Effects Of Drought Stress On Growth And Physiological Characteristics And Stem Thorns Development Of Lycium Ruthenicum

In this research,the tissue culture plantlets of Lycium ruthenicum used as experimental materials,these indexes include plant height,occurrence of stem thorns,net photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductance(Gs),intercellular CO2 concentration(Ci),chlorophyll,proline,soluble sugar,soluble protein,MDA,SOD of Lycium ruthenicum were studied by the method of pot trial under different soil water conditions with time change,and the anatomical changes of stem thorns in different developmental stages of Lycium ruthenicum were observed by the method of paraffin sectioning.The objective of the study is to explore the physiological and structural basis of drought resistance of Lycium ruthenicum and provide scientific basis for cultivation of Lycium ruthenicum with less or no stem thorns.The main results are as follows:1.In the tissue culture process of Lycium ruthenicum,the stem explants grew well and the highest survival rate was 82.22% when they were sterilized with 75% alcohol for 30 s and 0.1% Hg Cl2 for 5 min.In the multiplication culture of Lycium ruthenicum,the difference of different sucrose concentrations treatment on the multiplication of stem segments was extremely significant.The propagation coefficient of stem segments was 12.8 when the sucrose concentration was 40 g/L in MS medium.In the rooting culture of stem segments of Lycium ruthenicum,the rooting effect of stem segments is the best in 1/2 MS medium,which rooting rate is 93.5%,average rooting number is 10.8,average rooting length is 11.82 cm,and the earliest rooting time is on the 5th day.2.With the increases in drought stress,the plant height of Lycium ruthenicum were restrained clearly.Under 100% and 80% of the field water-holding capacity(WHC)conditions,the stem of Lycium ruthenicum had not produced stem thorns.While under 60% and 40% of the WHC conditions,the stem thorns appeared.3.With the increases in drought stress,the net photosynthetic rate,transpiration rate,stomatal conductance and chlorophyll content of leaves of Lycium ruthenium showed a decreased trend,while the intercellular CO2 concentration showed an upward trend,and the difference of every index reached significant level under the different field water-holding capacity(WHC)conditions.4.With the increases in drought stress,the soluble protein content,soluble sugar content,MDA content of Lycium ruthenicum leaves showed an increasing trend at different treatment time.The proline content also rised on the 15 th,30th and 45 th day with the increases in drought stress,while on the 60 th day,the proline content was highest under 60% WHC condition.SOD activity of Lycium ruthenicum leaves significantly increased with the increases of drought stress on the 15 th and 30 th days of treatment and SOD activity were highest under 60% WHC conditions on the 45 th and 60 th day.These results revealed the physiological regulation mechanism of osmotic regulatory substances and active enzymes in Lycium ruthenicum.5.With the increases in drought stress,the thorns grew on the stems of Lycium ruthenicum,and the hardness of the stem thorns changed from soft to hard.The anatomical structures of thorns at different stages of development were observed by the method of paraffin sectioning and the results showed that the stem thorns structure was similar to the main stem structure and there were still hidden buds in the axil after stem thorns appeared.