IntroductionSoilspolluted with toxic heavy metals are an environmental problem that threatsliving organisms (Nascimento and Xing, 2006). Cadmium (Cd) is one of the mostharmful and widespread pollutants in agricultural soils (Lin et al., 2012),it has no metabolic role, but it has adverse negative effect (Tran and Popova,2013), which it causing oxidative damage to important cellular pathways such asphotosynthesis and respiration, due to enhances the generation and accumulationof reactive oxygen species (ROS) (Ahmed et al, 2015). Selenium (Se) isconsidered to be an important trace element with multiple roles in higheranimals and human (Rayman, 2000; Schrauzer, 2009). Although, Se is notconfirmed to be required by higher plant (Terry et al.
, 2000), but somefinding suggest that, Se which play a novel role in plant biology (Hatfield etal, 2014; Wu et al., 2015), including growth promoting activities,improving yield and quality and increase plant resistance against oxidativestress (Pukacka et al., 2011; Hasanuzzaman et al., 2012;Pezzarossa et al., 2012).
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Moreover, plants grown in Se-enriched mediashown resistance to certain abiotic stress, such as, salinity (Hawrylak-Nowak,2009), drought (Ahmed et al., 2016) and heavy metals (Wu et al.,2016). The results of Lin et al. (2012) indicated to alleviated ROSaccumulation and balanced nutrients in rice, also Wu et al.(2016)reported that, the supplementation of media by Se reduced Cd and Pbconcentrations in root and shoot of oilseed rape, furthermore, alleviated the negativeeffect of Cd and Pb on growth and led to decrease oxidative damage, Alyemeni et al.
(2017) was found theapplication of Se (10 µM) mitigated the negative effect of Cd on photosyntheticpigments content, leaf relative water content and other physiologicalattributes of tomato, further Se enhanced antioxidant enzymes including SOD,CAT, APX and GR, also osmolytes such as, proline, glycine and betaine. Salicylicacid (2-hydroxybenzoic acid) (SA) is endogenous phytohormone belong to phenoliccompounds in plants (Per et al.), SA act as a pivotal role in defensemechanism by regulating physiological biochemical processes (Joseph et al.2010). A various finding suggest that, SA reduces negative effect of abioticstress, including salinity stress (Palma et al., 2013), heat stress(Khan et al., 2013) and heavy metals stress (Al-Whaibi et al.
,2012; Zhang et al., 2015). SA interacts with nutrients synergisticallyor antagonistically and regulates plant growth and development under optimaland stressful environments (Nazar et al., 2011).
The aim of this studyis investigate the perhaps synergistic effect of Salicylic acid and Selenium tomitigate Cadmium stress on date palm Phoenix dactylifera L. plantlets.