地方高职院校服务乡村振兴的实践——以嘉兴职业技术学院为例

正乡村振兴需要一批具有规划美丽乡村建设的工匠师,需要一批"懂经营、会管理、有文化"的新型职业农民、需要一支"懂农业、爱农场、爱农民"的基层干部队伍,为乡村振兴提供人才保障,因此,乡村振兴战略对农村人才提出了新的要求。提出了人才振兴的重要性以及高职院校作为地方高校培养服务乡村振兴人才的责任和优势,介绍了嘉兴职业技术学院五年来围绕振兴乡村实施的人才培养机制及做法。1乡村振兴人才培养现状及问题分析     

公费农科生的政策创新与实践检视

培养一支懂农业、爱农村、爱农民的乡村人才队伍,从人才数量、结构和质量上精准服务乡村振兴战略需求,成为涉农高校的历史责任、重要使命和重大机遇。2018年,山东省依托省内农业高等院校实施基层农技推广人才定向培养,政策期望以公费教育为切入点,破解市场配置优秀人才资源流动不畅,致力于解决乡村振兴涉农人才短板问题。文章介绍了山东农业大学等高校在深化农科生教育改革,为乡村振兴人才培养方面的有益探索和实践,以期为其他农业院校服务乡村振兴提供借鉴。     

乡村振兴战略下高等农林院校本科教育人才培养质量的现状与优化

乡村振兴战略给农业农村经济发展带来了重大战略机遇,也给高等农林院校提供了广阔的舞台。产业兴旺是乡村振兴最为基础、最为关键的任务,人才兴旺则是产业兴旺的重要支撑和保障。因此,国家乡村振兴战略实施需要大量掌握农业先进科学技术,熟悉农业产业,勇于创新,敢于善于创业的农业专业技术人才。该文通过对乡村振兴战略下高等农林院校本科教育的内在要求和人才培养质量的进行梳理,分析了目前高等农林院校本科教育人才培养的现状,提出了基于乡村振兴的农业创新创业型人才培养的优化意见。     

乡村人才振兴视域下农业高校人才培养的困境与出路

乡村振兴战略是新时代做好"三农"工作的总抓手,重点是解决关系国计民生的农业农村农民问题。人才振兴是乡村振兴的关键所在,是破解乡村发展不充分的有效举措。农业高校是农科人才培养的主阵地,具有独特优势,也是使命所在,应为乡村人才振兴发挥好人才培育功能。农业高校人才培养过程中面临与产业需求不匹配、理论教学与实践教学相脱节、通识教育与专业教育相冲突、内涵发展与特色发展不契合等问题。结合乡村振兴人才需求,农业高校亟需主动对接产业发展与市场需求,调整培养结构;坚持实践教学与理论教学并重,完善保障措施;加强通识教育与专业教育融合,促进思想转变;促进内涵建设与特色发展机能共生,实现创新发展。     

乡村振兴视域下农业高校服务乡村人才振兴的路径探析

乡村振兴战略是新时代解决好"三农"工作的重要抓手,人才是乡村振兴的第一资源,乡村振兴要抓好人才这个关键要素。乡村人才振兴面临高校人才培养与产业需求不匹配、不契合;乡村人才数量不足、质量不高;农业高校毕业生下不去、留不住的难题。乡村振兴迎来新的机遇与挑战,人才需求更加趋于多方面宽领域。农业高校作为涉农人才培育的主要场所,应为乡村人才振兴承担起更大的责任与使命,亟需在保障乡村人才供给、提升乡村人才素质和能力、促进人才流入乡村上下功夫,切实通过服务人才振兴促进乡村全面振兴。     

涉农高职院校乡村振兴人才培养研究与实践

助力乡村人才振兴，培养懂农业、爱农村、爱农民的“一懂两爱”人才，是时代赋予涉农高校的重要使命。涉农高职院校是我国农业类高等院校的重要组成部分，目前在办学定位、办学模式、学科设置、培养模式、思政教育等方面存在诸多偏差，需要进一步研究和探索。以铜仁职业技术学院“乡村振兴专干班”为研究试点，通过实施多元主体协同办学、打造高水平专业群、强化“三农”情怀思政教育等措施，构建了具有贵州山地特色的农牧类乡村振兴人才培养范例，旨在为其他农业类职业院校提供经验借鉴。     

乡村振兴战略背景下农业高校人才培养的新要求

在大力实施乡村振兴战略的背景下,实现农业现代化人才培养是关键,改革传统的人才培养模式,构建人才培养新体系,是新形势下对农业高校人才培养的新要求。该文通过对乡村振兴战略下新型农业人才需求和培养途径的探索,以期高校能发挥主动性,不断创新人才培养模式,为乡村振兴提供人才保障和智力支持。     

乡村振兴背景下地方农业高校 服务三农人才培养研究

乡村振兴是新时代新农村全面建成的新契机，涵盖了农村经济、政治、文化、社会建设等诸多方面，需集全社 会之力共同推进。地方农业高校应该发挥人才培养、科技创新、社会服务、文化传承等优势，助力乡村振兴战略，推动 农业产业升级，激发农村全面发展潜力，谱写新时代农村建设的新篇章。本文从地方农业高校的视角解析了乡村振兴 战略，并对地方农业高校服务乡村振兴的思路进行整理，提出地方农业高校应改革人才培养模式、建立科技创新体系、 完善成果传化机制与大力发展“耕读教育”，为乡村振兴战略提供理论支撑和人才保障。     

乡村振兴视域下农村人才振兴实践路径探究

乡村振兴,人才先行。人才振兴是实现乡村振兴的重要支撑,也是落实乡村振兴“产业兴旺、生态宜居、乡风文明、治理有效、生活富裕”总要求的关键所在。在新时代将人才振兴贯穿到乡村振兴工作全过程中已成为推进农业农村现代化不可或缺的重大举措。本文主要针对当前乡村振兴背景下农村人才发展环境有待改善、农村人才培养力度不足和农村人才的激励政策与保障制度不健全等方面存在的问题进行深入分析,并提出相应实践路径,以期助力乡村振兴,加快农业农村现代化步伐。     

培养基层农技推广人才 做好乡村振兴排头兵

实现乡村的全面振兴需要培养一支懂农业、爱农村、爱农民的"三农"工作队伍,身处农业农村工作前沿的基层农业技术推广人才正是这支队伍的重要组成部分。研究认为,在实施乡村振兴战略的今天,我国基层农业技术推广人才具备的素质应重新定位,他们应该是懂现代农业产业、爱宜居乡村,同时能教化、引领农民的人才。因此,建议高等农业教育在人才培养中应突出新时代农业农村和农民的特点,树立"三产"融合发展的理念,注意强化基层农业技术推广人才培养的"全科性",关注生态理念教育和人文素质的养成,不断强化院校的农业推广服务提升等功能。     

不同授粉组合对‘富士’和‘新红星’苹果品质的影响

【目的】探讨不同授粉品种对苹果品质和香气物质成分差异的影响,为高效授粉树的选育和苹果品质的提高提供依据。【方法】采用自育高效授粉树‘红菱’‘红锦’‘红雾’的花粉,在‘富士’(Malus domestica‘Fuji’)、‘新红星’(M.domestica‘Starkrimson’)铃铛花期进行授粉,以授‘嘎拉’(M.domestica‘Gala’)花粉的果实为对照,对果实发育期间总类黄酮含量的变化进行研究,并在果实成熟时测定可溶性固形物、花色苷含量等品质指标及香气物质成分。【结果】不同的授粉品种条件下,‘富士’和‘新红星’苹果除可滴定酸外的各项品质指标均高于对照。‘富士’苹果经‘红菱’授粉后,其果形指数、硬度、花色苷、可溶性糖含量显著提高,分别为对照的1.12、1.15、1.28、1.12倍。‘新红星’苹果经‘红雾’授粉后,其单果重、果形指数、花色苷、可溶性固形物、可溶性糖含量均显著提高,分别为对照的1.22、1.12、2.48、1.10、1.11倍,其可滴定酸含量显著降低,仅为对照的75%。在果实发育的整个生长期内,不同授粉品种处理的‘富士’和‘新红星’苹果总类黄酮含量均高于对照,且不同品种间存在显著差异。在花后160 d,‘富士’经‘红菱’‘红锦’‘红雾’花粉授粉后,果实内总类黄酮含量与对照相比分别增长19.63%、28.72%、13.97%,‘新红星’在花后120 d分别增长14.18%、15.26%、4.24%,差异显著。‘红菱’‘红雾’‘红锦’和对照授粉处理的‘富士’和‘新红星’苹果总酯类挥发性物质的相对含量分别为50.20%、52.03%、42.68%、45.10%和71.08%、68.85%、71.83%、66.03%,‘红菱’授粉后‘富士’‘新红星’果实总酯类挥发性物质含量明显增加,其中2-甲基丁酸乙酯的含量分别为对照的1.14和203.91倍。‘富士’苹果中,‘红菱’‘红雾’‘红锦’授粉处理的果实乙酸-2-甲基丁酯的含量分别为对照的1.73、1.07、1.36倍;其己酸乙酯和乙酸丁酯的含量分别为对照的1.09、1.12、1.29倍和1.50、0.77、1.30倍。而在‘新红星’苹果中,经‘红菱’‘红雾’‘红锦’授粉后,乙酸-2-甲基丁酯和己酸乙酯的含量分别为对照的1.82、1.27、0.93倍和2.57、1.15、0.27倍;乙酸丁酯的含量分别为对照的7.83、3.48、3.30倍。此外,‘富士’和‘新红星’苹果经‘红菱’授粉后,其烃类物质含量明显高于对照,主要表现为法呢烯的增多。【结论】高效授粉树能显著提高‘富士’和‘新红星’苹果的外观和内在品质,并且与对照存在显著差异。不同授粉组合对‘富士’和‘新红星’苹果品质影响差异较大,经‘红菱’授粉,‘富士’和‘新红星’苹果品质有显著提高。     

海岛棉GbHCT14基因启动子克隆及上游调控因子筛选

为探究GbHCT14基因CDS区及启动子序列在棉花纤维发育中的作用,通过中国农业科学院棉花研究所数据库检索到GbHCT14基因CDS区及上游非编码区-2 000 bp片段序列,克隆CDS区及启动子,并检测启动子活性。构建cDNA文库,利用酵母单杂交技术筛选阳性克隆,获得候选转录因子,并进行生物信息学分析。结果表明:1)GbHCT14基因的CDS区全长1 144 bp,其翻译产物为亲水性稳定蛋白,预测定位在叶绿体,没有信号肽以及跨膜结构域。2)GbHCT14基因启动子预测到5个MYB结合位点参与植物苯丙烷代谢途径的调节,1个TCA-element参与水杨酸调节,6个ABA响应元件。3)GbHCT14启动子能够驱动GUS蛋白表达,具有启动活性。4)酵母单杂交初步筛选出16个候选基因,包括Gbar_D01G020710、Gbar_A09G017360、Gbar_A09G009680、Gbar_A11G003660、Gbar_A12G004430、Gbar_D04G021210、GbM_D09G1212、GbM_A11G0186、GbM_A03G0171、GbM_A09G1247、GbM_D10G0411、GbM_D10G1024、GbM_D02G1379、GbM_A11G1190、GbM_D12G0471和genome_Gbar-ZJU_D08。利用生物信息学分析预测表明,上述候选基因参与棉花纤维细胞壁的伸长、泛素化反应、细胞分裂、花发育以及果实成熟的过程,其中GbM_A09G1247与WAK2为相似基因,WAK2功能蛋白与果胶结合后促进细胞壁的伸长,而HCT家族基因则是影响果胶合成的关键因素之一。5)GbHCT14和WAK2基因在棉花开花后25 d内高表达,两者在棉花纤维发育调控存在相关性。综上,GbHCT14基因CDS区及启动子序列为首次获得,GbHCT14基因启动子具有启动活性,并且筛选到与裂合酶、转移酶、植物激素、质子泵和功能蛋白相关的16个上游调控的候选转录因子。     

酸化处理对猪场原水和沼液存储过程中气体排放的影响

为探索酸化处理对猪场原水和沼液存储过程中温室气体(CH_4、N_2O、CO_2)以及NH_3排放的影响,采用浓硫酸酸化处理猪场污水,利用动态箱法在线监测存储75 d内各气体排放通量。试验分别设置一个对照组和两个酸化处理组:原水对照组p H为6.5(RCK),加酸处理后p H分别为5.1(RT1)和5.7(RT2);沼液对照组p H为7.8(BCK),加酸处理后p H分别为5.7(BT1)和6.5(BT2)。对于原水组,RCK、RT1、RT2的CH4排放通量分别为32.2、2.37、3.10 g·m~(-3)·d~(-1),N_2O排放通量分别为336.45、23.36、29.79 mg·m~(-3)·d~(-1),NH_3排放通量分别为1.01、0.82、1.63 g·m~(-3)·d~(-1),CO2排放通量分别为109.14、99.66、110.55 g·m~(-3)·d~(-1),酸化处理显著降低原水CH_4和N_2O排放量;对于沼液组,BCK、BT1、BT2的CH_4排放通量分别为0.24、0.86、0.63 g·m~(-3)·d~(-1),N_2O排放通量分别为2.54、73.43、268.66mg·m~(-3)·d~(-1),NH_3排放通量分别为8.02、1.35、1.51 g·m~(-3)·d~(-1),CO_2排放通量分别为48.9、44.3、44.0 g·m~(-3)·d~(-1),酸化沼液显著增加CH_4和N_2O排放通量,但NH3排放可显著降低81%~83%,同时酸化组内氨氮含量较对照组增加40%~54%。根据CH_4和N_2O在100年尺度上的全球增温潜势计算各组的综合温室效应,猪场原水酸化后CO_2-eq降低91%~92%,沼液酸化后温室气体增加5~11倍。结果表明:酸化处理原水能够有效降低温室气体排放,而酸化处理沼液则一定程度上增加了温室气体排放,但可有效降低NH_3排放,同时保留沼液中氮养分。     

不同品种授粉对‘轮台白杏’坐果及果实品质的影响

 以‘轮台白杏’Armeniaca vulgaris ‘Luntaibaixing’与26个新疆杏品种进行正反交,探讨不同品种授粉对‘轮台白杏’坐果及果实品质的影响。结果表明：不同品种授粉均提高了‘轮台白杏’坐果率,以‘卡巴克胡安娜’‘Kabakehuanna’,‘伊犁阿克玉吕克’‘Yiliakeyulvke’,‘特尔湾玉吕克’‘Teerwanyulvke’等品种效果为佳,但反交中经‘轮台白杏’授粉,仅有‘库车白杏’‘Kuchebaixing’等8个品种的坐果率有所增加,其余品种坐果率则低于自然授粉;与自然授粉所得果实比较,‘轮台白杏’的单果质量、果核质量以及可溶性固形物、维生素C、可滴定酸、总糖均受授粉品种影响,其中‘早熟胡安娜’‘Zaoshuhuanna’,‘阿克达拉孜’‘Akedalazi’,‘阿克阿依’‘Akeayi’等品种授粉后果实维生素C极显著降低（P＜0.01）,‘阿克阿依’,‘贾格达玛依桑’‘Jiagedamayisang’,‘米录’‘Milu’等品种授粉后可滴定酸极显著提高（P＜0.01）;果形指数受授粉品种影响较少,仅‘库车白杏’,‘卡拉胡安娜’‘Kalahuanna’授粉对‘轮台白杏’果形指数有极显著影响,‘大果胡安娜’‘Daguohuanna’等5个品种授粉为显著降低（P＜0.05）;综合坐果率考虑,‘卡巴克胡安娜’,‘早熟胡安娜’,‘伊犁阿克玉吕克’适于做‘轮台白杏’授粉树。不同品种授粉对‘轮台白杏’坐果及果实品质存在效果差异,生产中可根据需要选择父本提高坐果率和改善果实品质。表5参10     

复合水平流人工湿地对氮和有机污染物的 去除效果和动态变化

将半咸水(S=7.5±0.1)复合水平流人工湿地同室内水泥池养殖暗纹东方鲀(Takifugu obscurus)结合,构建室内集约化养殖—湿地生态系统,研究了人工湿地处理养殖循环用水过程中,湿地不同沿程处理系统对NH4+-N、NO2--N、NO3--N、TSS和COD的去除规律和动态变化.结果表明,人工湿地对上述水质指标有良好的净化效果,NH4+-N平均去除率66.37％,NO2--N平均去除率97.68％,NO3--N平均去除率7.63％,TSS平均去除率80.39％,COD平均去除率16.50％.各水质指标在湿地床内的动态模型可表示为曲线:CL=C0·exp(K1L2+K2L+K).     

不同质地黑土净氮转化速率和温室气体排放规律研究

为探讨黑龙江省半干旱地区不同质地黑土的净氮转化速率和温室气体排放规律,以壤砂土和粉壤土为研究对象开展室内培养试验,对土壤净硝化速率和净矿化速率、N2O和CO2排放速率与累积排放量进行研究。结果表明:7d培养期间壤砂土的平均净矿化速率和CO2平均排放速率分别为0.49mgN kg-1 d-1和0.30mgCO2-C kg-1 h-1,显著低于粉壤土的平均净矿化速率(1.37 mgN kg-1 d-1)和CO2平均排放速率(0.47mgCO2-C kg-1 h-1)。壤砂土的平均净硝化速率和N2O平均排放速率分别为1.65mgN kg-1 d-1和212.6ngN2O-N kg-1 h-1,显著低于粉壤土的5.02mgN kg-1 d-1和521.3ngN2O-N kg-1 h-1。壤砂土和粉壤土的N2O排放比率分别为0.081%~0.301%和0.210%~0.254%。研究表明,土壤质地显著影响土壤净氮转化速率和温室气体排放,壤砂土较低的pH、有机碳和水溶性有机碳含量是导致其净硝化速率、净矿化速率以及N2O、CO2排放速率显著低于粉壤土的主要原因。     

Comparative analysis of genomes in Oryza sativa, O. officinalis and O. meyeriana with C 0 t-1 DNA and genomic DNA of cultivated rice

Fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH) were applied to somatic chromosome preparations of Oryza sativa, O. officinalis and O. meyeriana with labeled probes of C ₀ t-1 DNA and genomic DNA from cultivated rice. The coverage percentage (%) and size (Mb) of C ₀ t-1 DNA in O. sativa, O. officinalis and O. meyeriana were 47.1 ± 0.16, 38.61 ± 0.13, 44.38 ± 0.13 and 212.33 ± 1.21, 269.42 ± 0.89, 532.56 ± 1.68, respectively. The coverage percentage and size of probe signals with genomic DNA from O. sativa in O. officinalis and O. meyeriana were 91.0%, 93.6% and 634 Mb, 1 123 Mb respectively, in which there were 365 and 591 Mb in O. officinalis and O. meyeriana which came from O. sativa genomic DNA not from repetitive sequences of O. sativa, and the uncovered genome size in O. officinalis and O. meyeriana was 64 and 78 Mb, respectively. In addition, karyotype analysis was conducted based on the signal bands of C ₀ t-1 DNA in O. sativa, O. officinalis and O. meyeriana. The results showed that highly and moderately repetitive sequences in Oryza genus were conserved as the functional genes during the evolution process. The repetitive sequence reduplication might be one of the important causes of genome enlargement in O. officinalis and O. meyeriana; the O. officinalis genome enlarged more slowly compared with O. meyeriana. Based on the above results, it is concluded that O. officinalis and O. meyeriana formed by reduplication, rearrangement and gene selective loss during the evolution process. Translated from Scientia Agricultura Sinica, 2006, 39(6): 1083–1090 [译自: 中国农业科学]     

“空心菜-水芹”轮作对养殖池塘水质和底质环境的影响

通过测定TOC、COD、Chl、TN、NH_4~+-N、NO_2~--N、NO_3~--N、TP、PO_4~(3-)-P等水质指标和底泥中TOC、TN、TP指标,探究"空心菜-水芹"轮作模式对不同养殖品种和养殖数量情况下养殖池塘水质和底质环境的影响。结果表明,在轮作模式前期,空心菜(Ipomoea aquatica)种植能显著降低甘露青鱼(Mylopharyngodon piceus)养殖场TOC、Chl、TN、NH_4~+-N、NO_2~--N、NO_3~--N、PO_4~(3-)-P等水质指标,能显著降低苏州经济鱼亲本塘TOC、COD、Chl、NH_4~+-N、NO_2~--N、NO_3~--N、TP等水质指标。轮作后期水芹(Oenanthe stolonifera)种植能降低甘露青鱼养殖场TOC、NO_3~--N、TP等水质指标,降低苏州经济鱼亲本塘TOC、COD、NH_4~+-N、NO_3~--N、TP等水质指标。轮作前、后期均能降低底质TOC、TN和TP含量。"空心菜-水芹"轮作模式能显著降低养殖池塘水体中TOC、NH_4~+-N、NO_3~--N、TP指标和底泥中TOC、TN、TP指标。     

Effect of cell mediated immunity regulation of duck enhanced by duck IFN-α eukaryon expression plasmid and inoculated with DPV attenuated vaccine by gene-gun

In order to study the effect of cell mediated immunity regulation of duck IFN-α eukaryon expression plasmid (pcDNA-SDIFN-α) on duck plague virus (DPV) attenuated vaccine in ducks, pcDNA-SDIFN-α was administered to 28-day-old ducks at doses of 1, 3 and 6 μg per duck, respectively, by gene-gun. PBS and empty vector pcDNA were used as control. Fifteen days later, all ducks were injected with DPV attenuated vaccine and blood samples were collected at 3, 7, 14, 21, 28, 35, 49, 63 and 84 days after injection. T-lymphocyte proliferation tests (MTT) were used to detect the T-lymphocyte proliferation in the peripheral blood (PBL) of ducks. Blood samples collected at 7, 14, 21, 28, 35 and 49 days after injection were detected by fluorescence-activated cell sorter (FACS) for recording the number of CD₃ ⁺ T-lymphocytes of ducks. Results were as follows: (1) Reaction of T-lymphocytes in PBL to ConA (OD value) of ducks treated with pcDNA-SDIFN-α was higher than that of PBS and pcDNA control groups in 3–84 days. There were highly significant differences between the 1 μg per duck group and the two control groups in 3–84 days (P ⩽ (0.01), between the 3 μg per duck group and the two control groups in 3–84 days (P ⩽ 0.01, P ⩽ 0.05), and between the 6 μg per duck group and the two control groups in 7–49 days (P ⩽ 0.01, P ⩽ 0.05). The significant difference was also present between the groups of 1, 3 and 6 μg per duck in 3–35 days (P ⩽ 0.05). However, there was no significant difference between the 3 and 6 μg per duck groups (P ⩾ 0.05). The pcDNA control group was higher than PBS control group, but no difference was detected (P ⩾ 0.05). (2) Change of the number of CD₃ ⁺ T-lymphocytes in ducks administered with different doses of pcDNA-SDIFN-α was higher than that of PBS and pcDNA control groups in 7–49 days. The change in the 1 μg per duck group was significantly higher than that in PBS and pcDNA control groups in 14–49 days (P ⩽ 0.01). There were significant differences between the 3 μg per duck group and the two control groups in 21–49 days (P ⩽ 0.01, P ⩽ 0.05) and between the 6 μg per duck group and the two control groups in 7–49 days (P ⩽ 0.01, P ⩽ 0.05). However, no significant differences among the groups of 1, 3, and 6 μg per duck groups (P ⩾ 0.05) and between the two control groups (P ⩾ 0.05) were found. The results indicated that pcDNA-SDIFN-α administered 15 days before injection of DPV-attenuated vaccine could significantly enhance cellular immunity induced by DPV-attenuated vaccine. pcDNA-SDIFN-α is an excellent DPV-attenuated vaccine molecular adjuvant and the best result can be obtained with the dose of 1 μg per duck of pcDNA-SDIFN-α inoculated by gene-gun. __________ Translated from Acta Veterinaria et Zootechnica Sinica, 2007, 38 (10): 1066–1071 [译自: 畜牧兽医学报]     

Effects of aqueous leaf extracts of Populus tomentosa at different ages on the growth and photosynthetic characteristics of its own seedlings

Through the outdoor potted plant trials, the allelopathic potential of Populus tomentosa was tested against its species in the growth, chlorophyll content, and photosynthetic and chlorophyll fluorescence characteristics with aqueous extracts (0.01, 0.02, 0.05, and 0.1 g·mL⁻¹) obtained from leaves at different individual ages (1, 20, and 45 years old). The results showed that seedling height, basal diameter, fresh and dry weights, quantity of chlorophyll, the ratio of chlorophyll a/b, net photosynthetic rate (P _n ), stomatal conductance (G _s ), transpiration rate (T _r ), efficiency of primary conversion of light energy of PSII (F _v /F _m ), potential activity of PSII (F _v /F ₀), and photochemical quenching (q _P ) of the seedlings gradually decreased with the increase of extract concentration of all three ages when compared with the controls. The older the P. tomentosa used for extract preparation, the greater the percentage declined in the aforementioned parameters. Moreover, at the four concentrations used, there was a significant difference between treatments with the extracts from 1- and 45-year-old plants (except for q _P ), but occasionally, the effects were not obvious between the 1- and the 20-year-old plants, or the 20- and 45-year-old plants. The intercellular CO₂ concentration (C _i ) treated with the extracts from the 1-year-old decreased at the lowest concentration, whereas it increased at higher concentrations. The C _i treated with aqueous leaf extracts from the 20-year-old decreased at the lower concentrations and increased to similar levels to that of the control at the higher concentrations. C _i was always close to control levels in 45-year-old extract treatments. All the aqueous leaf extracts of P. tomentosa at all ages caused an increase of the initial fluorescence (F ₀ ). The older P. tomentosa used for the preparation of aqueous leaf extracts caused a greater percentage decline in F ₀ . The nonphotochemical quenching (q _N ) increased significantly at lower concentrations of all P. tomentosa extracts, whereas it decreased significantly at higher concentrations. It seemed that aqueous leaf extracts from P. tomentosa were harmful to the photosynthetic structure of its own seedlings, inhibited seedling growth, and led to an eventual decrease of biomass. Extracts from older P. tomentosa leaves had more negative effects on the seedling growth of poplar. The effects on photosynthesis are the more important mechanism of the allelopathy of poplar.