Critical role of air and soil temperature in the development of primary and secondary physical dormancy in Albizia julibrissin (Fabaceae)
2021
Author
Jaganathan G.K.
Abstract
Physical dormancy (PY) is typically induced by seed coat impermeability that develops once the moisture content of seeds drops below a species-specific threshold. Considering this, we utilized Albizia julibrissin (Fabaceae) to ask (i) whether seeds that mature on the outer branches of trees (directly exposed to sunlight) are more likely to be impermeable than seeds matured under canopy cover; (ii) whether this difference might be explained by the maternal environment in which the seeds mature; and (iii) which conditions impose secondary dormancy following dispersal? Temperature was tracked in both shaded and sun-exposed seed pods throughout the growing season using data-loggers. Temperatures remained lower in pods under canopy cover than those exposed to direct sunlight. Consequently, the moisture content of seeds collected from sun-exposed branches were significantly lower than seeds matured under canopy cover, thereby producing a higher percentage of impermeable seeds. A dispersal-mimicking experiment revealed that seeds matured in sun-exposed branches and subsequently dispersed to an open site for 4 months were more likely to develop impermeability (i.e. secondary dormancy). The opposite was found to be true for seeds matured in shaded branches and subsequently dispersed to a canopy-covered site. We conclude that the microclimate of both the maternal environment in which seeds mature, and the site to which they disperse, determines the development of primary and secondary dormancy, respectively. © The Author(s) 2021. Published by Cambridge University Press.
DOI
10.1017/S0266467420000206
Journal
Journal of Tropical Ecology
Source
Scopus