Antifungal activities of Alpinia galangal, Curcuma longa and Zingiber officinale extracts against Pyricularia oryzae, pathogen of rice blast disease / Nur Hidayatur Nabila Mat Lapi

This study screened the potential of natural product from Zingeberacea family like
Alpinia galangal, Curcuma longa and Zingiber officinale crude extracts as
biofungicides and their antifungal activities against Pyricularia oryzae which is the
pathogen of rice blast disease both in vitro and in vivo. The objectives of this study were
to evaluate and observe the efficacy of A. galangal, C. longa and Z. officinale crude
extracts as an antifungal agent against P. oryzae and to determine the active compound
in A. galangal, C. longa and Z. officinale crude extracts that act as antifungal agent.
Results from the study showed that A. galangal hexane crude extract possessed highest
antifungal activity and showed greater inhibition zone against P. oryzae with 52.9%
growth inhibition (1.88 cm radial growth) followed by C. longa hexane extract with
49.2% inhibition (2.03 cm radial growth) and Z. officinale methanol extract with 43.5%
of inhibition (2.18 cm). Other crude extracts also showed slight inhibition towards P.
oryzae. Furthermore, A. galangal hexane crude extract showed inhibition effect nearly
equal as the commercial fungicide (Mancozeb) that is commonly used in controlling
rice blast. The crude extracts have the effective inhibitory concentration (EIC) at
250,000 ppm concentration and LC50 was determined at 365,129 ppm. Based on
microscopic observation, it was found that antifungal activity of A. galangal crude
extract caused stunted, lysis, burst and disruption of P. oryzae mycelia and conidia. The
active antifungal properties in A. galangal hexane crude extract were detected and the
presence of phytochemical was screened using qualitative phytochemical screening and
GC-MS analysis. These results were able to detect the presence of alkaloids, saponin,
phenols, phenylpropanoids, eucalyptol and eugenol. The in vivo study showed that A.
galangal hexane crude extract have the potential to be used as curative control against
blast disease in the rice field.