02769naa a2200253 a 450000100080000000500110000800800410001902400540006010000180011424501110013226000090024352019680025265300260222065300260224665300230227265300380229565300130233370000190234670000200236570000200238570000200240570000200242577300700244519795492021-11-10       2013    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1016/j.gexplo.2012.10.0052DOI1 aAGUIAR, N. O.  aPrediction of humic acids bioactivity using spectroscopy and multivariate analysis.h[electronic resource]  c2013  aHumic substances (HS) represent the organic material most widespread in nature and have positive effects on plant physiology influencing nutrient uptake and root architecture. Understanding the structure-activity relationship has been considered an essential step to drive technological approaches to produce HS with enhanced plant growth promotion performance. In this studywe used solid state nuclear magnetic resonance (CP-MAS 13C NMR) and infrared spectroscopy with diffuse reflectance (DRIFT), a collection of data from humic acid-like substances (HA) obtained from vermicompost produced with different sources of raw material and maturation stage. The bioactivity was evaluated using the ability of HA to induce lateral root emergence sites as well acidification of the liquidmediumby treated-maize root seedlings. The structure-activity relationshipwas done using multivariate analysis including principal component analysis (PCA), principal component regression (PCR) and Spearman correlation joined with NMR and DRIFT results. The main variables (higher loadings) correlated with HA bioactivity were for NMR positive loadings for lignin (56 ppm, 124 ppm, 148 and 153 ppm) and COOH groups (174 ppm) and negative loadings for carbohydrates (64, 75 and 102 ppm). For DRIFT the main positive loadings were aryl stretching and bending (1560, 1480, 860 and 780 cm-1) probably from lignins; for 2926 cm-1 and 2852 cm-1 due to C-H asymmetric and symmetric stretching, respectively, probably from long chain fat acids due to the presence of rocking absorption band of (CH2)n with n&gt4 at 720 cm-1 and negative loadings due to carbohydrate moieties (around 1100 cm-1, C-O stretching) and carboxylic acids (1724 cm-1, C-O stretching and 1220 cm-1, C-OH stretching and CO-H bending). The use of spectroscopy data to attempt to relate structure to bioactivity may be of practical interest in developing plant growth promoters using renewed source of humic materials.  aAnálise multivariada  aEfeitos fisiológicos  aEspectroscopia RMN  aRelação bioatividade estrutural  aTração1 aNOVOTNY, E. H.1 aOLIVEIRA, A. L.1 aRUMJANEK, V. M.1 aOLIVARES, F. L.1 aCANELLAS, L. P.  tJournal of Geochemical Explorationgv. 129, p. 95-102, Jun. 2013.