Effect of feeding guppy fish fry (Poecilia reticulata) diets in the form of powder versus flakes

The effects of feeding guppy (Poecilia reticulata) fry a diet offered as either powder or flakes on their growth and survival were tested over a period of 8 weeks. The results show that the growth of both male and female fish was considerably enhanced when the diet was presented in the form of a finely ground powder compared with a flake form. Final average weights of fish given a diet containing the exact same ingredients (44.9% protein and 6.1% fat), from the same batch of raw materials in the powdered form were 280.0±12.1 mg compared with 114.6±19.9 mg for the diet given in the form of flakes. In a diet that had a higher fat level (45.1% protein and 10.6% fat), the difference in final weight attained was even more dramatic: 303.9±16.7 mg for the powder‐fed fish compared with 92.6±12.5 mg for the flake‐fed fish. The coefficient of variance in the fish fed a flake diet was significantly higher than that exhibited in the treatments fed the powder feed. The ability of the fish to consume the food in a rapid manner, preventing leaching of vital nutrients from the feed before being engulfed by the fish probably led to the better growth results exhibited by the fish given the powdered food.     

不同烤烟品种氮素施用量策略研究

为探究不同烤烟品种的适宜施氮量,以K326、OX2028、NC2326、云烟87、红花大金元5个烤烟品种在全国4个烤烟产区采用小区试验方式进行了在当地习惯施肥量基础上增施和减施氮肥对烤烟品种主要化学成分及产量和质量影响研究。试验结果表明:在当地习惯施肥量基础上适度增加施氮量有助于提高K326、红花大金元、OX2028 3个烤烟品种的产量和产值;施氮量的改变对5个供试品种的烤后烟叶主要化学成分影响较小;适度增加施氮量有利于K326、红花大金元2个烤烟品种香气品质的提升,而不同施氮量处理对OX2028、NC2326及云烟87 3个烤烟品种的评吸质量影响较小。在当地施氮量基础上,适度增加K326、红花大金元烤烟品种施氮量有利于提高烤烟种植经济效益,提高烟叶香气质量。     

A WAY TO SUSTAINABLE CROP PRODUCTION THROUGH SCIENTIST−FARMER ENGAGEMENT

● Farmer–scientist collaboration for improved farming was achieved. ● Wheat and maize yields of STB farmers improved by 13%. ● NUE increased 20% for wheat and maize production. ● GHG emissions and EEF decreased by 23% and 52%, respectively. Feeding a large and growing population with scientifically sustainable food production is a major challenge globally, especially in smallholder-based agricultural production. Scientists have conducted a considerable theoretical research and technological innovation to synergistically achieve increased food production and reduced environmental impact. However, the potential and feasibility of synergistic smallholder-led agricultural production to achieve increased food production and environmental friendliness is not yet clear. Exploring the potential and feasibility of smallholders to synergistically achieve these two goals, this research collected survey data from 162 farmers implementing standard farming practices and 112 farmers engaged in Science and Technology Backyard (STB) in Quzhou County, Hebei Province, China. Grain yield, nitrogen use efficiency (NUE), greenhouse gas emissions (GHG), and emergy ecological footprint (EEF) of the wheat-maize cropping system dominated by smallholders were analyzed. The results showed smallholders in the STB group improved wheat and maize yields by about 13% and NUE by 20%, respectively. Also, a reduction of 23% in GHG emissions and 52% in EEF were simultaneously achieved in the wheat-maize cropping system. Compared with standard farming practices, 75 kg·ha⁻¹ nitrogen-based fertilizer was saved in the STB farmers. In summary, this study shifts the main perspective of research from scientists to smallholder, and uses a combination of greenhouse gas emission calculations, EEF and material flow analyses to demonstrate from multiple perspectives that agricultural systems under the leadership of smallholders can synergistically achieve high crop yields and low resource use and environmental impacts. The results of this study also show that the smallholder-led scientist-farmer collaborative model established by STB can fully exploit the initiative and potential, and that this collaborative model can be a successful strategy for smallholders as operators to achieve food security at low environmental impacts. The results of this study can provide useful evidence for a sustainable shift toward more sustainable agricultural production systems.     

荷斯坦母牛生长激素受体基因F279Y突变 与产奶性状的关联分析

采用PIRA-PCR和RFLP法检测204头中国荷斯坦母牛生长激素受体(growth hormone receptor,GHR)基因F279Y突变,并分析其与产奶性状的关系。结果在中国荷斯坦母牛中检测到GHR基因F279Y突变,3种基因型TT、TA和AA的频率分别为0.461、0.495和0.044,等位基因T和A的频率分别为0.708和0.292。分析表明,AA基因型个体305天产奶量显著高于TA和TT基因型(P0.05);TT基因型个体乳脂率显著高于AA基因型个体(P0.05),乳蛋白率极显著高于TA和AA基因型个体(P0.01)。A等位基因对305天产奶量有正加性效应,显性度相对较高;而对其他4个乳成分性状有负加性效应,显性度相对较低。等位基因A具有提高产奶量的效应,等位基因T具有提高乳成分的效应。本研究初步表明F279Y突变可以用于中国荷斯坦牛产奶性状的标记辅助选择。     

烤烟感染赤星病后4种酶动态的研究

 本文研究11个烤烟品种接种赤星病病菌后,过氧化物酶(POD)同工酶、多酚氧化酶(PPO)、硝酸还原酶(NR)和抗坏血酸氧化酶(AAO)活性的变化规律,结果表明,相对抗赤星病强的品种,PPO在接种36h内活性升高,以后下降;POD同工酶活性变幅大,变化快,接种初期活性稍下降,然后增强,其中以阴极端2,4同工酶带增加较快,接种180h后就由弱酶带变为强带;NR活性变化不大;AAO活性提高.相反,抗赤星病弱的品种,ppo活性低于对照;POD同工酶变化不大,呈下降趋势;NR活性变幅大;AAO在接种初期活性下降,84h后回升.通过对不同品种的烤烟烟株接种赤星病菌后的4种酶活性的测定,探察到了一些抗病机理,为进一步筛选烟草抗赤星病的生化指标作了研究.     

不同钠钾配比对番茄幼苗生长及生理代谢的影响

选用''中杂9号''番茄品种,采用水培法,以K⁺浓度（4 mmol/L）为对照,以不同浓度Na⁺（1、2、3、  3.5、3.75、4 mmol/L）与K⁺（3、2、1、0.5、0.25、0 mmol/L）配施,探究不同钠钾配比对番茄幼苗生长及生理代谢的影响。结果表明：与T1处理（4 mmol/L KNO₃+0 mmol/L NaNO₃）相比,T3处理（2 mmol/L KNO₃+  2 mmol/L NaNO₃）对番茄幼苗长势的促进作用最显著,株高、茎粗、整株鲜质量和干质量分别增加28.94%、  16.54%、59.14%和44.96%。随着Na⁺比例增加,番茄根系形态指标和叶片叶绿素含量均呈下降趋势,膜脂过氧化程度加剧,与对照相比,T7处理（0 mmol/L KNO₃+4 mmol/L NaNO₃）下相对电导率和过氧化氢含量的增幅最显著。与对照相比,T2处理（3 mmol/L KNO₃+1 mmol/L NaNO₃）和T4处理（1 mmol/L KNO₃+3 mmol/L NaNO₃）叶片超氧化物歧化酶（SOD）活性分别显著降低,T4、T6（0.25 mmol/L KNO₃+3.75 mmol/L NaNO₃）和T7处理根系SOD活性分别显著增加;叶片过氧化物酶（POD）活性T6处理的降幅最显著,而根系POD活性T7处理增幅最显著;叶片和根系过氧化氢酶（CAT）均呈不同程度增加。Na⁺比例增大可诱导番茄叶片和根系不同程度地积累渗透调节物质,与对照相比,T7处理脯氨酸含量的变化最显著。隶属函数法综合评价表明,T3处理番茄幼苗各指标均优于其他处理。综上,适宜的钠钾配比可通过调节番茄不同器官的抗氧化防御能力和渗透调节能力来影响其生长发育,且K⁺和Na⁺的配比为1∶1时,番茄幼苗的整体长势较佳。     

文献导读模式在作物育种学“课程思政”中的应用

“课程思政”是习近平总书记关于教育论述的重要内容之一,但农学专业课“课程思政”在落实高校立德树人根本任务方面的功能性还未充分体现。针对农学专业人才培养现状,以作物育种学为例,采用文献导读教学方法将“多样化”“隐性化”“特色化”的思政元素融入课程,探索文献导读在作物育种学“课程思政”中的应用模式,发挥农学专业课程在“德育”和“智育”方面的作用,并为农学专业课“课程思政”建设提供参考。     

田间自然条件下葡萄黑痘病抗性鉴定

葡萄黑痘病是危害葡萄生产的重要真菌病害之一,进行葡萄黑痘病抗性鉴定筛选抗病种质具有重要的意义。采用田间自然鉴定的方法,分析48份葡萄材料(北美种群内种间杂种、中国野葡萄、欧美杂种及欧亚种)对黑痘病的抗性差异。结果表明:不同葡萄材料对黑痘病抗性有着很大的差异。北美种群2个砧木品种、中国野葡萄华东葡萄湖南-1和山葡萄通化3号、欧美杂种均较欧亚种抗病,5BB、SO4、湖南-1、通化3号、京亚、8611、夏黑、翠峰和巨峰等表现为高度抗病;欧亚种对黑痘病的抗性表现为抗病和感病2种类型,其中紫地球、红提、玫瑰香等表现感病。研究结果为葡萄生产栽培和抗黑痘病育种提供理论依据。     

山东大豆品种主要农艺性状的演进

对50多年来山东省不同时期42个主要推广大豆品种的主要农艺性状的遗传演进进行了研究,结果发现,品种的结荚习性由无限结荚习性为主到以有限、亚有限结荚习性为主;生育日数均缩短5.6d;株高降低23.2%,其中上世纪50年代至60年代降低27.1%,60年代至80年代降低0.4%,80年代至90年代以后增加5.8%;主茎节数减少3.1个;节间长度缩短0.4cm～0.9cm;分枝数减少1.5个;单株荚数减少33.7%;单株粒数减少31.7%;百粒重增加37.9%;单株生产力平均增加13.9%;产量提高48.7%.在本试验条件下,研究认为,今后大豆育种要从提高单株生产力着手,适当增加株高,缩短节间长度,增加主茎节数,进而增加主茎荚数,以达到提高产量的目的.