Phenotypic Responses of Forage Kochia under Different Environment Conditions

Phenotypic plasticity is a key factor in plant adaptation to heterogeneous environments. However, the extent to which plastic responses vary among traits under stress prone conditions remains poorly understood. This study examined plasticity, stability, and phenotypic integration at the trait level in forage kochia (Bassia prostrata), a perennial semi shrub species tolerant to drought and saline soils, commonly used in rangeland improvement. Plants were grown in three different environmental systems: a stress prone area (SASs), an irrigated site (IC), and an organically amended site (FWM). Nine morphological and color related traits were evaluated. Plasticity indices, coefficients of variation (CV), and Finlay–Wilkinson regression were used. Trait associations were calculated using Spearman’s rank correlation and adjusted with the Benjamini–Hochberg procedure. Trait correlation networks were constructed for each environment, and network metrics were calculated. Most traits exhibited high plasticity indices. Regression slopes (β) were low, indicating that genotype performance ranking was largely maintained. Within environment variation was high in the SASs environment. In the IC environment, stem color showed extreme variation, while leaf hairiness consistently had the lowest CV values across all three environments.Network analysis revealed that during the SASs environment, vegetative and generative traits separated into two distinct components; during the IC environment, a fully connected network was formed; and during the FWM environment, a sparse network with only two independent correlations was observed. These findings suggest that the ecological success of forage kochia in different environmental systems may arise from the combination of flexible trait means and consistent genotypic ranking.