Effect of Ultraviolet Radiation on Some Date Palm Varieties.

Man made chlorofluorocarbons have the potential to cause a depletion of ozone layers, which is responsible for the attenuation of solar UV-B radiation reaching the earth’s surface.  Solar radiation in the UV-B range (280–320 nm) corresponds to a minor percentage of the total solar energy but it is potentially harmful because these short wave lengths are capable of causing deleterious effect in the plant cells. The effects of UV-B on plants include inhibited growth, morphological changes and increase in the level of phenolic pigments and also lead many anatomical and morphological changes such as the reduction of plant height and leaf length/area. Thus, the effect of increased UV-B radiation on growth and physiology of many plants, including crop and terrestrial plant species, under both greenhouse and field conditions has become one of the most important subjects of investigation in the last decades.  So, the present investigation was aimed to study the effect of UV radiation on five varieties of date palm viz.  BARHI, FRDWT, NBTSF, FRDRD and KHD.  Plant height, leaf area, fresh and dry weight, chlorophyll a, b and total and carotenoid were analyzed after 4 hours and 8 hours of UVB radiation.  The results indicated that all the parameters are significantly affect the enhanced UVB radiation. The chlorophyll a, b, and total contents were decreased compared with the control values and reduced with the enhanced UV radiation, but the carotenoid was increased compared with the control and also reduced with the enhanced UV radiation.