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Li S, Jiang T, Ahmed W, Yang Y, Yang L, Zhang T, Mei F, Alharbi SA, Shan Q, Guo C, Zhao Z. Deciphering the impact of nitrogen morphologies distribution on nitrogen and biomass accumulation in tobacco plants. FRONTIERS IN PLANT SCIENCE 2024; 15:1377364. [PMID: 39011300 PMCID: PMC11246850 DOI: 10.3389/fpls.2024.1377364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Accepted: 06/10/2024] [Indexed: 07/17/2024]
Abstract
Background and aims Nitrogen (N) distribution in plants is intricately linked to key physiological functions, including respiration, photosynthesis, structural development, and nitrogen storage. However, the specific effects of different N morphologies on N accumulation and plant growth are poorly understood. Our research specifically focused on determining how different N morphologies affect N absorption and biomass accumulation. Methods This study elucidated the impact of different application rates (CK: 0 g N/plant; T1: 4 g N/plant; T2: 8 g N/plant) of N fertilizer on N and biomass accumulation in tobacco cultivars Hongda and K326 at different growth stages. Results Our findings emphasize the critical role of N distribution in various plant parts, including leaves, stems, and roots, in determining the complex mechanisms of N and biomass accumulation in tobacco. We found that in relation to total N, a greater ratio of water-soluble N (N w) in leaves facilitated N accumulation in leaves. In contrast, an increased ratio of SDS (detergent)-insoluble N (N in-SDS) in leaves and non-protein N (N np) in roots hindered this increase. Additionally, our results indicate that a greater proportion of N np in leaves has a negative impact on biomass accumulation in leaves. Furthermore, elevated levels of N in-SDS, N w, and N np in roots, and N np in leaves adversely affected biomass accumulation in tobacco leaves. The Hongda cultivar exhibited greater biomass and N accumulation abilities as compared to K326. Conclusions Our findings highlight the significant role of distribution of N morphologies on plant growth, as well as N and biomass accumulation in tobacco plants. Understanding N distribution allows farmers to optimize N application, minimizing environmental losses and maximizing yield for specific cultivars. These insights advance sustainable agriculture by promoting efficient resource use and reducing environmental impact.
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Affiliation(s)
- Shichen Li
- Yunnan Agricultural University, Kunming, Yunnan, China
| | - Tao Jiang
- Yunnan Agricultural University, Kunming, Yunnan, China
| | - Waqar Ahmed
- Yunnan Agricultural University, Kunming, Yunnan, China
| | - Yingfen Yang
- Yunnan Agricultural University, Kunming, Yunnan, China
| | - Linyuan Yang
- Yunnan Agricultural University, Kunming, Yunnan, China
| | - Tao Zhang
- Yunnan Agricultural University, Kunming, Yunnan, China
| | - Fupeng Mei
- Yunnan Agricultural University, Kunming, Yunnan, China
| | - Sulaiman Ali Alharbi
- Department of Botany & Microbiology College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Qu Shan
- Yunnan Agricultural University, Kunming, Yunnan, China
| | - Cuilian Guo
- Yunnan Agricultural University, Kunming, Yunnan, China
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Xia P, Zhang Y, Zhang X. The Potential Relevance of PnDREBs to Panax notoginseng Nitrogen Sensitiveness. Biochem Genet 2023:10.1007/s10528-023-10567-7. [PMID: 37999875 DOI: 10.1007/s10528-023-10567-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 10/26/2023] [Indexed: 11/25/2023]
Abstract
The dehydration response element-binding (DREB) transcription factor is a subfamily of AP2/ERF. It actively responds to various abiotic stresses in plants. As one of the representative plants, Panax notoginseng is sensitive to Nitrogen (N). Here, bioinformatics analysis, the identification, chromosomal location, phylogeny, structure, cis-acting elements, and collinearity of PnDREBs were analyzed. In addition, the expression levels of PnDREBs were analyzed by quantitative reverse transcription PCR. In this study, 54 PnDREBs were identified and defined as PnDREB1 to PnDREB54. They were divided into 6 subfamilies (A1-A6). And 44 PnDREBs were irregularly distributed on 10 of 12 chromosomes. Each group showed specific motifs and exon-intron structures. By predicting cis-acting elements, the PnDREBs may participate in biotic stress, abiotic stress, and hormone induction. Collinear analysis showed that fragment duplication events were beneficial to the amplification and evolution of PnDREB members. The expression of PnDREBs showed obvious tissue specificity in its roots, flowers, and leaves. In addition, under the action of ammonium nitrogen and nitrate nitrogen at the 15 mM level, the level of PnDREB genes expression in roots varied to different degrees. In this study, we identified and characterized PnDREBs for the first time, and analyzed that PnDREBs may be related to the response of P. Notoginseng to N sensitiveness. The results of this study lay a foundation for further research on the function of PnDREBs in P. Notoginseng.
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Affiliation(s)
- Pengguo Xia
- Key Laboratory of Plant Secondary Metabolism and Regulation of Zhejiang Province, College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, People's Republic of China.
| | - Yan Zhang
- Key Laboratory of Plant Secondary Metabolism and Regulation of Zhejiang Province, College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, People's Republic of China
| | - Xuemin Zhang
- Tianjin TASLY Modern Chinese Medicine Resources Co., Ltd., Tianjin, 300402, People's Republic of China
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Gao Z, Li J, Liu S, Chen Y. Within-leaf chloroplasts and nitrogen allocation to thylakoids in relation to photosynthesis during grain filling in maize. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2023; 196:830-840. [PMID: 36868131 DOI: 10.1016/j.plaphy.2023.02.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 02/04/2023] [Accepted: 02/20/2023] [Indexed: 06/18/2023]
Abstract
Nitrogen (N) is an important contributor to photosynthetic rate (Pn). However, during grain-filling stage in maize, some leaf N is remobilized to meet demands for grain protein accumulation rather than photosynthetic demands. Therefore, plants that can maintain a relatively high Pn during the N remobilization process would have the key to achieving both high grain yields (HGY) and high grain protein concentrations (HGPC). In this study, we investigated two high-yielding maize hybrids in photosynthetic apparatus and N allocation in a two-year field experiment. During grain filling, XY335 had a higher Pn and photosynthetic N-use efficiency than ZD958 had in the upper leaf, but not in the middle or lower leaves. In the upper leaf, the diameter and area of the bundle sheath (BS) were larger and the distance between bundle sheaths was greater in XY335 than in ZD958. XY335 had more bundle sheath cells (BSCs) and a larger BSC area, as well as a larger chloroplast area in the BSC, resulting in a higher total number and total area of chloroplasts in the BS. XY335 also had higher stomatal conductance (gs), intercellular CO2 concentration, and N allocation to the thylakoids. No genotypic differences were found in mesophyll cell ultrastructure, N content and starch content in the three types of leaves. Therefore, a trifecta of higher gs, greater N allocation to thylakoids for photo-phosphorylation and electron transport, and more and larger chloroplasts promoting CO2 assimilation in the BS confers a high Pn to simultaneously achieve HGY and high HGPC in maize.
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Affiliation(s)
- Zhan Gao
- College of Resources and Environment, Qingdao Agricultural University, Qingdao, Shandong, 266109, China
| | - Jiuzhou Li
- College of Resources and Environment, Qingdao Agricultural University, Qingdao, Shandong, 266109, China
| | - Shutang Liu
- College of Resources and Environment, Qingdao Agricultural University, Qingdao, Shandong, 266109, China
| | - Yanling Chen
- College of Resources and Environment, Qingdao Agricultural University, Qingdao, Shandong, 266109, China.
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Cun Z, Wu HM, Zhang JY, Shuang SP, Hong J, An TX, Chen JW. High nitrogen inhibits biomass and saponins accumulation in a medicinal plant Panax notoginseng. PeerJ 2023; 11:e14933. [PMID: 36846464 PMCID: PMC9951802 DOI: 10.7717/peerj.14933] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 01/31/2023] [Indexed: 02/23/2023] Open
Abstract
Nitrogen (N) is an important macronutrient and is comprehensively involved in the synthesis of secondary metabolites. However, the interaction between N supply and crop yield and the accumulation of effective constituents in an N-sensitive medicinal plant Panax notoginseng (Burkill) F. H. Chen is not completely known. Morphological traits, N use and allocation, photosynthetic capacity and saponins accumulation were evaluated in two- and three-year-old P. notoginseng grown under different N regimes. The number and length of fibrous root, total root length and root volume were reduced with the increase of N supply. The accumulation of leaf and stem biomass (above-ground) were enhanced with increasing N supply, and LN-grown plants had the lowest root biomass. Above-ground biomass was closely correlated with N content, and the relationship between root biomass and N content was negatives in P. notoginseng (r = -0.92). N use efficiency-related parameters, NUE (N use efficiency, etc.), NC (N content in carboxylation system component) and P n (the net photosynthetic rate) were reduced in HN-grown P. notoginseng. SLN (specific leaf N), Chl (chlorophyll), NL (N content in light capture component) increased with an increase in N application. Interestingly, root biomass was positively correlated with NUE, yield and P n. Above-ground biomass was close negatively correlated with photosynthetic N use efficiency (PNUE). Saponins content was positively correlated with NUE and P n. Additionally, HN improved the root yield of per plant compared with LN, but reduced the accumulation of saponins, and the lowest yield of saponins per unit area (35.71 kg·hm-2) was recorded in HN-grown plants. HN-grown medicinal plants could inhibit the accumulation of root biomass by reducing N use and photosynthetic capacity, and HN-induced decrease in the accumulation of saponins (C-containing metabolites) might be closely related to the decline in N efficiency and photosynthetic capacity. Overall, N excess reduces the yield of root and C-containing secondary metabolites (active ingredient) in N-sensitive medicinal species such as P. notoginseng.
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Affiliation(s)
- Zhu Cun
- College of Agronomy & Biotechnology, Yunnan Agricultural University, Kunming, China,National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China,Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
| | - Hong-Min Wu
- College of Agronomy & Biotechnology, Yunnan Agricultural University, Kunming, China,National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China,Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
| | - Jin-Yan Zhang
- College of Agronomy & Biotechnology, Yunnan Agricultural University, Kunming, China,National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China,Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
| | - Sheng-Pu Shuang
- College of Agronomy & Biotechnology, Yunnan Agricultural University, Kunming, China,National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China,Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
| | - Jie Hong
- College of Agronomy & Biotechnology, Yunnan Agricultural University, Kunming, China,National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China,Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
| | - Tong-Xin An
- College of Agronomy & Biotechnology, Yunnan Agricultural University, Kunming, China
| | - Jun-Wen Chen
- College of Agronomy & Biotechnology, Yunnan Agricultural University, Kunming, China,National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China,Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
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Cun Z, Wu HM, Zhang JY, Shuang SP, Hong J, Chen JW. Responses of Linear and Cyclic Electron Flow to Nitrogen Stress in an N-Sensitive Species Panax notoginseng. FRONTIERS IN PLANT SCIENCE 2022; 13:796931. [PMID: 35242152 PMCID: PMC8885595 DOI: 10.3389/fpls.2022.796931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 01/13/2022] [Indexed: 06/14/2023]
Abstract
Nitrogen (N) is a primary factor limiting leaf photosynthesis. However, the mechanism of N-stress-driven photoinhibition of the photosystem I (PSI) and photosystem II (PSII) is still unclear in the N-sensitive species such as Panax notoginseng, and thus the role of electron transport in PSII and PSI photoinhibition needs to be further understood. We comparatively analyzed photosystem activity, photosynthetic rate, excitation energy distribution, electron transport, OJIP kinetic curve, P700 dark reduction, and antioxidant enzyme activities in low N (LN), moderate N (MN), and high N (HN) leaves treated with linear electron flow (LEF) inhibitor [3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU)] and cyclic electron flow (CEF) inhibitor (methyl viologen, MV). The results showed that the increased application of N fertilizer significantly enhance leaf N contents and specific leaf N (SLN). Net photosynthetic rate (P n) was lower in HN and LN plants than in MN ones. Maximum photochemistry efficiency of PSII (F v/F m), maximum photo-oxidation P700+ (P m), electron transport rate of PSI (ETRI), electron transport rate of PSII (ETRII), and plastoquinone (PQ) pool size were lower in the LN plants. More importantly, K phase and CEF were higher in the LN plants. Additionally, there was not a significant difference in the activity of antioxidant enzyme between the MV- and H2O-treated plants. The results obtained suggest that the lower LEF leads to the hindrance of the formation of ΔpH and ATP in LN plants, thereby damaging the donor side of the PSII oxygen-evolving complex (OEC). The over-reduction of PSI acceptor side is the main cause of PSI photoinhibition under LN condition. Higher CEF and antioxidant enzyme activity not only protected PSI from photodamage but also slowed down the damage rate of PSII in P. notoginseng grown under LN.
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Affiliation(s)
- Zhu Cun
- College of Agronomy and Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
| | - Hong-Min Wu
- College of Agronomy and Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
| | - Jin-Yan Zhang
- College of Agronomy and Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
| | - Sheng-Pu Shuang
- College of Agronomy and Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
| | - Jie Hong
- College of Agronomy and Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
| | - Jun-Wen Chen
- College of Agronomy and Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
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Lei ZY, Wang H, Wright IJ, Zhu XG, Niinemets Ü, Li ZL, Sun DS, Dong N, Zhang WF, Zhou ZL, Liu F, Zhang YL. Enhanced photosynthetic nitrogen use efficiency and increased nitrogen allocation to photosynthetic machinery under cotton domestication. PHOTOSYNTHESIS RESEARCH 2021; 150:239-250. [PMID: 34669149 DOI: 10.1007/s11120-021-00872-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 07/30/2021] [Indexed: 06/13/2023]
Abstract
Domestication involves dramatic phenotypic and physiological diversifications due to successive selection by breeders toward high yield and quality. Although photosynthetic nitrogen use efficiency (PNUE) is a major trait for understanding leaf nitrogen economy, it is unclear whether PNUE of cotton has been improved under domestication. Here, we investigated the effect of domestication on nitrogen allocation to photosynthetic machinery and PNUE in 25 wild and 37 domesticated cotton genotypes. The results showed that domesticated genotypes had higher nitrogen content per mass (Nm), net photosynthesis under saturated light (Asat), and PNUE but similar nitrogen content per area (Na) compared with wild genotypes. As expected, in both genotypes, PNUE was positively related to Asat but negatively correlated with Na. However, the relative contribution of Asat to PNUE was greater than the contribution from Na. Domesticated genotypes had higher nitrogen allocation to light-harvesting (NL, nitrogen in light-harvesting chlorophyll-protein complex), to bioenergetics (Nb, total nitrogen of cytochrome f, ferredoxin NADP reductase, and the coupling factor), and to Rubisco (Nr) than wild genotypes; however, the two genotype groups did not differ in PNUEp, the ratio of Asat to Np (itself the sum of NL, Nb, and Nr). Our results suggest that more nitrogen allocation to photosynthetic machinery has boosted Asat under cotton domestication. Improving the efficiency of nitrogen use in photosynthetic machinery might be future aim to enhance Asat of cotton.
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Affiliation(s)
- Zhang-Ying Lei
- Key Laboratory of Oasis Eco-Agriculture, Xinjiang Production and Construction Corps, Shihezi University, Shihezi, 832003, People's Republic of China
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
| | - Heng Wang
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, 455000, People's Republic of China
| | - Ian J Wright
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
| | - Xin-Guang Zhu
- National Key Laboratory for Plant Molecular Genetics, Center of Excellence for Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 200032, People's Republic of China
| | - Ülo Niinemets
- Chair of Crop Science and Plant Biology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, 51006, Tartu, Estonia
| | - Zi-Liang Li
- Key Laboratory of Oasis Eco-Agriculture, Xinjiang Production and Construction Corps, Shihezi University, Shihezi, 832003, People's Republic of China
| | - Dong-Sheng Sun
- Key Laboratory of Oasis Eco-Agriculture, Xinjiang Production and Construction Corps, Shihezi University, Shihezi, 832003, People's Republic of China
| | - Ning Dong
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
- Georgina Mace Centre for the Living Planet, Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, SL5 7PY, UK
| | - Wang-Feng Zhang
- Key Laboratory of Oasis Eco-Agriculture, Xinjiang Production and Construction Corps, Shihezi University, Shihezi, 832003, People's Republic of China
| | - Zhong-Li Zhou
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, 455000, People's Republic of China
| | - Fang Liu
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, 455000, People's Republic of China.
| | - Ya-Li Zhang
- Key Laboratory of Oasis Eco-Agriculture, Xinjiang Production and Construction Corps, Shihezi University, Shihezi, 832003, People's Republic of China.
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He J, Qin L. Impacts of Reduced Nitrate Supply on Nitrogen Metabolism, Photosynthetic Light-Use Efficiency, and Nutritional Values of Edible Mesembryanthemum crystallinum. FRONTIERS IN PLANT SCIENCE 2021; 12:686910. [PMID: 34149787 PMCID: PMC8213338 DOI: 10.3389/fpls.2021.686910] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 05/06/2021] [Indexed: 05/13/2023]
Abstract
Mesembryanthemum crystallinum (common ice plant), as a nutritious ready-to-eat salad in Singapore, has become popular in recent years. However, basic data about the impacts of NO3 - supply on its NO3 - accumulation and nutritional quality are lacking. In this study, all plants were first grown indoor hydroponically in 10% artificial seawater (ASW) with modified full-strength Netherlands Standard Composition nutrient solution for 11 days, before transferring them to different reduced NO3 - solutions. All plants grew well and healthy after 7 days of treatment. However, plants grown with 3/4 N and 1/2 N were bigger with higher shoot and root fresh weight (FW), greater leaf number, and total leaf area (TLA) than those grown with full nitrogen (N), 1/4 N, and 0 N. Mesembryanthemum crystallinum grown with full N, 3/4 N, and 1/4 N had similar specific leaf area (SLA), while 0 N plants had significantly lower SLA. All plants had similar leaf succulence (LS). However, leaf water content (LWC) was lower, while leaf dry matter accumulation (LDMC) was higher in 0 N plants after 7 days of treatment. Compared with plants grown with full N, shoot NO3 - concentrations in 3/4 N, 1/2 N, and 1/4 N plants were constant or slightly increased during the treatments. For 0 N plants, shoot NO3 - concentration decreased significantly during the treatment compared with other plants. Shoot NO3 - accumulation was associated with nitrate reductase activity (NRA). For instance, after 7 days of treatment, shoot NO3 - concentration and NRA on a FW basis in 0 N plants were, respectively, 45 and 31% of full N plants. After transferring full N to 0 N for 7 days, all M. crystallinum had higher chlorophyll (Chl) content coupled with higher electron transport rate (ETR) and higher effective quantum yield of PSII, while full N plants had higher non-photochemical quenching (NPQ). The 0N plants had much higher concentrations of proline, total soluble sugar (TSS), and total ascorbic acid (ASC) than other plants. In conclusion, totally withdrawing NO3 - from the growth media prior to harvest could be one of the strategies to reduce shoot NO3 - concentration. Reduced NO3 - supply further enhanced nutritional values as concentrations of proline, TSS, and ASC were enhanced markedly in M. crystallinum plants after transferring them from full N to 0 N.
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Affiliation(s)
- Jie He
- National Institute of Education, Nanyang Technological University, Singapore, Singapore
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