title: Seed priming with KNO3mediates biochemical processes to inhibit lead toxicity in maize (Zea mays L.).
abstract: BACKGROUND
  Accumulation of lead (Pb) in agricultural soils has become a major factor for reduced crop yields and poses serious threats to humans consuming agricultural products. The present study investigated the effects of KNO3seed priming (0 and 0.5% KNO3) on growth of maize (Zea mays L.) seedlings exposed to Pb toxicity (0, 1300 and 2550 mg kg-1Pb).
  
  
  RESULTS
  Pb exposure markedly reduced the growth of maize seedlings and resulted in higher Pb accumulation in roots than shoots. Pretreatment of seeds with KNO3significantly improved the germination percentage and increased physiological indices. A stimulating effect of KNO3seed priming was also observed on pigments (chlorophyll a, b, total chlorophyll and carotenoid contents) of Pb-stressed plants. Low translocation of Pb from roots to shoots caused an increased accumulation of total free amino acids and higher activities of catalase, peroxidase, superoxide dismutase and ascorbate peroxidase in roots as compared to shoot, which were further enhanced by exogenous KNO3supply to prevent Pb toxicity.
  
  
  CONCLUSIONS
  Maize accumulates more Pb in roots than shoot at early growth stages. Priming of seeds with KNO3prevents Pb toxicity, which may be exploited to improve seedling establishment in crop species grown under Pb contaminated soils. © 2017 Society of Chemical Industry.
authors.affiliation: Department of Agronomy, MNS University of Agriculture, Multan, Pakistan.
authors.forename: Fahim
authors.identifier: http://orcid.org/0000-0001-7753-5087
authors.initials: F
authors.lastname: Nawaz
authors.affiliation: Department of Agronomy, UCA & ES, The Islamia University of Bahawalpur, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Naeem
authors.affiliation: Department of Agronomy, UCA & ES, The Islamia University of Bahawalpur, Pakistan.
authors.forename: Asim
authors.initials: A
authors.lastname: Akram
authors.affiliation: Nuclear Institute for Agriculture and Biology, Faisalabad, Pakistan.
authors.forename: Muhammad Y
authors.initials: MY
authors.lastname: Ashraf
authors.affiliation: Department of Botany, University of Poonch, Rawalakot, Pakistan.
authors.forename: Khawaja S
authors.initials: KS
authors.lastname: Ahmad
authors.affiliation: Department of Agronomy, UCA & ES, The Islamia University of Bahawalpur, Pakistan.
authors.forename: Bilal
authors.initials: B
authors.lastname: Zulfiqar
authors.affiliation: Department of Horticulture, Agriculture College, Bahauddin Zakariya University, Multan, Pakistan.
authors.forename: Hasan
authors.initials: H
authors.lastname: Sardar
authors.affiliation: Department of Agronomy, Agriculture College, Bahauddin Zakariya University, Multan, Pakistan.
authors.forename: Rana N
authors.initials: RN
authors.lastname: Shabbir
authors.affiliation: Department of Agronomy, UCA & ES, The Islamia University of Bahawalpur, Pakistan.
authors.forename: Sadia
authors.initials: S
authors.lastname: Majeed
authors.affiliation: Department of Agronomy, MNS University of Agriculture, Multan, Pakistan.
authors.forename: Muhammad A
authors.initials: MA
authors.lastname: Shehzad
authors.affiliation: Department of Agronomy, UCA & ES, The Islamia University of Bahawalpur, Pakistan.
authors.forename: Irfan
authors.initials: I
authors.lastname: Anwar
mesh_terms: D000975:Antioxidants / Q000032:analysis / Q000378:metabolism; D002338:Carotenoids / Q000032:analysis; D002734:Chlorophyll / Q000032:analysis; D005506:Food Contamination / Q000517:prevention & control; D018525:Germination / Q000187:drug effects; D007854:Lead / Q000032:analysis / Q000633:toxicity*; D009566:Nitrates / Q000494:pharmacology*; D018517:Plant Roots / Q000737:chemistry; D017680:Potassium Compounds / Q000494:pharmacology*; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development; D012639:Seeds / Q000187:drug effects* / Q000254:growth & development*; D012989:Soil Pollutants / Q000032:analysis; D003313:Zea mays / Q000187:drug effects* / Q000254:growth & development
chemical_list: D000975:Antioxidants; D009566:Nitrates; D017680:Potassium Compounds; D012989:Soil Pollutants; D002734:Chlorophyll; D007854:Lead; D002338:Carotenoids; C023844:potassium nitrate
keywords: KNO3; Pb toxicity; antioxidant machinery; maize; pigments; seed priming