Phenotypic plasticity of two invasive alien plant species inside a deciduous forest in a strict nature reserve in Italy

ABSTRACT

Invasive alien plant species (IAPs) represent one of the main biological threats to biodiversity worldwide. Information about their phenotypic plasticity are needed to increase awareness about their future invasive potential. A study about phenotypic plasticity in response to contrasting light regimes and its quantification by a plasticity index (PI) of two IAPs (Ailanthus altissima and Robinia pseudoacacia) inside a Strict Nature Reserve was conducted. R. pseudoacacia showed a 70% higher PI, with a strongly greater value at morphological leaf level, associated with a greater ability to survive and grow in forest understory, explaining its greater widespread. Otherwise, A. altissima showed its highest PI at physiological level, which was associated with the ability to colonize and grow in environments with high-light regimes. Based on these results, the conservative management has limited the presence of A. altissima by its lower ability to grow in forest understory. In fact, the small-scale gaps in the forest infrastructure, that could allow its recruitment, are originated only from the death of a single tree or small group of trees. Regarding R. pseudoacacia, it is critical to maintain this type of management because any disturbances resulting in large openings could further promote its presence inside the Reserve.     

长期施肥处理对双季晚稻叶绿素荧光特征及籽粒产量的影响

研究施肥模式对水稻叶绿素含量及荧光参数的调节作用,对提高水稻光能利用效率及籽粒产量具有重要意义。本研究以水稻品种赣929为试验材料,比较长期定位施磷钾肥(PK)、施氮磷钾肥(NPK)、等养分条件下70%氮磷钾肥配合施用30%有机肥(70F+30M)、50%氮磷钾肥配合施用50%有机肥(50F+50M)、30%氮磷钾肥配合施用70%有机肥(30F+70M)条件下水稻叶绿素荧光参数和产量变化特征。结果表明,水稻旗叶叶绿素含量从齐穗期到成熟期呈下降趋势,且表现为30F+70M50F+50M70F+30MNPKPK。水稻叶绿素荧光参数Fv/Fm随水稻生育期的推进呈降低趋势,其中PK处理Fv/Fm值最低,而施氮处理比不施氮处理Fv/Fm值增加了2.85%～4.18%。叶绿素荧光参数qL、ΦPSII在NPK处理中表现为齐穗期较高, 20 d之后显著降低;在50F+50M、30F+70M处理中表现为齐穗期较低, 20 d以后显著增加;在PK处理、70F+30M处理中一直处于较高水平。NPQ变化趋势与qL基本相反。ETR-PAR光响应曲线拟合结果表明, 70F+30M处理ETRmax、?和Ek值在齐穗期和20 d后值均最高。综合看来,等养分条件下配施30%有机肥具有最优的叶绿素荧光指标组合及籽粒产量;而配施超过50%有机肥由于前期热耗散增大使得用于光合作用的光能份额减少,而施用氮磷钾肥处理则由于后期的衰老使得光能利用效率下降。     

山东近海口虾蛄单位补充量渔获量评估

为完善口虾蛄的基础生物学资料,并为口虾蛄资源的管理提供科学指导和理论依据,本研究根据2016至2017年山东近海渔业资源底拖网调查获得的口虾蛄体长、体质量数据,估算了口虾蛄的生长、死亡参数,构建了基于体长结构的单位补充量渔获量(YPR)模型,研究口虾蛄的资源动态和管理策略。采集调查口虾蛄样品共5028尾,体长—体质量关系的表达式为W=0.0145L2.88,为负异速生长;使用ELEFAN方法估算出口虾蛄的渐进体长L∞为19.87 cm,生长速率K为0.62 a−1。口虾蛄的生长表现出明显的季节性变化规律,生长参数的季节振幅C为0.76,10月份生长最快,4月份生长最慢。通过体长转换的渔获曲线估算出口虾蛄的总死亡系数Z为3.24 a−1,根据不同方法估算自然死亡系数M的范围为0.75~1.27 a−1,捕捞死亡系数F的估算范围为1.96~2.49 a−1,开发率的均值为0.67。YPR模型结果显示,随着F增大,YPR值呈现先上升后下降的趋势,生物学参考点F0.1和Fmax的值分别为0.92a−1和1.88a−1。口虾蛄资源处于过度开发的状态,应降低捕捞压力,同时调整开捕体长,以维持口虾蛄渔业资源量和渔获量。     

Hydrodynamic method for estimating production carrying capacity of coastal finfish cage aquaculture in Southeast Asia

This paper presents the development of a simple and generally applicable hydrodynamic method for the estimation of production carrying capacity (PCC) of coastal finfish cage aquaculture. Dimensional analysis was used to find significant and general interdependencies between the hydrodynamics at fish farm locations and particulate wastes deposited on the seafloor by fish farms. Modeled ratios of deposition to emission of particulate wastes underneath fish farms were found to be primarily a function of the flow Reynolds numbers at the farming locations and the non-dimensional settling velocity of emitted wastes. In the non-dimensional model, farming conditions include daily feed rate, proportion of unconsumed feed, and carbon content in feed and fish feces. The relationship can be used to estimate the PCC of floating net cages imposing a threshold value for deposition. Results of in-situ assessments of the benthic impacts of several fish farms in an aquaculture site in the northwest of Bali, Indonesia were used to validate and demonstrate the effectiveness of the method. Predicted results were able to clearly identify fish farms operating beyond ecologically sustainable carrying capacity. The proposed method has broad applicability and could help make decisions regarding the estimation of production potential of individual farms in pristine areas, for providing first estimates in sites that have scarce data, and for assessment, expansion, and optimization of the currently operating aquaculture sites in Southeast Asia, China and potentially other data-poor island nations. As the method relies on dynamic models, it enables straightforward assessments over the entire aquaculture region.     

2018年进口奶牛检疫情况分析

随着十多年的超速发展,我国奶牛业已由单一品种的散养方式逐步转变为高产品种的规模化、集约化养殖方式。然而,我国奶牛整体遗传素质不高,多为进口高产奶牛与地方奶牛的低代次改良品种,以致原奶质量参差不齐,严重制约了我国奶业的健康发展。因此,大规模引进高品质的奶牛品种,已成为我国优化奶牛基因、推动畜牧业产业化发展的重要抓手,但同时也为检疫工作带来了挑战。本文通过分析2018年我国进口奶牛数量、来源国、疫病检出、进境口岸及隔离检疫场分布等数据,结合各来源国的疫病防控特点,有针对性地提出检疫要点,为我国全面提升进口奶牛的检疫水平、切实做好奶牛群体遗传改良计划、加快推进畜牧业转型升级提供参考。     

DG/T 082-2019《粪污固液分离机》推广鉴定大纲解读

推广鉴定大纲是进行农机鉴定工作时的技术要求,是推广鉴定项目实施的最主要依据。为了加大对推广鉴定大纲的宣传,便于农机生产企业、用户、管理部门和鉴定机构理解与使用,本文对DG/T 082-2019《粪污固液分离机》推广鉴定大纲中推广鉴定的产品型式、鉴定前的准备工作、鉴定内容和鉴定结论4个方面的主要内容进行了解读。     

施氮量对柳枝稷叶片叶绿素荧光特性及干物质积累的影响

研究施氮量对柳枝稷叶绿素荧光特性及干物质积累的影响,对提高盐碱地柳枝稷光能利用效率及生物质产量具有重要意义。在宁夏银北地区采用大田试验,以Cave-in-Rock品种柳枝稷为供试材料,在无氮添加(0 kg·hm^-2,N₀)、施低氮(60 kg·hm^-2,N₆₀)、中氮(120 kg·hm^-2,N₁₂₀)和高氮(240 kg·hm^-2,N₂₄₀)共4个施肥水平下,比较了开花期和成熟期柳枝稷叶片叶绿素荧光参数和干物质积累动态变化,采用灰色关联度分析法对柳枝稷叶片叶绿素荧光参数与干物质积累量进行研究。结果表明:与N₀相比,在N₆₀、N₁₂₀和N₂₄₀处理下柳枝稷开花期和成熟期叶片PSⅡ最大光化学效率(F_v/F_m)、PSⅡ实际光化学量子效率(Φ_PSⅡ)、潜在活性(F_v/F_o)、光化学猝灭系数(qP)、非光化学猝灭系数(NPQ)和干物质积累量均显著性提高,在N₂₄₀处理下达到峰值,而热耗散量子比率(F_o/F_m)显著性降低。在柳枝稷开花期,随着施氮量的增加,柳枝稷叶片PSⅡ潜在活性(F_v/F_o)显现出先上升后逐渐下降的总趋势。在N₁₂₀处理下柳枝稷叶片PSⅡ潜在活性(F_v/F_o)最大,为3.13,较N₀处理显著提高了16.26%。柳枝稷干物质积累量随着生育时期的推进和施氮量的增加,均有不同程度的提高,其中在开花期至成熟期,干物质积累缓慢,在灌浆期达到最大,成熟后期略有降低。柳枝稷成熟期干物质积累量在N₂₄₀处理下最高,每穴干物质积累达378.13 g,较N₀、N₆₀和N₁₂₀处理显著提高了24.33%、20.09%和7.24%。灰色关联度分析结果表明,在本试验条件范围内,N₂₄₀处理下加权关联度与理想施肥水平的关联度最大,有利于促进PSⅡ的光化学活性,从而提高柳枝稷干物质积累量。     

不同行距配比对玉米光合生理指标及茎秆特性的影响

以‘大丰30’为试验材料,在同一密度下（75000株/hm²）设置5种不同行距配比,研究不同行距配比对玉米光合生理指标及茎秆力学特性的影响。结果表明：行距配比为40 cm×80 cm时,棒三叶的叶绿素含量(SPAD)在灌浆期达到峰值;行距配比为30 cm×90 cm时,棒三叶净光合速率在灌浆期最高。大口期开始,行距配比为40 cm×80 cm时,叶面积指数(LAI)最高。单株干物质积累量以40 cm×80 cm最高。各行距配比的茎秆硬皮穿刺强度与茎秆弯曲性能随着节位的下降均呈逐渐增强的趋势,从大到小为 40 cm×80 cm>50 cm×70 cm>30 cm×90 cm>60 cm×60 cm>20 cm×100 cm。穗长、穗粗、千粒重和穗粒数各处理间均有不同变化,行距配比为40 cm×80 cm时产量最高,比等行距60 cm×60 cm增产7.96%。由此可见,行距配比为40 cm×80 cm,有利于大穗型品种‘大丰30’的光合性能和茎秆强度的提高,从而达到抗倒伏增产的目的。     

基于GC-MS流苏树种子挥发性成分分析

为研究流苏树种子的成分,探讨不同溶剂提取流苏树种子成分的差异。本研究分别采用石油醚、二氯甲烷和丙酮提取流苏树种子成分,以GC-MS联用技术对其化学成分进行分析。结果显示:石油醚提取物含有10种烷烃类、16种酯类和1种酰胺类化合物,占色谱总流出峰面积的91.36%,其中十六烷酸甲酯(10.83%)、反式-13-十八碳烯酸甲酯(60.67%)和6-十八碳烯酸甲酯(11.29%)含量较高;二氯甲烷提取物含有10种烷烃类、4种酯类、2种酸类和3种烯烃类化合物,占色谱总流出峰面积的80.85%,其中1,2-二甲基环戊烷(8.21%)、十六烷酸(14.51%)、(Z,Z)-9,12-十八碳二烯酸(35.93%)等化合物含量较高;丙酮提取物含有10种烷烃类、11种酯类和2种烯烃类化合物,占色谱总流出峰面积的98.23%,其中十六烷酸甲酯(14.07%)、(Z,Z)-9,12-十八碳二烯酸甲酯(44.65%)、(E)-9-十八碳烯酸甲酯(12.27%)和十八酸甲酯(15.62%)含量较高。石油醚和丙酮提取酯类的效果优于二氯甲烷,在提取酸类和烷烃类化合物时,二氯甲烷效果更佳。不同的溶剂提取流苏树种子成分的组成和含量存在一定的差异。     

基于纳米碳添加的减量施肥模式对寒地水稻产量及氮肥效率的影响

为解决减量施肥造成北方寒地水稻肥料供给不足和产量低的问题,以纳米碳增效剂为材料,采用仪器快速检测和植株常规测定分析方法,研究纳米碳添加的常规施肥和减量施肥模式对水稻产量性状和肥料利用效率的影响。结果表明：与常规施肥(CK)相比,纳米碳添加的常规施肥模式(SM-A)、减施氮肥10%(SM-B)和减施氮肥20%(SM-C)对水稻植株形态特征、光合生理特性、产量性状和肥料利用效率产生显著的影响,其中以SM-B增幅最大,SM-A次之,SM-C最小;SM-A、SM-B和SM-C增加经济效益分别为563.56、1374.20和-1391.08元/hm ²,以SM-B增效值最高。本研究表明,SM-B能改善生育期光合生理特性,提高植株产量和肥料利用效率,是寒地水稻较为理想的减量施肥安全利用模式。