The Origin of Flooded Rice Cultivation

Rice cultivation has long been considered to have originated from seeding of annual types of wild rice somewhere in subtropics, tropics or in the Yangtze River basin. That idea, however, contains a fatally weak point, when we consider the tremendous difficulty for primitive human to seed any cereal crop in the warm and humid climate, where weed thrives all year round, instead of the accepted theory, we have to see a reality that vegetative propagation of edible plants is a dominant form of agriculture in such regions. The possibility is discussed that Job＇s tears and rice, two cereal crops unique to the region, might have been developed via vegetative propagation to obtain materials for medicine or herb tea in backyard gardens prior to cereal production. This idea is supported by the fact that rice in temperate regions is still perennial in its growth habit and that such backyard gardens with transplanted taro can still be seen from Yunnan Province of China to Laos. Thanks to detailed survey of wild rice throughout China for 1970-1980, it is now confirmed that a set of clones of wild rice exist in shallow swamps in Jiangxi Province, an area with severe winter cold. In early summer ancient farmers may have divided the sprouting buds and spread them by transplanting into flooded shallow marsh. Such way of propagation might have faster improved less productive rice through a better genetic potential for response to human interference than quick fixation in seed propagation, because vegetative parts are heterogeneous. Obviously, such a primitive manner of rice cultivation did include the essential parts of rice farming, i.e., nursery bed, transplanting in flooded field of shallow marsh like. Transfer from the primitive nursery to true nursery by seed may have later allowed rice cultivation to be extended to northern regions. In thus devised flooded cultivation there were a series of unique advantages, i.e.; continuous cropping of rice in a same plot, no soil erosion, slow decline of soil fertility, availability of minerals, and resulting in high yield per unit area, which have collectively attained the highly productive cereal cultivation in the warm and humid region. Rice cultivation in marsh is also favorable to raise fish culture, both of which constituted a nutritionally balanced base. Development of irrigation technology to construct flooded farms gave strong bases for stable rice-cultivating society, which in the end formulated the rise of ancient kingdoms of Yue and Wu in China in BC 6th -5th centuries. They were direct descendents of those people who had developed the unique rice cultivation from the era of Hemudu culture, which is dated back to 5 000 BC. Their movement to the south is considered to have established rice-cultivating communities in South China and Southeast Asia, while to the north it transferred the rice-based technology to ancient Korea and Japan and had established there a base for a civilized society.

The Program of Fish Culture in rice fields has been developed in Zhejiang Province

1996 is the first year for realizing the object of fish culture in 66,600 ha of rice field in Zhejiang Province. The provincial government has appropriated $ 24,000 per ha for starting capital. Starting from this year, counties with the tradition of fish culture in rice fields as Youngjia and Qingtian have put stress on popularizing the new technique of fish culture in ditches and puddles to raise the yield for per unit area. In areas of Central Zhejiang and North Zhejiang with hilly land and plain area with double—season rice, people have changed traditional fish varieties into special and excellent fish varieties.

Mercury levels and estimated total daily intakes for children and adults from an electronic waste recycling area in Taizhou, China: Key role of rice and fish consumption

In order to assess the potential health risks of Hg pollution, total mercury（T–Hg） and methyl mercury（Me Hg） concentrations were determined in air, dust, surface soil, crops, poultry,fish and human hair samples from an electronic waste（e-waste） recycling area in Taizhou,China. High concentrations of T–Hg and Me Hg were found in these multiple matrices, and the mean concentration was 30.7 ng/m3 of T–Hg for atmosphere samples, 3.1 μg/g of T–Hg for soil, 37.6 μg/g of T–Hg for dust, 20.3 ng/g of Me Hg for rice and 178.1 ng/g of Me Hg for fish,suggesting that the e-waste recycling facility was a significant source of Hg. The inorganic Hg（I–Hg） levels（0.84 μg/g） in hair samples of e-waste workers were much higher than that in the reference samples. Pearson＇s correlation coefficients showed that strong positive correlations（p 〈 0.01） between hair I–Hg and time staying in industrial area（r = 0.81） and between Me Hg and fish consumption frequency（r = 0.91）, imply that workers were mainly exposed to Hg vapor through long-time inhalation of contaminated air and dust, while other population mainly exposed to Me Hg through high-frequency fish consumption. The estimated daily intakes of Hg showed that dietary intake was the major Hg exposure source,and Hg intakes from rice and fish were significantly higher than from any other foods. The estimated total daily intakes（TDIs） of Me Hg for both children（696.8 ng/（kg·day）） and adults（381.3 ng/（kg·day）） greatly exceeded the dietary reference dose（Rf D） of 230 ng/（kg·day）,implying greater health risk for humans from Hg exposures around e-waste recycling facilities.

Aquatic resources and feed diversification:Reviewing three case studies from South East Asia with a viewpoint of trophic intensification in rice fish culture

Management of fed-fish culture practices,at present,stands on two broad feed categories,(i)formulated proteinaceous aquafeeds and(ii)the natural resources.Judicious use of the later is gaining popularity since it offers sustainability to fish culture.Polyculture often targets phyto-and zooplanktonic resources,but mostly ignores periphyton.This review discusses the works on feed diversification performed independently at different times.Fishes,viz.Cyprinus carpio,Labeo rohita and Amblypharyngodon mola were projected as potential candidates for resource-nutrient management with feed diversification in rice fish culture.With C.carpio the rice fish culture called Aji Gnui Assonii in terrace water-logged rice field of Apatani Plateau,Arunachal Pradesh(India)is referred as self-substrating aquaculture practice.This monoculture practice experiences high carp productivity since there remains surplus of resources below the threshold level in these rice fields.Similarly,L.rohita,explores periphytic resources in ponds when substrates are installed.As a result,filter feeders get more foraging aquatic phase intensifying the resources for exploration in pond.This concept is suggested for rice fields with water depth above 50 cm where rice stems act as substrate.With trenches or refuge canals,resource intensification may be managed for more cultivable fishes in rice fields with<50 cm water depth.This model of resource intensification further allows inclusion of Small Indigenous Fish Species(SIFs)-which are rich source of many micronutrients.Thus,integration of SIFs confers huge potentiality for intensification of nutrients,especially protein and micronutrients in rice fields.

Globally Important Agricultural Heritage Systems(GIAHS)of China:the challenge of complexity in research

The challenge of researching Globally Important Agricultural Heritage Systems(GIAHS)as complex systems forms the subject matter of this study.Complex adaptive systems are those that combine natural ecological processes with human interactions to produce a mutually supportive agro-ecological system.In China,these highly varied systems have the added dimension of long historical time,in that they have evolved over many centuries and thus add a historical dimension to the natural and human dimensions of complexity.In preparing research on GIAHS,it is clear that seeing GIAHS sites as whole systems is an essential starting and ending point.Examining the adaptive capacity of a GIAHS with its multiple scales and complex interdependencies is a major challenge for researchers accustomed to specialized disciplinary thinking.A GIAHS represents a mature agro-ecological system with human agency as a central component that has been honed over many centuries,and has already adapted to many perturbations and changes.The beauty of the GIAHS is in the integration of custom,knowledge,and practice,and it should be studied for its"wholeness"as well as for its resilience and capacity for"self organization."The agro-ecological approach opens the possibility of researching a system as a whole and of taking its complexity seriously.This study reviews the essential features of the GIAHS as a complex adaptive system where uncertainty is normal and surprise is welcome and,in a case study of Qingtian rice–fish culture system,focuses on new perturbations,namely loss of young people and the introduction of tourism.