Coordination between stomatal conductance and leaf-specific hydraulic conductance in maize (Zea mays L.)
2005
Liu, L.(Chiba Univ. (Japan)) | Kon, H. | Matsuoka, N. | Kobayashi, T.
Field experiments were conducted on August 10 and 11 during the summer of 2004 in a maize field to investigate the correlation between stomatal conductance and leaf-specific hydraulic conductance. During these two days, stomatal conductance, transpiration rate, volumetric soil water content and leaf water potential were measured independently. Leaf-specific hydraulic conductance was calculated by the transpiration rate and the water potential difference between soil and leaf. The measured data were checked according to their diurnal variations and their respective standard deviations among samples. Results show that a strong positive correlation exists between leaf stomatal conductance and leaf-specific hydraulic conductance (r(2)=0.66 and 0.74, respectively on each day). Leaf-specific hydraulic conductance was strongly and positively correlated to transpiration rate on these two days (r(2)=0.87 and 0.84, respectively). The probable reasons explaining the relationship between hydraulic conductance and stomatal conductance are discussed. It is concluded that their respective relationship to transpiration rate cause the coordination between stomatal conductance and leaf-specific hydraulic conductance under the condition of no soil water stress. These results are expected to: (1) improve models involving plant gas exchange by incorporating the hydraulic constraints into these models; currently, most models do not take explicit account of plant hydraulics; and, (2) provide a new insight on the mechanism of hydraulic constraints on stomatal conductance and on related plant gas exchange, and hence enforce our understanding on SPAC water relations.
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