Caracterización morfofísica de almendras de cacao (theobroma cacao l.) de los genotipos de la colección utmach

Abstract

Cocoa is a crop distributed mainly in tropical areas, approximately 50 countries are producers of this crop, thanks to the genotype-environment interaction and ethnobotanical factors, three varieties of cocoa have been differentiated: criollos, forasteros and trinitarios. Ecuadorian cocoa is highly valued and recognized as "fine aroma cocoa". The general objective of this research is to characterize dry cocoa beans using tools and descriptors to understand the phenotypic diversity of each genotype. It was developed in the cocoa area of the Santa Inés Farm, belonging to the Faculty of Agricultural Sciences of the Technical University of Machala, a stratified selection was made from the collection established in the Farm collected from the National Cocoa Program in 1979, For this reason, each accession is a different genotype and a code was designated for each one, with a total of 72 accessions from which completely healthy cobs were harvested and then the whole post-harvest process was carried out to finally characterize the dry beans, the following variables were taken into account: kernel length (mm), kernel width (mm), kernel thickness (mm), kernel weight (g), husk weight (g), nib weight (g), kernels per ear, healthy ears per tree, ear index, kernel index, kernel percentage (%), husk percentage (%), annual yield (t/ha/year), dry grain color, grain plumule color, plumule length (mm), grain bulk density (g/cm³)), grain moisture (%), of which 16 were quantitative variables and 2 were qualitative. The results obtained were analyzed in IBM SPSS STATICS 22 software, where principal component analysis (PCA) was performed, where it was evidenced that the most discriminating descriptors for cocoa beans were, Component 1: bean weight (PG), bean index (GI), nib weight (Pni), ear index (IM); Component 2: percent husk (PoC), percent bean (PoG); Component 3: bean thickness (EG), beans per ear (GM), healthy ears per tree (MSA), which explained 62.169% of the total accumulated variance. In the cluster analysis for multistate data with values of the projections called factorial scores of the principal component analysis, a dendrogram was generated based on similarity distances, where 3 groups were generated: group 1 which was integrated with 7 subgroups, group 2 integrated by 2 subgroups and group 3 where only the accession FCA 65 was found, which is the genotype that presents greater phenotypic variability based on seed descriptors, the discriminant variables that allow to give reason for its diversity are: healthy ears per tree (5), annual yield (0.2 T/ha/year), grain color (5YR3/2), plumule color (5YR3/4), plumule length (6.8 mm) and relative humidity (5.7 %). Of the 72 accessions studied according to data obtained from formulas 10 accessions stand out for their high annual yield: FCA 72, FCA 60, FCA 32, FCA 34, FCA 68, FCA 27, FCA 57, FCA 52, FCA 3, FCA 56, where the following quantitative variables were taken into account, ears harvested per year, ear index, seed index.