Statistical interferometric technique (SIT) is a highly sensitive, high speed non-contact, and non-destructive optical technique developed by our group capable of measuring instantaeoues sub-nanometer displacements. SIT applied to plant leaf elongation revealed nanometric intrinsic fluctuaitons (NIF) that are robust and sensitive to variations in the environment making NIF as a measure of healthiness of the plants. In this study, exogenous plant hormones, auxin (2,4-dichlorophenoxyacetic acid-2,4-D), and gibberellic acid (GA 3 ), along with an auxin transport inhibitor 2,3,5-triiodobenzoic acid-TIBA, that affect plant growth were used to investigate their effects on NIF. Rice (Oriza sativa) seedlings were used, and their roots were exposed to 1, 2, and 4 µM 2,4-D, and the auxin transport inhibitor, TIBA, of 10, and 20 µM for 22 h and GA 3 solution of different concentrations of 10, 40, and 100 µM for 5 h. Results showed significant increment in NIF for 1 µM and reduction for 4 µM 2,4-D while applicaiton of both 10, and 20 µM TIBA led to reduction in NIF. On the other hand, significant increment in NIF for 40 µM, and a significant reduction at a higher concentration of 100 µM for 5 hours of GA 3 were also observed in comparison to those of control. Our results indicate that NIF as revealed by SIT could show both the positive and negative effects depending on the concentration of exogenous hormones, and transport inhibitors. Results suggest that SIT could be a valuable tool being sensitive enough to speedily assess the effects of plant growth hormones.

Objective: The aim of this study is to demonstrate the potential of applying the contrast of the speckles obtained as noise in optical coherence tomography (OCT) images to monitor short term activity changes during foliar application of phytohormones to a plant leaf. Plant growth hormone, gibberellic acid (GA 3) was sprayed onto the leaf of Chinese chives and after 60 min, OCT images (1 frame: 512 × 2048 pixels) were recorded at ten frames per second for a few tens of seconds. Results: Contrast across the temporal axis was calculated for each pixel of the structural images and biospeckle OCT contrast images were obtained under the conditions of before and after application of GA 3 for different concentrations 0, 40, and 100 μM. Application of 40 μM GA 3 failed to show any differences in the OCT structural images. However, bOCT contrast image was clearly different. Changes were found to be statistically significant. Although the mechanism for the contrast difference is not clear, it can be said there is a large change across the temporal scale with the application of GA 3. Demonstration of OCT utilizing the speckle contrast is believed to have the potential as a promising tool in plant physiology.

The aim of this study is to demonstrate the potential of applying the contrast of the speckles obtained as noise in optical coherence tomography (OCT) images to monitor short term activity changes during foliar application of phytohormones to a plant. Plant growth hormone, gibberellic acid (GA 3 ) was sprayed onto the leaf of Chinese chives and after 60 minutes, OCT images (1frame:512x2048pixles) were recorded at 10 frames per second for a period of 60 seconds. Contrast across the temporal axis was calculated for each pixel of the structural images and biospeckle OCT contrast images were obtained under the condition of before and after application of GA3 for different concentrations 0, 40, and 100 mM. Application of 40 mM GA 3 failed to show any differences in the OCT structural images; however, bOCT contrast image was clearly different. Although the mechanism for the contrast difference is not clear, it can be said there is a large change across the temporal scale with the application of GA 3 . This could be due to the changes in the leaf surface structures. Demonstration of OCT utilizing the speckle contrast is believed to have the potential as a promising tool in plant physiology.