Department of Horticulture, Foshan University, Foshan, 528000, China.
Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, 666303, China.
BMC Plant Biol. 2021 Mar 30;21(1):160. doi: 10.1186/s12870-021-02931-9.
Being a promising tropical woody oilseed crop, the evergreen and recurrent plants of Sacha Inchi (Plukenetia volubilis L.) has complex phenology and source-sink interactions. Carbon source-sink manipulations with control and two treatments (reduce source, ca. 10% mature leaf pruning; reduce sink, 10% fruitlet thinning) were conducted on 2.5-year-old field-grown P. volubilis plantation during the early-wet season in a seasonal tropical area.
Leaf photosynthetic rate and specific leaf area largely remained unchanged in response to defoliation or defloration. Compared with control, higher N contents on average were observed in both remaining leaves and branches of the defoliated plants, suggesting that N-mobilization was mainly due to the enhanced N uptake from soil. Carbon, but not N, is a source-driven growth process of P. volubilis plants, as defoliation reduced the contents of non-structural carbohydrates (especially sugar) in branches, although temporally, whereas defloration increased available C reserve. The seasonal dynamic pattern of fruit ripening was altered by source-sink regulations. Total seed yield throughout the growing season, which depends on fruit set and retention (i.e., number of matured fruit) rather than individual fruit development (size), was slightly increased by defloration but was significantly decreased by defoliation. Compared with control, defloration did not enrich the KEGG pathway, but defoliation downregulated the TCA cycle and carbohydrate and lipid metabolisms in fruitlets after 24 days of the applications of source-sink manipulation.
Carbohydrate reserves serve to buffer sink-source imbalances that may result from temporary adjustment in demand for assimilates (e.g., defloration) or shortfalls in carbon assimilation (e.g., defoliation). Defoliation is disadvantageous for the yield and also for carbohydrate and lipid accumulation in fruits of P. volubilis plants. Although more studies are needed, these results provide new insights to the further improvement in seed yield of the strong source-limited P. volubilis plants by source/sink manipulations.
Sacha Inchi（Plukenetia volubilis L.）是一种有前景的热带木本含油种子作物，其常绿和可再生植物具有复杂的物候学和源库相互作用。在季节性热带地区的早湿季，对 2.5 年生田间种植的 Sacha Inchi 进行了碳源库操纵处理，包括对照和两种处理（减少源，约 10%成熟叶片修剪；减少库，10%幼果疏果）。
叶片光合速率和比叶面积对去叶或去花处理基本保持不变。与对照相比，去叶植株的剩余叶片和枝条的氮含量平均较高，表明氮的动员主要是由于从土壤中增强了氮的吸收。碳而不是氮是 Sacha Inchi 植物的源驱动生长过程，因为去叶减少了枝条中非结构性碳水化合物（特别是糖）的含量，尽管在时间上，而去花增加了可用 C 储备。源库调节改变了果实成熟的季节性动态模式。整个生长季节的总种子产量取决于果实的结实和保留（即成熟果实的数量），而不是单个果实的发育（大小），去花略有增加，但去叶显著减少。与对照相比，去花没有丰富果实中的 KEGG 途径，但去叶在源库操纵应用 24 天后下调了果实中的 TCA 循环以及碳水化合物和脂质代谢。
碳水化合物储备有助于缓冲源库失衡，这种失衡可能是由于对同化产物的需求暂时调整（例如去花）或碳同化不足（例如去叶）引起的。去叶不利于 Sacha Inchi 植物的产量，也不利于果实中的碳水化合物和脂质积累。尽管还需要更多的研究，但这些结果为通过源库操纵进一步提高 Sacha Inchi 这种强源限制型植物的种子产量提供了新的见解。
