Development of Technique to Screen Cocoa for Resistance Against the White Root Disease Caused by Rigidoporus Lignosus (Klot.) Bres.

Rigidoporus lignosus, Phellinus noxius and Ganoderma philippii, Basidiomycetous fungi commonly associated with white, brown and red root diseases respectively, were isolated from infected cocoa roots. The disease symptoms and characteristics of each fungus were identified, and the prevalence of R. l...

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Main Author:	Che Ahmad, Azmi
Format:	Thesis
Language:	English English
Published:	2005
Subjects:	Cacao - Diseases and pests - Case studies
Online Access:	http://psasir.upm.edu.my/id/eprint/568/1/549649_FP_2005_28.pdf
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id	my-upm-ir.568
record_format	uketd_dc
spelling	my-upm-ir.5682013-05-27T06:49:21Z Development of Technique to Screen Cocoa for Resistance Against the White Root Disease Caused by Rigidoporus Lignosus (Klot.) Bres. 2005-02 Che Ahmad, Azmi Rigidoporus lignosus, Phellinus noxius and Ganoderma philippii, Basidiomycetous fungi commonly associated with white, brown and red root diseases respectively, were isolated from infected cocoa roots. The disease symptoms and characteristics of each fungus were identified, and the prevalence of R. lignosus and white root disease over the others was confirmed in a study of three cocoa planting areas in Peninsular Malaysia. Growth of R. lignosus on potato dextrose agar medium was significantly influenced by factors of temperature and pH. The temperature range favourable for growth was 30ºC, while the optimum pH was 5. A study was undertaken to induce production of basidiocarps of R. lignosus in vitro. Basidiocarps were formed on autoclaved and non-autoclaved soil by 14 days after incubation. Ultrastructural studies of R. lignosus basidiocarp and basidiospore were done. The viability of basidiospores were confirmed by germination on glass slides coated with malt extract agar. Artificial inoculation of R. lignosus using mycelial mats and basidiospores suspension failed to induce white root disease symptoms on cocoa seedlings. However, in this study a technique was successfully developed for screening cocoa seedlings for resistance against R.lignosus. The method involved the insertion of the tap root of 10-day old cocoa seedling into the hole of a R. lignosus colonized rubber wood block and subsequently covered in soil in a black polythene bag. Symptoms of white root disease were recorded within two weeks after inoculation and were measurable using a disease severity index. R. lignosus isolate CRD/LKM/10 was found to be the most virulent isolate as it had caused a significantly more severe white root disease infections in cocoa seedlings compared to six other R. lignosus isolates tested. The method of inoculation was subsequently used to screen cocoa seedlings of 15 selected cocoa clones (including the widely planted PBC 123 clone) for resistance against white root disease using R. lignosus isolate CRD/LKM/10 as the test fungal organism. The results revealed that cocoa seedlings of clones ICS 60 and PA300 were significantly less infected by white root disease thus indicating that they were more resistant to the disease compared to all other cocoa clones tested. Cacao - Diseases and pests - Case studies 2005-02 Thesis http://psasir.upm.edu.my/id/eprint/568/ http://psasir.upm.edu.my/id/eprint/568/1/549649_FP_2005_28.pdf application/pdf en public masters Universiti Putra Malaysia Cacao - Diseases and pests - Case studies Faculty of Agriculture English
institution	Universiti Putra Malaysia
collection	PSAS Institutional Repository
language	English English
topic	Cacao - Diseases and pests - Case studies
spellingShingle	Cacao - Diseases and pests - Case studies Che Ahmad, Azmi Development of Technique to Screen Cocoa for Resistance Against the White Root Disease Caused by Rigidoporus Lignosus (Klot.) Bres.
description	Rigidoporus lignosus, Phellinus noxius and Ganoderma philippii, Basidiomycetous fungi commonly associated with white, brown and red root diseases respectively, were isolated from infected cocoa roots. The disease symptoms and characteristics of each fungus were identified, and the prevalence of R. lignosus and white root disease over the others was confirmed in a study of three cocoa planting areas in Peninsular Malaysia. Growth of R. lignosus on potato dextrose agar medium was significantly influenced by factors of temperature and pH. The temperature range favourable for growth was 30ºC, while the optimum pH was 5. A study was undertaken to induce production of basidiocarps of R. lignosus in vitro. Basidiocarps were formed on autoclaved and non-autoclaved soil by 14 days after incubation. Ultrastructural studies of R. lignosus basidiocarp and basidiospore were done. The viability of basidiospores were confirmed by germination on glass slides coated with malt extract agar. Artificial inoculation of R. lignosus using mycelial mats and basidiospores suspension failed to induce white root disease symptoms on cocoa seedlings. However, in this study a technique was successfully developed for screening cocoa seedlings for resistance against R.lignosus. The method involved the insertion of the tap root of 10-day old cocoa seedling into the hole of a R. lignosus colonized rubber wood block and subsequently covered in soil in a black polythene bag. Symptoms of white root disease were recorded within two weeks after inoculation and were measurable using a disease severity index. R. lignosus isolate CRD/LKM/10 was found to be the most virulent isolate as it had caused a significantly more severe white root disease infections in cocoa seedlings compared to six other R. lignosus isolates tested. The method of inoculation was subsequently used to screen cocoa seedlings of 15 selected cocoa clones (including the widely planted PBC 123 clone) for resistance against white root disease using R. lignosus isolate CRD/LKM/10 as the test fungal organism. The results revealed that cocoa seedlings of clones ICS 60 and PA300 were significantly less infected by white root disease thus indicating that they were more resistant to the disease compared to all other cocoa clones tested.
format	Thesis
qualification_level	Master's degree
author	Che Ahmad, Azmi
author_facet	Che Ahmad, Azmi
author_sort	Che Ahmad, Azmi
title	Development of Technique to Screen Cocoa for Resistance Against the White Root Disease Caused by Rigidoporus Lignosus (Klot.) Bres.
title_short	Development of Technique to Screen Cocoa for Resistance Against the White Root Disease Caused by Rigidoporus Lignosus (Klot.) Bres.
title_full	Development of Technique to Screen Cocoa for Resistance Against the White Root Disease Caused by Rigidoporus Lignosus (Klot.) Bres.
title_fullStr	Development of Technique to Screen Cocoa for Resistance Against the White Root Disease Caused by Rigidoporus Lignosus (Klot.) Bres.
title_full_unstemmed	Development of Technique to Screen Cocoa for Resistance Against the White Root Disease Caused by Rigidoporus Lignosus (Klot.) Bres.
title_sort	development of technique to screen cocoa for resistance against the white root disease caused by rigidoporus lignosus (klot.) bres.
granting_institution	Universiti Putra Malaysia
granting_department	Faculty of Agriculture
publishDate	2005
url	http://psasir.upm.edu.my/id/eprint/568/1/549649_FP_2005_28.pdf
_version_	1747810250891722752

Development of Technique to Screen Cocoa for Resistance Against the White Root Disease Caused by Rigidoporus Lignosus (Klot.) Bres.

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