Philippine E-Journals

Rice blast incidence and morphological variation of Magnaporthe oryzae, Cav. in Ebonyi State, Nigeria

Buliaminu A. Yekini | Olaitan Chinenye Okechukwu | Clement Gboyega Afolabi

 

Abstract:

Blast disease is one of the major threats to rice production globally. This study investigates the prevalence, incidence, severity, damage index and morphological variation of blast disease in lowland rice in nine local government areas of Ebonyi State, Nigeria. Ebonyi State lies within Latitudes 6o15′57″N and 6o24′70″N, Longitudes 7o42′18″E and 8o26′20″E in the derived savannah zone of Nigeria. A survey was conducted on twenty-six (26) rice farms between October and November, 2017 when the rice had reached physiological maturity and infection of rice plants with blast was evident. Data collected from the farms included; rice variety cultivated, source of the seeds, area of land under cultivation, disease incidence, severity and damage, and control measures. Data obtained on disease incidence, severity and damage index were subjected to Analysis of Variance while significant means were separated with Tukey HSD test at p<0.05. Results on rice blast disease revealed that incidence, severity and damage index varied between fields and location due to the environmental conditions prevalent in each location. The highest mean disease incidence, severity and damage index 53.67%, 2.50 and 38.02% respectively due to blast, were recorded in Ishielu, while Ezza South had the least blast incidence (18.24%), Abakaliki had the least severity (1.30) and Ezza South the leastdamage index (6.59%). Twenty-two fungal isolates were identified andcharacterized from infected rice plants obtained from the field. The twenty-twoisolates, identified as Magnaporthe oryzae (Mo), grown on potato dextrose agarshowed various differences in their cultural and morphological characters suchas colony colour, margin, pigmentation, surface texture, shapes, septate andcells. Pathogenicity study revealed the five isolates Mo-03, Mo-05, Mo-06, Mo-10 and Mo-17 where more virulent than others. Therefore, the present studyrecommends that the governments should set up a modality to educate andtrain rice farmers on disease symptoms and the possible eco-friendly means ofcontrol in order to increase rice production both in the study areas and in Nigeriaat large.