PHOSPHATE DISTRIBUTION IN THE WHEAT ROOT-SOIL INTERFACE ZONE

The experiments were conducted in the artificlal climate laboratory using 32P labelled soll and soll-root plane system. It was found that although the phosphate in the soil-root interface zone was of depletive distrlbution, a relative accumulation zone of phosphate within 0. 5mm near the root surface was often observed at the 15th day or so after cultivating wheat. The depletion intensity of phosphate in soil near the root surface was stronger under higher soil moisture or lower air humldity. The depletive rate and range of phosphate in the root-soll interface zone increased along with growth. Moreover, the depletion intensity was greater by the bottom or the mlddle part of roots. The depletive distribution of phosphate near the root surface could be better described by a function in the form of C/Co-aXb or C/Co-a+blnX (C/Co is the relative content of fertllizer phosphate in a distance from the root surface; X. a and b are the regression constants),and against the growing time (t) and the distance from the root plane (X), it could be described by the non-linear regression equation and three times of X and t.