Leaf water potential and transpiration as affected by root xylem anatomy in rice
1987
Yambao, E.B. | Real, J.G. | Ingram, K.T. | De Datta, S.K. (International Rice Research Inst., Los Banos, Laguna (Philippines). Dept. of Agronomy)
Deep rooting enables the plant to maintain high leaf water potential during water deficit. Deep rooting should be coupled with low root axial resistance to extract water efficiently from deep soil layers. Based on the Poiseville-Hagen equation, longitudinal resistance to water flow is inversely proportional to the fourth power of the xylem vessel radius. Leaf water potential, transpiration rate, and number and size of metaxylem vessels were examined in five rice cultivars grown in culture solution. The equivalent root vessel radius (ERVR), which is the radius of a vessel that can transport the same amount of water as several vessels in parallel, was calculated. Leaf water potential and transpiration rate increased with increase in ERVR per plant. For individual roots, ERVR was positively correlated with root diameter. These results help to explain the ability of rice cultivars with deep and thick roots to maintain high leaf water potential during drought as compared to cultivars with shallow and thin roots.
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