Abstract

The current study aims to record the role of the pretreatment of Zea mays grains with a He-Ne laser damage repair of ultraviolet (UVA+B) radiation effect. Plants were divided into four groups; control group, group exposed to the He–Ne laser only for 1- 300 seconds, group exposed to UVA+B only and in the fourth group; grains were treated with different He-Ne laser irradiation duration and after 2 weeks were exposed to 3.6 and 7.2 KJ m−2 d−1 UVA+B radiation. Irradiation with He-Ne laser significantly (p≤0.05) increased shoot lengths, number of leaves, shoot biomass (week1), root dry weight, chlorophyll-a, chlorophyll b, and total chlorophyll. Superoxide free radical, hydrogen peroxide and lipid peroxidation was decreased at low doses and increased with higher doses of laser. Various deleterious effects of ultraviolet radiations were recorded in Zea mays including decreased photosynthetic pigments, shoot and root biomass, and root and shoot lengths. The pretreatment with a laser before exposure to UVA+B radiation causes a slight increase in plant length and leaves a number, an increase of root length, while a decrease of shoot/root length and an increase in leaf parameters at some laser treatments. The results revealed that the pretreatment of maize grains with He–Ne laser doses for 10s to 300s alleviated the damaging effects of UV-B radiation in the range of 7.2 KJ m−2 d−1 UVA+B radiation.

Key words: He-Ne laser, Ultraviolet radiation, protective role, pigments, oxidative stress, antioxidants, UV-B absorbing compounds, flavonoids