Studies on the Physiological Mechanisms of Salt Stress Tolerance in Djulis (Chenopodium formosanum Koidz)

• Main Authors: Hsueh, Yi-En, 薛貽恩
• Other Authors: Chao, Yun-Yang
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/j47p35

碩士 === 國立屏東科技大學 === 農園生產系所 === 106 === Abstract Student ID: M10411007 Title of Thesis: Studies on the Physiological Mechanisms of Salt Stress Tolerance in Djulis (Chenopodium formosanum Koidz) Total Page: 67 Name of Institute: Department of Plant Industry, NPUST Graduate Date: January 2018 Degree Conferred: Master Name of Student: Yi-En Hsueh Adviser: Yun-Yang Chao, Ph. D. The Contents of Abstract in This Thesis: Salinity is one of the major abiotic stresses. Sodium ion can cause plant osmotic stress, ion toxicity and oxidative stress. During recent time, climate change has led to rising sea levels and salinize the arable land in the coastal areas gradually and the crop yield has also been affected. Chenopodium quinoa Willd., which shows a remarkable tolerance to salt stress. However, the salt tolerance of Chenopodium formosanum Koidz., a relative genus of quinoa, remains unclear. Therefore, this thesis will studied on the physiological mechanisms of salt stress tolerance in Chenopodium formosanum Koidz. The growth of Djulis seedlings was treated with 400 mM NaCl for 5 days, and the survival rate, the plant height and dry weight decreased 45%, 9% and 36%, respectively. The results showed that 400 mM NaCl could be used as the critical salt concentration. Therefore, the physiological responses of Djulis at 400 mM NaCl treatment were further investigated. After treatment with 400 mM NaCl for 5 days, the total chlorophyll content and Malondialdehyde (MDA) contents of Djulis increased as the treatment days increased. Total chlorophyll decreased to 40%, while MDA content increased to 16%. In the content of reactive oxygen species (ROS), superoxide anion contents decreased as treatment days increased, but the content of hydrogen peroxide increased 1.5 times as much as that of the control on the fifth day of treatment. Hydrogen peroxide is one of the main ROS injury factor. The activity of APX, CAT, GR and SOD increased along with treatment days, and increased to 0.6 times, 0.4 times, 3.3 times and 0.9 times respectively on the fifth day of treatment. The ratio of antioxidants AsA and GSH also increased by 0.5 times and 6.8 times respectively. Forthermore, the content of proline also increased with the increase of treatment days, which was 3.7 times as much as that of the control on the fifth day. In the aspect of sodium and potassium contents, after treated with 400 mM NaCl for five days, sodium and potassium contents in shoot were 138.7 mg/kg and 27.8 mg/kg, increased by 5.3 times and 4 times respectively. Briefly, when Djulis grows under salt stress, we speculated that it can transfer sodium ions to salt bladders on leaves or stems to reduce ions toxicity, then enhance the osmoprotectant such as potassium ion and proline contents. To regulate the osmotic potential under high salt concentration, it further elevate their antioxidant capacity, so that it is able to eliminate free radicals and diminish the damage caused by salt stress. Key words：Djulis, Salt tolerance mechanism, Osmotic regulation, Antioxidant capacity, Na+/K+ content