Effect Of UV(A; B) Radiation On Stomata Complex In Viola tricolor

Ultraviolet spectrum of sunlight has high energy and is divided in to three wavelength band A, B and C. plants more than other creators are exposed to radiation because they create defense mechanism to protect themselves. In fact, the plants against UV radiation should tolerate it or neutralized it or avoid it. UV photons have enough energy destroy the chemical bond due to have chemical reaction, then the biological effect of UV due this process. The present study aims at assessing the effects of ultraviolet-A;B (UV-A; B) radiation in the morphological and anatomical features of Viola tricolor leaf. Fully developed third trifoliate leaves from the top on 30 (days after seed germination) Viola tricolor L. under supplementary UV-(A; B) radiation (4 hours daily for one month) were monitored. UV-(A; B) stress induced changes in the leaf morphology and caused several injuries which were not recorded in normal plants. The epidermis both on the adaxial as well as abaxial surfaces exhibited many changes after UV-A; B exposure. The cuticle on both the surfaces was thicker under UV-A; B irradiation compared to control leaves. UV-B irradiated plants had small, wrinkled, necrotic and shiny leaves compared to longer, broader and greener leaves of control plants. The stomata frequency under UV-B was increased on the abaxial surface but decreased on the adaxial surface. Abnormal stomata like, stomata with reduction in guard cell number, reduced size, malformations were more along with dead epidermal cells on the adaxial and abaxial surface of UV-(A; B) irradiated plants. Such aberrations were absent in leaves under control conditions.

کلیدواژه ها:

Viola tricolor Ultraviolet-(A ، B) Leaf epidermis Abnormal stomata