BASE TEMPERATURE AND HEAT UNITS FOR LEAF FLUSHING EMISSION AND GROWTHOF HEVEA-BRASILIENSIS MUELL ARG

In this study we determined the base temperature and Heat units for le af flushing initiation and growth of RRIM-600 and GT1 Hevea clones. Th e minimum base temperature was found to be approximately 16-degrees-C for leaf flushing emission and 19-degrees-C for shoot growth in terms of height. Approximately 420 degree days at 16-degrees-C as base tempe rature is required for successive leaf flushing initiation. Linear equ ations with correlation coefficients above 0.95 allow an estimation of the height increase from the accumulated degree days, corrected or ot herwise for photoperiod. The highest correlation coefficients demonstr ated a positive effect of the photoperiod among the factors influencin g the shoot growth.