By Dr. Guoxiong Chen, Senior Researcher, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences
Sand rice (Agriophyllum squarrosum) is an annual psammophyte found mostly on mobile sand dunes in the arid and semi-arid regions of Central Asia. It has evolved a number of physiological and morphological adaptations that allow it to survive on the unstable, nutrient-poor, drought-prone and hot sand dunes. Because of its edible seeds, its local name in Western China is shami, which translates as “sand rice”.
Freshly harvested, mature sand rice seed is capable of rapid germination with the right combination of moisture and temperature. However, the seeds disperse germination over a prolonged period of time to cope with unpredictable rainfall. Rapid root growth upon germination and a special shoot growth pattern at seedling stage ensure their survival on mobile sand dunes. The first pair of lateral branches develops shortly after emergence. A second pair and the main stem, protected from the aeolian sand flow by the first pair, grow later. The leaves and bracts, with their hard and acute apexes, play a major role in defense against herbivores.
A new study entitled “A psammophyte Agriophyllum squarrosum (L.) Moq.: a potential food crop” in the journal of Genetic Resources and Crop Evolution, describes the sand rice plant in Chinese desert landscapes and its significance for people, food, and nature.
Archaeological records dating to 688 CE show that soldiers collected sand rice seed to supplement their rations. The local population still retains the tradition of eating sand rice in a variety of dishes, the most popular of which is shami liangfen, a summertime dish of cold starchy jelly seasoned with vinegar, sesame paste, crushed garlic, shallot, chili and salt. Sand rice seed is 23.2% protein, 9.7% lipid, 45.0% carbohydrate, 8.6% crude fiber and 5.0% ash. The essential amino acids in the sand rice seed protein meet the requirements of a healthy human diet. The nutritional value of sand rice is as high, if not higher than quinoa, a pseudocereal which has a higher nutritional value than true cereals. However, unlike quinoa, sand rice has not as yet been domesticated. The local people collect sand rice seeds from the desert in winter, which is dangerous for both the collectors and the fragile desert landscape.
Plant domestication is generally a slow process of farmer-based selection. However, the designed domestication of sand rice can be achieved in a far shorter time frame since, first, the seeds can be improved or hybridized, and second, the traits which need to be selected for are already well defined. The most important traits for sand rice domestication will be the uniculm habit, the non-shattering of the seed and the large size of the seed. A large-scale breeding program based on mutagenesis and cross breeding has already been initiated to convert sand rice from a wild species into a managed crop.
Thanks to the remarkable high temperature tolerance in sand rice, the domestication of sand rice offers the prospect of a novel crop adapted to the warming global climate—a crop which could pay large dividends in the context of food security to rural populations based in the arid and semi-arid regions of Central Asia and beyond. In the future, consumers might incorporate sand rice into their daily diet as a healthy, nutritious, good tasting and versatile food.
Similarly, jackfruit has been identified as a potential food of the future. What other novel and adaptive plants that you foresee as future food sources that will play a role in humans’ agricultural adaptation to climate change?
Photo credits (1) Guoxiong Chen (2) Guoxiong Chen (3) Pengshan Zhao