Selection and genetic gains for juvenile traits in progenies of Hevea in São Paulo State, Brazil

Abstract

Five yield traits were investigated in three-year-old progenies from open-pollinated rubber trees [Hevea brasiliensis (Willd. ex Adr. de Juss) Muell.-Arg.]. Twenty progenies were evaluated in a randomized, complete block design replicated three times using 10 plants per linear plot at the North Central Experimental Station in Pindorama, São Paulo State, Brazil. The characters evaluated included the average yield of rubber, growth vigor, bark thickness, total number of latex vessel rings and latex vessel size. Highly significant (p < 0.01) genetic differences were observed among progenies for most traits. The genotypic variance components accounted for 13.2%, 12.3%, 9.4%, 3.4% and 0.23% of the phenotypic variance for yield, growth vigor, bark thickness, total number of latex vessel rings and latex vessel size, respectively. Heritabilities, as well as genotypic and phenotypic correlations among traits, were estimated. Heritabilities for the above traits at the individual plant level (h i 2 ) were 37%, 35%, 69%, 10% and 16%, respectively. Significant positive genotypic and phenotypic correlations were found between the yield of rubber and growth vigor (r g = 0.73, r p = 0.70), bark thickness (r g = 0.70**, r p = 0.75**) and the total number of latex vessel rings (r g = 0.64, r p = 0.80). There was no relationship between yield and latex vessel size, growth vigor or total number of latex vessel rings. Based on these data, selecting the best two out of 20 progenies would result in a genetic gain of 12.3% and 6.8% for yield of rubber and growth vigor, respectively. The two best individual ortets within each progeny would result in a genetic gain of 27.7% and 9.1%, with a total gain of 40% and 16% for these two traits, respectively.

Genetic parameters and estimated genetic gains in young rubber tree progenies

“…The positive selection gains obtained in all the assessment years and locations allows for a more reliable early selection. The values reported here are compatible with other studies, such as those by Gonçalves et al (2004b), which used a different methodology.…”

“…Higher values were reported by Gonçalves et al (2004b) and Gouvêa et al (2012). The relative variation index (CVr) showed very high values, greater than 1.0 in some cases, indicating high genetic variability for the evaluated variables, in all the years and locations.…”

Genetic variability for girth growth and rubber yield in Hevea brasiliensis

“…The predicted gain from a mass selection is about 0.60 to 19.14% for a selection intensity of 14% (i = 1.35). The heritabilities on clone mean levels and phenotypic standard deviations are close to those reported by Gonçalves et al (2004) in the same and other 10 year old trials. Heritabilities for rubber yield and bark thickness on site D were lower compared to the other sites, probably as a result of very uneven growth conditions.…”

Estimation of variance components and prediction of breeding values in rubber tree breeding using the REML/BLUP procedure

“…In general, their results have revealed that the genetic variation is largely accounted for by additive genetic variance (Valois et al, 1978;Paiva et al, 1982;Alika, 1985;Boock et al, 1995;Gonçalves et al, 1999Gonçalves et al, , 2004and Costa et al, 2000a and b). The results obtained in this study are in accordance with those.…”

“…Rubber tree improvement programs have been conducted in Brazil (Gonçalves et al, 1992(Gonçalves et al, , 1996(Gonçalves et al, , 1999(Gonçalves et al, , 2004Costa, 2000a and b;Paiva, 1994a and b) and in many other countries, such as Malaysia, Indonesia, Thailand, India and Ivory Coast (Tan, 1987;Simmonds, 1989;Priyadarshan, 2003;Clément-Demange et al, 1995. The yield improvement in rubber through breeding and selection has been spectacular.…”