Contributions of weather variables for specific adaptation of rubber tree (Hevea brasiliensis Muell.- Arg) clones

Abstract

The specific adaptation of 15 rubber tree (Hevea brasiliensis) clones was assessed by analyzing yield during a normal year ) and a year in which the yield was exceptional. Differences in yield in response to changes in weather conditions over the years were evident with clones RRII 203, RRIM 703, PB 5/51 and PB 235 which all exhibited a negative trend with increasing wind velocity during 1997-98, these clones also exhibited a negative correlation with minimum temperature during 1998-99. The prominent yield differences across the years made selection based on both yield and stability inevitable through computing weather variables and environmental index as covariant. To determine the contribution of variable(s) to genotype-environment (GE) interactions, the GE interaction was partitioned into heterogeneity and residual GE interaction. Heterogeneity only for environmental index was highly significant (p = 0.01), meaning that stability or instability of clones was due to a linear effect of the environmental index. The non-significant values of heterogeneity for the weather variables revealed that none of these factors individually was sufficient to explain heterogeneity. A QBASIC computer program called STABLE was used to select simultaneously for yield and stability. Clones PB 235, RRII 118, RRII 203, RRIM 703 and RRIM 600 were stable over the years investigated.

Current trends of rubber plantation expansion may threaten biodiversity and livelihoods

“…We then used a species distribution modelling approach, whereby the native rubber records were combined with environmental layers to produce a spatially explicit model of habitat suitability for rubber. We explored a range of modelling methods using the R library 'dismo' of which MaxEnt (Phillips and Dudik, 2008) produced results that were closest to areas known to be historically suitable for rubber (Li and Fox, 2012;Priyadarshan et al, 2005), and response curves that were in closest agreement with existing literature on agricultural trials (Mokhatar et al, 2011;Nair et al, 2010;Priyadarshan, 2003aPriyadarshan, , 2003bPriyadarshan, , 2011Priyadarshan et al, 2005;Rao et al, 1998). The final model achieved a mean Area Under Curve (AUC) of the receiver operating characteristic of 0.97 (AE0.014 SD) under 10-fold cross-validation.…”

Stimulation affecting latex physiology and yield under low frequency tapping of rubber (Hevea brasiliensis) clone RRIM 600 in southern Thailand

“…As observed by Sreelatha et al (2007). Priyadarshan (2003) reported low yield during May to September and high yield during October to January in any given year. In addition, high temperature, defoliation and refoliation were also impacted on latex yield (Rao and Vijayakumar, 1992).…”

Pengaruh Perbedaan Letak Geografi Terhadap Pola Produksi Tahunan Tanaman Karet

“…Data dari kedua kawasan di Vietnam tersebut menunjukkan bahwa pada bulan FebruariMaret, yakni saat gugur daun, produksi karet sangat kecil, sedangkan puncak produksi terjadi di sekitar bulan Oktober -Desember. Tingginya produksi ini dipengaruhi oleh letak geografis yang berhubungan dengan iklim dan fenologi tanaman (Thanh et al,1997;Priyadarshan, 2003).…”