ABSTRACT
Cuphea PSR23, a semi-domesticated potential oilseed crop, is a selection from an
interspecific cross between the wild species Cuphea lanceolata and C. viscosissima.
Understanding the extent to which its phenotype is integrated, by studying complex trait
interactions and interdependencies, is critical for its full domestication, as well as for
advancing our knowledge of its developmental plasticity, and adaptation to new environments
and alternative management practices. Phenotypic plasticity is necessary for Cuphea’s adaptation
to changing environments and may become inversely related to phenotypic integration, especially
under abiotic stress. Phenotypic integration was quantified using several multivariate statistical
procedures on log- or z-transformed raw data, or on latent variables derived from phenotypic or nutrient
variables within structural, metabolic and reproductive plant modules. Several estimates of the level of
phenotypic integration were used to generate phenotypic integration indices (PIIs) as the deviation of functionally
linked phenotypic, eco-physiological, and nutrient traits from the means of respective traits in its wild parents.
These traits were assessed in Cuphea PSR23 in response to directional selection for high seed weight, seed yield,
and oil content under cultivation. Under managed agro-ecosystems and in comparison with its wild parents, Cuphea
PSR23 displayed complex phenotypic traits that are naturally highly dimensional; it invested more in phenotypic and
eco-physiological traits that are related to larger biomass and to stronger inter-plant competition under high
population density; and displayed wide variation in the scale and significance of bivariate and multivariate
trait (dis)associations. However, Cuphea PSR23 may have become less phenotypically integrated due to directional
population selection for a few agronomic traits under cultivation. Reduction in phenotypic integration
if continued under cultivation, may render PSR23, as a semi-domesticated oilseed crop, more vulnerable
to abiotic stresses, and may delay its full domestication unless systemic germplasm enhancement and
breeding programs are launched for its genetic and agronomic improvement.
