Sustainability of the rice–crayfish farming model in waterlogged land: A case study in Qianjiang County,Hubei Province,China

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.       

盱眙龙虾品牌建设对农产品品牌构建的启示

农产品品牌的形成,对农产品的市场流通和消费量的增长具有显著的带动作用。针对我国农产品品牌缺失的问题,分析农产品品牌建设中存在的主要问题,结合盱眙龙虾品牌建设的经验,提出农产品品牌构建的对策。     

淡水螯虾免疫学的研究进展

在查阅近年来国内外有关淡水螯虾的免疫学研究的文献资料基础上,探讨了淡水螯虾血细胞的吞噬、包囊、修复和胞吐作用机理以及血淋巴中proPO、凝集素、溶菌酶、酸性磷酸酶、碱性磷酸酶、抗菌肽、蛋白酶抑制因子等免疫因子的生理生化特性、生物学功能、作用机制和应用前景等,并展望了淡水螯虾的免疫学研究方向,旨在为淡水螯虾免疫防御机制的深入研究和疾病预防提供参考依据。     

克氏原螯虾母体规格对后代生长特性的影响

对克氏原螯虾(Procambarus clarkii)两种规格母体后代的生长特性进行了研究.结果表明,从两种规格母体上刚离体的早期幼虾经过40 d的培育,后代的体重差异不显著(P＞0.05),小规格母体后代的个体间差异较大,存活率均较低.分级后,再培育40 d,两种规格母体的后代生长性状差异极显著(P＜0.01),大规格母本的后代显著大于小规格母本的后代,随着培育时间延长幼虾体重变异系数和体长变异系数下降明显.     

Effects of different feed stimulants on freshwater crayfish (Procambarus clarkii), fed diets with or without partial replacement of fish meal by biofeed

The feeding trials were carried out with freshwater crayfish (Procambarus clarkii) to evaluate the three feed stimulants betaine (Bet), squid extract (SE) and squid meal (SM) upon fish meal (FM) diets or biofeed (BF) diets in which FM were partially replaced by BF. Results showed the three feed stimulants had no significant effect on growth. By the relative concentration of markers in the faeces and diets, the preference for each diet was estimated, and the best stimulant was the mixture of Bet, SE and SM. As FM replaced by BF increased, added with the mixture, the relative weight gain showed an increasing trend, but decreased significantly by 30% replacement. With the substitution increasing, trypsin activities increased, whereas decreased too upon 30% substitution. Less than 30% replacement, there was no significant effect on muscle proximate composition, intestine amylase activities and serum haemocyanin contents, except the drop of lipid. The results indicated that the mixture of Bet, SE and SM could perform well as a feed stimulant. And with the addition of the mixture, FM in the diet could make about no more than 20% saving without any adverse effects.     

Crayfish in central and southern Ukraine with special focus on populations of indigenous crayfish Astacus pachypus (Rathke, 1837) and their conservation needs

相似文献   

Effects of Cottonseed and Alfalfa Meals as Fertilizers on Production of Palmetto Bass (Morone saxatilis × M. chrysops) Fingerlings in Plastic-Lined Ponds

Effects of cottonseed meal versus alfalfa meal fertilization on water quality, zooplankton density, and production of phase I palmetto bass, Morone saxatilis × M. chrysops, were compared in plastic-lined ponds. Cottonseed meal promoted better (P < 0.05) water quality, timing of high zooplankton density development, and growth and yield of palmetto bass. Cost of cottonseed meal toward fish production was $0.75/kg of fish, while that of alfalfa meal was $1.74/kg of fish.     

Effects of simulated precipitation extremes on crayfish (Procambarus clarkii Girard) oviposition in artificial burrows

Mature female Procambarus clarkii were housed individually in artificial burrows simulating conditions in natural burrows. Crayfish were exposed to conditions of simulated temporary flooding dislocation (Experiment 1) or simulated drought (Experiment 2). In Experiment 1, females were dislocated from burrows to simulate 0, 1, 3 or 6 temporary flooding dislocations, and in Experiment 2, females were exposed to the following simulated drought conditions: wet control (no drought), dry control (no free water), month‐long periods without free water during July, August, September and October (1 month drought), two consecutive months without free water (August–September), and three consecutive months without free water (August–October). In Experiment 1, no significant differences in survival or oviposition rate were observed following transfer of individuals from ‘settled/sealed’ burrows to ‘new burrow’ containers, even after six consecutive dislocations. In Experiment 2, simulated drought of 2 or 3 month's duration had a significant negative impact on oviposition. Survival was significantly reduced only among females exposed to no free water during the 6‐month study. No spawning occurred without the presence of free water in the burrows, and when free water was absent during the peak spawning months of September and/or October, oviposition was delayed until free water was returned. These results indicate that brood female P. clarkii can withstand short‐term conditions without free water in the burrow with little effect, but reproduction and survival are significantly reduced by prolonged drought.     

Effects of vitamin C inclusion in practical diets on survival and growth of juvenile crayfish (Pacifastacus leniusculus Dana,Astacidae) from the onset of exogenous feeding

The aim of this study was to evaluate the effects of practical diets with different levels of vitamin C on survival and growth of juvenile crayfish (Pacifastacus leniusculus). An 80‐day trial was conducted with stage 2 juveniles from the onset of exogenous feeding. Four practical diets differing in the content of l ‐ascorbyl‐2‐monophosphate‐Na were prepared: 0, 0.2, 0.4 or 0.8 g kg^?1 diet. Each diet was tested on grouped or individually isolated crayfish. Diets had no significant effects on survival of crayfish held in groups (average: 73.1%) neither on the isolated ones (average: 90%). Crayfish fed the diet with 0.2 g kg^?1 of l ‐ascorbyl‐2‐monophosphate‐Na had the highest growth (groups: 13.64 mm carapace length (CL), 542.4 mg weight; isolated: 17.05 mm CL, 1213.2 mg weight) and the lowest feed conversion ratio (average of grouped and isolated: 0.99). This study provides the first data on vitamin C requirements of freshwater crayfish. A level of 0.2 g l ‐ascorbyl‐2‐monophosphate‐Na kg^?1 diet (0.07 g ascorbic acid equivalent) can be recommended for juvenile P. leniusculus during the first period of intensive rearing.