root pressure


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Fig. 272 Root pressure . The mercury enables root pressure to be measured.

root pressure

a force exerted within a plant root that pushes water up towards the stem. The phenomenon is produced by the root cells having a solute concentration gradient which increases from outside the root towards the centre of the root. Thus, by OSMOSIS, water passes from the soil, across the root and into the xylem as a result of salt excretion by the ENDODERMIS into the xylem, creating pressure which can be observed in a plant with the aerial parts removed.
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or physical force theory or root pressure theory or the combination of
of root pressure in one way or the other hence causing the ascent of sap
mechanism of root pressure, its regulation and significance in plants
possible that root pressure reflects an unavoidable consequence of high
On the basis of correlation analysis, cultivars that interacted positively with Di and Dv had earlier maturity, higher root pressure under stress, higher soil water content at the end of the vegetative stress period, high leaf chlorophyll content at midgrainfilling, large reduction in radiation interception with vegetative stress, low %FW in WS and Fc, and high epidermal conductance.
Other traits that differed among cultivar groups, but were not consistently related to maturity, included root pressure in Di, %FW, leaf chlorophyll measured during grainfilling stress, and epidermal conductance.
The second principal component axis was negatively correlated with root pressure measured in WS (Table 4).
cordifolia can restore water transport during spring in vessels embolized during winter (Sperry, 1993), and because birches generally show root pressure in spring (Johnson, 1944), maximum stem conductivity (assumed to reflect the natural state of twigs in early summer) of the two species was used to test whether hydraulic limitations might be differentially affecting leaf P in B.
Root pressure is pronounced in some monocots (Davis, 1961) and is a widespread phenomenon in monocots as well as certain non-monocots (Ewers et al.
Root pressure (which is controlled by parenchyma in ways not fully demonstrated yet) may also play a rote in countering vulnerability in wide vessels such as those of palms (Davis, 1961).
Davis (1961) showed that root pressure in palms could exceed 10 m, thus accounting for conductive characteristics of palms--perhaps most notably, how embolisms could be reduced and cleared should they form.
1991) Results have suggested that temperate Vitis species use root pressure as a necessary feature to overcome freeze-induced cavitation during the winter (Fisher et al.