The current st udy aims to r ec ord the rol e of the pretreatment of Z ea m ays grains with a He-Ne las er in d amage rep air of ultr aviolet (UVA+B) radiati on eff ect. Plants wer e divided into f our groups; c ontrol group, group expos ed to t he He -Ne l aser onl y f or 1-300 sec onds, group expos ed t o U V A+ B only and protect ed group. In t he prot ect ed group the grains were tr eated with diff erent H e -Ne las er irradiation dur ation f or two w eeks t hen expos ed to 3. 6 and 7. 2 KJ m − 2 d −1 UVA+B radiation.Irradiation with H e-Ne las er significantl y (p ≤ 0.05) increas ed shoot length, number of l eav es, s hoot biomas s (week 1), root dr y w eight, c hl orophyll -a, chl orophyll -b, and t ot al c hlor ophyll . Sup eroxide free r adical, hydrogen peroxide and lipid peroxidation wer e decreas ed at l ow dos es and increas ed with higher dos es of las er. V arious d elet erious eff ects of ultravi olet r adiations w ere recorded in Zea m ays i ncluding decr eased phot os ynt hetic pigments, s hoot and root biomass, and root and shoot length. The pretreatm ent with a l aser bef ore expos ure t o UVA+B radiation c auses a slight i ncrease i n plant l engt h and t he number of leav es, an increase of r oot length, whil e a decreas e of shoot /root length and an i ncreas e i n l eaf paramet ers at s ome las er tr eatments wer e observed . T he res ults rev eal ed t hat the pretreatm ent of m aize grai ns wit h H e -N e laser dos es f or 10s to 300s allevi at ed the damaging eff ect s of U V-B radiati on in the range of 7.2 KJ m −2 d −1 UVA+B radiation. KEY WORDS:He-Ne las er, Ultravi olet r adiation, prot ectiv e role, pigments, oxidative stress, antioxidants, U V-B abs orbing compounds, flav onoids. I NTRODUCTI ON :Ultraviolet radiati ons (UV) ar e a nonionizing el ectrom agnetic spectr um t hat embraces about 8-9% of s ol ar energ y (Gill et al., 2015). O zone depleti on in the strat osphere has r esult ed in an increm ent i n ultravi olet-B irradiati on (UV-B ; 280-320 nm), which has pot entiall y destr uctiv e consequences for crop yield and production and aff ect nat ural environm ents (J ulkunenTiitto et al., 2005;Siipola et al ., 2015).Enhanc ed levels of ultravi olet r adiations trigger different str uct ural, p hysiol ogical and molec ular resp ons es i n plant s (Cas ati, 2003; Kum ari et al. , 2009; Sal ama et al. , 2011;Gill et al. , 2015). A higher d ose of UV-B prov ok es impairment and modific ation of macrom olec ules like DNA , RN A, and prot eins , decreas e net phot os ynthesis and adjust the activities of sev eral antioxidant enz ym es (Gill and T ut eja, 2010;Sharma et al., 2012). Nevert heless , plants hav e d evel oped v arious protectiv e strategies to m anage and withst and, agai nst high UV-B irradiation. The act ual accum ulation of U V -absorbing materi als c an cert ainl y help in the prev ention of U V penetrati on to vul ner able layers of the leaf . T his kind of c ompounds build -up withi n the upper epidermal l ayers of the leav es of sev eral higher plants purs uin...

Egyptian Journal of Botany http://ejbo.journals.ekb.eg/ interest on the effect of such events on plant life cycle starting from seed viability and germination to plant fitness (Münzbergová et al., 2017;Alshoaibi, 2021). On the other hand, several plants lose a few of their seeds, seedlings, or individuals (Funkenberg et al., 2012); others display adaptive plasticity under climatic changes (Mclean et al., 2014). Long day length and photoperiod during seed development of the maternal plant environment have been associated with high seed dormancy and low germinability (Baskin & Baskin, 1998;Gutterman, 2000). Several studies recorded changes in the reproductive traits and resource allocations of numerous species in response to climate changes (Hegazy, 2000

No abstract