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

Tapping and ethylene stimulation induce s the dynamic change of latex cell metabolism. Those changes under the implement of low frequency tapping systems with ethylene stimulation were investigated during the both periods ( low yield and the high yield) of the year of production. The experiment was established at Thepa Research Station, Songk hla province by using 9 - year - old rubber trees (clone RRIM 600). An experiment was arranged as One Tree Plot design, there were five treatments following T1: S/3 d1 2d/3, T 2: S/2 d2, T3: S/2 d3 ET 2.5% Pa1(1) 8/y (m), T4: S/3 d2 ET 2.5% Pa1(1) 4/y (m) and T 5: S/3 d3 ET 2.5% Pa1(1) 12/y (m). There were three replicates in each treatment. It was found that ethylene stimulation affected the responses of initial flow rate (IFR), plugging index (PI), average latex yield (AY) and sucrose content (Suc). There was a significant difference among the treatments in the both periods. After ethylene stimulation, IFR of the T3 and T5 were superior in the low yield period and showed inferior in the high yield period compared with the T1. PI rapidly decreased in the ethylene application treatments in the both periods. AY of the T3 was the highest in the low yield period and AY of the ethylene stimulation treatments was higher than non - stimulated treatments in the high yield period. Suc of the T3 only increased on the first ta pping day after stimulation in the both periods. Expression to the ethylene stimulation in the low yield period was higher than the high yield period. It was remarkable that the stimulation was effecti vely expressed during a full canopy stage. With the pos itive impact of stimulation on latex physiological parameters, latex yield under low frequency tapping could be compe nsated by ethylene application. (Résumé d'auteur)