| Abstract |
For rubber tree clone adaptation to water-limited areas, maintenance of trunk radial growth is a key performance of genetic material to limit the extension of the time without latex tapping, so called “immature” period, i.e. the time without income. The objective was to compare within a common field the performance of three important clones: GT1, the elder clone as control, which is still widely used in Cambodia and West Africa; RRIM600, the “allround” clone, the most planted clone in Thailand, the first world producer; and RRIT251, the expanding clone, recommended by the Rubber Authority of Thailand. The investigation was conducted in a drought-prone area of Northeast Thailand where the dry season lasts 5 to 6 months. The cumulated growth and the annual growth were analyzed 4.5 years after planting. The trunk girth and height were measured monthly. Main climatic variables were hourly recorded. The year was separated in three periods: the leaves-shed season from January to April, the wet season from May to September, and the dry season with canopy maintenance from October to December. The results showed significant clonal effect on both trunk girth and height, however with relatively low differences. The trunk girth of clone RRIT251 was about 29cm and 10% higher than GT1. The difference was not significant with RRIM600. The annual girth increment was mainly located in wet season (63%) without clonal effect. The clonal difference occurred in the dry season where RRIT251 better performed particularly in the leave-shed period preceding wet season. On a monthly basis, the relative trunk girth increment rate was highly negatively related to the vapor pressure deficit. We hypothesized that rubber clones shared a common strategy of dehydration avoidance while RRIT251 expressed a little less degree of avoidance. |
Publication
Journal Publication
ไทย