São Paulo State University (UNESP), Institute of Biosciences, Department of Botany, Phenology Lab, Rio Claro, São Paulo, Brazil.
Departamento de Botânica, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
Ann Bot. 2018 May 11;121(6):1197-1209. doi: 10.1093/aob/mcy006.
The relationship between fruiting phenology and seed dispersal syndrome is widely recognized; however, the interaction of dormancy classes and plant life-history traits in relation to fruiting phenology and seed dispersal is understudied. Here we examined the relationship between fruiting season and seed dormancy and how this relationship is modulated by dormancy classes, dispersal syndromes, seed mass and seed moisture content in a Brazilian savanna (cerrado).
Dormancy classes (non-dormancy and physical, morphological, morphophysiological, physiological and physiophysical dormancy) of 34 cerrado species were experimentally determined. Their seed dispersal syndrome (autochory, anemochory, zoochory), dispersal season (rainy, dry, rainy-to-dry and dry-to-rainy transitions), seed mass and moisture contents, and the estimated germination date were also determined. Log-linear models were used to evaluate how dormancy and dormancy classes are related to dispersal season and syndrome.
The proportions of dormant and non-dormant species were similar in cerrado. The community-estimated germination date was seasonal, occurring at the onset of rainy season. Overall, anemochorous non-dormant species released seeds during the dry-to-rainy transition; autochorous physically dormant species dispersed seeds during the dry season and rainy-to-dry transition; zoochorous species dispersed non-dormant seeds during the dry and rainy seasons, while species with morphological, morphophysiological or physiological dormancy dispersed seeds in the transitional seasons. Seed mass differed among dispersal seasons and dormancy classes, but seed moisture content did not vary with dispersal syndrome, season or dormancy class.
The beginning of the rainy season was the most favourable period for seed germination in cerrado, and the germination phenology was controlled by both the timing of seed dispersal and seed dormancy. Dormancy class was influenced by dispersal syndrome and season. Moreover, dormancy avoided seed germination during the rainy-to-dry transition, independently of dispersal syndrome. The variability of dormancy classes with dispersal syndrome allowed animal-dispersed species to fruit all year round, but seeds germinated only during the rainy season. Conversely, seasonally restricted wind-dispersal species dispersed and germinated their non-dormant seeds only in the rainy season.
果实物候与种子散布型之间的关系已得到广泛认可；然而，休眠类型与植物生活史特征与果实物候和种子散布之间的相互作用仍研究较少。本研究旨在探讨巴西塞拉多草原（cerrado）中果实季节与种子休眠之间的关系，以及休眠类型、散布型、种子质量和种子含水量如何调节这种关系。
实验确定了 34 种塞拉多植物的休眠类型（非休眠和物理休眠、形态休眠、形态生理休眠、生理休眠和生理物理休眠）。还确定了它们的种子散布型（自播、风播、动物播）、散布季节（雨季、旱季、雨季到旱季的转变、旱季到雨季的转变）、种子质量和含水量以及估计的发芽日期。使用对数线性模型评估休眠和休眠类型与散布季节和散布型之间的关系。
塞拉多的休眠和非休眠物种比例相似。群落估计的发芽日期是季节性的，发生在雨季开始时。总体而言，风播非休眠物种在旱季到雨季的转变期间释放种子；旱季物理休眠的自播物种在旱季和雨季到旱季的转变期间散布种子；动物播物种在旱季和雨季散布非休眠种子，而具有形态休眠、形态生理休眠或生理休眠的物种在过渡季节散布种子。种子质量在散布季节和休眠类型之间存在差异，但种子含水量与散布型、季节或休眠类型无关。
雨季开始时是塞拉多种子发芽最有利的时期，发芽物候受种子散布和休眠时间的共同控制。休眠类型受散布型和季节的影响。此外，休眠类型在旱季到雨季的转变期间避免了种子发芽，独立于散布型。散布型与休眠类型的可变性允许动物散布的物种全年都结果，但种子仅在雨季发芽。相反，季节性限制的风播物种仅在雨季散布和发芽它们的非休眠种子。
