Evaluation of selected genotypes from 1981 Hevea germplasm using morphological and physiological parameters in Sri Lanka

Most Hevea breeders believe they have exploited the maximum genetic variability of Wickham’s original introduction of Hevea brasiliensis (Willd.ex A. Juss.) Mull.Arg. Therefore, to broaden the genetic base of the major producers of natural rubber, it became necessary to undertake an expedition to the Amazon basin to obtain materials for the ‘gene pool’ in these populations. This expedition is called “Germplasm 81”. Sri Lanka received around 10,000 accessions from this expedition and they were planted in Neuchatel Estate of Kalutara District. But in Sri Lanka a proper selection evaluation of genotypes from 1981 Hevea germplasm collection has not been conducted. Therefore, this study was conducted to select superior genotypes from 1981 germplasm collection using morphological and physiological parameters. Twenty-five accessions were selected out of around 2000 accessions by evaluating their girth, bark thickness, canopy architecture and latex flow as preliminary selection criteria. These 25 accessions were multiplied and planted in a completely randomized blocked design with three replicates and each replicate contained five plants from each 25 accessions and clone RRIC 121 and RRISL 203 were used as control clones. Then, their girth, leaf area, chlorophyll content, leaf colour, tree height and inter whorl length were recorded. All parametric data were analyzed using one - way ANOVA and Duncan’s multiple range test to study the differences among accessions. According to results, accessions MT 11-76 I, MT 11-76 II, MT 10-146 and MT 11-13 were also shown to have better growth performances than other accessions and control clones. Also, their disease incidences were at a very low level. In addition to these four selections, accession MT 7-36, AC 6-13, MT 11-88 and RO 2-4 also showed good performances from observed parameters but they could not meet adequate performances as MT 11-76 I, MT 11-76 II, MT 10-146 and MT 11-13. However, it is important to take long term observations and yield parameters for further verifications of these accessions before adding them into the Breeding pool.