Structure-function relationship of vermicompost humic fractions for use in agriculture
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The use of humic substances (HS) in agriculture is beneficial and has positive environmental impacts. However, to optimize the use of HS possible links between their structural characteristics and bioactivity must be shown. The goal of this study is to evaluate the bioactivity of different humic fractions extracted from vermicompost (VC) in rice plants and to shed light to possible structure-function relationships.
Materials and methods
Humic-like fractions were obtained from cattle manure vermicompost processed by African nightcrawlers (Eudrilus eugeniae spp.). Humic-like acid fraction using only water as extractor (HLAw), HLA fraction extracted following the International Humic Substances Society (IHSS) recommended method, and the solid residue (humified residual (HR)) after extraction of HLA were characterized using complementary chemical, physic, and spectroscopic technics (elemental composition, UV-Vis and Fourier transform infrared spectroscopy (FTIR) spectroscopies, 13C-CP MAS NMR, and MEV). Biological activity of the three HS was conducted in growth chambers and measured in roots using WinRhizo Arabidopsis software. Principal component analysis (PCA) was used to find a grouping pattern between the structural variables evaluated and the obtained root parameters.
Results and discussion
Differences were found in elemental composition among HS with larger C/N ratio in HR than in HLA and HLAw. HLA and HLAw FTIR spectra showed carboxyl band at 1714.66 cm−1 better resolved than in HR. Bands at 1642 cm−1 (amide I) and 1510 cm−1 (lignin), were better resolved in HLA. 13C-NMR showed the following order of aromaticity: HLA > HLAw > HR. For HLAw bioactivity, the structures CAlkyl-H,R, CC=O, and CCOO-H,R correlated with the number and growth of smaller root. The aromatic CAr-H,R, CAr-O,N, and aliphatic CAlkyl-O,N, CAlkyl-O, and CAlkyl-di-O structures in HLA, correlated with larger roots growth. HR also stimulated root growth and development in rice plants.
Aliphatic and oxygenated structures in HLAw showed a relation with induction of initial root emissions, whereas the presence of aromatic compounds in HLA was related with root growth stimulation activity. Higher concentration of HLAw was necessary to produce an equivalent stimulus compared with HLA; it could indicate that, although both fractions showed similar types of structures in their composition, differences in the predominant structures may be determining different effects on the root.
Keywords13C NMR spectroscopy Bioactivity Humic substances Vermicompost
A.C.G. (sisFaperj 2012028010) thanks FAPERJ for his grant. A.C.G, R.L.L.B, and J.M.G.M thank the CNPq-CAPES for the PDJ scholarship and funding through the project Science without Borders—PVE A060/2013. The authors thank CAPES-MES project no. 46/2013, 215/13.
- Álvarez MR, Aragonés CR, Padiz AS, Vazquez MM (1998) Lombrices de Tierra con Valor Comercial. Biología y Técnicas de Cultivo [Commercial value of earthworms. Biology and cultivation techniques]. UQROO, Mexico, p 30Google Scholar
- Baigorri R, Fuentes M, González-Gaitano G, García-Mina JM, Almendros G, González-Vila FJ (2009) Complementary multianalytical approach to study the distinctive structural features of the main humic fractions in solution: gray humic acid, brown humic acid, and fulvic acid. J Agri Food Chem 57:3266–3272CrossRefGoogle Scholar
- Berbara RL, García AC (2014) In: Parvaiz A, Mohd RW (eds) Humic substances and plant defense metabolism. Springer, New York, pp. 297–319Google Scholar
- García AC, Izquierdo FG, Berbara RLL (2014a) Effects of humic materials on plant metabolism an agricultural productivity. In: P. Ahmad (ed) 1:449–466Google Scholar
- Hoagland DR, Arnon DI (1950) The water-culture method for growing plants without soil. Calif Agric Exp Station Bull 347:1–32Google Scholar
- IHSS (2013) International Humic Substances Society. Available at: http://www.humicsubstances.org/
- Jannin L, Arkoun M, Ourry A, Laîné P, Goux D, Garnica M, Fuentes M, Francisco MM, Baigorri R, Cruz F, Houdusse F, García-Mina JM, Yvin JC, Etienne P (2012) Microarray analysis of humic acid effects on Brassica napus growth: involvement of N, C and S metabolisms. Plant Soil 359:297–319CrossRefGoogle Scholar
- Mora V, Bacaicoa E, Zamarreño AM, Aguirre E, Garnica M, Fuentes M, García-Mina JM (2010) Action of humic acid on promotion of cucumber shoot growth involves nitrate-related changes associated with the root-to-shoot distribution of cytokinins, polyamines and mineral nutrients. J Plant Physiol 167:633–642CrossRefGoogle Scholar
- Salter CE, Edwards CA (2014) The production of Vermicompost Aqueous Solutions or Teas. In: Edwards CA, Arancon NQ, Sherman R (eds) pp 153–164Google Scholar
- Santos GA, Camargo FAO (1999) Fundamentos da Matéria Orgânica do Solo: Ecossistemas Tropicais e Subtropicais [Fundamentals of soil organic matter: tropical and subtropical ecosystems]. Ed. Genesis, Porto Alegre, Brasil, p. 102 ppGoogle Scholar