马铃薯晚疫病带菌种薯产孢与侵染行为观察

Observation on sporulation and infection of latent infected seed potatoes by potato late blight

为了明确带有马铃薯晚疫病菌的种薯播种后在土壤中产孢、传播进行初侵染这一途径存在的可能性及其影响因素。本试验通过盆栽和田间试验,研究带有马铃薯晚疫病菌的种薯播种后的产孢时间和部位,并采用诱钓法明确马铃薯晚疫病菌孢子经土壤传播引起初侵染的可能性及所需条件。结果表明,自然带菌种薯切块播种后4~6 d,菌丝在切面产生孢子囊;人工接菌的种薯切块播种后7~10 d,在花盆的土壤中成功诱钓到晚疫病菌。田间试验中,带菌种薯播种后可在土壤中产孢,且不受土壤湿度制约,切块播种较整薯播种更易产孢;种薯上产生的孢子囊可在土壤中传播并引起初侵染,此途径需要较高的土壤湿度(相对湿度为60%左右);从时间上看,带菌种薯播种后产孢的时间要早于种薯萌芽和出苗的时间。结果表明,马铃薯晚疫病菌可以在带菌种薯播种后通过土壤进行传播并造成初侵染,因此对种薯的灭菌和播种时的土壤消毒对于该病害的防治至关重要。

The study aims to clarify the possibility and influencing factors of the pathway that sporangia being produced on the seed tubers of potatoes infected by Phytophthora infestans after sowing and then spreads in the soil for primary infection.In this study,pots and field trail experiments were conducted to study the time and site of sporulation of the pathogen on latent infected seed tubers.The possibility and required conditions of the sporangia spreading in the soil and causing primary infection was tested using a baiting method.The results showed,4-6 days after the latent infected seed pieces were sowed,the hyphae of the P.infestans produced sporangia on the cutting surface.7-10 days after the artificially inoculated seed pieces were sowed,the P.infestans was successfully baited in the pot soil.In the field experiment,the latent infected seed tubers could produce sporangia after sowing in the soil,and was not limited by soil moisture.Sowing seed pieces was more likely to produce sporangia than sowing the whole tubers.Sporangia produced by the latent infected seed tubers could move in the soil and fulfill primary infection,which required high soil moisture(the relative humidity is about 60%).In the frame of time,the sporulation was early than sprout germination and crop emergence of the latent infected seed tuber after sowing.The above results indicate that after the latent infected seed tubers are sowed,P.infestans can spread in the soil and fulfill primary infection.Therefore,the sterilization of seed tubers and soil disinfection during sowing are very important for the prevention and control of this disease.