Estimating the potential of sugarcane families to produce elite genotypes using univariate cross prediction methods

Abstract

A quick, accurate method to determine the potential of a sugarcane (Saccharum spp.) cross to produce elite progeny is needed for maximizing genetic gain. Development of a practical cross appraisal method was initiated by evaluating 1,800 progeny from 15 crosses among 23 parents at two intrarow plant spacings (41 cm and 82 cm). Plant spacing was examined for its affect on stool weight variability. The goals were to identify the most reliable and/or easily obtained cross appraisal statistic and to determine the earliest breeding program stage and crop to collect these statistics. Three tests, on plant cane (PC) and first ratoon (FR) single stool seedlings and clonal plant cane plots, were conducted. Four statistics, the family mean, the estimated elite proportion (PROB), the observed elite proportion, and the best linear unbiased predictor (BLUP) were estimated and examined for each cross. These statistics were strongly correlated within each test (0.69≤r≤1.00). Family worth estimates based on single stool data were moderately correlated (ca. range 0.5≤r≤0.7) to the family worth estimates based on clonal plots.The research suggested that the potential of a cross to produce elite progeny for a trait could be accurately predicted by the cross mean of that trait. Data for the mean were the most easily obtained and, hence, would be the most practical family appraisal statistic to use in a breeding program. Correlations of statistics among the PC and FR seedlings and the clonal plots showed that the PC estimates of Brix, stalk weight, and its components, stalk length and stalk diameter, could be used for cross appraisal. Genotypic selection by the Louisiana Sugarcane Variety Development Program (LSVDP) occurs among the FR seedlings. FR stalk number and PC Brix and stalk weight data could be used to perform family selection prior to the currently practiced individual plant selection. The benefits of family selection to the LSVDP were demonstrated by the expected genetic gains for two selection scenarios. The gains were consistently larger for an initial 50% family selection and subsequent 20% individual selection than they were for simple individual selection at a 10% selection intensity. Our research also suggests that the use of a wider intrarow spacing may improve the ability to discern among seedlings due to its enhancement of stool weight variability.

Eficiência De Índices De Seleção Utilizando a Metodologia Reml/Blup No Melhoramento Da Cana-De-Açúcar

“…O índice multiplicativo é construído pela multiplicação dos valores padronizados de cada caráter avaliado (Subandi et al, 1973) e o TBH é resultante da associação dos caracteres altura, diâmetro, densidade e número de colmos e BRIX (Bressiani et al, 2001). Os três primeiros caracteres são determinantes da massa média de colmos (Chang & Milligan, 1992;Ferreira et al, 2007). Na Tabela 4 são apresentados os ganhos genéticos totais esperados com a seleção ao se utilizar os índices e a seleção direta para TBH, estes sendo conferidos pela estimativa denominada GS, e a seleção indireta para TBH via índices de seleção (GSI).…”

Consistency of the results of path analysis among sugarcane experiments

“…Therefore, the use of this methodology in sugarcane breeding programs is highly worthwhile in its initial stages because the methodology aims at indicating the most adequate characteristics so that indirect selection be made of the most productive families since quantifying their production is quite a slow job due to the large number of genotypes assessed in these stages (Barbosa and Silveira 2012). In addition, knowledge of a consistent pattern of relationship between the component variables of production may present new perspectives on estimating sugarcane weight (SW), which is usually practiced in studies where the plots are not harvested and sugarcane weight is estimated in accordance with Chang and Milligan (1992).…”

Evaluating sugarcane families by the method of Dynamic Technique for Order Preference by Similarity to Ideal Solution (DTOPSIS)

“…In the present study, weight coefficients of 0.30, 25, 0.25, 0.10 and 0.10 were given to traits Brix, MS, SD, PH and pith, respectively (Table 4). A high-yielding commercial variety requires satisfactory stalk number, stalk diameter, and stalk length (Chang and Milligan, 1992). Stalk number is the most important component of cane yield (James, 1971;Milligan et al, 1990) and stalk diameter is a reliable trait for selection at seedling stage (James and Miller, 1971;Tai and Miller, 1989) and it is also important for hand harvesting practiced by farmers in some sugarcane regions.…”

“…The potential of a cross to produce elite progeny for a trait could be accurately predicted by the cross mean of that trait (Chang and Milligan, 1992), and there are several traits such as Brix, millable stalks per stool (MS), stalk diameter (SD), plant height (PH), and percent pith which could be used to determine the superiority of sugarcane families. The objectives of this study were to determine the potential of the DTOPSIS method for the evaluation of sugarcane families by comparing the C i to the selection rate at later clonal selection stages.…”