Response Of Aloe Vera L. To Salt Stress And The Alleviative Effect Of Exogenous Silicon On Salt Injury

Aloe, a typical xerophyte, is of important value in medicine and therapeutics, cosmetics, food industry, landscape and ornamental horticulture. According to biological characteristics, aloe belongs to a glycophyte rather than a halophyte. So far, available information on response of aloe to salt stress is little. In this dissertation, salt tolerance of Aloe vera L. and its relationship with exogenous silicon (Si) were studied so as to supply science theory and technique basis in aloe cultivation in saline soil or inigated with brine or weakly brine water.The experimental results of seven-leaf old A. vera cultured in sand for 120 d showed that growth of aloe was closely correlated with salt concentration in irrigated solution. The treatment of 200 mmol/L NaCl significantly retarded growth of aloe, reduced length, width, thickness, weight, water content, and chlorophyll content of its leaves, perimeter of the root system, dense radical zone, biomass of different organs and a single plant, and increased the number of withered leaves, which were even more remarkable when sodium chloride concentration reached to 400 mmol/L. However, the negative effects of salt stress on aloe growth were not very marked when sodium chloride concentration was less than 100 mmol/L as was compared with control, no NaCl added into irrigated solution, especially when the concentration of NaCl was 50 mmol/L. The effects of salt stresses between 50 and 100 mmol/L NaCl treatments on physical- chemical properties of aloe leaf juice, such as rate of leaf juice, soluble solids content, rotation viscosity, relative density, absorbance, electrical conductivity, pH value, ash percentage, total carbohydrate concentration and polysaccharide concentration were not significant. Both of the treatments produced active effects on physical-chemical properties. The external salt concentration that does not inhibite aloe growth is between 50-100 mmol/L NaCl. Based on these results, considering absorption of salt by soils, washing of rain and snow, and effect of ground water, A. vera is suitable to be irrigated with brine or weakly brine water.