Estimates of genetic parameters for the rubber yield and secondary traits in rubber tree

Selection strategies for growth characters and rubber yield in two populations of rubber trees in Brazil

“…The experimental variation coefficient (CV e ) presented values considered as high magnitude for PBS, according to Pimentel- Gomes and Garcia (2002). These values are similar to the ones found by Costa et al (2000aCosta et al ( , 2000b and Souza et al (2017), being considered as common the high values of CV e for this character since the collection of this one is subjected to experimental errors of control relatively difficult and expresses intrinsic properties of the character. However, the accuracy (r aâ ) which indicates accuracy in access to true genetic variation from phenotypic variation, in the present study presented as "high" (70% to 85%) and "moderate" (50% to 65%) according to the classification by Resende and Duarte (2002).…”

“…The values of the genotype coefficient of variation between progenies (CV gp ) were of lower magnitude for PM, than for PS, in general from low to medium magnitudes, however, the CV gp for the PBS character was of high magnitude for the improved population with 44%. The heritability corresponds to the relative proportion of genetic and environmental influences on phenotypic expression and indicates ease or difficulty in improving certain traits (Souza et al, 2017). Resende (1995) classifies heritability values ranging from 0.01 to 0.15 as low, from 0.15 to 0.50 medians and above 0.50 as high.…”

“…Only AC and FOR presented inferior ĥ a 2 , with low magnitudes (8 and 6% respectively), para a PM. According to Souza et al (2017), it is common to note differences among the ĥ a 2 , since the characters evaluated have a quantitative inheritance, that is, they are influenced by the environment. In comparison to the values of ĥ m 2 , according to Resende (2002), it is expected to find, for quantitative characters, values of low magnitude for the individual heritability and that, in general, one conduces the estimate of magnitude from moderate to high for the heritability at the average progeny level.…”

“…Another interesting procedure for the prediction of genetic values is the BLUP (Best Linear Unbiased Prediction), being more appropriate when considering the genotypic effects as random, aiming to obtain the BLUPs of said effects (Resende, 2004). The REML/ BLUP methodology is used in several species, such as in Hevea (Souza et al, 2017), Eucalyptus (Costa et al, 2015); Pinus (Santos et al, 2016), Acacia (black wattle) (Dunlop et al, 2005). Resende (2016) suggests the use of the Selegen-REML/BLUP software for the application of analysis of mixed models in the estimation of variance components and estimation of genetic parameters to optimize the conduction of plant breeding programs.…”

Genetic diversity and structure in ex situ conserved populations of Hevea brasiliensis

“…While the species continues to be exploited and rubber extracted in natural populations in the Amazon region, there are very few areas with high levels of productivity. These areas are based on the system proposed by Kageyama et al (2002) and the increased productivity is due to the selection of genotypes, initially conserved ex situ (OLIVEIRA et al, 2015;SOUZA et al, 2017), that enabled planting in a variety of agroecosystems, such as agroforestry (RIGHI et al, 2008;VIRGENS FILHO, 2014) and monocultures (GONÇALVES et al, 2011). However, successful domestication occurred outside of the species' center of origin in ecosystems where the fungus Microcylus ulei (Henn,) Arx does not occur.…”