Pathogenicity evaluation of bipolaris oryzae isolates on egyptian rice cultivars

الملخص EN

The aim of this study was to evaluate the pathogenicity of Bipolaris oryzae, the causal agent of brown spot disease on Egyptian rice cultivars.

Sample of rice were collected from 10 cultivars namely (Sakha 101, Sakha 104, Sakha 106, Giza 176, Giza 177, Giza 178, Giza 182, Egyptian hybrid and Egyptian Yasmin).

Fungal genera were recovered from the rice samples.

These fungi were identified as(Curvularia lunata, Asprgillus niger, Asprgillus flavus, Penicillium sp.

, Trichoderma, Alternaria alternata, Bipolaris oryzae, Fusarium verticillioides, Fusarium chlamydosporum, Rhizopus oryzae, Curvularia tuberculate, Bipolaris hawaiiensis, Cephaliophora tropica and Negrospora sp.

).

Out of the fourteen fungi, Bipolaris oryzae (B.

oryzae) was characterized as one of the highest frequently exists fungus.

Ten isolates of B.

oryzae were investigated in terms of spore dimension, number of septa of conidia, linear growth and culture color.

These ten B.

oryzae isolates were used in the pathogenicity test on five commercial rice cultivars (Sakha 108, Sakha super 300, Giza 177, Giza 182 and Egyptian hybrid.

The disease severity was assessed 7days after inoculation, 21-days-old rice plants.

The most aggressive B.

oryzae isolates were B.

o10, B.

o7, B.

o9 and B.

o8.

On the other hand, the lowest aggressive once were B.

o2, and B.

o1.

Screening of the B.

oryzae isolates on the commercial rice cultivars in the rice cultivation area in Egypt could help develop prediction plane of brown spot disease, ultimately, facilitate the most proper decision for rice cultivars to be cultivated.