Evaluation of infection in Semnan wheat seed against Ustilago nuda in order to issue national seed standard

Seed health is one of the important aspects in seed quality investigation. Seed borne pathogens aretransmitted on, in and with seeds and under favorable conditions cause disease in plants. Loosesmut of wheat (U. nuda) as a seed borne disease is one of the important diseases that has enoughpotential to cause heavy damage if not managed. In the case of this disease, direct relation existsbetween amount of percentages of seed infection and appearance of disease in field. In the year١٣٩١, from ٩١ seed samples, ٣١ samples from commercial varieties Arg, Pishtaz, Kavir andAlvand that were produced in seed production fields were randomly taken and base on ISTA Rules,embryo test by weighing ١٠٠ g of seeds carried out. Seeds were kept for ٢٢-٢٤ hours in solutioncontaining ٢ liters of water plus ٥٠ g NaOH and ٠.١٥ g Trypan blue and salt. Then embryos wereseparated on sieves of different meshes under tape water. Lastly separated embryos were observedunder light microscope to see pathogen mycelium. In Breeder ٣ and foundation categories seedsamples no infection was observed but average infection percentages of certified seed categoryamong infected once (٢٢.٥%) was recoded as ٠.٤% with rage of ٠.٢ to ٠.٦%. Keeping in mind theabilities of pathogen in developing disease under existing situation and spreading disease to newfields, careful inspection along with observing phytosanitary measures such as accurate seedtreatment with poisons, isolation distance from source of infection and rouging of infected plant iscompulsory.

کلیدواژه ها:

seed ، disease ، embryo ، infection ، standard