Low tapping frequency to increase productivity in Thailand

The purpose of this study was to assess tapping systems to decrease tapping frequency with stimulation in order to increase yield per day and tapper productivity. This experiment was set up in Chachoengsao Rubber Research Center since 2016. Experimental design was a Split plot comprising 4 replications. 3 main treatments are clones (RRIT 251, RRIM 600 and PB 235) and 4 sub-treatments are tapping systems ( S/2 d2, S/3 d1 2d3, S/2 d3 ET2.5% without recovery of lost tapping days and S/2 d3 ET2.5% with recovery of lost tapping days). Three years of tapping showed that RRIT 251 and PB 235 increased yield by 62% and 27% in comparison with RRIM 600. Regarding sub-treatments, S/2 d3 ET2.5% and S/2 d3 ET2.5%with recovery of lost tapping days could increase productivity per day (g/t/t) by 18-23%. Yield in term of kilogram per tree per year was not significantly different among tapping systems. Tapping days in d3 were only 71-81 days per year and less than for d2 and d1 2d3 with 107 and 138 tapping days per year respectively

Tapping panel diagnosis, decision support tool for more sustainable rubber tapping system

The difficulty involved in performing an agronomic diagnosis of a tree crop is obtaining an accurate picture of current and past cultivation practices, to be able to assess their impacts on the agro-ecosystem as well as on sustainability. As latex harvesting involves tapping the bark, which leaves scars on the trunk, we hypothesised that these morphological traces would be good indicators of current and past practices and would thus enable a diagnosis based on the economic lifespan of plantation. To this end, we formalized a tapping panel diagnosis that involved reproducing the scars on tapping panel diagrams, and analysing them using two indicators: the amount of virgin bark consumed and the number of tapping years that remained. We characterised eight tapping management systems reflecting different levels of tapping intensity. Assessment of the respective share of each tapping practice on virgin bark consumption revealed major effects of tapping frequency and of shaving thickness. We showed that, used as a decision support tool, the tapping panel diagnosis can increase remaining tapping years. To conclude, the tapping panel diagnosis will be a useful support for the participatory development of innovating tapping management schemes involving both technicians and smallholders. (Résumé d'auteur

Comparative studies on yield potential of some hevea clones in Cambodia

Cambodian Rubber Research Institute is carrying out researches on tapping systems to assess the influence of intensity of stimulation on yield at a given tapping frequency 1/2S d/3 7d/7. The objectives of these trials are to determine the yield potential of each clone at various intensity of hormonal stimulation. Five clones have been studied since March 2005. These clones are IRCA111, PB330, GT1, IRCA230 and AF261. Each trial consists of Fisher block design with 3 replications and four treatments per replication. Two protocols of stimulation were set up for different clones. The preliminary results show that the highest yields for the clone IRCA111 and PB330 are obtained with ET 1.5% Pa 1(1) 5/y (75 mg) and ET 2.5% Pa 1(1) 2/y (50 mg), respectively. Interestingly, the clones GT1 and IRCA230 give significant high yield at the most intensive treatments, ET 2.5% Pa 1(1) 6/y (150 mg). However, the clone AF261 does not response to more intensive stimulation system than ET 1.5% Pa 1(1) 5/y as the same yields are obtained at different intensities of stimulation. The clone GT1 gives the highest yield at increased stimulation intensity compared with other clones. (Texte intégral

Characterization of the potential yield of clone IRCA230

The experiment on Yield Potential Comparison on S/2 d3 and S/2d4 Tapping Systems of Clones IRCA230 were practiced on farm research at Chup Rubber Research Station of Cambodian Rubber Research Institute (CRRI). The experimental design was the RCBD with 8 treatments and 4 replications with a total number 400 trees per replication. They were opened at the standard girth of 50 cm measured at 1m high. All the trees were opened at 1.3 m from the ground. The tapping systems were S/2 d3 7d/7 and S/2 d4 7d/7. This clonal typology is based on measurements issued from the latex diagnosis. The objective of the experiment was to investigate the yield potential comparison of the tapping system S/2 d3 7d/7 and S/2 d4 7d/7 based on frequency of ethephon stimulation. Stimulation was related to the sucrose and inorganic phosphorus contents of the latex cells. Clone IRCA 230, with higher sugar content, with high ethephon stimulations per year obtained the highest yield. The cumulative yield in gram per tree over 8 years of tapping showed frequency d3 higher yield than frequency d4. The yield of tapping frequency with stimulation 1.5% 7/y control was higher than them. (Résumé d'auteur

The "double cut alternative" (DCA) tapping system: an innovative tapping system designed for Thai rubber smallholdings using high tapping frequency

In Thailand, the continuous decrease in the size of rubber plantations has led to the general adoption of intensive tapping systems which may lead to over harvesting, high rates of tapping panel dryness (TPD), short life-cycles of the plantations, and low labour productivity. In Thailand, farmers usually use a half-spiral downward tapping system (S/2) or a one third-spiral (S/3) with a tapping frequency of once two days (d2) or more. To increase productivity, it is difficult to reduce tapping frequencies, even with ethylene stimulation, as this would result in days without work for tappers. The purpose of this study was to characterize the behaviour of the Hevea rubber yield under the double cut alternative tapping system (DCA). The aim was to ensure the long-term sustainability of latex yield by increasing the time required for latex regeneration between two tappings through splitting this high tapping intensity (100% or above) into two different tapping cuts tapped alternately (S/2 d4 7d7 (t,t). Over a period of 10 years, compared to a single cut tapping system (S/2 d2) of equivalent intensity, DCA increased cumulative rubber production by 9%. Ability of the trees to produce more latex under DCA was related to the sucrose and inorganic phosphorus contents of the latex cells in each tapping panel. DCA produced metabolic activity more favourable to yield during the first 10 years of tapping. But DCA also resulted in higher TPD rates, a sign of a metabolic dysfunction of the productive bark. DCA is a new tapping system. Further research is required to optimize the use of the DCA strategy. Such research, particularly those related to study of multiple-cut systems, should lead to new advances in our knowledge of the physiology of the rubber tree, mainly at the trunk scale. (Résumé d'auteur

Sustainable rubber production through good latex harvesting practices: stimulation based on clonal latex functional typology and tapping panel management

The purpose of this study was to characterize the long-term behaviour of the rubber tree under different ethephon stimulation treatments and under different panel management strategies. Over a period of seven years in Côte d'Ivoire, the effect of a gradient of ethephon stimulation frequencies on yield and latex cell biochemistry was compared in four rubber tree clones, IRCA130, IRCA230, GT1 and PB217. The ability of the trees to produce more latex under ethephon stimulation was related to the sucrose and inorganic phosphorus contents of the latex cells. For high-yielding clones with low sugar content and high inorganic phosphorus content like IRCA130, no stimulation was necessary to improve yield. Conversely, the effect of ethephon stimulation on latex yield increase was significant in clones with high sucrose content and low inorganic phosphorus content such as PB217. Clones IRCA230 and GT1 had an intermediary behaviour, explained by a median sucrose content. These results will help planters to optimize latex production by choosing the most adapted ethephon stimulation to clones according to their latex cells biochemistry and their position in a clonal functional typology. A comparison of two tapping panel management strategies of rubber plots was also performed, differing by the number of panel changes: 1 and 7 panel's changes over a total period of 9 years. These treatments were applied to the clones PB260, GT1 and PB217. The panel management strongly influenced annual yield in each of the clones tested. No panel changing appeared detrimental to immediate latex production after 6 consecutive years of tapping on panel BO-1. However, after 9 years, the cumulated rubber yield obtained with one panel change only was as high as that of treatments with more changes. (Résumé d'auteur

Influence of Ethephon stimulation on latex physiological parameters and consequences on latex diagnosis implementation in rubber agro-industry

Latex Diagnosis (LD) is currently considered by Cirad and most of its rubber agro-industry partners as a routine physiological tool to optimise, at block level, the rubber yield production of the rubber plantations. Without using LD, a general stimulation recommendation per clone and per tapping year is generally applied at plantation scale, as a function of tapping cut position and direction, whatever the local and actual yield potential is. Even though this general recommendation is based on clonal physiological latex characteristics, such a global approach does not permit to consider the local specificities of the yield potential, as it avoids considering factors like soil heterogeneity, microclimate variations in larger estates and differential expression of diseases (leaf diseases, root diseases...). In this case, plantations are almost "blind" regarding suitability of the applied stimulation intensities, and uniform application of the same rate of stimulant in all homogenous cultural units may sometimes lead to optimised exploitation but may also lead locally to underexploitation in higher yield potential areas or to overexploitation in lower yield potential areas. Using LD permits to optimize the stimulation at local level (decrease of stimulation when an overexploitation is detected, increase of stimulation intensity when an underexploitation is detected) and therefore permits the yield optimisation block per block, taking into account the plantations heterogeneities and therefore the actual local yield potential. Of course, LD interpretation depends on former set up LD parameters reference values. These ones are clonal and established for the 4 parameters used in LD: latex sucrose content, latex inorganic phosphorus content, latex reduced thiols content and DRC/TSC. These LD reference values are established for 5 limit levels (very low, low, normal, high and very high), for each LD parameter (Suc, Pi, RSH and DRC/TSC), either at regional scale or, in case of large estates and companies, at plantation scale when local LD parameters database is large enough. To set up correctly these LD reference values, it is required to know what can be the general evolution of the 4 LD parameters depending on exploitation intensity. These evolutions are detailed in the document. (Résumé d'auteur

Towards optimizing smallholders yield and productivity through adoption of appropriate latex harvesting technology

In the global rubber industry, yield gaps between rubber smallholdings and rubber agro-industries are important. These gaps are important regarding land productivity (kg/ha) and even more important regarding labor productivity (kg/tapper/day). However, technical packages of GAP (good agricultural practices) and BMP (best management practices) are available from decades of research in breeding, physiology, agronomy, crop protection and latex harvesting technology. Regarding latex harvesting, the differences between agro-industries and smallholdings are very often even more important than for other disciplines: reduced tapping frequencies compensated by accurate stimulation intensities or controlled upward tapping are scarcely encountered in smallholdings, tapping quality standards are often not respected, regarding bark consumptions, bark wounding, homogenous panel management… conversely to agro-industries. The bottlenecks to introduction of the latex harvesting GAP are multiple. Among them, psychological factors based on fear and risk management and educational factors due to a certain lack of training of smallholders on the parameters accounting for latex production and productivity (tapping quality, opening norms and panel management…). Smallholders are very (too) often on their own during the mature period, from the moment tapping starts. This is rather surprising as the risk is high of non-reversible mistakes during tapping, with non-reversible consequences on the plantation further yields. All efforts granted and services provided during the immature period can then be quickly and easily annihilated by a bad tapping quality or wrong tapping practices. This makes also the latex harvesting GAP and innovations particularly difficult to take on board by the smallholders, because of a rather limited possibility of transfer of technology (TOT). Some other factors are structural: for instance, small size of farms may prevent the possible introduction of reduced tapping frequencies when the tapping taskforce cannot be shared and mutualized among different owners. In latex harvesting, GAP introduction therefore requires to emphasize education and training of smallholders/tappers, so that they can know the possible technical packages that can help them to achieve higher productivity. This supposes that trainers in charge of TOT are themselves updated on the technologies to be transferred. TOT requires as well as to set up demonstration plots or experiments, on-farm and with a participative approach, in candidate leader smallholders farms accepting to test the possible innovations and GAP, so that “everybody can see the results” and afterwards take them on board in a spontaneous manner (“If it good for my neighbor, it should be good for me as well”). This communication presents the Cirad experience on this subject

Evaluation of low frequency tapping systems with stimulation on hevea in traditional area Cambodia

In Cambodia, the common tapping system which was widely adopted by smallholders and agro-industry plantations was S/2 d3 for downward tapping and S/4 d3 for upward tapping. However, under the decline of rubber price and increasing labor shortage, the application of low frequency tapping systems (LFT) may be a choice to solve these problems. Hence, different low frequency tapping systems were tested in traditional area of Cambodia. An experiment was established using seven-year old rubber trees of RRIM 600 clone at the Cambodian Rubber Research Station located in Tbong Khmum province. The experimental design was Randomized Complete Block Design with four treatments: T0: S/2 d37d/7 ET 2.5% 4/y, T1: S/2 d4 7d/7 ET 2.5% 5/y, T2: S/2 d5 7d/7 ET 3.3% 6/y and T3: S/2 d6 7d/7 ET 3.3 % 10/y comprising three replications (12 elementary plots). There were 120 trees per treatment in each elementary plot. After 3 years of tapping, LFT system S/2 d6 with Ethephon application (T3) provided the highest dry rubber yield per tree per tapping (g/t/t) but the lowest yield in gram per tree (g/t) and kilogram per hectare (kg/ha). As compared to d3, LFT systems (d4, d5 and d6) caused dry rubber yield loss in kg/ha by respectively 3, 9 and 11% but resulted in increased labor productivity (g/t/t) by respectively 11, 28 and 48%. Therefore, the increase in labor productivity (g/t/t) was higher than the loss in land productivity (kg/ha). Girth increment was not significantly different between treatments. Sucrose and reduced thiol contents of all treatments were not significantly different but inorganic phosphorus content was significantly different depending on the tapping system. Tapping panel dryness was similar for all treatments after three years of tapping

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