Viola calaminaria is an endangered metallophyte endemic to a small area close to the border between Belgium, Germany and the Netherlands, where it grows on rock outcrops rich in heavy metals (zinc, lead and cadmium). Because V. calaminaria reproduces mainly by seeds, it is of crucial importance to understand its germination requirements. Germination percentage and speed at constant (11–25°C) and alternating (23/09°C) temperatures were investigated in five large populations. Germination percentage was positively correlated to seed weight. Germination was low (<25%) at 11 and 16°C, intermediate (around 65%) between 20 and 25°C and the highest (93%) at the alternating temperature regime (23/09°C). V. calaminaria is a slow germinator requiring 41 days on average to germinate at 23/09°C and considerably more at 20 to 25°C (105 days on average). Our results also highlighted that the species is desiccation tolerant and can therefore be safely conserved under standard seed bank conditions.

中文翻译：

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一种分布狭窄的濒危金属植物——紫堇菜的种子萌发生态学

Viola calaminaria 是一种濒临灭绝的金属植物，分布在靠近比利时、德国和荷兰边境的小地区，它生长在富含重金属（锌、铅和镉）的岩石露头上。由于 V. calaminaria 主要通过种子繁殖，因此了解其发芽要求至关重要。在恒定 (11–25°C) 和交替 (23/09°C) 温度下，在五个大型种群中研究了发芽百分比和速度。发芽率与种子重量呈正相关。在 11°C 和 16°C 下发芽率较低 (<25%)，在 20°C 到 25°C 之间发芽率居中（约 65%），在交替温度范围 (23/09°C) 下发芽率最高 (93%)。V. calaminaria 是一种缓慢的发芽者，在 23/09°C 下平均需要 41 天才能发芽，而在 20 到 25°C 下发芽的时间要长得多（平均 105 天）。