عـــزل وتشخيص الفطـــريات المـــرافقة لحبوب الحنطة ومـــقاومتها إحيائياً وكيميائياً وفيزيائياً

ISOLATION AND DIAGNOSIS MYCOFLORA ASSOCIATED WITH WHEAT SEEDS AND THEIR CONTROL BY USING BIOLOGICAL , CHEMICAL AND PHYSICAL METHODES

The study was conducted to evaluate fungal contamination in six sample of local and methods for controlling the contamination .Although all local and important sample were found to be contaminated fungi at different levels the highest percentage of this contamination ( 83.32% ) was recorded  the sample of  American wheat seeds .Moreover , 120 fungal isolates were taken from all samples involved .It was found that the fungi Aspergillus parasiticus  and  A . niger were note only found in all samples but they also occupied the first and second ranks of contamination , respectively compared with all other fungi . These two species were responsible for 60.83 and 20 % of contamination , respectively . The highest level of contamination caused by the first  species   was found  in local wheat  No.2 while the highest level caused by the second species was found in local wheat No.1 Other species  of fungi including  A. terrus , Rhizopus sp. , Cladosporium sp. , A. sp.1 , found at low levels of  frequency . It was found that all contaminating fungi reduced the rates of seed germination in all samples . A preliminary chemical checkup of active secondary metabolites in Cuscuta plant indicated the presence of resins , saponins and phenolates . The amoisture content varied from sample to another , but it was at its highest level ( 8.68 % ) in  the American sample  Both of cold aqueous extract and the powder of Cuscuta plant were effective in controlling most of contaminating fungi in wheat seed samples . The acetic acids at 3% concentration inhibited all contaminating fungi completely . Treating the seeds with dry and wet temperatures caused effect on some of the contaminating fungi of stored wheat grains .