基于空间聚类的西藏耕地后备资源开发组合模型

耕地后备资源开发科学合理布局直接影响土地资源可持续利用以及区域生态环境保护。以西藏自治区为研究区,以西藏第二轮耕地后备资源调查评价成果为基础,针对西藏特殊环境,提出基于自然和社会适宜性的西藏耕地后备资源开发适宜性评价模型;并以乡镇为聚类单元,以各乡镇耕地后备资源综合适宜性指数、集中连片指数以及增产潜力指数为变量,考虑空间近邻关系,采用基于图论的SKATER算法进行聚类分析,确定西藏耕地后备资源开发组合。结果显示:依据开发适宜性评价模型,西藏自治区耕地后备资源最适宜、中等适宜和勉强适宜的地块分别占全区耕地后备资源总面积的27.98%、49.09%、22.93%;根据开发组合模型,将具有耕地后备资源的乡镇分为3个组合,分别为近期重点开发、中期适度开发及后期开发区域。此分区结果保持了区块间的近邻关系及行政区界的完整性,为耕地后备资源开发区划提供借鉴,同时为发挥农业规模效益提供了科学依据。     

农业装备虚拟试验系统平台的建立

针对农业装备数字化设计技术研究的需求,利用虚拟现实场景建模工具MultiGen Creator和实时场景驱动软件Vega Prime,结合VC++编程语言,开发出一套完整的农业装备虚拟试验系统平台.阐述了系统平台的软硬件组成、功能、结构以及系统的开发流程,对建模过程中运用到的方法、步骤和所涉及到的关键技术进行了研究,此外对Vega Prime应用中的关键技术和难点进行了探讨.测试试验表明,该系统平台运行稳定,具有可靠性和有效性.     

国际市场对中国有机农业发展的启示

1．美国有机食品市场 美国是目前全球最大的有机农产品销售市场,市场规模大,且种类繁多,销售途径多种多样。有机谷物、水果、蔬菜、坚果和香料市场已经具有一定规模;其他如有机葡萄酒、糖浆、有机番茄酱、食用油、麦片、冷冻蔬菜和速冻食品等高附加值产品也发展很快。     

中国有机畜牧业发展现状、问题及对策

所谓有机畜牧业,就是在牲畜的饲养过程中,禁止使用化学饲料或含有化肥、农药成分的饲料来喂养。在预防和治疗畜禽疾病时尽可能不使用具有残留性的药物,以免人们食用牲畜肉类及其制品后损害人体健康。有机畜牧业的根本目的是对环境有利．保证动物健康的持续性,关注动物福利,生产高质量的产品。     

Improved Yield Prediction of Ratoon Rice Using Unmanned Aerial Vehicle-Based Multi-Temporal Feature Method

Pre-harvest yield prediction of ratoon rice is critical for guiding crop interventions in precision agriculture.However,the unique agronomic practice(i.e.,varied stubble height treatment) in rice ratooning could lead to inconsistent rice phenology,which had a significant impact on yield prediction of ratoon rice.Multi-temporal unmanned aerial vehicle(UAV)-based remote sensing can likely monitor ratoon rice productivity and reflect maximum yield potential across growing seasons for improving the ...     

注射多巴胺对中华绒螯蟹打斗行为的影响

选同一家系规格相似、健康有活力的中华绒螯蟹新品种“光合1号”1龄雄蟹100只,分为4组,放入直径20 cm、高40 cm PE管(底部均匀钻12个直径为5 mm的孔洞)中,PE管置于120 L水槽中。用2个不透明烧杯将2只中华绒螯蟹分别倒扣于试验容器中,置于PE管两侧1 h。在中华绒螯蟹第三步足的动脉膜中分别注射20μL生理盐水(对照组),10^-8 mol、10-7 mol和10-6 mol的多巴胺液,利用闭路摄像头记录4 h内2只中华绒螯蟹打斗时长、次数、打斗分数及胜负关系等指标。打斗结束后,迅速取出中华绒螯蟹血淋巴,用ELISA酶联免疫法测定多巴胺含量。试验结果显示,对照组中华绒鳌蟹打斗时间最长,与各注射组差异显著(P<0.05);注射组中,随注射量的增加,打斗时长下降。对照组中华绒螯蟹打斗强度低于10^-8 mol组,高于其他注射组,与各注射组间差异显著(P<0.05)。注射组中,随注射多巴胺量升高,打斗强度下降,10^-8 mol组打斗强度最高,各组间差异显著(P<0.05)。对照组打斗次数与10-7 mol组差异不显著(P>0.05),与其余各组差异显著(P<0.05)。注射组中,随注射量的增加,打斗次数下降,10^-8 mol组与其余各组差异显著(P<0.05),10-7 mol组与10-6 mol组差异不显著(P>0.05)。打斗结束后,胜利方体内多巴胺含量与正常水平差异不显著(P>0.05),但显著高于失败方(P<0.05)。试验结果表明,注射多巴胺极显著影响中华绒螯蟹打斗行为(P<0.01),随多巴胺注射量的升高,中华绒螯蟹打斗行为整体下降。     

Long‐chain polyunsaturated fatty acid metabolism in carnivorous marine teleosts: Insight into the profile of endogenous biosynthesis in golden pompano Trachinotus ovatus

Golden pompano Trachinotus ovatus is an important farmed carnivorous marine teleost. Although some enzymes for long‐chain polyunsaturated fatty acid (LC‐PUFA) biosynthesis have been identified, the ability of T. ovatus for endogenous biosynthesis is unknown. Here, we evaluated in vivo LC‐PUFA synthesis in a 56‐day culture experiment using six diets (D1–D6) formulated with linseed and soybean oils to produce dietary linolenic/linoleic acid (ALA/LA) ratios ranging from 0.14 to 2.20. The control diet (D0) used fish oil as lipid source. The results showed that, compared with the corresponding indices of fish fed D0, the weight gain rate and specific growth rate as well as the contents of eicosapentaenoic (EPA) and docosahexaenoic acids in tissues (liver, muscle, brain and eye) of D1–D6 groups were significantly lower (p < .05). These data suggested that T. ovatus could not synthesize LC‐PUFA from C₁₈ PUFA or such ability was very low. However, tissue levels of 20:4n‐3 in fish fed diets D1–D6 were higher than that of D0 fish (p < .05), and positively correlated with dietary ALA/LA ratio, while levels of EPA showed no difference among the D1–D6 groups. These results indicated that Δ5 desaturation, required for the conversion of 20:4n‐3 to EPA, may be lacking or very low, suggesting incomplete LC‐PUFA biosynthesis ability in T. ovatus.     

Digestive characteristics and blood chemistry profile of triploid rainbow trout Oncorhynchus mykiss: influence of body size and seasonal variation

Fisheries Science - Two experiments were conducted to evaluate the effects of body size and seasonal variation on organ indexes, digestive enzymes and plasma biochemistry parameters of triploid...     

Microtopographic structures facilitate plant recruitment across a saltmarsh tidal gradient

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Year‐round natural spawning,early development,and the effects of temperature,salinity and prey density on captive ornate goby Istigobius ornatus (Rüppell, 1830) larval survival

Natural spawning, early development and larviculture of the ornate goby Istigobius ornatus in captivity were studied for the first time. I. ornatus spawned 46 times from 31 October 2013 to 31 October 2014. Fecundity ranged from 246 to 10,214 eggs per clutch, with an average hatching rate of 77.8% ± 9.9% (M ± SEM). Fertilized eggs (1.31–1.54 × 0.46–0.50 mm in diameter) were adhesive demersal and oval‐shaped. Embryonic development lasted 84 hr at 27.5 ± 0.5°C. Newly hatched larvae [2.12 ± 0.04 mm in total length (TL)] transformed to the juvenile stage completely when TL was 7.79 mm. Effects of different water temperatures (24, 28 and 32°C) and salinities (10, 15, 20, 25, 30, 35 and 40 g/L) on per cent survivals (%) and survival activity indices (SAIs) were tested. Survival was not significantly different under different temperatures; SAIs was significantly higher at 28°C. Larvae showed the significantly higher survival and SAIs at salinities 10–30 g/L than at 35 and 40 g/L. Effect of different prey densities on survival was significantly higher in 7 days post hatch larvae fed 20 and 30 rotifers/ml. These findings could guide future programs in captive breeding technology development and commercial production of other marine ornamental gobies.