Allelopathic Effects Of Camptotheca Acuminata Alkaloids On 8herbaceous Ornamental Plants

Allelopathy is of great significance to the ecological configuration of plants.The ecological adaptability of herbaceous plants cultivated under the forest is of high application value.This study uses indoor petri dish experiments and greenhouse pot experiments to studies on the synergistic effect of camptothecin and its natural derivative 10-hydroxycamptothecin,on 8 common herbaceous ornamental plants Salvia splendens,Oxalis corymbose,Mirabilis jalapa,etc.By studying the germination rate,germination index,relative leaf conductivity,chlorophyll content,peroxidase?POD?,superoxide dismutase?SOD?,catalase?CAT?,and malondialdehyde?MDA?,Changes in proline?Pro?,soluble protein?SP?,light response curve,photosynthetic gas exchange parameters and chlorophyll fluorescence parameters changes,The effect of camptothecin alkaloids on the allelopathic effects of 8 plants was analyzed.The findings are as follows:?1?With the increase of the doses of camptothecin?CPT?and 10-hydroxycamptothecin?HCPT?,the inhibition of seed germination of 8 kinds of plants increased.Under the treatment conditions of 20 mg·L^-1 and 40 mg·L^-1,the germination rate and germination index of 8 plants were significantly reduced?P <0.05?.The sensitivity of allelopathic substances to the allelopathic effects of 8 plants is as follows: Salvia splendens > Oxalis corymbose > Mirabilis jalapa > Trifolium repens > Viola tricolor > Iris tectorum > Farfugium japonicum > Ophiopogon japonicus.The results of plant root hair observation showed that the density of root hairs of eight plants decreased and rotten.?2?Under the synergistic effect of CPT and HCPT,the relative electrical conductivity and MDA content of the leaves of the eight plants increased significantly,indicating that after allelopathy,the plant cells were damaged and the cell electrolyte extravasated,increasing the cell membrane permeability.The plant itself activates the active oxygen system and the osmotic system,which is adjusted by increasing the activities of SOD,POD and CAT,but the resistance of the plant itself to stress is limited.The content of SOD,POD and CAT decreased to varying degrees.?3?Under the synergistic effect of CPT and HCPT,the light response characteristic parameters AQY,R_d,LSP,LCP and P_nmax values of 8 plants basically showed significant differences?P<0.05?,but the impact of Farfugium japonicum and Ophiopogon japonicus was compared Small,Salvia splendens,Mirabilis jalapa,Trifolium repens,Oxalis corymbosa,Viola tricolor and Iris tectorum are more affected,therefore,in the garden configuration,it is not considered to plant the latter 6 plants with camptotheca or Plant at a certain distance.?4?Under the synergistic effect of CPT and HCPT,the P_n values of the eight experimental plants showed a downward trend,which was basically consistent with the change trend of G_s and T_r.The C_i value and the L_s value showed the opposite trend,and the L_s value did not change in the later stage of allelopathy Obviously,it indicates that the plants in the early stage of allelopathy may regulate the allelopathy by closing the stomata.After the allelopathy is strengthened in the later stage,the plant growth is weak and the physiological regulation is slow.The changes in VPD and WUE values indicate that the plants can autonomously adjust the water use efficiency under the allelopathy and improve their adaptability to allelopathy conditions.?5?Both F_v/F_m and F_v/F_o can reflect the ability of the optical system to utilize light energy.In this study,the changes of F_v?/F_m?,F_v/F_m,and F_v/F_o reflect that 8 plants have been subjected to different degrees under adversity Photoinhibition,but has relatively little effect on Ophiopogon japonicus and Farfugium japonicum.In addition,the NPQ of Farfugium japonicum and Ophiopogon japonicus was significantly increased,and the ETR also maintained at a high level,and the change of q P was not obvious,indicating that Farfugium japonicum and Ophiopogon japonicus may be carried out by heat dissipation under light inhibition.Self-protection.The experimental detection index again shows that the allelopathy effect of Farfugium japonicum and Ophiopogon japonicus is relatively small,and it can be considered to be planted under the Camptotheca acuminate forest.