欧亚国际

  西班牙巴塞罗那大学和德国杜塞尔多夫大学科学家利用EGC公司的GC-15植物生长箱对榕树属热带植物进行了CO2气体交换和生长动物研究，研究成果发表在先进期刊Journal of Plant Physiology，下文是对材料和方法部分的描述。

材料和方法-植物材料和生长条件

  Ficus insipida Willd. (Moraceae)种子采集自成熟树木，并于2012年1月在Jiff 7泥炭土颗粒peat pellets (Jiffy Products of America Inc.,  Lorain, OH, USA)进行发芽。抽叶4-5片的幼苗转植入直径15 cm，体积 2.2 L的充满土的花盆中。收了3株幼苗，并就初发叶面积以及总干重进行测量，同时36 株植物均匀分布在2间GC-15 植物生长培养室（环境控制室，EGC,  Chagrin Falls,  OH,  USA)。植物施加了初始剂量缓释肥 (‘Osmocote Plus’,  Scotts Miracle-Gro, Marysville, OH, USA，并浇水达每日田间所需量。培养室光照周期保持在12 h，叶面(Philips TL841  fluorescent bulbs)光合有效辐射 (PAR) 范围为520 ~590 µmol photons m−2 s−1 ，相当于晴朗天气下综合环境PAR的50%左右。照明期间两间培养室内的气温均为39 ◦ C 。 暗期温度保持在22或32 ◦ C。培养室温度设置通过带屏蔽 107-L 气温传感器(Campbell, Logan,  UT, USA)保证。叶温度使用近红外温度计在正面叶面测量获得(MiniTemp  MT, Raytec, Santa Cruz, CA, USA)，照明期间叶温范围在 37~40 ◦ C。两个培养室内，气温保持在露点∼18 ◦ C 以及环境CO2浓度 (∼400 µL L−1 )。32–42 天后，测定Chl a荧光、 CO2净交换以及生物量累积以及分布。

Thermaltolerance,netCO2exchangeandgrowthofatropicaltreespecies,Ficus insipida, cultivatedatelevateddaytimeandnighttimetemperatures

G.HeinrichKrausea,b,∗, AlexanderW.Cheesmana, Klaus Wintera, BarbaraKrausea, AurelioVirgoa 

aSmithsonianTropicalResearchInstitute,P.O.Box0843-03092,Balboa,Ancón,RepublicofPanama

bInstituteofPlantBiochemistry,HeinrichHeineUniversityDüsseldorf,Universitätsstraße1,40225Düsseldorf,Germany

Abstract

Global warming and associated increases in the frequency and amplitude of extreme weather events, such as heat waves, may adversely affect tropical rainforest plants via significantly increased tissue tempera- tures. In this study, the response to two temperature regimes was assessed in seedlings of the neotropical pioneer tree species, Ficus insipida. Plants were cultivated in growth chambers at strongly elevated day- time temperature (39 ◦ C), combined with either close to natural (22 ◦ C) or  elevated (32 ◦ C) nighttime temperatures. Under both growth regimes, the critical temperature for  irreversible leaf  damage, deter- mined by changes in chlorophyll a fluorescence, was approximately 51 ◦ C. This  is comparable to values found in F. insipida growing under natural ambient conditions and indicates a limited potential for heat tolerance acclimation of this tropical forest tree species. Yet, under high nighttime temperature, growth was strongly enhanced, accompanied by increased rates of net photosynthetic CO2 uptake and diminished temperature dependence of leaf-level dark respiration, consistent with thermal acclimation of these key physiological parameters.

Journal of Plant Physiology

Materialsand methods

Plant materialand growth conditions 

Seeds of Ficus insipida Willd. (Moraceae) were collected from mature  trees  and germinated in January 2012 in Jiffy 7 peat pellets (Jiffy ProductsofAmericaInc., Lorain,OH,USA).Individ- ual seedlingswith4–5 leavesweretransferredinto15cm high

2.2Lplasticpotsfilledwithsoil(‘Pottingmix’,MiracleGroLawn, Marysville,OH,USA).Threeseedlingswereharvestedandmea-suredfor initialleaf areaandtotaldry mass,while36 plants weredistributedevenlybetweentwoGC-15 controlledenviron-mentchambers(EGC, ChagrinFalls, OH, USA). Plantsreceived an initialdoseof slowreleasefertilizer(‘OsmocotePlus’, Scotts Miracle-Gro,Marysville,OH,USA)andwerewateredtofieldcapac- ity daily.Chambersweremaintained witha 12h lightperiod, withphotosyntheticallyactiveradiation(PAR)between520 and590µmolphotonsm−2s−1  atleaf level(PhilipsTL841  fluorescentbulbs),whichcorrespondedtoabout50%ofintegrateddailyambi- entPARon sunnydays.Air temperaturewas39◦Cduringlight periodsinbothchambers.Temperatureduringthe12hdarkperiod wasmaintainedateither22 or 32◦C.Chamber-setair tempera- tureswereconfirmedwithashielded107-LAirTemperatureSensor (Campbell,Logan, UT,USA).Leaf temperature,measuredon the adaxialleafsurfacewithaninfraredthermometer(MiniTemp  MT, Raytec,SantaCruz,CA,USA)rangedfrom37to40◦Cduringthelightperiod.Inbothchambers,airwasmaintainedwithadewpointof∼18◦CandambientCO2concentration(∼400µLL−1).After 32–42 days,Chlafluorescence,netCO2exchangeandbiomassaccumula- tionand allocationsweredetermined.