High irradiance induces photoprotective mechanisms and a positive effect on NH4+ stress in Pisum sativum L.

摘要: Abstract Photosynthesis provides plant metabolism with reduced carbon (C) but is also the main source of oxidative stress in plants. Likewise, high doses NH 4 + as sole N have been reported to be toxic for most plants, resulting growth and restricting C availability. The combination photosynthetic photon flux densities (PPFD) nutrition may provide higher availability could a detrimental effect on therefore objective this study evaluate whether induces photo-oxidative that exacerbated under light conditions. Pea plants ( Pisum sativum cv. sugar-snap) were grown hydroponically (0.5, 2.5, 5 10 mM) (750 μmol photons m −2  s −1 ) or low PPFD conditions (350 μmol photons m ). High contributes tolerance ammonium by pea it originated biomass content due rates. However, deficit (0.5 2.5 mM caused an antioxidant response, indicated increased photoprotective pigment chloroplastic superoxide dismutase contents. Plants showed less need photoprotection. An increase specific leaf weight (SLW) ratio was observed associated not only PPFDs highest dose. Overall, these results demonstrate that, despite activation some responses at PPFD, there no photoinhibitory symptoms positive toxicity, thus suggesting harmful effects are directly related generation stress.