Studies Of Exogenous Betaine On The Adversity Physiological Characteristic And Nitrogen Metabolism Of Pinellia Ternate Under Drought Stress

In this study, the pinellia was used as materials which were grouped as the control group (CK, moisture content of75%±2), drought group (D, moisture content of35%±2), drought group20(D20,20mmol·L-1betaine) and drought group40(D40,40mmol·L-1betaine). All groups were sprayed different concentration of solution. Through the differently experimental treatments, the effects of the physiological indexes, photo synthetic indicators, the enzyme activity of nitrogen metabolism, total alkaloids, guanosine and adenosine on the pinellia under drought stress were studied. The goals were to reduce the drought stress on the growth progress of pinellia, which increased the pinellia drought resistance. And to discuss the secondary metabolic regulation mechanisms of the pinellia which were withstanding drought stress. That might provide theoretical basis for the actual production to reduce the drought damage.Main conclusions are as follows:1. The physiological indicators of the pinellia under drought stress, such as the conductivity, osmotic adjustment substance content, peroxidization of cytomembrane and antioxidant enzyme activity were increased. Compared with the D group, there were some significant differences on the above indicators in the D(20) and D(40) group,(a) Although the conductivity of the D, D(20) and D(40) group was increased quickly with the time, the conductivity value of the D(20) and D(40) group was below the D group. As a result, the exogenous betaine could effectively reduce leakage of the electrolyte solution and maintain the osmotic pressure and cellular morphology. The phenomenon in the D(40) group was obvious which the betaine solution concentration was40mmol·L-1.(b) With the extension of treatment time, the proline and soluble sugar content in all groups was increased. But the proline content in the D group was below the D(20) and D (40) group. The soluble sugar content in the D (40) group was highest, and the the D group was lowest. The soluble sugar content in the D, D (20) and D(40) group reached peak in the first27d.(c) The O2-content in the D, D (20) and D (40) group increased fast, which reached peak in the first27d. The O2-content in the D group was highest. The MDA content is positively correlated with the O2-content, which the D group was highest.(d) The SOD activity in all groups was increased, which reached peak in the first27d. The POD and CAT activity were increased firstly and then decreased in the first18d. The enzymes activity in groups with spraying exogenous betaine were higher the groups without spraying exogenous betaine.2. Exogenous betaine in the the pinellia under drought stress improved the chlorophyll a, chlorophyll b, total chlorophyll and carotenoid content. With the drought time increasing, the fluorescence parameters Fo, qN were increased, but the Fv/Fm, qP were declined. And the ETR and Yield were increased firstly and then decreased. Under the drought stress, the Fo in D, D (20) and D(40) group was increased, which were higher than CK group. But the the Fo in creasement amplitude in D(20) and D(40) group was less than D group. The Fv/Fm and qP were decreased throughout the drought stress, which were significantly lower than CK group. But the Fv/Fm and qP in D (20) and D(40) group were higher than D group. The ETR and Yield were increased firstly and then decreased, which the groups with drought treatment were lower than CK group, but the D(20) and D(40) group were higher than the D group. That indicated the drought stress could affect the proportion of the PS II photoelectron energy to the light energy absorption. It was likely to induce the excess energy accumulation and hinder the electron transfer. The40mmol·L-1betaine solution concentration in the D(40) could ease this damage to some extent. However, with the time increasing, the photosynthetic apparatus could be damaged so severely that the effect of the betaine gradually became unconspicuous.3. With the drought stress time increasing, the GOG AT and GS activity in the D(40) group were decreased, which were lower than the D and D(20) group. The GDH activity increased firstly and then decreased, but the CK group did not change significantly. Compared to the D(20) group, the total alkaloid content in D(40) group increased by6.3%,10.3%,12.3%in the first9-27d.As the time increasing, the adenosine and guanosine contents were increased, but the adenosine tended to decrease during the first27d. Which the CK group were highest, while the the D(40) group were higher than the D(20) group.Compared to the D and D(20) group, the soluble protein content in D(40) group increased by7.3%,3.1%in the first27d. Which showed the40mmol·L-1exogenous betaine solution could improve the enzymes activity of nitrogen metabolism under the drought stress. It could accelerate the inorganic nitrogen to assimilate, which might promote the secondary metabolites accumulation and improve the capacity of the pinellia against the droughts stress.