Cd and Pb are an air serious wide global pollution problem, leadinglto great
losses in agricultural yield and hazardous man's health through the cont~minated
food. Their foliage a bsorption and direct shoot uptake represent potentiallmode of
entry to plant tissues, beside their entry through roots. However, very little Is known
about their toxicity uptake by leaves, comparing to those known by roots. Accordingly.
this study is dealing with their probable toxicity under foliage uptake in relation to
foliar spray with certain varieties of growth regulators (GAJ, NAA or Bg), using sugar
beel planl grown under field conditlons during successive seasons exten ed from
1999 to 2001. The interaction treatments of Cd or Pb (HM) x growth regula!ors (GR)
during the first season trail were 20 or 50 mgll from each beside control x 50 mgtl
from everyone of GA3, NAA and Bg beside control. While during the second season
trial the levels used of ce or Pb were 50 or 100 mg/l from everyone x 50 o~~oo mgtl
from each of GAJ or Bg only, beside control of HM or GR. Every factor, H or GR,
treatments were applied as foliar spray to sugar beet I eaves separately lith 24 h
interval using GR treatments at first, followed by HM treatments. The treated plants
received the above mentioned rates from each factor twice with the sawe serial
successive application of GR at first followed by HM treatments. The first a~plication
ones were after 69-70 days after sowing, followed by the second one after 21 days.
The following results may be summarized as follows: (1) Both Cd 0 r P b could be
absorbed through leaf surfaces of sugar beet plant with variable degree according to
the used concentration and the used metal species and seemed to be traqslocated
into roots. (2) Both used species of HM, exerted their obvious toxicity in sugar beet
plant in the form of ret:!~dation eHects on most plant growth parameters, ith more
pronounced decline in whole plant leaf area, with the association of decrements in the
concentrations of photosynthetic pigments, sharp decline In SLA and troublness in
leaf water balance, beside their minimizing actions in the concentrations f sugars
fractions in root and the total uptake of N, P, K and Na. These finding lead to
suggest that, the main sited of phytotoxification action of Cd or Pb seemed to be on
leaf 0 rgan properties and its physiological functional processes, and it is the most
sensitive organ in sugar beet plant to the adverse eHects of Cd and p < /em>b. These
adverse eHects on leaf must be reflected their actions on the other parameters. These
adverse eHects were mostly increased with increasing the dose of the used HM and
the c:or.centraticn of them in planllissue c:gan. !t was found tha~ Cd seemed to have
mostly more toxification actions on sugar beet plant than Pb. (3) It was found that GR
especially GAJ and some time Bg could be used with some extend to regulate the
desfunctional effects of Cd or Pb in sugar beet plants, and that seemed to be through
their detOxification actions on most properties of the functional sensttive organ
(leaves), and also to their minimizing effects on the accumulation of Cd or Pb in different plant tissues. (4) The interaction effects of Cd or Pb in relations to GAJ on 89
treatments, seemed to be connected with the rate of both tested factors which judged by many factors, such as the used HM species, the tested variety of G.R, the used rates of both factors, the proportion degree of their uptake and translocation vvi hin plant organs, the sensitivity degree of the tested process, the plant age and the
prevailing environmental conditions during both experimental trails. (5) It may be
concluded that, it is difficult to determine the primary toxic and antitoxic action~ of
GRx HM, as many series of progressive subsidiary reactions may be interfere
through most studies characters. Thus, it is difficult to distinguish between the primary and the subsidiary action. (6) It may be recommended to use GAJ at the rate Of~OO mg/l to alleviate the toxic effects and may be the foliar uptake oi either Cd or P by sugar beet plant. In addition, the facior(s) affecting the uptake of Cd or Pb by lea es of sugar beet plant are still unclear, and addilional work must be carried out if the question is to be fully answered.