Preliminary Studies On Drought-resistance Characteristics Of Glycyrrhiza Uralensis

Glycyrrhiza uralensis Fisch., with high value of medicine and high ecological protection function, is belongs to the second degree protective plants in our country. In order to breed and cultivate new species of G.uralensis with the characteristic of water-saved and high medicine value, to fit drought condition in West of China, its drought resistance was Studied. The seedlings, which were two-year-old and planted in pots, were treated with different water stress by means of weighing and watering in the afternoon every day. Its response index to drought stress, including form, growth, photosynthesis, water status change, membrane lipid peroxidation and osmotic matter content, are shown as below.(1) In the response of form and growth, it is discovered that G. uralensis has the characteristic of adapting drought conditions on the ground and under ground. There were so huge roots and rhizome system under ground that they could absorb water from deep soil; Stems and leaves on ground could decrease water loss. The huge biomes of G.uralensis had strong drought resistance superiority. In the same time, drought stress significantly restrained the growth of G.uralensis. On the contrary, in some extent, drought stress could improve the growth of roots under ground and resulted in increasing the rate of root/shoot; moreover, made the color of velamen become red and enhanced the output and the quality.(2) In the response of photosynthesis, when the relative water content (RWC) of soil dropped to 40%~50%, the stomatal conductance of G.uralensis enlarged, the net-photosynthesis rate and the water use efficiency reach the top; but with RWC of soil further decreasing, the fluorescence dynamics curve changed obviously so as to affect seriously the performance of photosynthesis in the leaves of G.uralensis.(3) In water status change, with the water stress increasing, leaves water potential and relative water content of tissue in G.uralensis decreased; the water loss rate decreased; the tissue density increased; bound water content enhanced; which made the ability of cell absorbing and saving water increased gradually so as to maintain turgor by powerful tissue elasticity.(4) In the membrane lipid peroxidation and osmotic matter content, under the condition of drought stress, the relative membranes permeability of the leaves in the G.uralensis increased; the membrane lipid peroxidation effect enhanced. However, because the activity of SOD could maintain a high level in a long time, it reduced the4 9membranes lipid peroxidation so as to lessen the harm to the membranes. In addition, under the condition of drought stress, the continuous rise of the content of fusibility total sugar and proline increased the osmotic adjustment ability.Through comprehensive analysis,, the results showed the range of 45%~50% relative water content of soil was the best condition to suit the growth of G.uralensis, which benefited to cultivate the artificial resources of high production and high medicine value, recovered wild area of G.uralensis plant. In the same time, the results also demonstrated G. uralensis was active to the response of drought stress with multiple ways of drought resistances.