Transpiration Response of C3 and C4 Plants of Northern Chinese Steppe Ecosystem to Water Vapor Pressure Deficits (VPD)

Publikations-Art

Kongressbeitrag

Autoren

Jiang, L., Guo, J., Giese, M., Gao, Y., Wei, H., Brueck, H., Asch, F.

Erscheinungsjahr

2012

Veröffentlicht in

Resilience of agricultural systems against crises

Herausgeber

Tielkes, E.

Verlag

DITSL GmbH , Witzenhausen

Seite (von - bis)

215

Tagungsname

Tropentag 2012

Tagungsort

Göttingen / Kassel

Since water is often limiting plant growth in semi-arid ecosystems, the regulationof transpiration is an essential component of adaptation strategies. Transpiration ofplants is usually increasing with water vapor pressure deficits (VPD) of the atmo-sphere; however, different species vary in the regulation of water losses which mighthelp to explain plant community dynamics in semi-arid environments. Chamber ex-periments were performed with five dominant plant species originating from steppeecosystems of northern China. These comprised three C3 plants and two C4 annualgrasses. Canopy transpiration of these five plants cultivated in pots under full wa-ter supply was measured in a chamber allowing to adjust VPDs ranging from 0.5(low pressure deficit) to 2.5 kPa (high deficit). The results showed that C3 plantLey-mus chinensisreached a maximum transpiration rate at VPD 1.3 kPa with little orno further increase in transpiration rate above this value as VPD was increased. Incontrast, the other four species showed continued linear increase in transpiration ratewith increasing VPD. The annual dicotyledonous species showed highest transpira-tion rates, while C4 annual grasses showed less water loss per unit leaf area. Theseresults indicated different water household strategies of dominant plant species in theSongnen grassland.L. chinensiswith high transpiration under low VPD and downregulation under higher VPD indicate effective stomata regulation during mid-dayVPD peaks resulting in water conservation. Low transpiration rates of C4 annualsmight be explained with comparably small rooting systems limiting the water uptakeunder high pressure gradients. The C3 annual dicotyledonous plant, however followsan opportunistic strategy with high water consumption. Plants photosynthetic perfor-mance combined with morphological and functional traits are promising indicationsfor studying the adaptation mechanisms of plant species under semi-arid conditions.