The rice–crayfish farming model has been rapidly developed and become an economically viable method to supply food in China in recent years.  However, its environmental and economic sustainability has not been thoroughly investigated.  This study uses a survey in 2016 and a field experiment in 2017 in Qianjiang, Hubei Province, China to assess the relative economics of concurrent rice–wheat (RW), rice–crayfish (RC), and crayfish monoculture (CM) models in waterlogged land areas.  The field survey indicated that the RC model had a higher benefit–cost ratio (3.5:1) than the RW (2.0:1) and CM (3.1:1) models and the RC model protected farmers’ enthusiasm for grain production facing unfavourable weather conditions.  The field experiment aimed to explore nitrogen management strategies in RC fields.  In the experiment, four levels of nitrogen concentration gradient - 0 kg N ha^–1 (0 N), 75 kg N ha^–1 (75 N), 150 kg N ha^–1 (150 N) and 225 kg N ha^–1 (225 N), were set in a 2-year-old rice–crayfish (RC2) field, an 8-year-old rice–crayfish (RC8) field, and a RW field as a control.  The field experiment results suggested that the peak  rice yield in RW, RC2, and RC8 occurred when 225 N, 150 N and 75 N were used, respectively.  In RC2 and RC8, however, residual feed-nitrogen that was not used by crayfish was utilized by rice plants.  Thus, an optimal amount of nitrogen in RC fields was proposed to improve the nitrogen use efficiency and reduce environmental pollution by nitrogen fertilizer.  Farmers use less nitrogen but have higher net income in RC than in RW and CM.  It is necessary to sustainably develop integrated farming technologies (i.e., proper field configurations for rice fields) to effectively sustain rice production.  The results also showed that the RC farming model was a viable diversification option for rice farmers in waterlogged land.  

The present study investigates the chemical composition and antioxidant capacity of juice from the Gannan navel orange, which is harvested at one- to two-week intervals during the ripening period.  The total soluble solid (TSS), total polyphenol content (TPC), total flavonoid content (TFC), sucrose and hesperidin contents gradually increase with the ripening of the fruit, followed by slight declines at the late maturity stage.  Contrary to these observations, the contents of titratable acid (TA), vitamin C (Vc), and limonin trend downward throughout the ripening period.  However, the contents of fructose, glucose, and narirutin fluctuate throughout the harvest time.  Three in vitro antioxidant assays consistently indicate that the harvest time exerts no significant influence (P>0.01) on the antioxidant capacity.  Furthermore, principal component analysis (PCA) and Pearson’s correlation test are performed to provide an overview of the complete dataset. This study provides valuable information for evaluating the fruit quality and determining when to harvest the fruit in order to meet the preferences of consumers.  Meanwhile, our observations suggest that the fruits subjected to juice processing should be harvested at the late maturity stage to alleviate the “delayed bitterness” problem without compromising the antioxidant capacity and the flavonoid content in the juice.