Induced Soybean Resistance To The Parasitic Weed Dodder

Soybean is an important food, oil and forage crops. It is affected by many biotic and abiotic factors during production, in which a vicious stem parasitic weed is widely distributed and harmed to soybean increasing year after year and difficult to control. It has become a major biotic limiting factor on soybean production. Induced resistance of plants has been applied to control not only pest and disease, but also parasitic weed. Screening high efficient inducers to enhance soybean natural immunity for against parasitic plant would beneficial to the development of parasitic weed control strategy. This study is of important academic and practical significance for comprehensive control system of disease.In this experiment, the best elicitor of BTH (acibenzolar) was screened from BTH, PHDC (prohexadione-Ca), BABA (β-amino-n-butyric acid) and SA (salicylic acid) elicitors with high susceptibility variety of soybean (Yue-chun No.2) in pot trials. The biochemical mechanism of BTH inducing resistance against the parasite was determined. It aims to provide a new approach to control Cuscuta in soybean production. The results were as following:1. Four elicitors did not directly inhibit on germination and biomass of Cuscuta at tested concentrations. The reduction of growth of Cuscuta on soybean was due to the elicitors inducing the host resistance, not directly killing the parasite.2. The four elicitors could enhance soybean resistance against the parasite. BTH at 250mg/L is the best one among them and up to 62.2% control.3. Effects of induction of soybean against the parasite were different in applications of spray, root irrigation and seed soak, of which spray was the best one; Effect of induction of soybean against Cuscuta was stable with BTH at 250mg/L sprayed soybean seedlings and with the extension of the inoculation interval. The best induced interval was 3d. The control effect was up to 66.5% maximum. Duration was at least 10d; The control effect was increased with the application times when BTH at 250mg/L was sprayed with 1,2 and 3 times, respectively. The control effect was up to 100% after three times application. In a certain induction interval and the induced concentration, resistance in plants could be improved with increasing the induction frequency; The control effect was the best at the soybean five-leaf-stage treated with BTH at 250mg/L in the different growth stages of soybean seedling; The control effect was decreased with the increase of the number of inoculation of the parasite treated with BTH at 250 mg/L. It was no control effect if inoculation with 5 or more than 5 parasites; The combination effect with BTH,PHDC,BABA and SA together was showed addition effect. 4. Activities of SOD, POD, CAT, PPO and PAL in soybean were increased in treatments with BTH at 250mg/L and inoculation with the parasite. This might indicate that defense-related enzymes were involving in the expression of induced resistance.