PAPER TITLE :EFFICACY OF N-HEXANE PLANT EXTRACTS IN THE CONTROL OF RICE BLAST DISE

APPLIED TROPICAL AGRICULTURE | VOLUME 20 NUMBER 1 2015

Paper Details

  • Author(s) : Adeosun, B.O and Onasanya,O.
  • Abstract:

Studies were carried out to determine antifungal attributes of n-hexane extracts of six plant species (Leaves of African Basil; Ocimum
gratissimum, Siam weed; Chromolaena odorata, Lemmon grass; Cymbopogon citratus, seeds of Clove; Eugenia aromatica, West African black
pepper; Piper guineense, and nuts of bitter kola; Garcinia kola) on Pyricularia oryzae, the incitant of rice blast disease. Plant parts were
separately air-dried and ground. Active ingredients were extracted with the aid of n-hexane, using soxhlet apparatus. Antifungal activity of
-2 extracts were evaluated in different concentrations (10, 20, 30, 40, 50 and 100%) of plant extracts and carbendazim at 0.5 mg. ml a standard
chemical, using the poisoned food technique. Mycelial growth was determined after 7 days of inoculation and incubation at each concentration
and control. All plant extracts reduced the growth of Pyricularia oryzae at all tested concentrations. Highest growth inhibition was achieved at
100 % concentration with E. aromatica, 100%; P. guineense 98% and G. kola, 97.3% growth inhibition, hence Cybopogon
citratus,Chromolaena odorata,Ocimum gratissimum and lower concentrations (10-50%) were discarded from the study. Only the extracts from E.
aromatica, G. kola and P. guineense at 100% concentration were used subsequently. Leaf blast was evaluated on Nerica and Faro-44 varieties. The
rice seeds were inoculated with spores of pure culture of P. oryzae and treated with 100% extracts concentration of E. aromatica, P. guineense and
G. kola each being the most promising botanicals among the six evaluated ones from the in vitro study. The untreated seeds stood as control while
-2 seeds treated with Carbendazim at 0.5 mg.ml stood as negative control. Extracts from P. guineese and E. aromatica reduced leaf blast incidence
by 45.8% and 37.5% respectively. Subsequently, rice seeds could be treated with 100% n-hexane extract concentration of P. guineense and E.
aomatica against the growth and development of Pyricularia oryzae with a resultant control of rice blast disease.