Articles
WATER EXPLOITATION IN SUBSTRATE PROFILE DURING CULTURE
A cubic root third degree polynomial was used to describe waterrelease data at low tensions.
From both, regression function and container geometry, water distribution at container capacity was predicted.
Water exploitation in the substrate was studied during a 5 stages drying cycle from container capacity to 10 kPa tension.
In containers without plants (Evaporation model) water content decreased from the bottom to the top of the profile in the drying stages.
Relative water losses of the substrate segments were similar in each of the drying stages, suggesting that segments released water according to its own water content at container capacity.
Substrate density increased from the top to the bottom of the profile during the drying cycle.
In containers planted with Ficus benjamina (Evapotranspiration model) coarse root density decreased from the top to the bottom, and fine roots tended to accumulate at the upper and at the lower segments.
During the drying cycle, relative water content of substrate segments tended to be similar along the profile, indicating that root water uptake homogenized water distribution.
Maximal water losses occurred in the two lowest segments.
Water exploitation was discussed in relation to fine root distribution.
Minimum substrate density was observed in the segment with less fine root and maximal values in those where fine root is accumulated.
Two kinds of substrate particle movements, downward and upward, were suggested.