The Effect of Various Population Densities of Bacillus sp. in Suppressing Blast Disease (Pyricularia oryzae) in Rice Plants

Hanifa, Imala Umi (2026) The Effect of Various Population Densities of Bacillus sp. in Suppressing Blast Disease (Pyricularia oryzae) in Rice Plants. Undergraduate thesis, UPN Veteran Jawa Timur.

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Abstract

This study aimed to evaluate the effectiveness of Bacillus sp. isolate D28 in suppressing Pyricularia oryzae, the causal agent of rice blast, and determine the optimal population density for biological control. The study was conducted from March to June 2026 at the Plant Health Laboratory 1 of UPN “Veteran” East Java (in vitro) and the East Java Greenhouse Unit (in vivo). A Completely Randomized Design (CRD) with four treatments and six replicates was used: a control (P. oryzae alone) and Bacillus sp. at 10⁷, 10⁸, and 10⁹ CFU/mL combined with P. oryzae inoculation. Pathogenicity tests confirmed virulence, with symptoms appearing 3 days after inoculation (DAI) and disease severity of 33.33%. In vitro antagonism tests showed the largest inhibition zone at 10⁹ CFU/mL (9.58 mm), although it was not significantly different from 10⁸ CFU/mL (7.50 mm). Suppression occurred through competition, lysis, and antibiosis, causing hyphal deformation, including shrinkage, swelling, and loss of septa. In vivo, 10⁸ and 10⁹ CFU/mL significantly reduced disease severity at 28 DAI to 10.41–11.11%, compared with 23.61% in the control, whereas 10⁷ CFU/mL was ineffective. The highest efficacy was observed at 10⁹ CFU/mL, with 55.87% inhibition and improved growth, particularly leaf number at 49 days after sowing (DAS), reaching 40.33 leaves. Thus, Bacillus sp. isolate D28 effectively suppressed rice blast, with 108 CFU/mL identified as the optimal concentration. Keywords : Bacillus sp., Pyricularia oryzae, Blast, Densities, Oryza sativa

Item Type:

Thesis (Undergraduate)

Contributors:

Contribution	Contributors	NIDN/NIDK	Email
Thesis advisor	Prasetyawati, Endang Tri Wahyu	NIDN0703126403	endang_tp@upnjatim.ac.id
Thesis advisor	Wiyatiningsih, Sri	NIDN0002106605	sri.wiyatiningsih@upnjatim.ac.id

Subjects:

S Agriculture > SB Plant culture > SB950-989 Pest Control and Treatment of Diseases, Plant Protection

Divisions:

Faculty of Agriculture > Departement of Agritechnology

Depositing User:

Imala Umi Hanifa

Date Deposited:

08 Oct 2026 03:56

Last Modified:

08 Oct 2026 07:10

URI:

https://repository.upnjatim.ac.id/id/eprint/60499