On 24 August 2026, at VNUHCM–University of Science (HCMUS), doctoral researcher Trà Đông Phương successfully defended a doctoral thesis in Biotechnology entitled ‘Investigation into improving cadmium absorption and accumulation capacities of selected ornamental plant species in Viet Nam’. The research was conducted under the scientific guidance of Associate Professor Bùi Văn Lệ and Associate Professor Tô Thị Hiền.

Heavy metal pollution, including cadmium (Cd), represents an environmental issue affecting human health and living organisms. Remediation of heavy metal-contaminated soil using plants has attracted significant interest, as this approach is cost-effective, straightforward to implement, and environmentally friendly. Viet Nam possesses numerous ornamental plant species, offering favourable conditions for researching and selecting species capable of absorbing and accumulating Cd from soil. Proceeding from this basis, the thesis focused on investigating the Cd absorption and accumulation capacities of several common ornamental plant species in Viet Nam, whilst studying the supplementation of selected factors to enhance these capacities in promising species.

Research findings revealed that Madagascar periwinkle (Catharanthus roseus) and cockscomb (Celosia argentea) exhibited the best Cd absorption and accumulation capacities among the five species surveyed. Between the two, cockscomb demonstrated superior improvements in Cd uptake and accumulation when provided with supporting factors. The study identified several factors capable of helping cockscomb increase Cd absorption and accumulation. Notably, supplementation with Na₂EDTA at appropriate concentrations enabled the amount of Cd absorbed and accumulated in the above-ground parts of the plant to reach 494.94 mg/kg of dry weight, whilst the translocation of Cd from roots to above-ground parts increased approximately ninefold. Other factors, such as cysteine and the bacterium Pseudomonas taiwanensis PS01, helped increase cockscomb biomass, thereby contributing to enhanced Cd-contaminated soil remediation efficiency. When combining selected factors, results showed that treatments supplemented with Na₂EDTA consistently increased Cd absorption and accumulation in both the root systems and above-ground parts of cockscomb. This result demonstrates that Na₂EDTA can be used in combination with other factors to assist cockscomb in remediating Cd-contaminated soil.

A novel contribution of the thesis provides evidence regarding the potential of utilizing common ornamental plant species in Viet Nam — including Madagascar periwinkle, sunflower, marigold, alfalfa, and cockscomb — for Cd-contaminated soil remediation. Among these, cockscomb was identified as the most promising species studied. The thesis also established suitable conditions for supplementing supporting factors, contributing to the enhancement of Cd absorption and accumulation in cockscomb.

The research findings serve as a foundation for further investigating the Cd tolerance, absorption, and accumulation capacities of cockscomb across Cd-contaminated soil areas in Viet Nam to evaluate remediation efficiency under field conditions. With these achieved results, doctoral researcher Trà Đông Phương successfully defended the doctoral thesis in Biotechnology at HCMUS.