Int J Biometeorol (2005) 49:189–196 DOI 10.1007/s00484-004-0222-6 ORIGINAL ARTICLE Shammi Raj · Gitali Das · Jacob Pothen · Sushil Kumar Dey Relationship between latex yield of Hevea brasiliensis and antecedent environmental parameters Received: 14 January 2003 / Revised: 14 June 2004 / Accepted: 24 June 2004 / Published online: 28 July 2004  ISB 2004 Abstract A study on the relationship between latex yield and antecedent environmental data was undertaken for five clones (RRII203, RRII118, RRIM600, RRII105 and GT1) of Hevea brasiliensis (rubber) in Agartala, northeast India, a region in which rubber is not traditionally culti- vated. The explained variance for the regression equations based on parameters determined on the day of tapping and up to 3 days prior to it, varied from 72% to 37% during the NWT period and 94–83% during the WT period. Soil moisture storage, 1 and 3 days prior to tapping, was found to be the primary parameter affecting yield for the NWT and WT periods, respectively. It was observed that the clone RRII105, with a comparatively lower yield to that of RRIM600, was more susceptible to daily WD condi- tions during the non-winter season. RRIM600 and RRII105 being high-yielding clones were also found to be fairly dependent on the AT of the day prior to tapping. The mean lag period correlation of this parameter with yield was also found to be higher during the WT period than during the NWT period. As a whole, the mean lag period based on prior measurements of environmental variables showed optimum correlation with yield at 15–20 days prior to the day of tapping. The study also confirms that varied responses of yield with environmental factors in this non-traditional region of rubber cultivation depend on clonal character. Keywords Agroclimate · Yield · Soil storage · Lag period · Winter tapping period Abbreviations Computed parameters AT: Average temperature · DT: Difference between maximum (previous day) and minimum temperature (succeeding day) · PE: Potential evapotranspiration · RD f–a : Difference in relative humidity values between succeeding day (morning) and previous day (afternoon) · SI: Sine of the Julian day of year · ST: Soil storage · T 5–10 D: Difference in soil temperature between 5 cm and 10 cm depth · T 10–20 D: Difference in soil temperature between 10 cm and 20 cm depth · T 5 D, T 10 D and T 20 D: Decrease in respective soil temperature of 5, 10 and 20 cm depths of the previous day (afternoon) to that of the succeeding day (morning) · VD: Vapour pressure deficit · VP f–a : Difference in vapour pressure values between succeeding day (morning) and previous day (afternoon) · WD: Water deficit · WS: Water surplus · WT: Winter tapping · NWT: Non-winter tapping · CC: Correlation coefficient · CV: Coefficient of variation Observed parameters E: Evaporation · P: Rainfall · R: Relative humidity · T n : Minimum temperature · T x : Maximum temperature · T 5 ,T 10 ,T 20 : Soil temperatures at 5, 10 and 15 cm depths, respectively · V: Vapour pressure Subscripts a: Afternoon · f: Forenoon Introduction Rubber (Hevea brasiliensis) is traditionally cultivated in the equatorial belts and humid zones of tropical and monsoon climates. Exuberant foliage of rubber does not depend solely on high incident radiation and abundant precipitation in humid tropical climates (Monteny et al. 1985). Attempts have been made to extend rubber culti- vation to areas as far north as 29N in China and 23S in S. Raj ( ) ) · S. K. Dey Rubber Research Institute of India, Regional Research Station, Agartala, 799006, Tripura, India e-mail: shammiraj@rubberboard.org.in Tel.: +91-381-2352354 Fax: +91-381-2353149 G. Das RES, RRII, Nagrakata, West Bengal, India J. Pothen Central Experimental Station, RRII, Chethakkal, Kottayam, India