Genetic variation in growth traits and yield of rubber trees (Hevea brasiliensis) growing in the Brazilian state of São Paulo

Abstract

Analysis of variance and covariance was preformed on growth traits (stem girth, bark thickness, total height gain and rubber yield) of 22 open-pollinated progenies of the rubber tree Hevea brasiliensis from an Asian Hevea collection introduced to Agronomic Institute (Instituto Agronômico, Campinas, São Paulo, Brazil; IAC) in 1952. This progeny trial was replicated at three sites in São Paulo state and it was found that at three years from sowing there was statistically significant variation for girth, bark thickness, height and rubber yield. An individual test sites, values of individual plant heritability for girth ranged from $ h i 2 = 0.36 to $ h i 2 = 0.89 whereas values for heritability for progeny means ranged from $ h i 2 = 0.77 to $ h i 2 = 0.87. These moderate and high heritabilities suggest that a combination of progeny and within-progeny selection would be effective at increasing girth in this population at individual sites. Across sites, values of individual-plant heritability for girth ranged from $ h i 2 = 0.36 to $ h i 2 = 0.47, whereas values for heritability of progeny means girth ranged from $ h X 2 = 0.77 to $ h X 2 = 0.87. There were high positive genetic correlations between increased girth and bark thickness suggesting that breeding aimed at increasing girth would also increase bark thickness and possibly height.

Genetic variation and realized genetic gain from rubber tree improvement

“…Gonçalves et al (2005) working on mature trees found positive correlation (r = 0.54) between h i 2 and mean annual increment (r = 0.67), indicating that location productivity influences positively h i 2 values. However, there are contradictory results found in the literature.…”

“…Although the results obtained are based on relatively young progeny tests (three years), they can be used for preliminary decisions, such as initial selection of the clonal population. To increase the efficiency of the breeding and testing Hevea program at Instituto Agronômico (IAC), a research institute in São Paulo State, Brazil, Gonçalves et al (2005) analyzed 12 first generation progeny tests to find the optimum time for growth assessment. Under reasonable assumptions for age-age correlation and heritability changes over time, they concluded that the expected genetic gain per year in the breeding program was the greatest for selection between, two and three years.…”

“…Such methodologies are backed by the theory of quantitative genetics, which derives clones well adapted to a given environment. Elements of breeding methodologies are available with major contribution from Tan (1987); Simmonds (1989); Gonçalves et al (1998); Gonçalves et al (2005) and Priyadarshan & Clément-Demange (2004).…”

Variabilidade genética e seleção para caracteres de crescimento da seringueira

“…Diversos trabalhos que visam maximizar os ganhos genéticos da seringueira têm sido realizados no Sri Lanka (JAYASEKERA, 1983), Indonésia (DASLIN et al, 1986), Nigéria (ONOKPISE et al, 1986), Índia (MEENATTOR et al, 1991), Malásia (TAN, 1995) e Brasil (GONÇALVES et al, 1998;COSTA et al, 2000 a;GONÇALVES et al, 2005;FURLANI et al, 2005), dentre outros.…”

“…O método Reml/Blup, desenvolvido para o melhoramento de plantas perenes tem maximizado os ganhos genéticos com seleção (RESENDE, 2002b, COSTA et al, 2002COSTA et al, 2005;MISSIO et al, 2005), por se tratar de um procedimento estimativo, especialmente para dados desbalanceados, predizendo valores genéticos dos indivíduos em testes de progênies (RESENDE e FERNANDES, 1999).…”