A protocol for identifying breeding groups to select sugarcane genotypes (Saccharum spp.) according to sucrose accumulation curves

OSTENGO, S.; RUEDA CALDERÓN, M.A.; BRUNO, C.; CUENYA, M.I.; BALZARINI, M.

Sugar Tech

Springer India

Año: 2023

0972-1525

Sucrose accumulation curves represent the maturity profile of sugarcane, which is considered as a character of interest for the selection of genotypes in breeding programs. However, variations due to the environment (E) and interaction between genotype and environment (G×E) may be confused with the effect of genotype (G) and hinder the selection process of promising clones. The objective of this study was to identify a group of accumulation curves with high intra-group genotypic variability in the sucrose accumulation process throughout several E. This breeding group is then used to select genotypes according to their maturity profile. A protocol is presented whereby the following statistical tools are integrated: (i) classification of non-linear accumulation curves according to parameters associated with the beginning of the maturity process, sucrose accumulation rate and the time elapsed until the accumulation rate decreases, (ii) estimation of the genotypic contribution to intragroup variability of each accumulation curve parameter within each group, and (iii) identification of the group of accumulation curves to be considered as a breeding group. i.e. with the higher contribution of genotypic variability to total variance of sucrose accumulation parameters. The novelty of the work lies in the sequence of analytical steps to identify information useful to select genotypes according to their maturity profile. The protocol involves estimating parameters of nonlinear models for fitting maturity curves in multi-environment trials, clustering of curves according to the sucrose accumulation parameters and estimation of variability due to G, E, and G×E within each cluster to identify the breeding group. Its implementation is illustrated using 175 sucrose accumulation curves of nine sugarcane clones evaluated in different crop cycles (first and second ratoons) and several environments (7 to 50 for each clone) in Tucumán, Argentina. The proposed protocol allows identifying sucrose accumulation curves that exhibit a high genotypic variance, thus facilitating the selection of the best clones.