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Natural Rubber Research, 24(1): 44-53, 2011 YIELD OF MODERN HEVEA CLONES AND THEIR RESPONSE TO WEATHER PARAMETERS ACROSS DIVERSE ENVIRONMENTS T. Meenakumari, J.R. Meenattoor, T.A. Soman 1 , S.K. Dey 2 , Gitali Das 3 , Shammi Raj, T. Sailajadevi, Ramesh B. Nair 4 , Anitha Raman, K 5 ., T. Gireesh and Kavitha K. Mydin Rubber Research Institute of India, Kottayam-686 009, Kerala, India 1 Hevea Breeding Sub-Station, Rubber Research Institute of India, Kanyakumari-629 851, India 2 Regional Research Station, Rubber Research Institute of India, Agartala-799 006, India 3 Regional Research Station, Rubber Research Institute of India, Nagrakata, West Bengal-735 225, India 4 Rubber Board, Kottayam-686 002, India, 5 International Rice Research Institute, Philippines Received: 3 January 2011 Accepted: 27 April 2011 Meenakumari, T., Meenattoor, J.R., Soman, T.A., Dey, S.K., Das, G., Raj, S., Sailajadevi, T., Nair, R.B., Raman, K.A., Gireesh, T. and Mydin, K.K. (2011). Yield of modern Hevea clones and their response to weather parameters across diverse environments. Natural Rubber Research, 24(1): 44-53. A total of 12 promising clones, including the newly released RRII 400 series clones were evaluated in three geographically diverse locations across the traditional and non traditional rubber growing tracts in India. The present paper reports the yield performance of these clones for the 4 th to 6 th year of tapping. The response of the clones to changes in meteorological variables in different locations in the same period was also examined. In Kanyakumari, RRII 105, RRII 430 and RRII 203 were on par. In Agartala, RRII 422 and RRII 429 were the top yielders and registered significantly superior yield to both the controls, RRII 105 and RRIM 600. In Nagrakata, RRII 429 was the highest yielder and RRII 417 and RRII 422 also recorded significantly superior yield than the controls. Genotype Environment Interactions (GEI) for rubber yield was analysed from the trials with a view to identify clones with wide adaptability as well as specific adaptation. AMMI model was selected to quantify GEI and the analysis revealed that environment (E) and GEI together contributed to the major proportion (72.8%) of the variations in rubber yield. Twenty seven percent of the total variation was attributed to genotypes (G). Genotype means ranged from 35.31 g/t/t to 56.24 g/t/t. Clones RRII 429, RRII 422, RRII 417, RRII 430 and RRII 105 were high yielding ones across environments. RRIM 600 was found to be the widely adapted clone. RRII 429 showed the highest interaction. Weather parameters viz., maximum and minimum temperatures, RH, sunshine hours and rainfall were studied in relation to rubber yield in the three locations. Maximum temperature was negatively correlated with yield in Kanyakumari, irrespective of clones. In Agartala and Nagrakata the results were however inconclusive. Key words: Environments, Hevea clones, Weather parameters, Yield.
Natural Rubber Research, 24(1): 54-60, 2011 RUBBER YIELD OF CERTAIN CLONES OF HEVEA BRASILIENSIS AND ITS RELATIONSHIP WITH CLIMATE VARIABLES T. Gireesh, Shammi Raj, Kavitha K. Mydin and V.C. Mercykutty Rubber Research Institute of India, Kottayam 686 009, Kerala, India Received: 1 February 2011 Accepted: 30 April 2011 Gireesh, T., Raj, S., Mydin, K.K. and Mercykutty, V.C. (2011). Rubber yield of certain clones of Hevea brasiliensis and its relationship with climate variables. Natural Rubber Research, 24(1): 54-60. The relationship between long term yield of seven Hevea clones and climatic parameters such as minimum temperature (Tmin), maximum temperature (Tmax), sunshine hours (s), rainfall (R) and relative humidity [RH1 (morning) and RH2 (afternoon)] was studied under a typical tropical humid climatic regime. Of the seven genotypes, RRII 105 was significantly high yielding (68.0 g/t/t), while Gl 1 (40.5 g/t/t) and RRIM 600 (43.8 g/t/t) registered relatively low yields. Climatic parameters were regressed on yield. Tmax was found to be the most important influencing factor with a negative relationship in each clone (slopes from -7.299 to - 3.353). Tmax showed less monthly variability when compared to RH in the corresponding period. RH was seen to be low during the winter and pre-monsoon seasons. Yield was found to be the most important function of Tmax (R 2 = 0.21). Most of the clones showed an increase in yield with time mainly during the monsoon season (slopes from 4.94 to 2.56 per year). The R 2 ranged from 0.30 (RRII 105) to 0.76 (RRII 203) during the monsoon season. The clone RRII 208 did not show any increase in yield, while RRIM 600 showed a varied response of yield with time over different seasons. The study indicated the moderate level of decrease in yield with increasing Tmax. However, rising temperature in the long-term climate change scenario, the yield decline in rubber clones need to be evaluated further in large scale. Keywords: Hevea clones, Rubber yield-climate relations, Selection.
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