Molecular identification of indigenous arbuscular mycorrhizal fungi in the rhizosphere of black pepper (Piper nigrum) in West Lampung, Indonesia
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Abstract. Hidayat R, Rini MV, Evizal R, Karyanto A, Timotiwu PB, Azzahra S. 2026. Molecular identification of indigenous arbuscular mycorrhizal fungi in the rhizosphere of black pepper (Piper nigrum) in West Lampung, Indonesia. Biodiversitas 27 (5): d270526. https://doi.org/10.13057/biodiv/d270526. Black pepper (Piper nigrum) serves as a vital economic spice commodity in Indonesia, yet its agricultural productivity is frequently constrained by suboptimal soil conditions, particularly in acidic marginal drylands. The use of indigenous Arbuscular Mycorrhizal Fungi (AMF) offers a sustainable, environmentally friendly strategy to mitigate these abiotic stresses. However, the specific diversity of AMF communities in the black pepper plantations of West Lampung remains largely underexplored. Therefore, this study aimed to conduct a species-level molecular identification of indigenous AMF isolated from the black pepper rhizosphere in this region. Five distinct spore isolates were successfully recovered using a trap culture method and were initially characterized based on morphological attributes. For accurate taxonomic resolution, molecular analysis was performed using nested Polymerase Chain Reaction (PCR) targeting the 18S Small Subunit (SSU) rRNA gene with AML1/AML2 primers. This was followed by DNA sequencing and phylogenetic reconstruction using the Neighbor-Joining method. The phylogenetic analysis confirmed the presence of four distinct evolutionary lineages: Ambispora leptoticha (SP1), Acaulospora cf. spinosa (SP2), Acaulospora colombiana (SP4), and unclassified Glomeromycotina sp. (SP3 and SP5). Interestingly, the typically ubiquitous genus Glomus was entirely absent from the analyzed isolates, while the sampled soil exhibited extreme acidity (pH 4.13) and unexpectedly high available phosphorus (77.17 ppm). This study provides a crucial molecular baseline for indigenous AMF, confirms the first molecular record of the Ambispora lineage, and supports the future development of site-specific bioinoculants tailored for acidic soils.
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References
Addharu E, Barus B, Kinseng RA, Shiddiq D. 2022. Development of contemporary pepper crop (Piper nigrum L.) in West Lampung Regency, Indonesia. IOP Conf Ser: Earth Environ Sci 974: 012055. https://doi.org/10.1088/1755-1315/974/1/012055.
Aguilera P, Marín C, Oehl F, Godoy R, Borie F, Cornejo P. 2017. Selection of aluminum tolerant cereal genotypes strongly influences the arbuscular mycorrhizal fungal communities in an acidic Andosol. Agric Ecosyst Environ 246: 86-93. https://doi.org/10.1016/j.agee.2017.05.031.
Akib MA, Nuddin A, Prayudyaningsih R, Kuswinanti T, Syaiful SA, Antonius S. 2022. Keragaman fungi mikoriza arbuskula pada pola tanam Piper nigrum yang berbeda di areal sekitar lahan tambang nikel. J Biologi Indonesia 18 (2): 183-192. https://doi.org/10.47349/jbi/18022022/183. [Indonesian]
Alotaibi MO, Saleh AM, Sobrinho RL, Sheteiwy MS, El-Sawah AM, Mohammed AE, Abd Elgawad H. 2021. Arbuscular mycorrhizae mitigate aluminum toxicity and regulate proline metabolism in plants grown in acidic soil. J Fungi 7 (7): 531. https://doi.org/10.3390/jof7070531.
Amir H, Gensous S, Cavaloc Y, Wantiez L. 2021. Phosphorus fertilization of an ultramafic soil reduced effects of arbuscular mycorrhizal fungi but not mycorrhizal colonization. J Soil Sci Plant Nutr 21: 3544-3554. https://doi.org/10.1007/s42729-021-00626-6.
Azzahra S, Rini MV, Evizal R, Karyanto A. 2024. Study on the population and diversity of arbuscular mycorrhizal fungi in the rhizosphere of Piper nigrum in West Lampung, Indonesia. J Trop Mycorrhiza 3 (2): 79-86. https://doi.org/10.58222/jtm.v3i2.73.
Battini F, Grønlund M, Agnolucci M, Giovannetti M, Jakobsen I. 2017. Facilitation of phosphorus uptake in maize plants by mycorrhizosphere bacteria. Sci Rep 7: 4686. https://doi.org/10.1038/s41598-017-04959-0.
Bilgili A. 2025. The effectiveness of arbuscular mycorrhizal fungal species (Funneliformis mosseae, Rhizophagus intraradices, and Claroideoglomus etunicatum) in the biocontrol of root and crown rot pathogens, Fusarium solani and Fusarium mixture in pepper. PeerJ 13: e18438. https://doi.org/10.7717/peerj.18438.
Bills RJ, Morton JB. 2015. A combination of morphology and 28S rRNA gene sequences provide grouping and ranking criteria to merge eight into three Ambispora species (Ambisporaceae, Glomeromycota). Mycorrhiza 25: 485-498. https://doi.org/10.1007/s00572-015-0626-7.
Błaszkowski J, Sánchez-García M, Niezgoda P, Zubek S, Fernández F, Vila A, Al-Yahya’ei MN, Symanczik S, Milczarski P, Malinowski R, Cabello M, Goto BT, Casieri L, Malicka M, Bierza W, Magurno F. 2022. A new order, Entrophosporales, and three new Entrophospora species in Glomeromycota. Front Microbiol 13: 962856. https://doi.org/10.3389/fmicb.2022.962856.
Boussageon R, Eigenmann M, Frommenwiler J, van der Heijden MGA. 2025. Poor quality of commercial arbuscular mycorrhizal inoculants used for agriculture and home gardening. J Sustain Agric Environ 4 (4): e70107. https://doi.org/10.1002/sae2.70107.
Bowles TM, Jackson LE, Loeher M, Cavagnaro TR. 2017. Ecological intensification and arbuscular mycorrhizas: A meta-analysis of tillage and cover crop effects. J Appl Ecol 54 (6): 1785-1793. https://doi.org/10.1111/1365-2664.12815.
Brundrett MC, Bougher N, Dell B, Grove T, Malajczuk N. 1995. Working with Mycorrhizas in Forestry and Agriculture. Australian Centre for International Agricultural Research, Canberra.
Cahyaningtyas A, Ezawa T. 2023. Disturbance tolerance of arbuscular mycorrhizal fungi: Characterization of life-history strategies along a disturbance gradient in a coastal dune ecosystem. Plant Soil 495: 535-549. https://doi.org/10.1007/s11104-023-06337-4.
Cheng S, Zou Y-N, Kuča K, Hashem A, Abd_Allah EF, Wu Q-S. 2021. Elucidating the mechanisms underlying enhanced drought tolerance in plants mediated by arbuscular mycorrhizal fungi. Front Microbiol 12: 809473. https://doi.org/10.3389/fmicb.2021.809473.
Corradi N, Brachmann A. 2017. Fungal mating in the most widespread plant symbionts? Trends Plant Sci 22 (2): 175-183. https://doi.org/10.1016/j.tplants.2016.10.010.
Crossay T, Antheaume C, Redecker D, Bon L, Chedri N, Richert C, Guentas L, Cavaloc Y, Amir H. 2017. New method for the identification of arbuscular mycorrhizal fungi by proteomic-based biotyping of spores using MALDI-TOF-MS. Sci Rep 7: 14306. https://doi.org/10.1038/s41598-017-14487-6.
da Silva GA, Sieverding E, de Assis DMA, Goto BT, Corazon-Guivin MA, Oehl F. 2025. Revision of Entrophosporales, with three genera and an identification key for all species currently attributed to this order. J Fungi 11 (2): 97. https://doi.org/10.3390/jof11020097.
da Silva KJG, Fernandes JAL, Magurno F, Leandro LBA, Goto BT, Theodoro RC. 2022. Phylogenetic review of Acaulospora (Diversisporales, Glomeromycota) and the homoplasic nature of its ornamentations. J Fungi 8 (9): 892. https://doi.org/10.3390/jof8090892.
Delavaux CS, Bever JD. 2022. Evidence for the evolution of native plant response to mycorrhizal fungi in post-agricultural grasslands. Ecol Evol 12 (7): e9097. https://doi.org/10.1002/ece3.9097.
DJP [Direktorat Jenderal Perkebunan]. 2025. Outlook Perkebunan Komoditas Lada Tahun 2025. Direktorat Jenderal Perkebunan, Kementerian Pertanian Republik Indonesia, Jakarta. [Indonesian]
Enebe MC, Erasmus M. 2023. Symbiosis: A perspective on the effects of host traits and environmental parameters in arbuscular mycorrhizal fungal richness, colonization and ecological functions. Agriculture 13 (10): 1899. https://doi.org/10.3390/agriculture13101899.
Fang X, Lee X, Twagirayezu G, Cheng H, Lu H, Huang S, Deng L, Ji B. 2024. A critical review of the effectiveness of biochar coupled with arbuscular mycorrhizal fungi in soil cadmium immobilization. J Fungi 10 (3): 182. https://doi.org/10.3390/jof10030182.
Felsenstein J. 1985. Confidence limits on phylogenies: An approach using the bootstrap. Evolution 39 (4): 783-791. https://doi.org/10.1111/j.1558-5646.1985.tb00420.x.
Ferrol N, Azcón-Aguilar C, Pérez-Tienda J. 2019. Review: Arbuscular mycorrhizas as key players in sustainable plant phosphorus acquisition: An overview on the mechanisms involved. Plant Sci 280: 441-447. https://doi.org/10.1016/j.plantsci.2018.11.011.
Gill J, Tharp CL, Suseela V. 2025. Arbuscular mycorrhizal symbiosis enables efficient phosphorus uptake in sorghum accessions with contrasting root traits. Plant Cell Environ 48 (10): 7699-7713. https://doi.org/10.1111/pce.15666.
Gu S, Wu S, Guan Y, Zhai C, Zhang Z, Bello A, Guo X, Yang W. 2020. Arbuscular mycorrhizal fungal community was affected by tillage practices rather than residue management in black soil of northeast China. Soil Tillage Res 198: 104552. https://doi.org/10.1016/j.still.2019.104552.
Hajoeningtijas OD, Mardatin NF, Suyadi A, Ma’ruf F. 2024. Characterization of indigenous arbuscular mycorrhizal fungi in seedlings and production of pepper (Piper nigrum L.) cultivation. J Trop Mycorrhiza 3 (2): 57-78. https://doi.org/10.58222/jtm.v3i2.70.
He X, Shao C, Wu A, Xia L, Li T, Pei J, Zhang N, Wang Y. 2022. Arbuscular mycorrhizal fungi enhance nutrient acquisition and reduce aluminum toxicity in Lespedeza formosa under acid rain. Environ Sci Pollut Res 29: 29904-29916. https://doi.org/10.1007/s11356-021-18248-x.
Huang J, Liu L, Liu J, Zhang W, Wang S, Ye Q, Mo J, Zheng M. 2023. Seven years phosphorus addition has no effect on soil acidity in two tropical plantations. For Ecol Manag 532: 120822. https://doi.org/10.1016/j.foreco.2023.120822.
Ijdo M, Schtickzelle N, Cranenbrouck S, Declerck S. 2010. Do arbuscular mycorrhizal fungi with contrasting life-history strategies differ in their responses to repeated defoliation? FEMS Microbiol Ecol 72 (1): 114-122. https://doi.org/10.1111/j.1574-6941.2009.00829.x.
Kaonongbua W, Morton JB, Bever JD. 2010. Taxonomic revision transferring species in Kuklospora to Acaulospora (Glomeromycota) and a description of Acaulospora colliculosa sp. nov. from field collected spores. Mycologia 102 (6): 1497-1509. https://doi.org/10.3852/10-011.
Kebede JY, Pagano MC, Beyene BB, Tuji FA. 2023. Diverse arbuscular mycorrhizal fungi species associate with indigenous trees in a natural forest. Mycol Prog 22: 77. https://doi.org/10.1007/s11557-023-01922-4.
Kokkoris V, Banchini C, Paré L, Abdellatif L, Séguin S, Hubbard K, Findlay W, Dalpé Y, Dettman J, Corradi N, Stefani F. 2024. Rhizophagus irregularis, the model fungus in arbuscular mycorrhiza research, forms dimorphic spores. New Phytol 242 (4): 1771-1784. https://doi.org/10.1111/nph.19121.
Kolaříková Z, Slavíková R, Krüger C, Krüger M, Kohout P. 2021. PacBio sequencing of Glomeromycota rDNA: A novel amplicon covering all widely used ribosomal barcoding regions and its applicability in taxonomy and ecology of arbuscular mycorrhizal fungi. New Phytol 231 (1): 490-499. https://doi.org/10.1111/nph.17372.
Krüger M, Krüger C, Walker C, Stockinger H, Schüßler A. 2012. Phylogenetic reference data for systematics and phylotaxonomy of arbuscular mycorrhizal fungi from phylum to species level. New Phytol 193 (4): 970-984. https://doi.org/10.1111/j.1469-8137.2011.03962.x.
Kumar A, Kumar R, Singh P, Kalaichelvan S, de los Santos-Villalobos S, Kumar N, Fernando L, Kumar R, Solanki MK, Joshi NC, Babalola OO. 2025. Emerging role of arbuscular mycorrhizal fungi in sustainable agriculture: From biology to field application. MicrobiologyOpen 14 (5): e70082. https://doi.org/10.1002/mbo3.70082.
Kumar S, Stecher G, Li M, Knyaz C, Tamura K. 2018. MEGA X: Molecular Evolutionary Genetics Analysis across computing platforms. Mol Biol Evol 35 (6): 1547-1549. https://doi.org/10.1093/molbev/msy096.
Lee J, Lee S, Young JPW. 2008. Improved PCR primers for the detection and identification of arbuscular mycorrhizal fungi. FEMS Microbiol Ecol 65 (2): 339-349. https://doi.org/10.1111/j.1574-6941.2008.00531.x.
Lethielleux-Juge C. 2025. Review: Roles of mycorrhizal symbioses and associated soil microbiomes in ecological restoration. Front Microbiol 16: 1456041. https://doi.org/10.3389/fmicb.2025.1456041.
Liu W, Zhang Y, Jiang S, Deng Y, Christie P, Murray PJ, Li X, Zhang J. 2016. Arbuscular mycorrhizal fungi in soil and roots respond differently to phosphorus inputs in an intensively managed calcareous agricultural soil. Sci Rep 6: 24902. https://doi.org/10.1038/srep24902.
Maússe-Sitoe S, Dames J. 2024. Characterization of arbuscular mycorrhizal fungal species associating with Zea mays. Front Plant Sci 15: 1345229. https://doi.org/10.3389/fpls.2024.1345229.
Nilsson RH, Larsson K-H, Taylor AFS, Bengtsson-Palme J, Jeppesen TS, Schigel D, Kennedy P, Picard K, Glöckner FO, Tedersoo L, Saar I, Kõljalg U, Abarenkov K. 2019. The UNITE database for molecular identification of fungi: Handling dark taxa and parallel taxonomic classifications. Nucleic Acids Res 47 (D1): D259-D264. https://doi.org/10.1093/nar/gky1022.
Oehl F, Sieverding E, Ineichen K, Mäder P, Wiemken A, Boller T. 2009. Distinct sporulation dynamics of arbuscular mycorrhizal fungal communities from different agroecosystems in long-term microcosms. Agric Ecosyst Environ 134 (3-4): 257-268. https://doi.org/10.1016/j.agee.2009.07.008.
Öpik M, Davison J, Moora M, Zobel M. 2014. DNA-based detection and identification of Glomeromycota: The virtual taxonomy of environmental sequences. Botany 92 (2): 135-147. https://doi.org/10.1139/cjb-2013-0110.
Pacioni G. 1992. 16 wet-sieving and decanting techniques for the extraction of spores of vesicular-arbuscular fungi. Methods Microbiol 24: 317-322. https://doi.org/10.1016/S0580-9517(08)70099-0.
Pan S, Wang Y, Qiu Y, Chen D, Zhang L, Ye C, Guo H, Zhu W, Chen A, Xu G, Zhang Y, Bai Y, Hu S. 2020. Nitrogen-induced acidification, not N-nutrient, dominates suppressive N effects on arbuscular mycorrhizal fungi. Glob Change Biol 26 (11): 6568-6580. https://doi.org/10.1111/gcb.15311.
Perez-Lamarque B, Öpik M, Maliet O, Silva ACA, Selosse M-A, Martos F, Morlon H. 2022. Analysing diversification dynamics using barcoding data: The case of an obligate mycorrhizal symbiont. Mol Ecol 31 (12): 3496-3512. https://doi.org/10.1111/mec.16478.
Redecker D. 2020. Single-spore extraction for genetic analyses of arbuscular mycorrhizal fungi. Methods Mol Biol 2146: 93-97. https://doi.org/10.1007/978-1-0716-0603-2_8.
Rini MV, Pertiwi KO, Saputra H. 2017. Seleksi lima isolat fungi mikoriza arbuskular untuk kelapa sawit (Elaeis guineensis Jacq.) di pembibitan. J Agrotek Tropika 5: 138-143. https://doi.org/10.23960/jat.v5i3.1820. [Indonesian]
Rini MV, Yelli F, Tambunan DL, Damayanti I. 2021. Morphological and molecular identifications of three native arbuscular mycorrhizal fungi isolated from the rhizosphere of Elaeis guineensis and Jatropha curcas in Indonesia. Biodiversitas 22 (11): 4940-4947. https://doi.org/10.13057/biodiv/d221128.
Sahur A, Nasaruddin, Muthmainnah. 2020. Growth response of pepper (Piper nigrum L.) on application Arbuscular Mycorrhizal Fungi (AMF) and the shallot filtrate. IOP Conf Ser: Earth Environ Sci 486: 012130. https://doi.org/10.1088/1755-1315/486/1/012130.
Saitou N, Nei M. 1987. The neighbor-joining method: A new method for reconstructing phylogenetic trees. Mol Biol Evol 4 (4): 406-425. https://doi.org/10.1093/oxfordjournals.molbev.a040454.
Salomon MJ, Demarmels R, Watts-Williams SJ, McLaughlin MJ, Kafle A, Ketelsen C, Soupir A, Bücking H, Cavagnaro TR, van der Heijden MGA. 2022. Global evaluation of commercial arbuscular mycorrhizal inoculants under greenhouse and field conditions. Appl Soil Ecol 169: 104225. https://doi.org/10.1016/j.apsoil.2021.104225.
Sarathambal C, Jeevalatha A, Sivaranjani R, Biju CN, Charles S, Srinivasan V, George P, Peter B, Radhika R. 2023. Arbuscular mycorrhizal colonization alters biochemical, molecular defense responses and root exudate composition against Phytophthora capsici infection in black pepper. Rhizosphere 25: 100651. https://doi.org/10.1016/j.rhisph.2022.100651.
Schenck NC, Perez-Collins Y. 1990. Manual for the Identification of VA Mycorrhizal Fungi. Synergistic Publications, Gainesville.
Schenck NC, Spain JL, Sieverding E, Howeler RH. 1984. Several new and unreported vesicular-arbuscular mycorrhizal fungi (Endogonaceae) from Colombia. Mycologia 76 (4): 685-699. https://doi.org/10.1080/00275514.1984.12023899.
Schwarzott D, Schüßler A. 2001. A simple and reliable method for SSU rRNA gene DNA extraction, amplification, and cloning from single AM fungal spores. Mycorrhiza 10: 203-207. https://doi.org/10.1007/pl00009996.
Sieverding E, Oehl F. 2012. Revision of Entrophospora and description of Kuklospora and Intraspora, two new genera in the arbuscular mycorrhizal Glomeromycetes. J Appl Bot Food Qual 80 (1): 69-81.
Stürmer SL, Morton JB. 1999. Taxonomic reinterpretation of morphological characters in Acaulosporaceae based on developmental patterns. Mycologia 91 (5): 849-857. https://doi.org/10.1080/00275514.1999.12061090.
Susila E, Chan SROS, Achmad BS, Maulina F. 2022. Exploration and morphology identification of spores arbuscular mycorrhizal fungi from horticultural plantation. J Appl Agric Sci Technol 6 (1): 20-30. https://doi.org/10.55043/jaast.v6i1.31.
Symanczik S, Błaszkowski J, Koegel S, Boller T, Wiemken A, Al-Yahya’ei MN. 2014. Isolation and identification of desert-habituated arbuscular mycorrhizal fungi newly reported from the Arabian Peninsula. J Arid Land 6: 488-497. https://doi.org/10.1007/s40333-014-0021-9.
Tamura K. 1992. Estimation of the number of nucleotide substitutions when there are strong transition-transversion and G+C-content biases. Mol Biol Evol 9 (4): 678-687. https://doi.org/10.1093/oxfordjournals.molbev.a040752.
Tedersoo L, Bahram M, Zinger L, Nilsson H, Kennedy P, Yang T, Anslan S, Mikryukov V. 2021. Best practices in metabarcoding of fungi: From experimental design to results. Molecular Ecology 31: 2769-2795. https://doi.org/10.1111/mec.16460.
Thiéry O, Vasar M, Jairus T, Davison J, Roux C, Kivistik P-A, Metspalu A, Milani L, Saks Ü, Moora M, Zobel M, Öpik M. 2016. Sequence variation in nuclear ribosomal small subunit, internal transcribed spacer and large subunit regions of Rhizophagus irregularis and Gigaspora margarita is high and isolate-dependent. Mol Ecol 25 (12): 2816-2832. https://doi.org/10.1111/mec.13655.
Tiwari J, Ma Y, Bauddh K. 2020. Arbuscular mycorrhizal fungi: An ecological accelerator of phytoremediation of metal contaminated soils. Arch Agron Soil Sci 68 (2): 283-296. https://doi.org/10.1080/03650340.2020.1829599.
Van LN, Herrmann L, Le Dinh T, Van CN, Van LN, Enez A, Brau L, Lesueur D. 2025. Liming effect on soil chemical and biological properties, pests and diseases, and crop yields in robusta coffee and black pepper in Vietnam. Soil Res 63 (3): SR24143. https://doi.org/10.1071/sr24143.
Varghese R, Ray J. 2024. Sustainability of black pepper production: A critical analysis of physicochemical soil parameters concerning variables in pepper fields of South India. Ecol Front 44 (4): 788-801. https://doi.org/10.1016/j.ecofro.2024.01.005.
Vázquez-Santos Y, Castillo-Argüero S, Espinosa-García FJ, Montaño NM, Martínez-Orea Y, Hernández-Cuevas LV. 2025. Ecological filters shape arbuscular mycorrhizal fungal communities in the rhizosphere of secondary vegetation species in a temperate forest. PLoS One 20 (1): e0313948. https://doi.org/10.1371/journal.pone.0313948.
Wahab A, Muhammad M, Munir A, Abdi G, Zaman W, Ayaz A, Khizar C, Reddy SPP. 2023. Role of arbuscular mycorrhizal fungi in regulating growth, enhancing productivity, and potentially influencing ecosystems under abiotic and biotic stresses. Plants 12 (17): 3102. https://doi.org/10.3390/plants12173102.
Wang P, Snijders R, Kohlen W, Liu J, Bisseling T, Limpens E. 2021. Medicago SPX1 and SPX3 regulate phosphate homeostasis, mycorrhizal colonization, and arbuscule degradation. The Plant Cell 33: 3470-3486. https://doi.org/10.1093/plcell/koab206.
White TJ, Bruns T, Lee S, Taylor J. 1990. Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. In: Innis MA, Gelfand DH, Sninsky JJ, White TJ (eds). PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA. https://doi.org/10.1016/B978-0-12-372180-8.50042-1.
Willis A, Rodrigues BF, Harris PJC. 2013. The ecology of arbuscular mycorrhizal fungi. Crit Rev Plant Sci 32 (1): 1-20. https://doi.org/10.1080/07352689.2012.683375.
Yao Q, Li Z, Song Y, Wright SJ, Guo X, Tringe SG, Tfaily MM, Paša-Tolić L, Hazen TC, Turner BL, Mayes MA, Pan C. 2018. Community proteogenomics reveals the systemic impact of phosphorus availability on microbial functions in tropical soil. Nat Ecol Evol 2: 499-509. https://doi.org/10.1038/s41559-017-0463-5.
Yoneyama K, Xie X, Nomura T, Yoneyama K. 2020. Do Phosphate and Cytokinin Interact to Regulate Strigolactone Biosynthesis or Act Independently?. Frontiers in Plant Science 11: 438. https://doi.org/10.3389/fpls.2020.00438.
Zu C, Li Z, Yang J, Yu H, Sun Y, Tang H, Yost R, Wu H. 2014. Acid soil is associated with reduced yield, root growth and nutrient uptake in black pepper (Piper nigrum L.). Agric Sci 5 (5): 466-473. https://doi.org/10.4236/as.2014.55047.