Background : The chlorophyll fluorescence imaging as non-destructive imaging methods have been used widely for efficiently early detection of plant responses to various stresses. The information from images acquired from different condition has the potential to generate specific signatures for particular stresses. Light-energy absorbed by plants is distributed over three competing processes: photosynthesis, thermal dissipation and chlorophyll fluorescence emission. An increase in Chl-FI thus implies a decrease in photosynthesis. The stresses in growing stage will change the efficacy of photosynthesis. As a example, Chl-FI of plant infections was carried out previously for a number of different viral and fungal plant–pathogen systems. Therefore, image can be used for differentiation of various stress index. Methods and results : 2-years-old ginseng plants were transplanted to plastic pots and each stress factors were treated. The stress factors used in this study were high temperature, low temperature, fungicide, and fungal pathogen. High temperature stress was induced by placing pots inside incubator adjusted at 35℃. For treatment of low temperature stress, ginseng plants were stored at 5℃ refrigerator for 5 minutes. Pathogen stress was carried to inoculate mycelial disk. Alternaria panax was inoculated potato-dextrose-medium and cultured for 10 days at 25℃. Mycelial disk obtained from cultured plate were placed on the one leaf of ginseng. Azoxystrobin wp was diluted 500, 1,000 times in tap water and sprayed to ginseng plants. Chlorophyll fluorescence image was acquired from each plant that stress treated and analyzed with sigma plot software. Conclusion : Important value, Fv/Fm (maximum efficiency of photosystem II), Fp (peak fluorescence during the initial phase of the operating efficiency of the Kautsky effect), NPQ-lss (steady-state, non-photochemical), etc., were significantly changed by variable stress index. But it was impossible to differentiate kind of stress by acquired value.

The objective of this study was to find a rapid determination of the hot air stress in maize (Zea mays L.) leaves using a portable chlorophyll fluorescence imaging instrument. To assess the photosynthetic activity of maize leaves, an imaging analysis of the photochemical responses of maize was performed with chlorophyll fluorescence camera. The observed chlorophyll imaging photos were numerically transformed to the photochemical parameters on the basis of chlorophyll a fluorescence. Chlorophyll a fluorescence imaging (CFI) method showed that a rapid decrease in maximum fluorescence intensity (Fm) of leaf occurred under hot air stress. Although no change was observed in the maximum quantum yield (Fv/Fm) of the hot air stressed maize leaves, the other photochemical parameters such as maximum fluorescence intensity (Fm) and Maximum fluorescence value (Fp) were relatively lowered after hot air stress. In hot air stressed maize leaves, an increase was observed in the nonphotoquenching (NPQ) and decrease in the effective quantum yield of photochemical energy conversion in photosystem II (Φ PSII). Thus, NPQ and ΦPSII were available to be determined non-destructively in maize leaves under hot air stress. Our results clearly indicated that the hot air could be a source of stress in maize leaves. Thus, the CFI analysis along with its related parameters can be used as a rapid indicating technique for the determining hot air stress in plants.