Effect of light on seed germination and seedling shape of succulent species from Mexico
Effect of light on seed germination and seedling shape of succulent species from Mexico
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DOI：
10.1093/jpe/rtv046
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发表时间：
2016-04-01
影响因子：
2.7
通讯作者：
Jurado, Enrique
中科院分区：
文献类型：
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作者：
Flores, Joel;Gonzalez-Salvatierra, Claudia;Jurado, Enrique
目的：仙人掌种子萌发的光照要求被认为与它们的成虫株高和种子质量有关，但这还没有对其他多肉植物进行深入的研究。为了解天门冬科（Agavoideae亚科）和仙人掌科荒漠植物种子的光敏性，对来自奇瓦瓦沙漠南部的1种植物的12种和2个变种进行了光照和无光照的萌发试验。我们还确定了仙人掌成虫的生长是否完全取决于幼苗的“生长形式”。方法对来自奇瓦瓦沙漠南部的天门冬科10个莲座种、1个球形种、1个柱状种和1个凹球形种（仙人掌科）的2个品种进行光照和黑暗萌发试验。响应变量为种子发芽率和相对光照发芽率。此外，为了确定成年球形仙人掌是否可以有圆柱形的幼苗，我们计算了长叶仙人掌（Coryphanta clavata）和压缩仙人掌（mamillaria compressa）的形状指数（高/宽比）。重要发现所有的物种都被认为是中性光性的。11种种子在光照和黑暗条件下的发芽率相似，3个分类群（M. compressa和Ferocactus latispinus两个变种）在光照条件下的发芽率高于无光照条件。salmiana龙舌兰、压缩龙舌兰和2个品种的RLG均高于其他品种。种子质量是一个重要因素，因为种子质量越大，对光的依赖性越低。这些发现支持了一种假设，即小种子质量和对光的要求共同进化，以确保发芽。一种成球状仙人掌和一种成柱状仙人掌种子小，成胚发育中性。光照条件下的幼苗呈柱状，黑暗条件下的幼苗呈柱状。也许这个物种的种子能够在黑暗中发芽，因为它们产生柱状幼苗，能够从阳光无法穿透的更深的土壤中萌发。
AimsLight requirements for cactus seed germination have been considered to be associated with their adult plant height and seed mass, but this has not been thoroughly studied for other succulent species. In order to understand seed photosensitivity from desert species belonging to Asparagaceae (subfamily Agavoideae) and Cactaceae, we performed a germination experiment with and without light for 12 species and 2 varieties from 1 species from the Southern Chihuahuan Desert. We also determined if adult growth is totally determined by seedling 'growth form' in cacti.MethodsWe performed a germination experiment using light and darkness for 13 species from Southern Chihuahuan Desert: 10 rosette species (Asparagaceae), as well as 1 globose, 1 columnar and 2 varieties from 1 depressed-globose species (Cactaceae). The response variables were seed germination percentage and relative light germination (RLG). In addition, in order to determine if adult-globose cacti could have cylindrical seedlings, we calculated the shape index (height/width ratio) for Coryphanta clavata and Mammillaria compressa.Important FindingsAll species were considered neutral photoblastic. Eleven species had similar seed germination in both light and dark conditions, and three taxa (M. compressa and the two varieties of Ferocactus latispinus) showed higher germination with light than without it. Agave salmiana, M. compressa and the two varieties of F. latispinus had higher RLG than the other species. Seed mass was an important factor because with higher seed mass there was lower dependence to light. These findings support the hypothesis that small seed mass and light requirements have coevolved as an adaptation to ensure germination. One adult- globose cactus species, M. compressa, and one adult- columnar species, C. clavata, had small seeds and neutral fotoblasticism. Seedlings from these two species exposed to light were cylindrical and those under darkness conditions were columnar. Perhaps seeds from this species are able to germinate in the dark because they produce columnar seedlings with the ability to emerge from greater soil depths where sunlight cannot penetrate.