Selection of Theobroma grandiflorum clones adapted to agroforestry systems using an additive index

Abstract

In fruit tree breeding, selection indices are used to identify the genotypes that combine desirable commercial and non-commercial characteristics. As Theobroma grandiflorum is generally cultivated in agroforestry systems (AFS), there is a need to develop cultivars that are adapted to such environments. In this study, the objective was to select the most promising genotypes for their future use in AFS based on the additive index, a pioneering method for this crop. The trial was carried out for 12 years in an agroforestry system in the municipality of Tomé-Açu, Pará State, Brazil. The 16 evaluated clones were completely randomised with a variable number of repetitions. The average number of fruits produced as well as the morpho-agronomic characteristics of the fruits were analysed. Mixed linear models were used to estimate the components of variance and predict the genotypic values. The genetic correlation between the variables was estimated, and the selection of genotypes was based on the additive index, with a positive orientation of all variables except the thickness of the fruit shells and the weight of the fruits. Clones 42, 44, 46, 47, 57, 61, and 64 performed well for all the analysed variables, resulting in a selection gain of 7.3% and low incidence rates of witches’ broom disease. These genotypes can be made available to producers in the form of clones for use in AFS and can further be included in future hybridisations in T. grandiflorum breeding.

Analysis of repeated measures data through mixed models: An application in Theobroma grandiflorum breeding

“…The average fruit yield per year was increasing until the fifth year, the eighth year after planting, a pre-climax period. At this stage, T. grandiflorum reaches productive maturity, a behaviour that is usually observed at commercial orchards and was also perceived by Alves and Chaves (2023) and Alves et al (2021).…”

Genomic decoding of Theobroma grandiflorum (cupuassu) at chromosomal scale: evolutionary insights for horticultural innovation

“…by Amazon indigenous populations approximately 5,000 to 8,000 years ago, has spread geographically mainly in the past 2 centuries [ 6 ]. In Brazil, cupuassu is especially important for small-scale farmers in agroforest systems in Pará, Amazonas, and Bahia, the leading states in its production [ 7 ]. In 2022, Brazilian cupuassu production reached about 28,800 tons of fresh seeds from 8,900 hectares, averaging 3.2 tonnes per hectare (State Secretariat for Agricultural Development, Agricultural Indicators, Belém, PA, Brazil, 2022).…”

“…These diseases significantly reduce pod yield and the overall health of infected plants, resulting in substantial economic losses [ 8 ]. While breeding programs have identified resistant cacao and cupuassu genotypes [ 7 , 8 ], managing WBD and FP remains challenging [ 9 , 10 ], impacting local producers and family farmer systems.…”

Genomic decoding ofTheobroma grandiflorum(cupuassu) at chromosomal scale: Evolutionary insights for horticultural innovation

“…Cupuassu, domesticated from T. subincanum by Amazon indigenous populations approximately 5,000 to 8,000 years ago, has spread geographically mainly in the last two centuries [6]. In Brazil, cupuassu is especially important for small-scale farmers in agroforest systems in Pará, Amazonas, and Bahia, the leading states in its production [7]. In 2022, Brazilian cupuassu production reached about 28,800 tons of fresh seeds from 8,900 hectares, averaging 3.2 tonnes per hectare (State Secretariat for Agricultural Development.…”

“…These diseases significantly reduce pod yield and the overall health of infected plants, resulting in substantial economic losses [8]. While breeding programs have developed resistant cacao and cupuassu genotypes [7,8], managing WBD and FP remains challenging [9,10], impacting the local producers and family farmers systems.…”