Establishment of the Method for Oxygen Concentration Measurement in Rice Caryopsis during Grain-Filling Stage
Date Issued
2015
Date
2015
Author(s)
Yen, Jen-Hsiang
Abstract
Rice chalky grain formation under high temperature is known to be related to the metabolic alteration under stress. Internal oxygen concentration is crucial for maintaining energy balance for starch, protein, and lipid assimilations during rice grain development. Documents revealed that hypoxia metabolism may occur in developing endosperm under high temperature. Therefore, it has hypothesized that internal oxygen level might be correlated with the chalkiness formation of rice grain under high temperature. However, no method for measuring internal oxygen concentration in rice grain has been developed in the world so far. Thus, the aim of the present study was to establish possible methods for measuring oxygen level in developing rice grain, and hope to clarify the relationship between oxygen concentration and grain chalkiness formation under high temperature. A high quality cultivar Tai-keng 9 (TK 9) was used as material which were exposed to high temperature (35 oC) or control temperature (25 oC) treatment during the grain-filling stage . Caryopsis samples were collected at different development stages base on the cumulative temperature after flowering. In this research, a planar oxygen sensor (PreSens, Germany) was used to measure internal oxygen of caryopsis and an oxygen microsensor (PreSens, Germany) was used to verify the value of oxygen concentration. The results showed that oxygen concentration of caryopsis decreased from external to internal at every grain-filling stage, that is, it is hypoxia at central endosperm. At the same time, caryopsis oxygen concentration under high temperature seemed to be lower than the control, although it didn’t show statistically significant difference. Due to the high time consuming for the oxygen measurement of rice caryopsis, the number of experimental replicate was very much limited; which would lead a large measurement variation at the present study. In summary, the present study has established the method of measuring internal oxygen concentration in developing rice caryopsis, and showed the preliminary results about the change of oxygen concentration at different stages. In the future, the method can be modified and improved to understand the relationship among internal oxygen level, metabolism process, and grain quality formation, especially under stressful environments.
Subjects
high temperature
rice quality
hypoxia
rice grain-filling
oxygen sensor
Type
thesis
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