A test in Japan has concluded that grains of rice unearthed from 3,000-year-old ramparts in Hanoi and germinated this past May belong to contemporary varietals.
However, Vietnamese scientists argued that the results "aren't 100 percent trustworthy."
The findings were reported at the annual national archaeological conference held in Hanoi, on Thursday.
Dr. Nguyen Quang Mien from Vietnam's Archaeological Institute said the Accelerator Mass Spectrometry (AMS) method used by the Institute of Accelerator Analysis Ltd. only yields trustworthy results for "dead" samples.
Husks of the grains discovered at the Den ramparts in Me Linh District were still exhibiting active metabolic processes, meaning that they are "alive," he said.
Dr. Lam Thi My Dung of the University of Social Sciences and Humanities in Hanoi said the Japanese experts confirmed it was the first time AMS was applied to live samples.
"The method, according to my (Japanese) partners, isn't suitable for dating the grains' age," she said.
In May, Dung caused a buzz by claiming that the grains unearthed nearly one meter below an area that contains the remains of a 3,000-3,500-year-old kitchen had sprouted into rice after being soaked in water for two days in a laboratory.
Since then, the discovery has drawn interest from scientists in different fields--from archaeology to agriculture. It has also sparked debates on the grains' origins.
Some were convinced that the grains dated back 3,000 years, while others were skeptical, saying that more tests and experiments were needed.
At the latest conference, Mien said that he had seen instances in which contemporary samples had been subsumed into ancient soil layers up to 50 meters underground, due to natural causes.
Local experts have called for a new excavation at the Den ramparts site. They have suggested more careful preparations and further tests on the rice that are being grown in the laboratory.
Dung, meanwhile, said she would send dead grains found at the same location to foreign organizations to determine their age. If the grains are determined to be ancient, the designation would serve as the basis for further study on the sprouted grains.
Last month, Vietnam's Agricultural Genetics Labratory announced at a conference that their tests showed the rice's belonged to Khang Dan No.18 a contemporary varietal. Several scientists then called for a halt to related studies on the rice.
However, others denied the results, saying that they weren't thorough and exact enough.
Some scientists called into question the procedures that Dung and her team used to extract the grains from the Den ramparts. They also raised questions about methods applied in growing the rice for experiments.