Authors
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Albert Ling Sheng Chang
Malaysian Cocoa Board, 5-7th Floor, Wisma SEDCO, Lorong Plaza Wawasan, Off Coastal Highway
Author
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Suhaida Salleh
Cocoa Research & Development Centre Jengka, Malaysian Cocoa Board, Jalan Jengka 23, P.O. Box 34, 28000 Temerloh, Pahang, Malaysia.
Author
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Nuraziawati Mat Yazik
Cocoa Research & Development Centre Bagan Datuk, Malaysian Cocoa Board, P.O. Box 30, Sg. Dulang Road, 36307 Sg. Sumun, Perak, Malaysia
Author
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Haya Ramba
Malaysian Cocoa Board, 5-7th Floor, Wisma SEDCO, Lorong Plaza Wawasan, Off Coastal Highway, Locked Bag 211, 88999 Kota Kinabalu, Sabah, Malaysia.
Author
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Ahmad Kamil Mohd Jaaffar
Malaysian Cocoa Board, 5-7th Floor, Wisma SEDCO, Lorong Plaza Wawasan, Off Coastal Highway, Locked Bag 211, 88999 Kota Kinabalu, Sabah, Malaysia.
Author
Abstract
Coffea liberica is a variety of coffee that tolerant to marginal land, especially peatlands. One of propagation methods in C. liberica is somatic embryogenesis
(SE) which producing large number of true-to-type plant seedlings in a short time. This research aimed at studying the effect of application of plant growth
regulator (PGR) on quality and weight of somatic embryo of C. liberica. Somatic embryo in development stage was induced by Murashige and Skoog medium containing cytokinin as benzyl amino purin (BAP) and auxin as 2,4-dichlorophe-noxyacetic acid (2,4-D). While cotyledonary embryo in germination stage was induced by Murashige and Skoog medium containing cytokinin (BAP) and auxins as 2,4-D, indole acetic acid (IAA) and naphthaleneacetic acid (NAA). The results
showed that the application of auxins and cytokinins on development stage affected the formation of embryos, texture of calli, color of calli and embryos, and weight of somatic embryo. It also influenced the shoot and root formation, color and weight of geminating embryos of C. liberica at the germinating stage. During the development stage, addition of 1 mg/L BAP in the absence of 2,4-D in MS medium produced the highest quality of somatic embryo of C. liberica. This medium also produced heaviest somatic embryos but with lighter callus. While in germination stage, all medium treatments produced a typical germinating embryo. Coffea liberica germinating embryo growth optimally on MS medium containing 0.5 mg/L BAP as a single chemical or 0.5 mg/L BAP in combination with 0.5 mg/L IAA for shooting development. Whereas on rooting development, addition of 0.5 mg/L NAA on MS medium produced an optimal germinating embryo. Moreover, germination embryo of C. liberica recorded the highest in terms of dry weight on MS media with addition of 0.5 mg/L BAP. Application of appropriate concentration of auxin and cytokinin is needed to support the formation of somatic embryo and germinating embryo.
Author Biography
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Albert Ling Sheng Chang, Malaysian Cocoa Board, 5-7th Floor, Wisma SEDCO, Lorong Plaza Wawasan, Off Coastal Highway
Cocoa pod rot disease (CPRD), caused by Phytophthora palmivora, is
the main disease that caused major losses in Malaysia. It is important for screening the cocoa genotypes available in Malaysia for their tolerance level against the CPRD. This paper has an objective to select the potential genotypes tolerant to P. palmivora by grouping the cocoa genotypes available in Malaysia based on four tolerant levels such as tolerant, moderately tolerant, moderately susceptible and susceptible. The experiment was carried out at the laboratory of Plant Pathology
at the Cocoa Development and Research Centre Jengka, Pahang using the detached pod test. Isolate of P. palmivora was obtained from a naturally infected cocoa pod in cocoa field at the Cocoa Research and Development Centre Tawau, Sabah, Malaysia then inoculated by a single point on the ridges of pod to 40 mature unripe pods of each tested genotypes. Fifty genotypes were tested in this study. The assessed disease severity was the rate of lesion area development from 1 to 7 days after inoculation and the proportion of pod area infected by CPRD. The disease severity was significantly different among tested genotypes showing tolerance variability against CPRD. Four nonlinear models consisted of Monomolecular model, Exponential model, Logistic model and Gompertz model were used to fit the proportion pod infection area curve. The best fitted Gompertz model was used in calculated the area under disease progress curve (AUDPC). The variability of both disease severity variables was used to group the genotypes into four tolerant levels using thin group I (torelant), 14 genotypes in group II (moderately tolerant), 13 genotypes in group III (moderately susceptible) and 13 genotypes in group IV (susceptible). Six genotypes in group I, namely MCBC 13, PBC 221, BAL 209, KKM 19, QH 1176 and KKM 22 were identified to have lower disease severity values compared to control tolerant genotype PBC 123 that could be suggested to the farmers to be planted in the field.
