Chin J Plant Ecol ›› 2009, Vol. 33 ›› Issue (2): 387-396.DOI: 10.3773/j.issn.1005-264x.2009.02.017

Special Issue: 稳定同位素生态学

• Research Articles • Previous Articles     Next Articles

ECOLOGICAL RESPONSES TO SOIL WATER CONTENT IN FOUR HYBRID POPULUS CLONES

GONG Ji-Rui1, HUANG Yong-Mei1, GE Zhi-Wei1, DUAN Qing-Wei1, YOU Xin1, AN Ran1, ZHANG Xin-Shi1,2,*()   

  1. 1State Key Laboratory of Earth Surface Processes and Resource, Beijing Normal University, Beijing 100875, China
    2State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
  • Received:2008-03-24 Accepted:2008-10-09 Online:2009-03-24 Published:2009-03-31
  • Contact: ZHANG Xin-Shi

Abstract:

Aims Pot experiments were conducted to investigate effects of water deficit and duration of the deficit (0, 15, 36 and 14 days recovery) on four hybrid Populus: 15-29 (P. trichocarpa × P. deltoids), DN-2 (P. deltoids × P. nigra), DN-14274 (P. deltoids × P. nigra) and R-270 (P. deltoids × P. nigra). Our objective was to examine the responses of Populus plants to soil water deficit by analyzing eco-physiological, morphological, and growth characteristics, as well as several parameters of plant performance.

Methods Seedlings were exposed to four treatments: 100%, 70%, 50% and 30% of soil field water capacity (treatments T1-T4, respectively).

Important findings The four hybrids were sensitive to water deficit. All developed physiological adaptive mechanisms as well as configurational strategies to cope with water shortages to different degrees by closing stomata and reducing leaf number and leaf area to regulate water loss, by depressing net photosynthetic rate (Pn), transpiration rate (Tr) and leaf water potential (ψ) to enhance water use efficiency (WUE), or by changing allocation of biomass productivity (Bp). Under water stress, R-270 only decreased its leaf dry weight but the other three hybrids decreased their dry weight of leaf, stem and root. With declining soil moisture, root/shoot of 15-29 and R-270 increased, implying the roots obtained more carbohydrates, which favors water absorption. Carbon isotope composition (δ13) of DN-2 was significantly positively correlated to WUE, but δ13 of R-270 was significantly negatively correlated to WUE. Pn, stomatal conductance (Gs), Tr,ψ, biomass and canopy areas of the seedlings in T1 and T2 are higher than those in T3 and T4, suggesting that the four hybrids can obtain high production in arid areas under sufficient-moderate irrigation. LowerPn, Gs, Tr,ψ, biomass, canopy areas and higher WUE of the seedling in T3 and T4 indicate that the four hybrids can develop survival strategies under water stress, but biomass production was negatively affected. Clone 15-29 and R-270 showed a stronger adaptive response than DN-2 and DN-14274 under water stress, implying they have greater drought-resistance ability.

Key words: hybrids poplar clones, water deficit, biomass partitioning, gas exchange, carbon isotope discrimination