| Lilium longiflorum,as an important economic crop with the same origin of medicine and food,has serious problems of continuous cropping.At present,it has been shown that the disturbance of continuous cropping is caused by the change of soil microbial population structure,deterioration of soil physical and chemical properties,aggravation of plant diseases and insect pests and allelopathic autotoxicity.In this paper,the allelopathic autotoxicity of Lilium longiflorum was verified,the isolation and identification of allelopathic autotoxic substances of Lilium longiflorum and the activity and mechanism of allelopathic autotoxic substances of Lilium longiflorum were studied in view of the disturbance of continuous cropping of Lilium longiflorum.In order to find out the allelopathic autotoxicity is one of the reasons for the continuous cropping obstacle of Lilium longiflorum.Effective relief of Lilium longiflorum continuous cropping obstacles to provide theoretical and practical basis.The contents and results of the study are as follows:The main results are as follows:(1)study on the allelopathic autotoxic effect of Lilium longiflorumThe seedlings of Lilium longiflorum were cultured for 20 days with the new nutrient soil without any crops and the soil for 2 years as the control5:0(control),4:1?3:2?2:3?1:4and 0:5,respectively,in proportion of 5:0(control),4:1?3:2?2:3?1:4 and 0:5,and the results showed that the seedlings of Lilium longiflorum were cultured in vitro for 20 days.With the increase of soil ratio,the chlorophyll(SPDA)content of Lilium longiflorum seedlings decreased gradually,the chlorophyll contents were 30.63,33.37,26,22.23,19.27 and 13.7,respectively,and the content of chlorophyll was 30.63,33.37,26,22.23,19.27 and13.7,respectively.The seedling height decreased gradually with the increase of the soil ratio of continuous cropping,and the seedling height were 5.90,8.60,4 respectively.The root length became shorter with the increase of soil ratio,the root length was 2.53,4.17,2.23,1.87,1.73 and 0.8 cm,respectively,and the root length was 0.74 cm,3.90 cm and 3.07 cm,and the root length was 2.53,4.17,2.23,1.73 and 0.8 cm respectively.The root length of Lilium longiflorum seedlings decreased with the increase of soil ratio,which showed thatroot growth was poor and even root necrosis occurred.The longest root length could reach4.17 cm,and the root length of Lilium longiflorum seedlings decreased with the increase of soil ratio.The chlorophyll(SPDA)content of Lilium longiflorum tissue culture seedlings decreased with the increase of soil ratio,the highest content was 33.37,the lowest content was 13.7..The results showed that there were some substances in the soil which could inhibit the growth of Lilium longiflorum,which could inhibit the growth of Lilium longiflorum,decrease the chlorophyll content of Lilium longiflorum,slow the growth of seedlings and stunted the root system of Lilium longiflorum.And with the increase of soil proportion of continuous cropping,the more the growth substance of Lilium longiflorum was,the more obvious the inhibition effect was.In addition,the soil of Lilium longiflorum under continuous cropping had the effect of promoting plant growth when the content of soil was low.The plantlets of Lilium longiflorum were cultured in nutrient solution for 10 days,20 days and 30 days.The effects of nutrient solution containing root exudates on the growth of cucumber,Chinese cabbage,rice,radish and hollow cabbage were studied.The results showed that with the increase of the water culture time of Lilium longiflorum,the germination inhibition rate of the five tested seeds also increased,and the inhibition rate of the root exudates of the lily root exudates cultured for 30 days was the highest(59.29%).The root exudates of Lilium longiflorum had obvious inhibitory effect on root growth,and the stronger the inhibition effect was with the increase of water culture time of Lilium longiflorum.The root exudates of Lilium longiflorum cultured for 30 days had the highest inhibition rate on the root length of rice(93.6%).The root secretion of Lilium longiflorum also had a certain effect on stem growth,and the inhibition rate of stem length increased with the increase of water culture time.The root exudates of Lilium longiflorum cultured for 30 days had the highest inhibition rate on stem length of cucumber and cabbage.It reached73.15%.The results showed that there were allelopathic autotoxic substances in the root exudates of Lilium longiflorum which inhibited the growth of plants.(2)isolation and identification of allelopathic autotoxic substances from Lilium longiflorumThe culture medium containing root exudates of Lilium longiflorum was collected and obtained for 30 days.Three organic solvents,trichloromethane,acetone and ethyl acetate,were used to extract the root exudates of Lilium longiflorum and acidic alumina,respectively.The root exudates of Lilium longiflorum were separated by neutral alumina and XAD4 ion exchange macroporous adsorption resin column.The samples obtained by the above six methods were identified by GC-MS/MS(GC / MS).Three kinds of compounds were obtained,one of which was phthalate esters(25 kinds).One is phenolic acids,a total of 6;the other is amides,common One species was identified as N,N-diethyl-dimethylbenzamide by comparing the structure of the reference material in the library.It has been reported that phthalates and phenolic acids are common allelopathic autotoxic substances,but there are no reports that N,N-diethyl-dimethylbenzamide has allelopathic autotoxicity.(3)Bioassay of allelopathic autotoxicity of N,N-diethyl-dimethylbenzoamideBuy N,N-diethyl-dimethylbenzoamide standard,diluted to 0.125,0.25,0.5,1,2 and4mmol/L respectively.The results showed that(N,N-diethyl-dimethylbenzoamide)treated with N,N-diethyl-dimethylbenzamide(N-diethyl-dimethylbenzamide),the germination rate of Allium scallium seeds decreased with the increase of concentration.At the low concentration of 0.125mmol/L,the germination rate of the tested seeds was the highest,which was 9.7.87%,at high concentration of 4mmol/L,the germination rate of tested seeds was 25.55%.(N,N-diethyl-dimethylbenzoamide-treated plant root protective enzyme superoxide dismutase(SOD),The activity of catalase(CAT)increased first and then decreased with the increase of N,N-diethyl-dimethylbenzoamide concentration.On the contrary,with the increase of N,N-diethyl-dimethylbenzoamide concentration,the peroxidase(POD)decreased first and then increased,and the malondialdehyde(MDA)content increased with N,N-diethyl-dimethylbenzoamide concentration.The increase of degree showed a trend of gradual increase.The results showed that N,N-diethyl-dimethylbenzoamide had allelotoxic activity,which could not only inhibit the sprouting of seeds,but also decrease the activity of protective enzymes in plant roots and increase the content of malondialdehyde(MDA).(4)the mechanism of action of N,N-diethyl-dimethylbenzamide1,2 and 3mmol/L solutions were prepared with N,N-diethyl-dimethylbenzamide(N,N-diethyl-dimethylbenzoamide)as control treatment(containing 0.2% methanol)in deionized water.The root tip of Lilium longiflorum was cultured in water and cultured for 5days.The root tip of Lilium longiflorum was observed by transmission electron microscopy(TEM)and the root tip of Lilium longiflorum was stained with crimson and green.The results showed that compared with the control,N-diethyl-dimethylbenzoamide(N-diethyl-dimethylbenzoamide)-treated plant root tip cells showed an increase in vacuole volume,cytoplasm concentration,nuclear shrinkage,cell wall thickening,and cell genesis in the root tip of plants treated with N-diethyl-dimethylbenzoamide.Severe deformation,eventually,the cell wall degrades,the cell forms a cavity.The effect of N,N-diethyl-dimethylbenzoamide on the structure of root tip cells was more serious with the increase of concentration. |
PDF Full Text Request