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ARS Home » Southeast Area » Mayaguez, Puerto Rico » Tropical Crops and Germplasm Research » Research » Publications at this Location » Publication #312211
Title: Yield performance and bean quality traits of cacao propagated by grafting and somatic embryo-derived cuttings

Author
item Goenaga, Ricardo
item GUILTINAN, MARK - Pennsylvania State University
item MAXIMOVA, SIELA - Pennsylvania State University
item SEGUINE, ED - Seguine Cacao Cocoa & Chocolate Advisors
item IRRIZARY, HEBER - Retired ARS Employee

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2014
Publication Date: 4/1/2015
Citation: Goenaga, R.J., Guiltinan, M., Maximova, S., Seguine, E., Irrizary, H. 2015. Yield Performance and bean quality traits of cacao propagated by grafting and somatic embryo-derived cuttings. HortScience. 50(3):358-362.

Interpretive Summary: Cacao (Theobroma cacao) has great potential as a component of a small tropical farming system. It adapts to a wide range of soils of climatic conditions, grows well under minimum tillage, adapts to temporary intercropping, has the potential of being sold in local and export markets and the pods are harvested year-round providing a ready source of cash income. The U.S. chocolate industry alone generated $19.5 billion in sales of chocolate products in 2012. However, it is estimated that diseases in cacao production cause losses of potential crop amounting to 43% in America, 20% in Africa, 13% in Oceania and 9% in Asia. In order to satisfy future global demand for cacao products and reduce crop losses, research is needed to develop and/or identify superior cacao genotypes possessing disease tolerance and high yielding traits. In addition, methods of propagation that are more efficient in producing true-to-type genotypes are needed. We evaluated 12 cacao clones propagated by grafting and orthotropic rooted cuttings of somatic embryo-derived plants on an Ultisol soil at Corozal, Puerto Rico for six years under intensive management. Propagation treatments had a significant effect on dry bean yield. Dry bean yield of varieties propagated by grafting was 7% higher (2,166.7 kg.ha-1.yr-1) than those propagated by orthotropic rooted cuttings of somatic embryo-derived plants (2,009.2 kg.ha.yr-1). This yield difference could not be attributed to grafted plants being more vigorous nor by differences in root architecture. In general, flavor characteristics were not significantly affected by propagation treatments. Although there were significant differences between plant propagation treatments for some of the variables measured in this study, these were not of a magnitude that would preclude the use of somatic embryogenesis as a viable propagation system for cacao. The use of somatic embryogenesis for cacao propagation could contribute to efforts to improve yield per area, germplasm conservation and rapid distribution of high yielding clones.

Technical Abstract: Twelve cacao (Theobroma cacao) clones propagated by grafting and orthotropic rooted cuttings of somatic embryo-derived plants were grown on an Ultisol soil at Corozal, Puerto Rico and evaluated for six years of production under intensive management. Year, variety, year x variety and propagation treatment x variety interactions showed significant effects for dry bean yield, number of pods produced, pod index, plant height and stem diameter. Propagation treatments had a significant effect on dry bean yield and pod index but not on number of pods produced. Average yield across varieties for both propagation treatments was 2,087.9 kg.ha-1. yr-1 of dry beans. There was a highly significant variety effect. ‘UF-668’ was the top yielder averaging 2,536.7 kg.ha-1.yr-1.yr-1 of dry beans; however, this yield was not significantly different than the average yield of varieties TARS-30, TARS-1, TARS-13, TARS-14 and TARS-2 which averaged 2,427.0 kg.ha-1.yr-1. Except for ‘UF-668’, the TARS varieties were released in 2009 as high-yielding selections. Propagation treatments had a significant effect on dry bean yield. Dry bean yield of varieties propagated by grafting was 7% higher (2,166.7 kg.ha-1.yr-1) than those propagated by orthotropic rooted cuttings of somatic embryo-derived plants (2,009.2 kg.ha.yr-1). This yield difference could not be attributed to grafted plants being more vigorous nor by differences in root architecture. The lowest pod index value in both propagation treatments was obtained by ‘UF-668’ however, pod index for this variety did not differ significantly from values for ‘TARS-2’ and ‘TARS-23’ in grafted plants and from ‘TARS-2’, ‘TARS-23’, and ‘TARS-1’ in plant propagated by orthotropic rooted cuttings of somatic embryo-derived plants. With few exceptions, flavor characteristics were not significantly affected by propagation treatments. Although there were significant differences between plant propagation treatments for some of the variables measured in this study, these were not of a magnitude that would preclude the use of somatic embryogenesis as a viable propagation system for cacao.