Rubber trees (Hevea brasiliensis) are the main source of natural rubber, extracted from latex, which exudes from the trunk after tapping. Tapped trees require large amounts of carbon (C) to regenerate the latex after its collection. Knowing the contribution of C sources involved in latex biosynthesis will help in understanding how rubber trees face this additional C demand. Whole crown ¹³CO₂ pulse labelling was performed on 4-year-old rubber trees in June, when latex production was low, and in October, when it was high. ¹³C content was quantified in the foliage, phloem sap, wood, and latex. In both labelling periods, ¹³C was recovered in latex just after labelling, indicating that part of the carbohydrate was directly allocated to latex. However, significant amounts of ¹³C were still recovered in latex after 100 d and the peak was reached significantly later than in phloem sap, demonstrating the contribution of a reserve pool as a source of latex C. The contribution of new photosynthates to latex regeneration was faster and higher when latex metabolism was well established, in October, than in June. An improved understanding of C dynamics and the source–sink relationship in rubber tree is crucial to adapt tapping system practices and ensure sustainable latex production.

中文翻译：

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橡胶树的原位13 CO 2标记揭示了乳胶再生中碳源贡献的季节性变化

橡胶树（巴西橡胶树）是天然橡胶的主要来源，天然橡胶是从胶乳中提取的，而胶乳在出胶后从树干中渗出。砍伐的树木需要大量的碳（C）才能在胶乳收集后使其再生。了解胶乳生物合成过程中碳源的贡献将有助于理解橡胶树如何应对这种额外的碳需求。在乳胶产量低的六月和十月的高树龄橡胶树上，对4岁的橡胶树进行了全冠¹³ CO ₂脉冲标记。树叶，韧皮部汁液，木材和乳胶中的¹³ C含量被定量。在两个标签期间，¹³标记后刚在乳胶中回收了C，表明部分碳水化合物直接分配给了乳胶。但是，在100 d后，乳胶中仍回收了大量¹³ C，并且到达峰值的时间比韧皮部汁液晚得多，这表明储备池作为乳胶C的来源。新的光合产物对乳胶再生的贡献是当乳胶代谢在10月建立得比6月快时，速度更快。更好地了解橡胶树中的碳动力学和源－汇关系对于适应分接系统实践并确保可持续的胶乳生产至关重要。