A Study On The Physiological Response Of Arachis Duranensis Under Low Temperature Stress

Arachis duranensis Krap.et Greg or A.duranensis, papilionideae giseke, leguminasae, belonging to the perennial herbaceous plant, is originated from Tropical Asia and the South America. It has obovate leaf and vine stem. The flower, golden and butterfly shaped, blossoms from spring to autumn. Plant high is mainly about 10～15 cm. The plant also serves as excellent herbage or green manure, even as the plant preventing soil erosion. Arachis duranensis is also a perfect landscape greening material because of its beautiful shape. At present, the Arachis duranensis has been widely used in ecological management and landscaping. This species has worked as greening material in Fujian, Guangdong, Hainan provinces and achieved a good result. After years of screening and ecological adaptability study it has confirmed that Arachis duranensis has higher adaptability, application value, ecological and social benefits, and landscape efficiency in tropical and subtropical regions. Because of Arachis duranensis's original habitat, the temperature becomes its limiting factor of introduction and domestication, as well as planting. This experiment directs at verifying the physiological alteration rule under low temperature stress through measuring its physiological index under low temperature stress and the index with certain artificial measures.By examining and analysing the physiological indicators of Arachis duranensis, it is found that under the natural and artificial low temperature stress, the soluble sugar content, soluble protein content, the activities of SOD and POD, MDA content, chlorophyll content and the RPP have changed as the temperature decreased. These changes display correlations. By comparative analysis, it is found that Arachis duranensis removes excess oxygen free radical by increasing the activities of SOD and POD to adapt to the low temperature. But when temperature drops to a certain degree, activities of SOD and POD decrease thereupon. The excess oxygen free radical can not be removed, resulting in inadaptability to the low temperature. In addition, soluble sugar content of Arachis duranensis leaves were firstly decreased and later increased, indicating that with the drop of temperature, the soluble sugar in Arachis duranensis is converted into other substances, and later accumulated into sugar again. All these show that Arachis duranensis has good adaptability within a certain temperature range, or it doesn't work well or even suffers from cold or freezing damage.The result of correlation analysis shows that the activities of SOD and POD, the soluble protein content, MDA content, and the RPP of Arachis duranensis leaves are closely related to each other under low temperature stress. The SOD, POD, the soluble protein in Arachis duranensis have synergistic effect in controlling MDA content and adjusting relative penetrability of Arachis duranensis cell protoplasmic membrane, thus affecting the Arachis duranensis on the capacity to adapt to low temperature stress. These are all important physiological factors to measure the adaptability of Arachis duranensis to low temperature.The result also shows that spraying Arachis duranensis leaves with 0.1g/kg～0.9g/kg PP₃₃₃or1.0g/kg～9.0g/kg KH₂PO₄ can enhance the soluble sugar content, POD, the soluble protein content, the chlorophyll content, while reducing the MDA content, the RPP of Arachis duranensis, which can reduce the effect of low temperature on the physiological index of the Arachis duranensis. By the Fuzzy subordination function analysis, the processing method of 0.3g/kg PP₃₃₃ and 5g/kg KH₂PO₄ has the best effect.