Assessing growth, early yielding and resistance in rubber tree clones under low South American Leaf Blight pressure in the Amazon region, Colombia

Abstract

In Latin America, there are areas that favor the cultivation of rubber (Hevea brasiliensis) and reduce the risk of South American Leaf Blight (SALB), produced by the pathogen Pseudocercospora ulei. This study aimed to analyze the growth, early yielding and SALB resistance of nine promising clones and IAN 873 (control) in the pre-tapping and early tapping phases in a large-scale clone trial in a low SALB pressure zone in the Colombian Amazon, 2010−2019. San Vicente del Caguán (Caquetá) has climatic characteristics that are not very favorable for SALB (mean precipitation < 2600 mm year−1 and average relative humidity < 82 %). After 10 years, the better clones (FX 3899 P1, FDR 4575, FDR 5578, GU 198 and FDR 5597) presented an acceptable average for the main trunk circumference (CMT < 52 cm) at the end of the pre-tapping phase (9th year), a favorable CMT (< 58 cm) in the early tapping phase (1 st year tapping or 10th year), a superior early dry rubber yield (EDRY) (< 43 g.tree−1.tap−1), a high partial resistance to SALB (low severity, with mean scores for AT1 and AT2 < 1 and low asexual and sexual sporulation, with mean scores for TR and ST < 1) and a high percentage of leaves retained in the canopy (80–100 %), as compared to clone IAN 873. This study provides the basis for final clonal selection once peak yield (5th year tapping) is identified for later development in the Amazon region, Colombia.