Photoelectric Signal Acquisition And Analysis Of Maize Seedling Leaves Under Osmotic And Saline-alkali Stress

Osmotic and saline-alkali stress are the most common abiotic stress in plant growth process, so it is important to study the response of plant to osmotic and saline-alkali stress. Plant cell can generate spontaneous luminescence and delayed luminescence during plant life activities. These light signals are important information of cell, study and explain the regulation and meaning of plant light signal could provide a new technology of non-invasive optical biopsy to the change of cell metabolism and function state under osmotic and saline-alkali stress. In the process of plant life activities, there are potential fluctuation inside the plant. The reading of potential fluctuation signal could give a new method of real-time in-situ monitoring and non-destructive evaluation ?NDE? to plant cell function and metabolic regulation under osmotic and saline-alkali stress.To study and interpret the photoelectric signal of plant leaves under osmotic and saline-alkali stress, osmotic stress was formed by PEG-600 solution with osmotic potential -0.1 Mpa, salt stress was formed by NaCl solution with concentration 100mmol/L and saline-alkali stress was formed by Na₂CO₃?Na₂SO₄?NaHCO₃?NaCl, with pH 9.09 were added to the maize seedling. under such conditions, the characteristics and change regulation of spontaneous luminescence, delayed luminescence and potential fluctuation of maize seedling leaves were analyzed, the change of physiological and biochemical indexes of maize seedling leaves also be measured and analyzed. The study found that under osmotic stress, salt stress and saline-alkali stress, spontaneous luminescence was reduced, and kinetic parameters of delayed luminescence from leaf cells, both initial photon number 10, dimensionless decay parameter ?,coherent time ? and delayed luminescence integral intensity I?T?showed a downtrend, indicated that photosynthetic capacity and respiratory metabolism of maize seedling leaves were restrained, the interaction between the functional molecules in cells were weakened. The result also found that seemingly chaotic potential fluctuations changes on the leaf surfaces had a certain regularity in the spectra, the differences of which could be quantified and distinguished by characteristics parameters of marginal spectra such as spectral edge frequency ?SEF?,spectral center frequency ?SCF? and marginal spectrum entropy ?MSE?. During the stress of osmotic and saline-alkali, the values of SEF, SCF and MSE presented continuous fluctuations, the migration of SEF and SCF to low frequencies indicates the inhibition of the electrophysiological activities of cell populations, the inhibition level of maize seedling in different varieties are also different.To illustrate the biological significance of the characteristics parameters of the potential fluctuations and the luminescence on leaf surfaces, the changes of the fresh weight, contents of MDA and chlorophyll content in the leaves were also investigated and compared in this study. The result found that, under the osmotic stress the fresh weight and chlorophyll content in the leaves were decreased, while the contents of MDA increased significantly, showed that osmotic stress affected the normal growth of maize seedling, and caused increased MDA content and decreased chlorophyll content, maybe this is the reason of luminescence decreased and the migration of SEF and SCF to low frequencies. This indicated that the changes of luminescence and potential fluctuations could be used for the real-time in-situ monitoring and non-destructive evaluation of the stress tolerance.Recently, biological effect of extremely low frequency pulsed electric field?ELF-PEF? draws great attention, it may provide a new technology for physical agriculture. Accordingly, as the expansion of research, the effect of ELF-PEF on maize seedling leaves under osmotic stress also be studied in this paper, based on the feasibility of plant luminescence evaluate the effect of ELF-PEF on maize seedling leaves under osmotic stress quantitatively and quickly, the result can provide the reference to the development of physical agriculture and its optical nondestructive testing technology.