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Turkish Journal of Agriculture and Forestry

Author ORCID Identifier

SYED AIZAZ ALI SHAH: 0009-0006-1736-5155

YUZI SHI: 0000-0001-9283-0308

JING NIE: 0000-0002-0474-9647

XUEHUI YAO: 0000-0002-2427-0158

YICONG GUO: 0000-0001-9078-2111

MUHAMMAD AHMAD: 0009-0009-5280-3191

SYED ATIZAZ ALI SHAH: 0009-0004-1679-6143

FAISAL HAYAT: 0000-0001-8762-9693

YASMIN NIAMAT: 0009-0007-2789-3426

HALİL ÖZTÜRK: 0000-0002-8977-0831

XIAOLEI SUI: 0000-0002-4109-0722

DOI

10.55730/1300-011X.3225

Abstract

Photosynthesis is critically dependent on both adequate light and nitrogen availability. In controlled agricultural environmentswith limited natural light, cucumber faces substantial challenges, including reduced photosynthetic efficiency and biomass accumulation.Nitrogen (N) is a vital component for the synthesis of various macromolecules, metabolites, and signaling molecules in plants. This studyassessed the impact of different nitrate levels (LL-N, LL-1/2N, and LL-2N) on the physiological, biochemical, and metabolic responsesof cucumber under low light conditions (80–100 μmol m–2 s–1 photosynthetic photon flux density) in comparison to standard light(400–500 μmol m–2 s–1 photosynthetic photon flux density) and unchanged nitrate. We observed that increasing nitrate levels to twicethe standard concentration (LL-2N) significantly enhanced shoot morphology, including weight and size, and improved photosyntheticperformance, stomatal conductance, and transpiration rates. In contrast, lower nitrate levels (LL-1/2N) exacerbated stress, leading todiminished photosynthesis and biomass. Biochemical analyses indicated that elevated nitrate concentrations activated key enzymesinvolved in the metabolism of carbon and nitrogen, including glutamine synthetase, sucrose phosphate synthase, nitrate reductase, andglutamate synthase. This led to improvement in the amounts of sucrose, fructose, soluble sugars, free amino acids, and soluble proteins.Additionally, the activities of antioxidant enzymes including superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase wereconsiderably greater under conditions of increased nitrate, which reduced the levels of malondialdehyde and H2O2 as oxidative stressmarkers. Furthermore, enhanced nitrate levels upregulated critical photosynthetic genes (rbcL, rbcS, FBPase, and SBPase mRNA),supporting the RuBisCO contents and overall photosynthetic capacity. These findings underscore the effectiveness of strategic nitrateenrichment in mitigating low light stress, providing essential insights for optimizing cucumber cultivation in controlled environmentsand improving productivity.

Keywords

Photosynthesis, biomass, metabolites, biochemicals, photon flux density

First Page

841

Last Page

858

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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