Popular Science | "Centennial Sugarcane" - The Legend of the Chinese Species of Sugarcane

[ Introduction ] Sugarcane is the fifth largest crop in the world. 80% of the world's sugar and 40% of the raw materials for fuel ethanol come from sugarcane. Sugarcane sugar accounts for about 90% of China's total sugar production. Sugarcane is mainly distributed between 33° north latitude and 30° south latitude, mainly between 25° north and south latitude, and is widely planted in tropical and subtropical regions. More than 100 countries and regions in the world grow sugarcane.

Sugarcane is the main sugar crop in the world and China. India and China are the first countries in the world to grow sugarcane. Sugarcane was first recorded in the Vedas of India and the Chuci of China. About 5,000 years ago, sugarcane was recorded in the Atharva Veda of ancient India. In 296 BC, Qu Yuan's Chuci·Soul Calling recorded that "turtles and lambs are cooked, and there is mulberry juice". The "mulberry juice" here is sugarcane juice. Sugarcane is one of the delicacies for "tonifying winter". It is sweet, flat and astringent in nature. The sweet taste can nourish and relieve. There is a saying among the people that "eating sugarcane at the beginning of winter will not hurt your teeth". Therefore, eating sugarcane at the beginning of winter is as sweet as sugarcane, and the cold winter is as warm as spring.

Since the Tang and Song dynasties, scholars and writers have had a special fondness for sugarcane and left behind many poems. Among them, there is a poem by Su Shi, a writer of the Northern Song Dynasty: "I am getting less and less comfortable with old age, and my stubborn nature has remained the same as that of the old autumn cliff. I laugh at people for thinking when the cooked sugar cane will be ready, and I will eat it raw in a row of green bamboos." "A row of green bamboos" refers to the traditional cultivated variety of Chinese sugarcane - bamboo sugarcane.

Sugarcane with black skin (right) and yellow skin (left) Sugarcane represents a sweet and happy life and a career that is rising steadily. The Indian goddess of wealth, Laxmi, holds sugarcane in one hand, which is a symbol of wealth. Sugarcane is a must-have for the Fuzhou people to offer to the Kitchen God, and the sugarcane head must be kept intact. This means "rising steadily" and "getting a good name on the list of successful candidates", which is auspicious.

Laxmi, the Indian goddess of wealth (left picture from a book compiled by Hunsigi, 1993)

1. The discovery of sugarcane

Generally speaking, the life span of sugarcane perennial roots is 3 to 6 years. The longest-lived sugarcane perennial roots on Puglika Island in the western Indian Ocean are only 25 years old. However, in Songxi County, Fujian Province, there is the world's oldest perennial sugarcane - the century-old sugarcane, which has been cultivated for more than 290 years. In May 1959, the late famous sugarcane expert and former Fujian Agricultural College Professor Zhou Keyong verified that the century-old sugarcane belongs to the bamboo sugarcane of the Chinese species of the genus Saccharum. In November 1959 and May 1964, the former Fujian Agricultural College and relevant units set up an investigation team to conduct a special investigation on the century-old sugarcane. After checking the Wei family tree of Wanqian Village and conducting a comprehensive analysis, it was confirmed that the "century-old sugarcane" was planted in the fourth year of Yongzheng in the Qing Dynasty (1727 AD). Because the century-old sugarcane is regarded as "feng shui sugarcane", it has been fortunately preserved by local villagers for generations.

The earliest report on Songxi’s 100-year-old sugarcane (Fujian Daily, August 6, 1958)

2. Taxonomic status

Sugarcane belongs to the Spermatophyta, Monocotyledons, and Saccharum of the Poaceae family. The genus Saccharum includes the Chinese species S. sinense, the tropical species S. officinarum, the Indian species S. barberi, the cut-hand dense S. spontaneum, the large-stemmed wild species S. robustum, and the fleshy flower spike wild species S. edule. The first three are original cultivated species, and the last three are wild species. Except for the fleshy flower spike wild species, the other five original species are of use value in sugarcane hybrid breeding.

According to the results of a study using genomic in situ hybridization conducted by the National Sugarcane Engineering Technology Research Center of Fujian Agriculture and Forestry University, Centennial Sugarcane is a natural hybrid of China's tropical species and the cut-handled sugarcane, and is an ancient local variety formed through natural selection and artificial domestication by ancestors.

Tropical species, cut-handed sugarcane, and century-old sugarcane (the photo of cut-handed sugarcane was provided by Dr. Wang Qinnan, deputy director of the South China Seed Research Institute of Guangdong Academy of Sciences)

3. Plant morphological characteristics

Sugarcane has the same morphological characteristics as Gramineae plants, with monocotyledons, fibrous root system, stems with nodes, one leaf at each node, alternate leaves, leaf sheaths covering the stems, buds on the nodes, alternate buds, complete flowers, and caryopsis. Sugarcane roots can be divided into seed roots, plant roots (seedling roots), and aerial roots according to the different locations of occurrence. The characteristics of the century-old sugarcane species are strong tillering ability, well-developed root system, well-developed underground runners, good perennial roots, cold and drought resistance, tolerance to extensive cultivation, and high sugar content.

Morphology of the aerial parts of century-old sugarcane

(1) Centennial sugarcane stem. Small stem, mostly between 1.5 cm and 2.0 cm. The stem bark is green and turns yellowish green after exposure. The leaves are long and drooping. The leaf sheath is tightly wrapped around the stem and is difficult to remove.
(2) Buds of century-old sugarcane. There are three types of buds: one is that many of them grow downward first and then turn to grow above the ground. The second is that some buds grow horizontally to 10-25 cm first and then turn to grow out of the ground. The third is that they grow directly out of the ground. Due to the alternation of these three situations, the node position of perennial sugarcane will not be raised, and there is no need to worry about the lack of soil for cultivation. The lowering of the node position is also beneficial to keep warm in winter.
(3) Root system of century-old sugarcane. Both the surface root system and the root system of the resident sugarcane are very developed, especially the deep root system of the perennial sugarcane is more developed than that of the newly planted sugarcane.
Centennial sugarcane underground stems

4. Local cultivation techniques

The reason why century-old sugarcane can remain perennial for so long is, in addition to its unique species, cultivation and management techniques are also key factors.
(1) Songxi Centennial Sugarcane usually sprouts around the Qingming Festival every year and is harvested around the Beginning of Winter. Use a quick hoe to cut the stems 3 cm into the soil, leaving the stems in the soil about 10 cm long. This can prevent frostbite and head rot, and also prevent them from drying out when exposed to the air.
(2) Loosening the ridges around Qingming Festival is beneficial to cut off some of the surface roots and stationary roots, promote the growth of new roots, and promote the germination and growth of buds at the base of the sugarcane ridges.
(3) Centennial sugarcane plants are slender and prone to lodging in the late stage of maturity. It is necessary to build bamboo supports in combination with soil cultivation to prevent them from lodging.
(4) Centennial sugarcane is susceptible to mosaic disease and sugarcane woolly aphids. In the cultivation and management of perennial sugarcane, attention should be paid to preventing the spread of mosaic disease and timely preventing sugarcane aphids and woolly aphids. It is recommended to sample virus-free healthy seedlings for planting new sugarcane.

V. Development and Utilization Value

The continuous perennial cultivation of century-old sugarcane has lasted for 295 years and can still maintain a considerable yield, which is an unprecedented feat and has great research and utilization value in scientific research and nutrition.
(1) Analysis of strong perennial root characteristics. According to local farmers, less than 10% of the perennial sugarcane plants are replaced each year, and the seedlings of the replacement plants are also divided from the original sugarcane fields. This shows that the perennial sugarcane has a strong perennial root characteristic, which is worthy of further study.
(2) Analyze the mechanism of tolerance to continuous cropping. The planting area of ​​100-year-old sugarcane mother plants is about 0.7 mu, and the continuous cropping period is nearly 300 years. The mechanism of tolerance to continuous cropping of 100-year-old sugarcane is studied from the aspects of soil microorganisms, soil nutrition, and plant root characteristics.
(3) Exploring excellent cold-resistant gene resources. Songxi County, which belongs to Nanping City, Fujian Province, is located on the southeast side of the foothills of Wuyi Mountain and has a mid-subtropical humid monsoon climate. There is frost in winter all year round, and the annual extreme minimum temperature is -7.6℃. The underground buds of century-old sugarcane can survive in low temperature conditions and can still germinate the following year, indicating that they have strong cold resistance.
(4) Develop the nutritional value of century-old sugarcane. According to the research results of the Shanghai Institute of Materia Medica, Chinese Academy of Sciences, century-old sugarcane contains rich functional active substances, such as polysaccharides, polyphenols, sterols, flavonoids, triterpenes, etc., which are the current research focus of plant functional active substances.

About the author <br /> Gao Sanji, PhD, researcher, PhD/Master's tutor. Chairman of the Sugarcane Professional Committee of the Chinese Society of Crop Science, member of the 10th Council of the Chinese Society of Crop Science, Executive Deputy Director of the National Sugarcane Engineering Technology Research Center of Fujian Agriculture and Forestry University, post scientist of the National Sugar Industry Technology System, member of the Expert Committee of the China Sugar Association, science and technology/popular science expert of the China Science and Technology Press, member of the Expert Committee of the Guangxi Shuangxin Sugar Industry Science and Technology Innovation Research Institute, editorial board member of 4 Chinese and English journals, peer reviewer of more than 40 SCI journals. He has worked at the National Sugarcane Engineering Technology Research Center (formerly the Sugarcane Comprehensive Research Institute) of Fujian Agriculture and Forestry University since 1996; worked as a visiting scholar and postdoctoral fellow at Texas A&M University in the United States from 2008 to 2010. He is mainly engaged in the research of sugarcane disease prevention and control and disease-resistant breeding.