Casual agent of ginger bacterial wilt in Sabah and effect of Brassica juncea var. rugosa as its control

• Main Author: Linda @ Lily Cosmas
• Format: Thesis
• Language: English; English
• Published: 2017
• Subjects: SB183-317 Field crops Including cereals, forage crops, grasses, legumes, root crops, sugar plants, textile plants, alkaloidal plants, medicinal plants
• Online Access: https://eprints.ums.edu.my/id/eprint/38499/1/ABSTRACT.pdf; https://eprints.ums.edu.my/id/eprint/38499/2/FULLTEXT.pdf; https://eprints.ums.edu.my/id/eprint/38499/

The objectives of this study were to identify the causal agent of Sabah ginger bacterial wilt, to quantify the glucosinolates (GSLs) content in Brassica Juncea var rugosa based on selected growth stage and to evaluate the inhibitory effect of B. Juncea var rugosa against the causal agent of ginger bacterial wilt. The ginger plants with foliar yellowing and wilting symptoms collected from six ginger-growing areas in the Tambunan and Ranau districts were observed to have signs of bacterial pathogen (i.e. bacterial ooze). A total of 19 bacterial strains were isolated, and all of the isolates were characterized as rod-shaped and Gram-negative by Gram-staining and potassium hydroxide test. MALDI-TOF analysis identified six species of the isolates as Enterobacter cloacae complex (57.9%), Ralstonia pickettii (10.5%), Agrobacterium tumefaciens (10.5%), Bac11/us pumilus (10.5%), Stenotrophomonas maltophilia (5.3%) and Serratia marcescens (5.3%). In pathogenicity test, £ cloacae, which constituted most of the isolates, induced mild rot symptoms ( discoloration and decaying) on ginger rhizome slices, but no disease symptoms were produced in ginger plants. The quantification of GSLs content and the dry matter production of B. Juncea var rugosa showed that there was a significant different at the p<0.05 between the GSLs concentration and dry matter production at three different growth stages. The highest GSLs concentration (126.55 μmol 100 g-1 DM) and dry matter production (18.88 g DM planr1) were obtained at the early senescence stage. In the evaluation of the inhibitory effect of B. Juncea var rugosa against the £ cloacae, bioassay analysis showed that there was a significant effect at p<0.05 between the B. juncea var rugosa concentration rate and its inhibitory effect. The highest percentage of inhibition over control was at the highest concentration rate, 4.0 g after 48 hours. However, the inhibitory effect was not able to be replicated when the experiment was conducted in the green house. Difficulties were experienced with the survival of the introduced £ cloacae in soil and the B. Juncea var rugosa biofumigation effect could not be evaluated. This study deserved further investigation by future research. In this research, the relationship between £ cloacae with the ginger bacterial wilt disease is a first record in Sabah, Malaysia. The locally grown B. Juncea var rugosa was found to have low concentration of GSLs but it had significant inhibition effect on the growth of £ cloacae in the in vitro condition.