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  • Joint prediction  (1)
  • Path-coefficient analysis  (1)
  • 1
    Electronic Resource
    Electronic Resource
    The role of pith, tube, and stalk density in determining sugarcane sucrose content and stalk weight (1990)
    Springer
    Theoretical and applied genetics 79 (1990), S. 273-277 
    Details
    ISSN: 1432-2242
    Keywords: Saccharum spp. ; Genetic variance ; Heritability ; Path-coefficient analysis ; Genetic correlation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Selection against pith and tube is one of the major criteria used to eliminate inferior sugarcane (Saccharum spp.) cultivars in early stages of new cultivar evaluation. Understanding the genetic relationships for these traits would facilitate crossing and selection decisions. This study was conducted to determine heritability, genetic coefficient of variation, and the potential for genetic advance by selection for pith, tube, and stalk density. Correlation and path-coefficient analysis studies were conducted to determine the effects of Brix, pith, and stalk density on sucrose content and the effects of stalk volume, tube, and pith on stalk weight. Eighty randomly selected cultivars (four progeny from each of 20 crosses), representing a first clonal stage of a Louisiana sugarcane breeding population, and their parents were planted at St. Gabriel/LA, and yield data were collected in 1986, 1987, and 1988. Pith and tube exhibited large genotype and genotype-by-year variation, whereas variation in stalk density was nonsignificant. Broad-sense and narrow-sense heritabilities were high, moderately high, and low for pith, tube, and stalk density, respectively. Path-coefficient analysis revealed that stalk volume was the major factor determining stalk weight. Tube and pith were factors that decreased stalk weight. As expected, Brix was the single most important factor determining sucrose content, however, high stalk density and low pith were also associated with high sucrose content. Sugarcane breeders should practice stringent selection for low pith across years to increase stalk weight and sucrose content. Since stalk density was effectively increased by high sucrose content and low pith, the use of stalk density in breeding and selection should be avoided. The minimal effect of tube on stalk weight suggests that its use as selection criteria be minimized or dropped.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225963
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  • 2
    Electronic Resource
    Electronic Resource
    Estimating the potential of sugarcane families to produce elite genotypes using bivariate prediction methods (1992)
    Springer
    Theoretical and applied genetics 84 (1992), S. 633-639 
    Details
    ISSN: 1432-2242
    Keywords: Sugarcane ; Joint prediction ; Bivariate normal probability ; Best linear unbiased predictors(BLUPs) ; Family selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Three bivariate statistical methods to predict the family potential to produce elite progeny were studied to improve the efficiency of a sugarcane (Saccharum spp.) breeding program. Progeny from 15 piparental crosses were evaluated in plant cane and first ratoon seedlings, and in clonal plant cane plots during 1989 and 1990. The bivariate predictions of Brix combined with cane yield components (stalk number, stalk weight, stalk diameter, stalk length, and stool weight) were investigated. The best linear unbiased predictors (BLUPs) and the sum of ranks based on family mean values of two traits (RANK) were repeatable among tests in the estimation of family potential. Bivariate normal probabilities (PROB) estimated with family means, phenotypic standard deviations, and genetic correlations generally demonstrated poor repeatability among tests. The three statistical predictions were compared with the progeny selection rate within the crosses through three selection stages. Predictions were not correlated to the selection rates of eight crosses with smaller initial progeny populations (〈 500 progeny). However, when the predictions were compared with the 7 of 15 families over which 1,000 progeny for each cross had been evaluated, the rankings based on BLUP and RANK bivariate predictions of Brix and stool weight identified the better crosses. PROB was inconsistent in this regard. Early selection work is highly subjective. We speculate that near-random selection occurs for stalk number at the initial selection stage and that the high selection rate at this stage (≈5%) generates a first clonal population (10 to 25) that is too small to accurately base selection rates for stalk number. Larger initial progeny populations produce sufficiently large clonal populations (〉50) to appraise crosses using selection rates. The study suggested that family evaluations for breeding programs can use bivariate predictions. The comparative ease of calculating the RANK estimate versus the BLUP along with the absence of any apparent loss of predictive value suggests that the RANK method would be the most suitable statistic to use for bivariate predictions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224162
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