ĐỒNG THÁP, VIET NAM – “It’s been so long I can barely remember. It’s delicious, fragrant, soft but not sticky,” said Trần Văn Lựa, 53, a farmer from Phú Thọ Commune in Đồng Tháp Province, recalling the taste of wild rice. As a child, he used to harvest the plants during flood season, but now they are a rare sight.

Wild rice, known locally as ‘ghost rice’ (lúa ma) or ‘god rice’ (lúa trời), is the common name for Oryza rufipogon, a perennial native to Viet Nam’s Mekong Delta and the ancestor of modern Asian rice (Oryza sativa). It carries target genes that confer resistance to pests like stem borers, leaf folders and viral diseases like rice grassy stunt, ragged stunt – traits lost in modern varieties. Its high genetic diversity is also a rich resource for scientists to develop new genes that are adaptive to drought, flooding, heat and acidic soils.

Việt Nam is one of the last global refuges for the species, but its conservation is fraught with challenges.

A lifeline during flood season

In the 1970s, wild rice was a lifeline during food shortages, which thrived in seasonal floods that submerged the Đồng Tháp Mười region. A sack of wild rice, locals say, was worth three of regular rice.

Once abundant, it has since become a rarity, and is now often mistaken for weedy rice (Oryza spp.), a troublesome weed that behaves like rice but produces far fewer grains, causing mass crop failures. This confusion persists in Vietnamese state media and even among international scientific circles. For example, the North American Plant Protection Organization used to misclassify wild rice as a weed and recommended its eradication.

Viet Nam is home to four of the world’s estimated 19 – 21 wild rice species: Oryza rufipogon, Oryza nivara, Oryza officinalis and Oryza granulate. Only rufipogon and officinalis are still found in the Mekong Delta; Oryza nivara was last seen in Tràm Chim in 1980, and is now still present in Hồ Lắk of Đắk Lắk province.

Bùi Chí Bửu, a Vietnamese scientist and former director of the Institute Of Agricultural Science For Southern Vietnam (IAS), one of the few Vietnamese scientists studying wild rice, says the species’ remarkable genetic diversity make it ideal for rice breeding climate-resilient genotypes.

Wild rice grows low across wetland plains, rising with the floodwaters. Its seeds can lie dormant for years, germinating only when conditions align. The grains ripen unevenly, its panicles are wide and the hard grains are covered with long, red spikelets.  

Harvesting them takes skill and timing: wild rice sheds grains at the slightest breeze, so often before dawn, farmers spread a blanket across their boat and tap the stalks with bamboo poles to catch the falling grains.

This ghostly shedding is what earned it the name lúa ma – ghost rice.

But its true value lies in its genes.

“Wild rice possesses a highly diverse genetic foundation,” Bửu said. “The species contains rare genes that cultivated and native rice varieties have lost over the evolutionary pathway, with rare alleles [specific genes] having largely been wiped out.” These include resistance to pests such as brown planthoppers and stem borers, tolerance to extreme environmental stress and resistance to toxic metals in acidic soils.

Research by Bửu’s team found that while cultivated rice in Viet Nam has a low genetic diversity index of 0.2, landraces of 0.2-0.4, wild rice in the Mekong Delta ranges from 0.4 to 0.6, sometimes higher. “For a country with weak genetic diversity like Viet Nam, preserving species with a rich genetic foundation is essential,” he added.

Despite low yields – only 20 to 100 kg per hectare – wild rice (Oryza australiensis) fetches a high price in niche markets. In Australia, for example, it is processed into functional foods for diabetics and the elderly.

By contrast, weedy rice (lúa cỏ) – often confused with its wild cousin – is a genetic throwback, a segregant population after outcrossings. It resembles cultivated rice but sheds all its grains at maturity, slashing yields by up to 60% and spreading aggressively. Its genetic instability makes it unsuitable for breeding, and its similarity to farmed rice renders it resistant to herbicides, making it especially hard to control.

Tracking a vanishing gene bank

In his garden in Cần Thơ city, Bửu tends to several wild rice species collected from across southern Viet Nam. At first glance, they resemble weeds.

Wild rice is remarkably resilient, but not invincible. “Even as a perennial, if left alone, they will exhaust themselves and die,” Bửu explained. To keep them alive, he must propagate the plants every few years.

On-farm conservation is a low-cost method used in Việt Nam and parts of Africa, but it is not without risks. Plants are vulnerable to cross-pollination and small gene pools can collapse with a single failed generation.

A more secure backup lies at the Mekong Delta Rice Institute, where hundreds of wild rice pots are maintained alongside a small genetic seed bank. The institute stores 600 samples of Oryza rufipogon and Oryza officinalis in net houses and freezers. To keep them viable, sample seeds are periodically revived, grown and re-stored to prevent the gradual loss of germination.

“In the past, funding for our gene bank came entirely from the Plant Resources Center, which is used to support cold storage and seed rejuvenation,” said Trần Ngọc Thạch, the institute’s director. “But now, we fund the cold storage ourselves, so preservation is less than ideal.”

There are two main strategies for conserving wild rice: ex-situ, through storage in seed banks, and in-situ, conserving the plants in their natural habitats. While gene banks safeguard genetic material, they halt natural evolution. In-situ conservation, on the other hand, allows species to continue adapting to changing conditions.

Globally, more than 1,700 gene banks house some 650,000 rice seed samples, including 11 collections under the CGIAR system (Consultative Group on International Agricultural Research). The largest of them all, the Svalbard Global Seed Vault in Norway, serves as a final safeguard. Asia holds about 23,000 wild rice samples across six major seed banks, forming the backbone of many countries’ gene-mining  and biotechnology strategies for climate-resilient rice.

Despite being a signatory to the Convention on Biological Diversity (CBD), Việt Nam still lacks a well-equipped gene bank preservation facility, said Bửu.

The Indigenous Rice Gene Bank at Cần Thơ University is among the few well-funded facilities in the country. But its 5,000 accessions focus on seasonal, lowland and rainfed varieties from the Mekong Delta – none of them wild.

“Wild rice seeds require special regeneration conditions, which we are not prioritizing due to limited funding and manpower,” said Nguyễn Thành Tâm, head of agricultural development at the Mekong Delta Development Research Institute.

Meanwhile, in-situ conservation – widely regarded as the best way to protect and evolve wild rice – faces pressure from agriculture. Farmers prefer high-yield hybrids and floodplain habitats are shrinking or degraded.

Tràm Chim National Park, Việt Nam’s largest in-situ wild rice conservation site, has drawn international interest for its biodiversity. It is home to Oryza rufipogon populations with the highest recorded genetic diversity in the Mekong Delta.

Before 2015, Tràm Chim’s wild rice fields covered nearly 1,000 hectares, thriving alongside wetland species like Eleocharis dulcis (năn ống), Eleocharis atropurpurea (năn kim), Panicum repens (cỏ ống), Agrostis stolonifera (cỏ bắc), and Cynodon dactylon (cỏ chỉ).

But pure wild rice fields were limited – spanning only 33 hectares – and have continued to shrink.

Today, park officials estimate only 520 hectares remain – half the area of a decade ago. “Wild rice is now scattered across many areas rather than concentrated in one place,” said Đoàn Văn Nhanh, deputy director of the park’s Center for Conservation and International Cooperation.

Cruising through Tràm Chim’s waterways in early January, the usual blooming season, there was little sign of the plant – only stretches of Eleocharis dulcis (năn ống). A few clumps of wild rice clung to levees.

Each year, wild rice sprouts tall as Mekong floodwaters rise, flowering at peak inundation. But the rhythms are changing. “It seems that this year, the flood surged and retreated unusually fast, leaving barely any wild rice,”said local farmer Trần Văn Lựa.

Nhanh agrees. He believes erratic floods have disrupted the plant’s natural cycle. Roaming cattle, often released into the park, graze on what little remains.

Our observation of wild rice, in the end, was only possible from inside a net house.

Rebuilding a habitat

“At Tràm Chim, we are restoring and rehabilitating the ecosystems, with a focus on Eleocharis atropurpurea (năn kim), and cranes, using the cranes as a benchmark for overall management,” said Nhanh.

The effort is part of a 10-year VND 184 billion (US$7 million) project launched by the Đồng Tháp Provincial People’s Committee to restore the sarus crane – a symbol of weltand health – to the park.

Covering 7,313 hectares, Tràm Chim National Park, a Ramsar site, shelters 130 plant species, 130 freshwater fish and 231 bird species, many endemic to the region. But years of mismanaged hydrology have disrupted this delicate balance.

To prevent forest fires, managers dug canals and built levees to maintain higher water levels year-round, altering the natural six-month cycle. Wild rice – unable to regenerate without dry periods and decomposed surface nutrients – began to disappear, even in its former stronghold, area A1.

According to Dương Văn Ni, a biodiversity expert at Cần Thơ University, in the Tràm Chim ecosystem, the roots, stems, leaves and wild rice seeds are crucial food for birds and fish during challenging periods such as deep flooding or drought. When wild rice disappears, the food chain is severely disrupted. Species dependent on wild rice see their numbers decline and eventually vanish.

In early 2023, park managers began reducing water levels during the dry season, maintaining levels recommended by scientists. Controlled burning of grasslands were reintroduced and the restoration of crane habitats, including Eleocharis atropurpurea (năn kim), Xyris indica(hoàng đầu ấn), and wild rice is also underway.

A pilot plot of five hectares of wild rice in the A1 area has shown tentative signs of recovery. But the long-term outlook remains uncertain.

“Currently, the water flow into the Mekong Delta no longer follows its usual patterns, and with unpredictable climate and hydrological factors, we must remain flexible in our activities at the park to avoid significant losses,” said Nhanh.

“For instance, we anticipated a hot and dry season this year, so we raised the water levels higher than recommended. If there is excessive rainfall, we’ll gradually lower the water levels. We adjust based on the actual conditions,” he added.

As Mekong flood patterns grow more erratic – driven by climate change and upstream hydropower – species like wild rice face an uncertain future. Their loss would not only threaten local biodiversity but erase genetic resources vital for climate-resilient agriculture across the region.

“Each species has its own adaptation limits, and wild rice is no exception,” said Dương Văn Ni. “Maintaining a healthy natural ecosystem, therefore, creates the best conditions for many species. Continuous, updated research to sustain the ecosystem as a living being will be essential.”

This article was written in Vietnamese and co-published in English by Mekong Eye and Dialogue Earth. Versions may differ slightly due to translation and editorial adaptation.