The Germination Mechanisms Of P. Aegyptiaca Seeds Stimulated By Two Growth Regulators And Preliminary Study On Control Effect To P. Aegyptiaca

Objective:The purpose of this study was to find out the effective and stable substances that can stimulate the germination of P.aegyptiaca seeds,meanwhile,the germination mechanisms of P.aegyptiaca seeds stimulated by different inhibitors were analyzed by transcriptome,and the effect of suicide germination prevention and treatment was explored by pot experiment.Finally,the final goal of this study was to provide a basis for the prevention and control of the weed by adopting the method of"suicide germination."Method:The modified petri dish method was used to study the germination of P.aegyptiaca seeds.Through different concentrations of strigolactone biosynthesis inhibitor TIS108 and different concentrations of plant hormones,inorganic salts and different concentrations of fluridone mixed preparation to stimulate P.aegyptiaca seeds germination,respectively.The effects of environmental factors such as temperature,humidity and pH on the germination of P.aegyptiaca seeds were studied.After orthogonal test,the germination conditions of P.aegyptiaca seeds were optimized.Through the transcriptome analysis of P.aegyptiaca seeds germination mechanism stimulated by fluridone,TIS108 and GR24,more germination stimulating substances were obtained.Pot experiment was used to study the effect of using"suicide germination"method to prevent and control P.aegyptiaca.Results:1.Strigolactone biosynthesis inhibitor TIS108 used alone,fluridone mixed with gibberellic acid can stimulate the germination of P.aegyptiaca seeds,and have a high germination rate and good stability.The optimal concentration of TIS108 was 100 mg/L,the optimal temperature was 25?,the optimal humidity was 70%and the optimum pH was 5,under this condition,the germination rate of P.aegyptiaca seeds reached more than 79.42%.The optimal combination concentration of fluridone and gibberellic acid was 50mg/L+1000mg/L,the optimum temperature is 25?,the optimum humidity was 50%,and the optimum pH was 5,under this condition,the germination rate of P.aegyptiaca seeds reached more than 85.61%.Both inhibitors could be used as new germination stimulating substances,which can efficiently,stably and rapidly stimulate the germination of P.aegyptiaca so as to reduce the seed bank of P.aegyptiaca seeds,and then provide a support for the prevention and control of the weed by adopting the method of"suicide germination."2.A large number of differentially expressed genes were screened by TIS108,fluridone+gibberellic acid,GR24,conditioned and dormant P.aegyptiaca seeds transcriptome analysis.119 DEGs were screened between TIS108 and conditioned treatment and many of the DEGs were annotated to hormone-related.The common pathway of TIS108,FL+GA₃,and GR24 in stimulating P.aegyptiaca seed germination included decreasing ABA content and increasing GA content.Target sites for these hormones differed.Results also provide theoretical bases for identification of additional P.aegyptiaca germination stimulants.3.The results of Fluridone pot experiment showed that the combination of fluridone and gibberellic acid could cause different degrees of phytotoxicity to the host melon,which was mainly caused by the whitening of the newly formed leaves and finally inhibited the growth of melon plants until death.However,the phytotoxicity will gradually weaken with the extension of time.After 120 days,the phytotoxicity of fluridone completely disappeared;the host melon can grow and develop normally.After 45 days of growth in greenhouse,the results showed that there had almost no effect the seedling emergence rate,leaf number,stem diameter and root-crown ratio while they have a more significant impact on the plant height,parasitic rate and parasitic intensity.FL,50mg/L+GA₃,50mg/L and FL,50mg/L+GA₃,1000 mg/L had certain promotion effect on plant height.The plant height of FL,50mg/L+GA₃,50mg/L was 45.13 cm,significantly higher than the control 37.43 cm,while the other concentrations were not significantly different from the control.For the parasitism rate,the concentration of FL,50mg/L+GA₃,50mg/L treatment,compared with the control parasitic rate decreased by 62.50%,significantly lower than the control of the parasitism rate of 100%,while other concentrations of the following when the parasitism rate and no signifcant difference.For the parasitic intensity,compared with the control,the parasitic intensities of FL,50 mg/L+GA₃,50 mg/L and FL,50 mg/L+GA₃,1000 mg/L decreased12.30 and 10.30,respectively.Parasitic intensity of the control was 13.43,while that of FL,100mg/L+GA₃ 100mg/L was 12.14,which was not significantly different from the control.4.The results of diflufenican pot experiment showed that when the melon grows 1-2 true leaves and then applied the concentration of diflufenican and gibberellic acid,the plant will not have a significant impact on the melon.After applying different concentrations of fluridone and gibberellic acid for 45 days on 2-3 true leaves,there had almost no effect on the stem diameter and root-shoot ratio,while they have a more significant impact on the plant height,number of leaves,parasitic rate and parasitic strength.Among them,Di,1mg/L+GA₃,100mg/L,Di,10mg/L+GA₃,50mg/L and Di,50mg/L+GA₃,50 mg/L had a certain control effect on P.aegyptiaca and will not cause adverse effects,but also to promote plant height and leaf number.The best control was the concentration of Di,10mg/L+GA₃,50mg/L,compared with the control parasitic rate decreased by 83.33%,parasitic intensity decreased 2.94.When applying Di,100mg/L+GA₃,10 mg/L treatment,the parasitic rate and parasitic strength were not significantly different from those of the control.The results of pot experiment with different sowing time showed that when the concentration of diflufenican and gibberellic acid were applying at the same time after sowing,the parasitism rate,parasitic intensity and biomass of host melon were measured.Similarly,when applying the concentration of Di,10mg/L+GA₃,50 mg/L,the best effect of prevent and control on P.aegyptiaca was obtained.Compared to the control,the parasitic rate was reduced by 40%and the parasitic intensity was reduced by 13.20,there was a significant difference from the control.While the parasitism and parasitism under other concentrations did not show any significant difference from the control.