Interações alélicas na cultura da cana-de-açúcar

Abstract

This study aims to investigate the predominance of allelic effects, as well as to estimate heterosis and selection gain from genetic crossing of sugarcane originating from Serra do Ouro. The base population for this study was obtained from crossing the genotypes RB041443 and RB9629. The seeds obtained from the crossbreeding were sent to the Sugarcane Genetic Improvement Program (PMGCA) of the Engineering and Agricultural Sciences Campus (CECA), linked to the Federal University of Alagoas (UFAL). The field experiment was conducted at the experimental unit of the Sugarcane Genetic Improvement Program (PMGCA), located on the Engineering and Agricultural Sciences Campus of the Federal University of Alagoas (PMGCA/CECA/UFAL) in the city of Rio Largo – AL. The experimental design used was augmented blocks with 10 blocks, each control was allocated to 1 plot per block. Within each block there were 10 individuals and 2 controls randomly distributed, totaling 120 plots. The experimental plot consisted of planting holes spaced 1.5 meters apart. The following characteristics were evaluated: number of tillers per plot (NFP), average stem diameter (DMC, mm), soluble solids content (°Brix), height The study evaluated the following characteristics: stem diameter (AC, m), number of internodes per plot (NEP), and stem weight per plot (PCP, kg). Statistical analyses were conducted using ANOVA, variance estimation, heritability, coefficients of variation, and selection parameters, complemented by heterosis and power ratio calculations. The results indicated genetic variability among individuals, with significance for four traits, except for the number of tillers and stem weight, which were more influenced by the environment. The high heritabilities observed for stem diameter, Brix, height, and number of internodes suggest considerable genetic control, reinforcing the possibility of selective progress. Stem diameter stood out due to the predominance of genetic variance over environmental variance, while traits such as the number of tillers and stem weight showed a low CVg/CVe ratio, evidencing a high environmental influence. Heterosis estimates revealed that all six traits presented negative values, indicating an inbreeding effect, which suggests a predominance of overdominance for the number of tillers per clump. (NPT, -8.60), average stem diameter (DMC, -4.25), soluble solids content (°Brix, -2.96), and stem weight per plot (PCP, -2.16). For the characters number of internodes (NEP, -0.09) and stem height (AC, - 0.35), partial dominance was observed. It is concluded that the cross RB041443 × RB9629 presents sufficient variability for exploration in subsequent selection cycles and that understanding allelic interactions contributes to more efficient strategies in sugarcane genetic improvement. It is concluded that the results indicated genetic variability for the six characters, although the cross RB041443 x RB9629 presented negative heterosis, indicating an absence of hybrid vigor and a predominance of unfavorable non-additive effects.