Annual growth increment and stability of rubber yield in the tapping phase in rubber tree clones: Implications for early selection

Abstract The annual girth or diameter growth in the tapping phase is an important trait associated with rubber production, resistance to wind breakage and wood production. The main objective of the present study was to assess the temporal stability of rubber tree genotypes for both natural rubber production and annual girth growth in the post-tapping phase. The phenotypic and genetic correlations of these variables over the years of evaluation were estimated in a rubber tree breeding program. Thirty-two clones were assessed along with the control genotype RRIM 600 for two traits, annual production and girth growth, which were evaluated for five and six years, respectively. A randomized complete block design, with effectively split-plots in time, was used with three replicates, six trees per plot, spaced at 7 m × 3 m. We observed that negative genetic correlations of the accumulated annual girth growth with the accumulated rubber yield ( r g  = −0.58, P