Responses Of Ramie Seedlings To Low Potassium Stress In Morphological And Physiological

Ramie is endemic to China bast fiber crops, has an important significance in the national economy. Potassium is one of ramie absorb most nutrients, the role of ramie for after nitrogen. China generally cultivated soil lack of potassium, and china is short of K fertilizer resources. The situation that the supply of K fertilizer does not meet the demand becomes increasingly serious. In order to alleviate this situation, breeding potassium efficient, low potassium resistant varieties become a trend.In order to explore morphological and physiological responses of ramie seedlings to low potassium stress, the hydroponic culture was carried out to investigate the differences of morphological and physiological characteristics between the treatment of normal K supply and three treatments of low K supplies. The four K levels settled were 0 mmol L-1, 0.25 mmol L-1, 0.5 mmol L-1 and 3 mmol L-1(normal), respectively. The experiment treatment time are 15 d and 30 d, respectively. The old and new leaves of ramie seedlings should be carried out physiological characteristics analysis.The major results obtained were summarized as follows.1.The low K supplies significantly decreased the plant height, number of green leaves, leaf size and the dry matter yield of the root, stem, leaf and whole plant.2. The root activity of ramie seedling gradually decreased in all treatments of low K supplies, the low K supply of 0 mmol L-1 significantly decreased the root activity of ramie seedling.3. Treatment for 30 days, the contents of chlorophyll a and chlorophyll b in the old leaves of ramie seedling were significantly decreased in the low K supply of 0 mmol L-1; the low K supplies decreased the contents of chlorophyll a and chlorophyll b in the new leaves of ramie seedling, and they were significantly different between the treatments of low K(below 0.25 mmol L-1) supplies and the treatment of the normal K supply.4. Treatment for 30 days, the soluble sugar contents(SSC) in the old leaves of ramie seedling were significantly increased in the low K supply of 0 mmol L-1, all treatments of low K supplies decreased SSC in the new leaves of ramie seedling, and SSC were significantly different between the low K(below 0.25 mmol L-1) supplies and the normal K supply. The low K supply of 0 mmol L-1 significantly decreased the soluble protein contents in the new leaves of ramie seedling. The low K supplies increased the Pro contents, and the Pro contents were significantly increased in the low K supply of 0 mmol L-1.5. The low K supplies having not significantly effects on the MDA contents. Treatment for 30 days, the low K supply of 0 mmol L-1 significantly increased the cell membrane permeability in the new leaves of ramie seedling. Under low K stress, the activities of superoxide dismutase(SOD) and peroxidase(POD) in the old leaves of ramie seedling were significantly increased, and treatment for 15 days, the activities of catalase(CAT) significantly increasing, too. Treatment for 30 days, the low K supplies significantly increased the activities of SOD in the new leaves of ramie seedling, but the activities of CAT being significantly decreased.6. Under low K stress, the K contents and accumulations in the root, stem and leaf of ramie seedling were significantly decreased, but the K utilization efficiencies being significantly increased. Moreover, the accumulations of nitrogen in all ramie seedling organs and the accumulations of phosphorus in the root and leaf were gradually decreased in all treatments of low K supplies.