Temporal stability of growth and yield among Hevea genotypes introduced to a non-traditional rubber growing region of peninsular India

Extensive cultivation of Hevea brasiliensis in India now focus onnon-traditional regions for rubber cultivation. As a prelude for selection of genotypes for commercial cultivation, many introduced genotypes are being tested in genotype adaptation experiments in these regions. Present study,reports for the first time, growth and yield adaptation of 28 genotypes in a non-traditional rubber growing region of peninsular India viz., the coastal Karnataka region. Agroclimate of this region was found favoring growth andestablishment of all the genotypes evaluated. However, not all the genotypes grew and yielded well. Only four genotypes, RRII 203, KRS 25, PB 260 and PB 235 showed good growth and yield. On grouping, the genotypes fell into categories of moderate high yielders, moderate low yielders and low yielders. The most popular variety of the traditional region, RRII 105 did not perform well in this region. Biological stability in growth and yield of RRII 203 and PB 260 was identified as stable and these genotypes were the best adapted. KRS 25 and PB 235 had unstable yielding pattern. The best identifiedgenotypes can be considered for extensive culture as single clone plantations or as major constituent of clone blends as well as parents in future breeding programmes. Other moderate stable yielders may be used for clone blending in smaller proportions and may be subjected to yield improvement.