Effect of spatial coherence of light on the photoregulation processes in cells

The effect of the statistical properties of light on the value of the photoinduced reaction of the biological objects, which differ in the morphological and physiological characteristics, the optical properties, and the size of cells, was studied. The fruit of apple trees, the pollen of cherries, the microcuttings of blackberries in vitro, and the spores and the mycelium of fungi were irradiated by quasimonochromatic light fluxes with identical energy parameters but different values of coherence length and radius of correlation. In all cases, the greatest stimulation effect occurred when the cells completely fit in the volume of the coherence of the field, while both temporal and spatial coherence have a significant and mathematically certain impact on the physiological activity of cells. It was concluded that not only the spectral, but also the statistical (coherent) properties of the acting light play an important role in the photoregulation process.

Figure 1

Scheme of the experiment with a thermal light source. LPM is a light-proof mantle, FL is high-temperature filament lamp, IRF is infrared filter, RF is red interference filter, and AD is aperture diaphragm with a round hole of the diameter of $2a$.

Figure 2

Dynamics of disease of apples exposed before laying on storage by (1) low-coherent or (2) high-coherent light. (3) is control (nonirradiated fruit). Duration of exposure is 60 s; power density is $4\mathrm{W}/{\mathrm{m}}^2$.

Figure 3

Dependence of plum pollen germination on the duration of exposure of quasimonochromatic light from thermal sources with the same temporal coherence ($L_{\mathrm{coh}}=32\mu \mathrm{m}$) and different spatial coherence: (1) $r_{\mathrm{cor}}=40\mu \mathrm{m}$, (2) $r_{\mathrm{cor}}=5\mu \mathrm{m}$. Power density is $0.7\mathrm{W}/{\mathrm{m}}^2$. Control (without irradiation) corresponds to the point of zero exposure duration.

Figure 4

Effect of quasimonochromatic light of different spatial and temporal coherence in the development of the blackberry explants, cultivated in vitro: (1) $L_{\mathrm{coh}}=135\mu \mathrm{m},r_{\mathrm{cor}}=30\mu \mathrm{m}$; (2) $L_{\mathrm{coh}}=135\mu \mathrm{m},r_{\mathrm{cor}}=5\mu \mathrm{m}$; (3) $L_{\mathrm{coh}}=5\mu \mathrm{m},r_{\mathrm{cor}}=30\mu \mathrm{m}$; (4) $L_{\mathrm{co}}=5\mu \mathrm{m},r_{\mathrm{cor}}=5\mu \mathrm{m}$. Control, without irradiation.

Figure 5

Stimulation coefficient $K_{\mathrm{st}}$ in plant tissue culture at different ratios between the cell size $D$ and $L_{\mathrm{coh}},r_{\mathrm{cor}}$ of exciting light. The volume of the coherence of the light field is represented as a rectangular projection with sides $L_{\mathrm{coh}}$ and $r_{\mathrm{cor}}$. The size of the cells is represented as a circle of diameter $D$, and the statistical evaluation of the differences with the control as a value of α (probability of the null hypothesis).

Figure 6

Effect of coherence of quasimonochromatic light in the development of the fungus Fusarium microcera colonies infected with the bacterium Pseudomonas syringae: (1) $L_{\mathrm{coh}}=135\mu \mathrm{m}, r_{\mathrm{cor}}=18\mu \mathrm{m}$; (2) $L_{\mathrm{coh}}=135\mu \mathrm{m}, r_{\mathrm{cor}}=5\mu \mathrm{m}$. Control, without irradiation.