Background: Rice–duck cultivation is the essence of Chinese traditional agriculture. A scientific assessment of the mechanism and its capacity is of theoretical significance and practical value in improving modern agricultural technology.Results: The duck's secretions, excreta and their treading, pecking and predation decrease the occurrence of plant diseases, pests and weeds, enrich species diversity and improve the field environment. The rice–duck intergrowth system effectively prevents rice planthoppers and rice leafhoppers. The control effects can be up to 98.47% and 100% respectively; it also has effects on the control of Chilo suppressalis, Tryporyza incertulas and the rice leafrollers. Notable control results are found on sheath blight, while the effects on other diseases are about 50%. Harm from weeds is placed under primary control; prevention of weeds is sequenced by broadleaf weeds > sedge weeds > Gramineae weeds. Contents of soil organic matter, N, P and K are improved by the system; nutrient utilization is accelerated, resulting in decreased fertilizer application. Greenhouse gas emissions are reduced by 1–2% and duck fodder is saved in this system. There is also an obvious economic benefit.Conclusion: Compared to conventional rice cultivation, rice–duck cultivation shows great benefits to ecologic cost and economic income. © 2013 The Authors. Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry

Increasing numbers of studies have suggested that a comprehensive assessment of the impacts of cropping practices on greenhouse gas (GHG) emissions per unit yield (yield-scaled), rather than by land area (area-scaled), is needed to inform trade-off decisions to increase yields and reduce GHG emissions. We conducted a meta-analysis to quantify impacts of rice varieties on the global warming potential (GWP) of GHG emissions at the yield scale in China. Our results showed that significantly higher yield-scaled GWP occurred with indica rice varieties (1101.72 kg CO₂ equiv. Mg⁻¹) than japonica rice varieties (711.38 kg CO₂ equiv. Mg⁻¹). Lower yield-scaled GHG emissions occurred within 120–130 days of growth duration after transplanting (GDAT; 613.66 kg CO₂ equiv. Mg⁻¹), followed by 90–100 days of GDAT (749.72 kg CO₂ equiv. Mg⁻¹, 100–110 days of GDAT (794.29 kg CO₂ equiv. Mg⁻¹), and 70–80 days of GDAT (800.85 kg CO₂ equiv. Mg⁻¹). The fertilizer rate of 150–200 kg N ha⁻¹ resulted in the lowest yield-scaled GWP. Consequently, appropriate cultivar choice and pairs were of vital importance in the rice cropping system. A further life cycle assessment of GHG emissions among rice varieties at the yield scale is urgently needed to develop win–win policies for rice production to achieve higher yield with lower emissions.

Rice-fish system is the first globally important agricultural heritage system (GIAHS) and could be a potential option to improve modern rice production. This paper investigates energy flows and economic profits of two rice production agroecosystems in China. Results suggest that total energy input in rice-turtle-fish co-culture (RTF) was 18,889.63 MJ ha⁻¹, less than that of rice monoculture (RM) (20,289.44 MJ ha⁻¹). Total energy output in RTF was 82,836.57 MJ ha⁻¹, higher than that of RM (77,221.21 MJ ha⁻¹). The product safety index (PSI) in RTF and RM were −0.23 and −0.77, respectively, which indicated the products safety potential in RTF was higher than that of RM. The energy sustainable development index (ESI) in RTF and RM were 9.03 and 0.66, respectively, which illustrated RTF has abundant developmental potential, while RM is more of a consuming-type ecosystem. The output/input, gross profits, and net profits in RTF were 5.17, 99,531.30 CNY, and 98,729.96 CNY, respectively, all higher than that of RM (4.58, 11,335.67 CNY and 11,034.33 CNY, respectively). Consequently, RTF has greater potential to reduce agro-chemicals, improve energy use efficiency, and increase economic profits compared to RM.

This study developed a technique system for the measurement, reconstruction, and trait extraction of rice canopy architectures, which have challenged functional–structural plant modeling for decades and have become the foundation of the design of ideo-plant architectures. The system uses the location-separation-measurement method (LSMM) for the collection of data on the canopy architecture and the analytic geometry method for the reconstruction and visualization of the three-dimensional (3D) digital architecture of the rice plant. It also uses the virtual clipping method for extracting the key traits of the canopy architecture such as the leaf area, inclination, and azimuth distribution in spatial coordinates. To establish the technique system, we developed (i) simple tools to measure the spatial position of the stem axis and azimuth of the leaf midrib and to capture images of tillers and leaves; (ii) computer software programs for extracting data on stem diameter, leaf nodes, and leaf midrib curves from the tiller images and data on leaf length, width, and shape from the leaf images; (iii) a database of digital architectures that stores the measured data and facilitates the reconstruction of the 3D visual architecture and the extraction of architectural traits; and (iv) computation algorithms for virtual clipping to stratify the rice canopy, to extend the stratified surface from the horizontal plane to a general curved surface (including a cylindrical surface), and to implement in silico. Each component of the technique system was quantitatively validated and visually compared to images, and the sensitivity of the virtual clipping algorithms was analyzed. This technique is inexpensive and accurate and provides high throughput for the measurement, reconstruction, and trait extraction of rice canopy architectures. The technique provides a more practical method of data collection to serve functional–structural plant models of rice and for the optimization of rice canopy types. Moreover, the technique can be easily adapted for other cereal crops such as wheat, which has numerous stems and leaves sheltering each other.