frucol).
These fluids are hydrolyzing through dilution and carbonation,
leaving on the leaf surface a freshly precipitated layer of new biological
active moieties.
Chitu, V., Chitu, E. Nicolae, S., Ionita A. D., M. Cirjaliu-Murgea, Filipescu L. (2009). Relationships
between shelf life, health and quality of apple fruit. Acta Hort. (ISHS) 825:539-546; Cirjaliu-Murgea, M.,
Ionita, A. D. Chitu, E. Chitu V., Filipescu L. (2008). Emulsified nutritive fluids and their proprieties control.
6th International ISHS Symposium on Mineral Nutrition, Faro, Portugal.
Foliar application.
Before application the foliar nutritive sample were diluted with
hard water up to 1.0% mass concentration and applied in the first part of
the day using a low pressure sprayer.
Experimental plots were set on 5 variants for each apple cultivar:
V1 – untreated blank plot, just spread with water at the same rate
and at the same time intervals as the rest of foliar treated plots;
V2 – foliar treated plot with the nutritive fluid Nutrinaft A;
V3 – foliar treated plot with the nutritive fluid Nutrinaft B;
V4 – foliar treated plot with the nutritive fluid Amochem dual B;
V5 – foliar treated plot with the nutritive fluid Frucol.
Chlorophyll fluorescence measurements
2007 – Chlorophyll fluorescence data were collected with an OS 30
(Opti-Sciences) chlorophyll fluorometer.
2009 – Chlorophyll fluorescence data acquisition was made with
portable FluorPen FP 100 chlorophyll fluorometer (Photos Systems
Instruments).
EXPERIMENTAL RESULTS
Parameter A: Fv/Fm = (Fm - Fo)/Fm which is the maximum potential
quantum efficiency of Photosystem II (PSII)
Fig. 4. Variation of the FV/FM indicator versus the time elapsed since foliar
application of the new emulsified nutritive fluids.
 FV/FM ratio mean value of this indicator was found to be 0.755, very
close to optimal accepted figure (0.830). Even if FV/FM correlates
negatively with F0 (r= -0.877**) and FM (r= -0.249**), the experimental
data point out to a low level of stress, induced by all the emulsified
nutritive fluids.
 Figure 4 clearly unveil certain significant jumps in FV/FM indicator
values immediately in hours after application on the foliage for all the
products. This behavior might be explained by fast penetration of nutritive
and growth enhancing fluids through cuticula, and excedentary energy
comsumption during this short period of overfeeding. After some 24-48
hours, this unharmful transitory overfeeding stress settles down to
common potential quantum efficiency of Photosystem II (0.750-0.800),
reflecting the safety health state of foliage.
FV/FM ratio, or the maximum potential quantum efficiency of Photosystem
II (PSII), finely correlates with carbon fixation under any of circumstantial
conditions (Schreiber et al., 1986; Baker & Rosenkuist, 2004).
Parameter B: Y(II) = (Fm’-Ft)/Fm’, which is measuring the magnitude
of effective quantum photosynthesis yield under steady-state
photosynthetic lighting conditions.
Figure 5. Variation of yield Y(II) versus the time elapsed since foliar
application of the new emulsified nutritive fluids
Closure of reaction centers and heat dissipation are nonquenching energy consumers and share with yield Y(II) the total
potential quantum efficiency FV/FM.
Yield Y(II) low values (average mean 0.310) recorded
during run tests for emulsified nutritive fluids under experimental
conditions should be explained just in terms of comparison with
the blank (figure 2).
Significant fluctuation in yield Y(II) are taking place first 24
hours, as in figure 4. Afterwards the yield Y(II) value come back to
those of normal blank ones.
These observations sustain non quenching energy
consumption for nutritive moieties transport under leaf
overfeeding in first hours after emulsified nutritive fluids
application.
All the products do not impair the yield of light energy
conversion into quenching energy.
Parameter D: OJIP chlorophyll parameter ET0/RC, which quantifies the
flux of electrons beyond QA (PS I) can be seen in the figure 6.
Figure 6. Variation of the ET0/RC parameter over three day
treatment with emulsified nutritive fluids
The raise in electron transport per reaction centre (expressed by ET0/RC
level) is significant for all the treatments
This raise is continual for all the products till the second day after
application.
Slight decrease in the third day is factually evidencing the active
components have been adsorbed and consummated in the metabolic process.
Thus, the nutrients consumption was not occurring on the spot, but
metabolized at a rate controlled by the specific plant nutrition mechanism.
Also the overfeeding and leaf burning under excessive foliar nutritive
products could not come about with the frequency met to the common NPK foliar
fertilizers.
All the above data back up the formulation principles of emulsified
nutritive fluids and sustain their capacity to promote growth stimulation and
alleviate mineral stress at the foliage surface.
Chitu, V., E. Chitu, A. Hororoi, M. Calogrea, M. Cirjaliu-Murgea and L. Filipescu (2004).
Researches concerning Nutrinaft products effects on apple production and fruit quality,
Annals of the University of Craiova, Vol. IX (XLV):123-128.
CONCLUSIONS
 In dark adapted test the measured FV/FM ratio, standing for the maximum
potential quantum efficiency of Photosystem II (PSII), experimental data point out to
a low level of stress induced by all the emulsified nutritive fluids;
 In the light adapted leaves the fluorescence indicator yield (Y(II), which is
measuring the magnitude of effective quantum photosynthesis yield under steadystate photosynthetic lighting conditions, did take uncommon low values around the
average mean of 0.310. Because the light reaction centers remained open and
potential quantum efficiency Fv/Fm was normal (around 0.755 averaged mean), it is
reasonable to consider the yield Y(II) was low due to the non quenching energy
consumers (nutrient transport through cuticula);
 The ET0/RC chlorophyll fluorescence parameter (measured under mild
environmental stress), which quantifies the flux of electrons beyond QA during the
initial fluorescence rise after saturated light impulse, was found significantly
increasing for all the emulsified nutritive fluids applied as diluted solutions. Its slight
decrease in the third day is factually evidencing the active components carried by
the emulsified nutritive fluids have been adsorbed, and consummated in the
metabolic process at a rate controlled by the specific plant nutrition mechanism;
 All the above data back up the formulation principles of emulsified nutritive fluids
and acknowledge these products capacity to promote growth stimulation and
alleviate mineral stress at the foliage surface.
MULTUMESC !
ACKNOWLEDGMENT:
The work was carried out with the financial support of the
CNCSIS Program, ‘Ideas’, within the Research Project 1035/2007.