Abstract Tuber greening causes potato quality decline and economic loss. We investigated physiological mechanisms of greening by fluorescence and transmission electron microscopy. We then explored the effect of nitrogen level (0, 210, and 315 kg N ha−1) on starch granule size and tuber greening of three commercial cultivars. Results showed that chlorophyll content of tuber skin increased (5–8 times) in a quadratic manner with increasing duration of light exposure (0–7 d) in all cultivars. Light-induced greening occurred in cortical parenchyma 0–1.5 mm below the periderm, where chloroplast auto-fluorescence was evident under ultraviolet light. The greening process involved membrane lose, starch granule dissolution, and grana formation in amyloplasts, along with chloroplast development. Formation of grana lamellae was observed around amyloplasts with a diameter of 9–30 μm. Nitrogen application increased the percentage of small granule starch (

中文翻译：

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光致淀粉体超微结构变化及施氮对马铃薯块茎（Solanum tuberosum L.）绿化的影响

摘要 块茎绿化导致马铃薯品质下降和经济损失。我们通过荧光和透射电子显微镜研究了绿化的生理机制。然后，我们探讨了氮水平（0、210 和 315 kg N ha-1）对三个商业品种的淀粉颗粒大小和块茎绿化的影响。结果表明，在所有品种中，随着光照时间（0-7 天）的增加，块茎皮的叶绿素含量以二次方方式增加（5-8 倍）。光致绿化发生在周皮下 0-1.5 mm 的皮质薄壁组织中，在紫外光下叶绿体自发荧光明显。绿化过程涉及膜脱落、淀粉颗粒溶解和淀粉体中的颗粒形成，以及叶绿体的发育。在直径为 9-30 μm 的淀粉体周围观察到颗粒层的形成。施氮增加了小颗粒淀粉的百分比（