Seeds photoblastism and its relationship with some plant traits in 136 cacti taxa

Seed germination triggered by light exposure (positive photoblastism) has been determined in quantitative studies for numerous plant families and species. For Cactaceae, positive photoblastism is thought to be associated with life form and seed mass, but this association has never been evaluated. To explore hypotheses on associations between seed mass, seed dispersal, seed dormancy, life form, taxa and plant height with Relative Light Germination (RLG) in Cactaceae, we evaluated the effect of light on seed germination of 136 taxa. The taxa studied are native to several countries: México, Chile, Argentina, Brazil, Perú, USA, and Venezuela. Seed traits contrasted with RLG were life form, seed mass, seed dispersal, seed dormancy, adult plant height and taxon. We found some differences between RLG among taxa; Cacteae, Pachycereeae and Trichocereeae had higher RLG than Notocacteae. RLG was lower for seeds from taller than for shorter taxa, and lower for taxa with heavier seeds than for taxa with lighter seeds. Dispersal syndrome groups varied with RLG. RLG did not differ between cylindrical and globose taxa. Trends found here were in agreement with expectations for small-seeded species to have a light requirement to germinate more often than large-seeded species. This is the first time that cactus height is related to photoblastism. It is possible that seeds from tall plants are larger and thus have the capacity to produce taller seedlings than those from small plants, and that seedlings from large seeds with more resources have the ability to emerge from greater soil depths than those from small seeds.Fil: Flores, J.. Instituto Potosino de Investigación Científica y Tecnológica; MéxicoFil: Jurado, E.. Universidad Autónoma de Nuevo León; MéxicoFil: Chapa Vargas, L.. Instituto Potosino de Investigación Científica y Tecnológica; MéxicoFil: Ceroni Stuva, A.. Universidad Nacional Agraria La Molina; PerúFil: Dávila Aranda, P.. Universidad Nacional Autónoma de México; MéxicoFil: Galindez, Guadalupe. Instituto Nacional de Tecnología Agropecuaria. Centro Nacional de Investigaciones Agropecuarias. Centro de Investigación de Recursos Naturales. Instituto de Recursos Biológicos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gurvich, Diego Ezequiel. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: León Lobos, P.. Instituto de Investigaciones Agropecuarias; ChileFil: Ordóñez, C.. Universidad Nacional Autónoma de México; MéxicoFil: Ortega Baes, Francisco Pablo. Universidad Nacional de Salta. Facultad de Cs.naturales. Escuela de Agronomia. Laboratorio de Investigaciones Botanicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; ArgentinaFil: Ramírez Bullón, N.. Universidad Nacional Agraria La Molina; PerúFil: Sandoval, A.. Instituto de Investigaciones Agropecuarias; ChileFil: Seal, C. E.. Royal Botanic Gardens; Reino UnidoFil: Ullian, T.. Royal Botanic Gardens; Reino UnidoFil: Pritchard, H. W.. Royal Botanic Gardens; Reino Unid