Relationship between five climatic parameters and ... - CiteSeerX

2School of Forest Resources, Pennsylvania State University, 410 Life Sciences Building, University Park, PA 16802,. USA. 3Laboratoire de Phytopathologie, Centre National de Recherche Agronomique (CNRA), BP 808 Divo, Côte d'Ivoire. 4Department of Biological Sciences, Higher Teachers Training College, University ...
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African Journal of Biotechnology Vol. 9(40), pp. 6614-6625, 4 October, 2010 Available online at http://www.academicjournals.org/AJB DOI: 10.5897/AJB09.1423 ISSN 1684–5315 ©2010 Academic Journals

Full Length Research Paper

Relationship between five climatic parameters and somatic embryogenesis from sporophytic floral explants of Theobroma cacao L. Auguste Emmanuel Issali1*, Abdoulaye Traoré2, Jean Louis Konan1, Joseph Mpika3, Emile Minyaka4, Jeanne Andi Kohi Ngoran5 and Abdourahamane Sangaré5 1

Centre National de Recherche Agronomique (CNRA), Station de Recherche sur le Cocotier "Marc Delorme" Port Bouët, 07 BP 13 Abidjan 07, Côte d’Ivoire. 2 School of Forest Resources, Pennsylvania State University, 410 Life Sciences Building, University Park, PA 16802, USA. 3 Laboratoire de Phytopathologie, Centre National de Recherche Agronomique (CNRA), BP 808 Divo, Côte d’Ivoire. 4 Department of Biological Sciences, Higher Teachers Training College, University of Yaoundé 1, P. O. Box 47 YaoundeCameroun. 5 Centre National de Recherche Agronomique (CNRA ), Laboratoire Central de Biotechnologies (LCB), 01 BP 1740 Abidjan 01, Côte d’Ivoire. Accepted12 April, 2010

To analyse the relationship between climatic parameters and somatic embryogenesis (SE), some favourable and unfavourable periods were identified. Likewise, to optimize SE in unfavourable periods the relationship among 2,4-D/TDZ, SE and year was analysed. Staminodes and petals of six hybrids and two clones as controls were sown in bulk onto three different calli induction media. Minimal temperature, rainfall, maximal temperature, mean temperature, temperature gaps, sunshine and relative humidity as climatic parameters were simultaneously recorded the day of the harvest of flower buds. Student-Fisher’s test at 5% level, Principal Component Analysis and Pearson’s linear correlation at 5%, 1% or 1‰ were used to separate the averages, identify the best climatic parameters and analyse the link between the climate and SE, respectively. The relative humidity and mean temperature were eliminated from the study. The period that spreads out from January to September favoured SE. In favourable periods, the SE variation was independent of that of concentration in 2,4-D/TDZ. This shows that these are the metabolites coming from 2,4-D/TDZ that activate the genes rather than these two compounds themselves. In unfavourable periods, in the first year, the weakest concentration in 2,4D/TDZ of PCG3 medium favoured SE, while in the second year that is the strongest concentration of PCG4 which increased it. This could indicate an interaction among year, concentration in 2,4-D/TDZ and SE. However, the link thus established is only statistical. It did not allow the quantification of the contribution level of these climatic parameters to variations of SE. Key words: Somatic embryogenesis variations, staminodes, petals, PCG calli induction media, favourable and unfavourable periods. 2,4-D/TDZ concentration in periods. INTRODUCTION Cocoa tree is a plant native of rainforest of Tropical

*Corresponding author. E-mail: [email protected] Tel: +225-05-82-17-28, +225-01-13-58-52. Abbreviation: SE, Somatic embryogenesis; dichlorophenoxyacetic acid; TDZ, thidiazuron.

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America belonging to the Malvaceae (Whitlock et al., 2001). In Côte d’Ivoire, cocoa provides 30% of export global incomings and approximately contributes to 15% at gross domestic product (ICCO, 2000). The covered area by cocoa trees farms represents 6% of national territory. The life of 6 millions of people directly or indirectly depends on incomings of cocoa. These peoples represent

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30% of the working population (Anonymous, 2004). Moreover, its average yields in merchant cocoa in the order of 250 - 500 kg/ha obtained in fields are relatively low (Mossu, 1990). However, in research stations, some yields in the order of 1 – 2.5 t/ha are obtained (Clement et al., 1996). One of the ways able t