The role of salicylic acid in alleviating boron toxicity in mung been cuttings

Abstract

The role of salicylic acid (SA) in alleviating boron toxicity in terms of adventitious
root formation (ARF) of mung bean cuttings were studied after determination of toxic level
of B and the promontory concentration of SA . Besides SA is not effective in high level of
significancy in un- treated cuttings with auxin and the role of SA was tested via three kinds of
applications in relation to IAA:-Post-, pre-, and simultaneous application. The results
revealed the followings:
1- The toxic levels of B were (250- 600) μg/ml which reduced growth parameters in
terms of rooting response to one third compared to the control , morphological
symptoms represented by bleaching of primary leaves, in addition to chlorosis &
necrosis .
2- The solitary and promotory concentration of SA is 10-4 M that enhanced rooting
response by 36% over control.
3- Simultaneous application of SA & IAA at their optimum concentrations enhances
rooting response by doubling the root number (110 roots) compared to IAA alone (52
root).
4- The later rooting response is better than SA pre- treated to stock plants (promotes 54.5
root / cutting) . Meanwhile, it doesn't raised to the rooting level when SA supplied to
cuttings after auxin post- application) , particularly for 2-days (promote 138.2 root /
cutting).
5- Complete B detoxification by treating cuttings with SA after auxin (post- application)
and before exposure to the toxic level of B, was obvious Through retention of primary
leaves in their normal morphological color, significantly raising the rooting responses,
and verifying the synergistic effect between SA & IAA, particularly when SA supplied
after 36- 40 h of cuttings excision.
6- The discussion was focused on the protective role and value of SA in preventing
photosynthetic pigment damages that occurred by B, biosynthesis of protein for
repairing damages , and improving the Anti-oxidant defense mechanisms.