Yielding Potential of Rubber (Hevea brasiliensis) in Sub-Optimal Environments

Abstract

SUMMARY Rubber production has been extended to many sub-optimal environments worldwide during late 1970s. Prominent among them are northeast India, highlands and coastal areas of Vietnam, southern China and southern plateau of Brazil. In addition to near-ideal growing conditions, these areas offer stresses like low temperature, higher altitude, diseases and wind. South China experiences all these stresses due to expanse of land mass and extremely diverse climate. A number of rubber clones are being evaluated along with derivation of new recombinants adaptable to these areas. Rubber clones are seen to exhibit specific adaptation in these areas. A negative relationship of yield with minimum temperature, wind velocity and evaporation is very distinct in all clones in Tripura (NE India). While RRIM 600 can be adjudged as a universally adapted clone with moderate yield under all these sub-optimal environments, specificity in yield adaptation goes in favor of PB 235, RRII 208, RRII 203 and HAIKEN 1 (India); RRIM 600, GT 1 (Vietnam); REYAN 8-333, PB 235 (China) and PB 235, FX-3864 (Brazil). Though PB 235 gave higher yield in these areas, recommendations for commercial cultivation are impeded as a result of high wind damage. Clonal specificity for adaptation is distinct.