SEED HEALTH TESTING OF RICE AND EFFECT OF SOME FUNGICIDAL SEED TREATMENTS ON SEED - BORNE PATHOGENIC FUNGI

Forty rice seed samples of five varieties obtained from lots desig­nated for seed production were used in this investigation. Seed-borne fungi, germination, seedling abnormality, and chemical control have been studied. According to the mean percentage of infected seed with differ­ent seed-borne fungi, the varieties could be arranged as follow: Riho (14.36%), Giza 171 (11.45%), IR 28 (8.14%), Giza 172 (2.45%) and 1R 1626 (2.09%). The most common pathogens were Drechslera oryzae (28.0%) followed by Trichoconiella padwikii (18.8%) and Pyricularia ory­zae (11.4%). Meanwhile, Sarocladium oryzae, the sheath rot pathogen of rice, had been observed for the first time in Egypt. Moreover, it has been observed that the aforementioned pathogens caused four different kinds of seedling abnormality, i.e. decay in shoot and root, decay in shoot only, twisted shoots and weak spindly primary root. However, the last type of abnormality was associated with some saprophytic fungi. Therefore, samples of lots showing high germination but infected with important pathogens should be rejected. Elimination of seed-borne fungi inocula has been obtained effec­tively by soaking seeds in the fungicide Hinosan 50% (Edifenphos) at concentration of 1000 ppm for 24hr. Besides, germination of treated rice seed was increased 8.43% more than the control.