Efficacy of Secondary Metabolites From Bacillus sp. D28 Against the Severity of Purple Blotch Disease in Shallot Plants

Anggraeni, Lina (2026) Efficacy of Secondary Metabolites From Bacillus sp. D28 Against the Severity of Purple Blotch Disease in Shallot Plants. Undergraduate thesis, UPN Veteran Jawa Timur.

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Abstract

Purple blotch disease caused by Alternaria porri is a major constraint in shallot production and can significantly reduce plant productivity. This study aimed to identify the secondary metabolites produced by Bacillus sp. D28 using gas chromatography–mass spectrometry (GC-MS) and evaluate their efficacy in suppressing purple blotch disease and promoting shallot growth. An in vivo experiment was conducted under greenhouse conditions using a Completely Randomized Design with five treatments, namely untreated control, secondary metabolite concentrations of 20%, 30%, and 40%, and mancozeb at 0.40%. Each treatment consisted of five replications with four plants per replication. The observed parameters included disease incubation period, disease intensity, plant height, number of leaves, and control efficacy. The application of secondary metabolites delayed symptom development and reduced disease intensity. The 40% treatment reduced disease intensity to 20.00% compared with 65.00% in the control, resulting in 69.23% control efficacy. It also increased plant height by approximately 59.96% compared with the control at 35 days after planting. Based on the calculated efficacy ratio, the 40% treatment showed 100% relative efficacy equivalence to mancozeb. These results indicate the potential of Bacillus sp. D28 secondary metabolites as an environmentally friendly alternative for purple blotch disease management in shallot production. Keywords: Alternaria porri, Bacillus sp., shallots, GC-MS, secondary metabolites, purple blotch

Item Type:

Thesis (Undergraduate)

Contributors:

Contribution	Contributors	NIDN/NIDK	Email
Thesis advisor	Prasetyawati, Endang Tri Wahyu	NIDN0703126403	endang_tp@upnjatim.ac.id
Thesis advisor	Mujoko, Tri	NIDN0009056605	trimujoko.agri@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:

Lina Anggraeni

Date Deposited:

08 Oct 2026 04:01

Last Modified:

08 Oct 2026 07:12

URI:

https://repository.upnjatim.ac.id/id/eprint/60497