environmental friendLy foliar nutritive fluids chemical stress by chlorophyll fluorescence. Aura Dana Ionita, Viorica Chitu, Emil Chitu, Marina Cirjaliu-Murgea, Nicoleta Teodorut, Laurentiu Filipescu Department of Technology of Inorganic Substances and Environmental Protection
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environmental friendLy foliar nutritive fluids chemical stress by chlorophyll fluorescence
Aura DanaIonita, Viorica Chitu, Emil Chitu, Marina Cirjaliu-Murgea, Nicoleta Teodorut, Laurentiu Filipescu
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
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 fluorescence level is reached upon complete reduction of Q.
Schreiber, U., Chlorophyll fluorescence yield changes as a tool in plant, physiology I. The measuring system Photosynthesis Research 4, 1983, p.361-373.
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
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 of environmental stressfactors on the photochemical reactions rate.
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
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).
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.
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 non-quenching 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.
The work was carried out with the financial support of the CNCSIS Program, ‘Ideas’, within the Research Project 1035/2007.