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ARS Home » Southeast Area » Miami, Florida » Subtropical Horticulture Research » Research » Publications at this Location » Publication #189777
Title: CAN WE SELECT FOR SHORTER CACAO PLANTS?

Author
item MONTEVERDE-PENSO, EDGARDO - CATIE
item PHILLIPS, WILBERT - CATIE
item MACHADO, R - MASTERFOODS
item Brown, James
item Schnell Ii, Raymond
item MOTAMAYOR, JUAN - MASTERFOODS

Submitted to: Ingenic Newsletter
Publication Type: Trade Journal
Publication Acceptance Date: 7/1/2005
Publication Date: 9/1/2005
Citation: Monteverde-Penso, E.J., Phillips, W., Machado, R., Brown, J.S., Schnell II, R.J., Motamayor, J.C. 2005. Can we select for shorter cacao plants?. Ingenic Newsletter. 10:16-19.

Interpretive Summary: Normal growth for cacao is a medium size tree obtaining heights of 20 to 25 feet. Mature trees are difficult to harvest as many of the fruits are in the upper canopy. Genetic variation for plant size exists in cacao germplasm, and developing new short stature varieties would be useful for certain growing areas. This research characterizes the type of genetic variation for plant size in two experiments, one in Costa Rica and another in Brazil. In both experiments General Combining Ability (GCA) was found to be the most important type of variation. GCA indicates that this variation is additive and can be manipulated to produce new short stature cultivars. The most promising source of genes for short stature was identified as the Trinitario germplasm. This germplasm will be further characterized with the objective of producing new short stature cultivars.

Technical Abstract: Cacao breeding programs have concentrated on producing higher yielding cultivars. Selection based mainly on yield has resulted in taller and more vigorous plants which do not perform well under high-density plantings or mixed cropping systems. Selection for yield, while considering height and other aspects of plant architecture, should allow the development of short plants with higher yield efficiency. Two experiments were used to estimate genetic variation for plant height. Both experiments were planted in an incomplete factorial design in 2003 and 2004. The experiments were located at CATIE in Costa Rica and Almirante, Mars farm in Brazil. Parents were selected for resistance to frosty pod in Costa Rica and witches’ broom in Brazil. Three cultivars were selected for short plant height, LF-1, Santa Clara-3, and SCA24. Plant height was measured one year after the plants were placed in the field. Analyses of variance were carried out for jorquette and plant height, and Specific and General Combining Ability (SCA and GCA) were estimated for these traits. Significant SCA and GCA were found among the genotypes tested. The progeny identified with shorter height were of Trinitario origin. The results suggest that it is possible to select for shorter plants and clones with positive and negative GCA for jorquette and plant height can be identified. Shorter plants should allow higher yield efficiency, if combined with other traits related to tree architecture, and higher planting densities in the field.