Competition effects in cocoa (Theobroma cacao L.) hybrid trials

Lachenaud Philippe, Montagnon Christophe. 2002. Competition effects in cocoa (Theobroma cacao L.) hybrid trials. Euphytica, 128 (1) : 97-104.

Résumé : A method developed in coffee tree breeding to assess family competition effects (partner effects) in comparative variety trials was applied to the cocoa tree (Theobroma cacao L.). The study was conducted in a hybrid comparative trial planted in French Guiana, involving twelve families of 50 trees in a totally randomized single-tree plot design, at a density of 1,667 trees per hectare. The trial was thinned at 10 years, at a rate of two out of four rows. Competition was studied with reference to juvenile and adult vegetative vigour, and to periodic and cumulative yields (number of pods, potential weight, average weight of one pod, and the production: vigour ratio). At the end of the trial, after thirteen years of monitoring, competition effects were revealed which explained 8 to 10% of the residual variance after removal of the hybrid and micro-environment effects. These effects, which were detected as early as 18 months, occurred earlier than generally acknowledged. Under the trial conditions, the families could be classed as aggressive, stimulating or passive for their neighbours. Vegetative vigour (trunk cross-section) explained 34% of the competition effects (partner effects), which, with hindsight, vindicated the use of the production : vigour ratio as the main selection criterion in cocoa breeding. The partner effects noted on the production variables were never explained by any production variable, hence non-aggressive high-yielding families can be selected.

Mots-clés Agrovoc : Theobroma cacao, compétition biologique, facteur de rendement, santé des plantes, vigueur, amélioration des plantes, densité de population

Mots-clés géographiques Agrovoc : Guyane française, France

Classification Agris : F30 - Génétique et amélioration des plantes

Auteurs et affiliations

• Lachenaud Philippe, CIRAD-CP-CACAO (CIV)
• Montagnon Christophe, CIRAD-CP-CAFE (CIV)

Source : Cirad - Agritrop (https://agritrop.cirad.fr/511112/)

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