Seleção recorrente em sorgo sacarino visando o aumento no rendimento de açúcares

Abstract

Sweetsorghum is an alternative crop for ethanol production. Traits association studies have shown that the sugar content in the juice has high and positive correlation with the ethanol yield, and its inheritance is polygenic and predominantly additive, which makes justifiable the use ofintrapopulation recurrent selection in order to increase the frequency of favorable alleles. Thus, the objectives in this work were: i) to select half-sib progenies of high genetic value, as well as to estimate genetic and phenotypic parameters foragroindustrialtraits in sweet sorghum; and ii) to estimate the genetic progress after one recurrent selection cycle. In EmbrapaMilho e Sorgo (SeteLagoas/MG) was developed a base population in greenhouse with fertility restorer lines (R). After development of the base population (cycle 0), 196 sterile male progenies were selected based on total soluble solids content, so they were sown and evaluated individually in the field in two environments (Lavras and SeteLagoas). In the two sites the following traits were evaluated: flowering time (FLOW), plant height (PH), fresh biomass yield (FBY), total soluble solids content (TSS) and tons of brix per hectare (TBH). In SeteLagoas were also evaluated: dry biomass yield (DBY), sucrose (S), fiber (FIB), total reducing sugars (TRS), total recoverable sugars (TRES), hydrateethanol (HE) and ethanol yield (EY). There was genetic variation among the half-sib progenies for all the agronomic and technological traits studied, expressing the existence of genetic variability in this population. Based on the results obtained, the best 40 progenies were selected for the variable tons of brix per hectare to proceed with a new recombination step in order to constitute the population of cycle 1. Subsequently were taken 40 random half-sib progenies of each cycle (cycles 0 and 1), which were evaluated in Lavras and SeteLagoas in order to estimate the genetic progress. The genetic progress was 1.17% for FLOW, 3.73% for PH, 8.04% for FBY, 0.24% for TSS and 8.65% for TBH.