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The evolution of the mesostructure (structuring dynamics) of natural rubber (NR) during maturation after different modes of coagulation is poorly known, especially inside wet coagula. Therefore, coagula made from 3 different coagulation modes (sulfuric acid, formic acid, and natural coagulations) with different maturation durations (0, 2, 9, 16, 30, and 44 days) were studied. The mesostructure of NR samples was analyzed using SEC-MALS on wet coagula and on wet and dry crepes. For wet coagula coagulated with acids, only Mz and Mw decreased slightly with maturation time, while Mn and Gel>1 μ had no significant evolution during maturation. On the other hand, for wet coagula after natural coagulation, all mesostructure indicators evolved significantly with maturation time. The results showed that structuration increased along maturation time, generating microaggregates with larger size and more structured macrogel inside wet coagula after natural coagulation. This study found that creping process (comparison of wet coagula and wet crepes) had only a moderate effect on the structuration of NR samples. However, the drying process (comparison of wet and dry crepes) had an important effect on the structuration of rubber, especially for natural coagulation and formic acid coagulation. Coagulation with sulfuric acid appeared to slow down the phenomena related to the structuration of microaggregates and macrogel.

In a situation of global health crisis still present in 2021, the year was marked by a surprising stability of natural rubber prices in a context of rising raw materials in general (including oil), but also of synthetic elastomers such as styrene-butadiene rubber (SBR)—the main competitor of natural rubber—with an increase of 58% between January and October 2021. Except for the month of January 2021 when the Standard Malaysian Rubber (SMR) 20 FOB Kuala Lumpur price caught up with its December 2020 backwardation, the price of natural rubber (SMR 20 FOB Kuala Lumpur) remained stable throughout the year - in the range of $1,700/t for SMR 20 FOB Kuala Lumpur with small swings in the range of ±$100/t, or ±6%.

The purpose of this paper is to present research results relative to impacts of Climate Change on natural rubber production, potential means of adaptation and contribution of rubber to livelihoods resilience to climate change following a recent workshop organized by IRSG in collaboration with CIFOR/FTA, IRRDB and CIRAD. Climate change already impacts rubber production. In some regions longer dry seasons and more variable precipitations threaten the survival of young plants. Rubber has never been planted in areas with an average temperature higher than 28°C; as latex flow after tapping depends on temperature, higher temperatures may have a severe impact on production. Abnormal rains can also disrupt tapping. These modifications will drive a shift of climatically favourable areas. Most pests and diseases affecting rubber are strongly influenced by climate conditions. Climate change is thus likely to modify their distribution and impacts. Without adaptation natural rubber production is projected to decline, in a context of otherwise increasing rubber demand. Three types of adaptation measures can be mobilized: management, breeding, and medium-term planning of plantation renewals and expansion in marginal areas. Management measures include partially shading young plants, mulching them, partial irrigation and life-saving irrigation to address increased risks of drought as well as adopting measures that reduce runoff. Systematic use of rain guards can address impacts of heavy rains on tapping. Better monitoring, prevention and early intervention can reduce damage by pests and diseases. Genomic assisted selection and collection of wild germplasm can support breeding progress towards high yielding, climate resilient and disease resistant clones. Such measures need to be supported by policies promoting the renewal of plantations and changes of practice. As shown by Sri Lanka the National Adaptation Plan (NAP) can offer opportunities to develop an integrated approach to adaptation of rubber to climate change and to contribute to the adaptation of smallholders.

Dans un contexte de crise sanitaire mondiale ayant entraîné une crise économique d'une ampleur exceptionnelle, l'année 2020 a été marquée par de fortes évolutions du cours du caoutchouc naturel (à la hausse comme à la baisse) mais aussi par une récession tant en termes de production qu'en termes de consommation. La crise du Covid-19 a été, pour le moment, un énorme catalyseur des évolutions déjà engagées en 2019 dans la filière Hévéa.

CIRAD, the French Agricultural Research Centre for International Development, is a public establishment (EPIC) working for the sustainable development of tropical and Mediterranean regions. The research in CIRAD is dedicated to various tropical value chains, including natural rubber (NR). Several CIRAD's research units are mobilized to study NR in various fields such as agronomy, genomics, socio-economy or technology/quality. NR is a biopolymer produced from the latex of Hevea brasiliensis. NR exhibits very specific properties (low heat build-up, crystallization under strain, etc.) never mimicked by synthetic rubbers and it is thus a highly strategic material, in particular for tire industry which uses 80% of the global NR production. However, NR presents a drawback: the rather non consistency of its quality linked to the variability of the latex composition used to manufacture NR. As a consequence, an additional energy cost is required by industrial processes to tackle the NR/latex variability. This presentation will focus on different research projects led by CIRAD's researchers of UMR IATE and their partners to address the question of the variability of NR quality. A first part will be dedicated to the description of the tools used to characterize NR and latex at various scales, i.e. macroscale (NR bulk properties), mesoscale (macromolecular chains and aggregates) and microscale (biochemical/mineral compositions and structures). Then, a few results will be exposed in the second part to illustrate how this multiscale characterization approach is implemented to study various factors of influence (e.g. genotype, agronomic and post-harvest practices), in order to identify and possibly rank the drivers of the variability of NR/latex quality.

Against the backdrop of a global health crisis that has led to an economic crisis of exceptional proportions, 2020 has been marked by strong changes in the price of natural rubber (both upwards and downwards) but also by a recession in terms of both production and consumption. The Covid-19 crisis has, for the moment, been a huge catalyst for the developments already underway in 2019 in the rubber sector.

L'année 2019 est assez atypique tant sur le plan de l'évolution du cours du caoutchouc naturel que sur les quantités produites et consommées dans le monde. Si l'année 2018 avait été marquée par une lente, mais durable chute des cours tout au long de l'année, en revanche, 2019 présente un profil assez chahuté, mais avec un niveau moyen légèrement plus rémunérateur comparé à l'année 2018.

2019 was quite an atypical year for natural rubber both in terms of price evolution, as well as the quantities produced and consumed worldwide. While 2018 was marked by a slow, but lasting fall in prices throughout the year, 2019 was more fickle in character, but slightly more remunerative on average than 2018.

Malgré des fondamentaux favorables, le prix du caoutchouc naturel a continué à baisser en 2018, victime d'un climat automobile défavorable en particulier en Chine. Les efforts consentis par les producteurs en termes de diminution des productions et des exportations de recherche de nouveaux débouchés se sont révélés vains. Peu à peu, la géographie du caoutchouc change au profit de nouveaux producteurs asiatiques et africains profitant de coûts de production plus faibles.

La reprise tant attendue n'a pas eu lieu alors que la reprise économique mondiale est devenue une réalité en 2017. Et pourtant, l'année 2017 avait bien débuté avec une hausse des cours qui avait commencé en août 2016. Rappelons que, pendant cette période, le cours du caoutchouc SMR 20 Fob Kuala Lumpur est passé de $ 1 300 par tonne (22 août 2016) à $ 2 430 par tonne au 31 janvier 2017, soit une hausse de 87 % en cinq mois. Mais voilà, le marché en a décidé autrement, et depuis le 1er février 2017, le cours a baissé tout au long de l'année. La baisse a été rapide et brutale jusqu'au 6 juin, atteignant $ 1 400 par tonne SMR20 Fob KL et perdant ainsi 42 % de sa valeur en quatre mois, puis le marché s'est stabilisé aux alentours de$ 1 450 jusqu'à la fin de l'année 2017, avec une légère remontée très ponctuelle début septembre à$ 1 680 par tonne SMR20 Fob KL. Dans le même temps, le cours du Brent passait de $ 55 à $ 48 le baril au cours du premier semestre, suivant ainsi la tendance baissière du caoutchouc naturel, pour remonter ensuite fortement à$ 63 le baril à fin novembre 2017, ce qui n'a pas été suivi par le caoutchouc naturel en 2017 et au début de 2018. Ainsi, les évolutions ont été bien différentes en 2017 et au début de 2018.

L'inversion des cours sur le marché international tant attendue s'est enfin produite au cours de l'année 2016. Rappelons que, depuis février 2011 et ses $ 5 700 la tonne, le cours du caoutchouc SMR 20 FOB Kuala Lumpur n'a pas cessé de baisser, malgré quelques remontées ponctuelles de courte durée et de faible amplitude, pour atteindre son niveau le plus bas en janvier 2016 ($ 1 090/t) perdant 80% de sa valeur en cinq ans. Pendant l'année 2016, le cours du SMR 20 FOB Kuala Lumpur a doublé passant de $ 1 090/t à $ 2 059/t le 3 janvier 2017. Dans le même temps, le cours du Brent passait de $ 30 à $ 58 le baril. Si globalement ces deux matières premières ont suivi la même tendance, en revanche, au cours de l'année, les évolutions ont été différentes.

Quality of the produce is crucial in ensuring fair price to the farmers. Farmers' practices followed in harvesting and post harvesting affects the quality of rubber produced. The present study identified the practices most commonly adopted by cup coagulum producers in different regions of Thailand and its possible effect on quality of the produce. Data were collected through individual interviews with 771 farmers distributed in the historical and new rubber-producing areas. The classification of farmers based on the combination of three practices with a potential adverse impact on rubber quality viz. non-rubber contaminants, latex coagulation process and coagulum maturation, identified the diversity of harvesting and post-harvest practices. Practices were not uniform within regions. However, regional specificities could be highlighted. The main risks for rubber quality were systematic coagulation with sulfuric acid in the Centre-east and North-east and the presence of non-rubber contaminants in the South. Farmers were unaware of the good practices for quality production, the kind of acid that they used, and the impact of their practices on quality. Significant gap exists between the processors' concerns and the farmers' perception of rubber quality. Since the sustainability of smallholders' production largely depends on their ability to meet the quality requirements, interactions between the stakeholders is highly warranted.

Si l'espoir d'une remontée a réussi à tenir le temps du premier semestre 2015, en revanche tout s'est effondré cet été pour atteindre en tout début 2016 un niveau jamais atteint depuis douze ans (soit en 2003) à $ 1 070 par tonne de SMR 20 Fob Kuala Lumpur. Fin 2003, le Brent s'appréciait à$ 27 par baril soit à un niveau assez proche du cours actuel. Rappelons-nous que le début de l'année 2015 avait bien mal commencé puisque le cours du SMR 20 avait atteint son plus bas niveau depuis de nombreuses années en atteignant le niveau de $ 1 500 par tonne Fob Kuala Lumpur. Au cours du premier semestre, après une période de stabilisation à $ 1 400 par tonne SMR 20 pendant les quatre premiers mois, le cours s'est redressé atteignant $ 1 620 par tonne SMR 20 au premier jour de juin. Les mauvaises nouvelles de la croissance en Chine et la dévaluation du Yuan ont inversé la tendance et la baisse a pratiquement été continue jusqu'à la fin de l'année avec une résistance sur les deux derniers mois aux alentours de$ 1 150 par tonne SMR 20. Puis de nouveau en fin d'année et en début 2016, le même scénario s'est reproduit de la part de la Chine faisant décrocher le cours du caoutchouc naturel une seconde fois. Après avoir perdu 32 % de sa valeur en 2014, le caoutchouc naturel a perdu 26 % en 2015. Les niveaux atteints aujourd'hui ne sont plus du tout rémunérateurs pour les acteurs de la première transformation et en tout premier lieu pour les petits producteurs qui représentent 79 % de la production mondiale de caoutchouc naturel. Le petit planteur thaïlandais ne touche plus que 35 bath/kg de caoutchouc, loin des 100 bath/kg de l'année 2011. Cette grave crise remet en cause la durabilité de cette filière et provoque même dans certaines régions la disparition de certaines plantations, ce qui est encouragé par certains pays. Rien n'a pu contrebalancer cette baisse malgré de nombreuses initiatives. On peut citer la volonté de créer un nouveau marché "physique" géré par l'ITRC/IRCo (International Rubber Consortium), mais aussi la volonté du Vietnam, troisième pays producteur de caoutchouc, de rejoindre l'ITRC. Enfin les discours de la nouvelle directrice de l'IRCo qui dénonçaient les fausses informations sur la prétendue présence de nombreux stocks de caoutchouc naturel dans différents pays producteurs. Et même El Nino n'a rien pu faire et pourtant l'impact sur la production a été réel dans certains pays !

Farmers' harvesting and post-harvest practices affect the quality of rubber coagulum with consequences for rubber processing factories. Many smallholders in Thailand sell their rubber as coagulum, especially in the North-East where rubber plantations widely expanded since the 1990s. But for this new rubber producing area, we lack information on farmers' practices to produce and sell coagula. Therefore, a survey was conducted with 340 rubber farmers in four northeastern provinces: Bueng Kan, Nakon Phanom, Mukdahan and Ubon Ratchatani. Results show that considering the practices one by one, there is a relatively homogeneity among farmers. But considering several harvesting and post-harvest practices together, many combinations are possible resulting in a high diversity of practices. Nevertheless, a typology with seven groups was established. The two groups gathering the highest proportion of farmers are those with practices that could have negative impact on rubber quality. We conclude that it is necessary to get into a dialogue among all the stakeholders involved in the production and marketing of coagulum to raise awareness on the quality issue and on the requirement of rubber processing factories.

La tendance baissière de l'année 2013 s'est malheureusement poursuivie tout au long de l'année 2014 avec une affligeante régularité au grand désespoir des petits producteurs qui ont encore perdu de l'ordre de $ 0,8/kg de caoutchouc sec au cours de l'année 2014 comme en 2013. Cependant, si le niveau moyen du SMR 20 restait encore rémunérateur en fin 2013 - $ 2 200/tonne SMR 20 fob Kuala Lumpur - il devient franchement catastrophique fin décembre 2014 atteignant le cours de $ 1 510/tonne. Il faut remonter à la grave crise financière de 2008-2009 pour retrouver un tel niveau mais à l'époque, la reprise avait été très rapide, ce qui ne semble pas être le cas pour le moment.

Industrial tree crop plantations often enter in direct competition for land with forests. In those cases, the net result on climate is detrimental. In other cases, the possibility for tree crops to fulfil the objectives of CSA deserves a deeper investigation. This study analyses the case of natural rubber production in Thailand. The natural rubber (NR) commodity chain presents two promising features to reach CSA objectives. First, family farms represent the majority of surface areas under rubber plantations. These production systems may contribute to local sustainable development and food security. Second, NR is a natural competitor of synthetic rubber (SR) made from crude oil. Substituting SR by NR may hence allow for reductions in GHG emissions from fossil sources. We developed a multi-disciplinary research project with these two features as a backbone. The goal was to improve the productivity and the sustainability of rubber smallholdings, while making sure that their NR output would suit for SR substitution particularly in terms of consistency. Results showed a high diversity of farm structures and agricultural practices in rubber smallholdings. The diversification of farm activities, of income source and latex harvesting methods appeared to be important adjustment variables to cope with uncertainties linked to price fluctuations and natural hazards. The impact of clone, latex harvesting and post-harvesting practices on the physico-chemical properties of NR was assessed. Results also showed how rubber plantations could improve the soil ecosystem services and particularly the soil carbon content when rubber trees were planted on lands previously used for intensive annual crops. The next step of the research project is to integrate these results into a multi-criteria analysis, such as Life Cycle Assessment, in order to design and assess adaptation strategies of the NR supply chains to global changes. This project was conducted under the umbrella of the Hevea Research Platform in Partnership (HRPP) and with the financial support of the Thai International Cooperation and development Agency (TICA). (Texte intégral)

Thailand has adjusted its production strategy by increasing the manufacturing of standard rubber or block rubber (Standard Thai Rubber or STR) in order to meet global market demand. About 90% of block rubber is STR20, for which the major raw material is cup coagulum. Consequently, demand for this raw material is increasing. The quality of cup coagulum produced by smallholders is so variable. Harvesting and post-harvest practices may influence the quality of cup coagulum. However, this has yet to be studied in Thailand. A study was therefore conducted in Surat Thani province to fill this gap. The methodology combined a survey of 79 farmers using a structured questionnaire to describe farmers' behaviour in cup coagulum production. Analysis of the physical and chemical properties of cup coagulum collected from a subsample of 26 farmers, as well as the properties of the dry rubber obtained from those cup coagula were also carried out. Cup coagula sampled from the 26 farmer subsample were characterised for foreign matter content. The dry rubber samples obtained from the processing of these collected cup coagula (creping-drying) were characterised for initial Wallace plasticity (P 0 ) and the plasticity retention index (PRI). We found that farmers' harvesting and post-harvest practices were very diverse. A classification of farmers based on these practices was proposed. The quality related parameters showed significant differences between farmers, with some of them being interestingly correlated with certain groups identified by the survey. This study confirmed that the quality of Thai natural rubber starts to be established much earlier than on the factory processing line producing STR bales. Smallholder behaviour may also be of great influence, and training/communication drives could improve the quality of the cup coagulum sold to factories and thereby help the Thai industry to continue producing excellent quality natural rubber.

Under the umbrella of the Canaopt Project financed by French private and public institutions the objectives of this study are to develop new grades (CNR) through the knowleldge of the factors of variability and their impact on properties of Natural Rubber. The production of samples in 5 countries (Vietnam, Thailand, Indonesia, Ghana and Cote d'Ivoire and 3 different grades (TSR 3CV, TSRIO and TSRIOCV) under control postharvest conditions allowed to correlate the process and bulk properties of NR. Mesostructure of NR samples have been studied and curing characterization.

The objective ofthis work is to develop a method to get the protein composition of latex. Additionally to the extraction method itself, different preservation methods ofwhole latex (WL) were tested to prevent latex from any deterioration and/or destabilization (which might induce protein degradation) during the time elapsed between latex collection in the field and protein analysis in the laboratory. These treatments include: stabilization ofwhole latex with an adequate buffer to generate stabilized latex (SL) as well as freezing WL and SL in liquid nitrogen to generate frozen whole latex (FWL) and frozen stabilized latex (FSL), respectively. Proteins were extracted using three extraction buffers of different compositions and the protein composition was revealed by one-dimensional gel electrophoresis (SDS-PAGE). The SDS-PAGE gels were studied by image analysis to provide qualitative and quantitative information on protein content. The comparison of the SDS-PAGE gels allowed us to determine the most appropriatepreservation method oflatex (i.e. stabilizing latex and freezing stabilized latex for short and long storage periods, respectively) as well as to determine the most efficient protein extraction buffer (i.e. 100 mM Tris, 100 mM EDTA, 10% glycerol, 2% Triton X-100, 20 mM DTT and 2 mM PMSF, pH 8).

Quand la tendance baissière s'arrêtera-t-elle? se demande chaque jour la majorité des millions de petits planteurs producteurs de caoutchouc naturel à travers le monde. En effet, conjugué à une demande atone avec des chiffres de croissance de la Chine revus à la baisse et une offre importante, le cours du caoutchouc naturel (SMR20 FOB Kuala Lumpur) a perdu plus de 26% de sa valeur durant l'année 2013 passant ainsi, pour le SMR 20, de $ 3 000 la tonne FOB Kuala Lumpur début janvier 2013 à $ 2 200 la tonne FOB Kuala Lumpur fin décembre 2013 et même allant sous le seuil des $ 2 000 la tonne le 29 janvier 2014. Si nous avons assisté, comme souvent, à une légère remontée avant le nouvel an chinois et le début du wintering, le cours a chuté régulièrement tout au long de l'année sauf à deux périodes, tout d'abord en mai puis fin août ce qui pourrait être lié aux mouvements de protestations des petits producteurs thaïlandais mais aussi aux achats de la Chine, voire à des mouvements de spéculation suite à des prévisions de croissance de la Chine légèrement plus élevées que prévu. Les annonces du gouvernement thaïlandais pour diminuer la quantité de caoutchouc exporté n'ont pas suffi à faire remonter les cours. De même les trois grands pays producteurs (Thaïlande, Indonésie et Malaisie) regroupés au sein de l'International Tripartite Rubber Council (IRCo) et représentant environ 65 % de la production mondiale, soit plus de 60% des exportations mondiales, ne sont pas arrivés à se mettre d'accord pour diminuer la quantité de caoutchouc naturel exporté au cours des différentes réunions du premier semestre 2013. Rappelons que les réunions d'octobre 2012 et mars 2013 avaient abouti à une limitation de l'offre de plus de 300 000 tonnes.

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