A seed consists of two functional components, the seed kernel (i.e., the seed reserve, including the embryo and the endosperm/perisperm) and the seed coat (i.e., the protective tissue surrounding the seed kernel, sometimes including an endocarp, and the testa. Numerous studies have treated the mass of a whole seed as an integrated unit, although the components seed kernel and seed coat play different roles and are subject to different evolutionary selection pressures.
Researchers from Xishuangbanna Tropical Botanical Garden (XTBG) compiled a global‐scale data set from the published literature. They aimed to quantify the relationship between seed kernel mass and seed coat mass on a broader scale and across diverse taxa.
The researchers tested the hypothesis that the relationship between seed kernel mass and seed coat mass shows a negative allometry and, therefore, that seed coat ratio is negatively correlated with seed mass.
By using the global‐scale database, they identified a weak but significant allometry between seed reserves and protective tissue, which in turn resulted in a negative relationship between seed mass and seed coat ratio.
The finding that smaller seeds invest more in protective tissues but less in stored reserves may explain the general prediction that larger seeds suffer greater predation than smaller seeds.
“Our study suggests that the allometry between the two parts of a seed must be considered when evaluating both the ecological significance and evolutionary history of seed mass”, said Dr. WANG Bo, principal investigator of the study.
The study entitled “An allometry between seed kernel and seed coat shows greater investment in physical defense in small seeds” has been published online in American Journal of Botany.
WANG Bo Ph.D
Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China