Effects of humic substances

S. Nardi, M. R. Panuccio, M. R. Abenavoli, and A. Muscolo, Auxin-like effect of humic substances extracted from faeces oi Allolohophora Caliginosa and A. rosea. Soil Biol. Biochem. 26 1341 (1994). 

This chapter focuses on the effects of humic substances present at the rhizo-sphere on plant growth and nutrient uptake. The main structural features of humic substances, their nutritional function, and the capacity to interact with plant metabolism are also presented. 

Y. Chen and T. Aviad, Effects of humic substances on plant growth. Humic Substances in Soil and Crop Sciences Selected Readings (P. Mac Carthy, C. E. Clapp, R. L. Malcolm, and P. R. Bloom, eds.), American Society of Agronomy and Soil Science Society of America, Madison, Wisconsin, 1990, p. 161. 

G. Concheri, S. Nardi, F. Reniero, and G. Dell Agnola, The effects of humic substances within the Ah horizon of a calcic luvisol on morphological changes related to invertase and peroxidase activities in wheat roots. Plant Soil 179 65 (1996). 

Artinger R, Kienzler B, Schii(31er W, et al. 1998. Effects of humic substances on the 241 Am migration in a sandy aquifer Column experiments with Gorleben groundwater/sediment systems. J Contain Hydrol 35 261-275. 

Fig. 6.5 Effect of humic substances in an aqueous solution on the dissolution of kerosene (Dror et al. 2000a)...

If released to water, 1,3-DNB and 1,3,5-TNB may be subject to direct photolysis when exposed to sunlight because both compounds can absorb light at wavelengths greater than 290 nm (ERA 1976 Mill and Mabey 1985). However, no data were located regarding the photolysis of 1,3,5-TNB in water. The photolytic half-life of 1,3-DNB in pure water was calculated to be 23 days (Simmons and Zepp 1986). A three-to four-fold increase in the rate of photoreaction of 1,3-DNB was observed in ambient waters containing natural humic substances or in distilled water containing dissolved humic materials compared to reaction without humic substances (Simmons and Zepp 1986). This enhancement of the reaction rate has been attributed to catalysis of the photoreaction by photosensitization effects of humic substances. 

Flaig, W. (1997) Aspects of the biochemistry of the healing effects of humic substances from peat. In Hayes, M.H.B. and Wilson, W.S. (eds) LJumic Substances in Soils, Peats and Waters. The Royal Society of Chemistry, Cambridge, UK, pp. 346-356. 

Warwick, P. W., Hall, A., Pashley, V., Bryan, N. D. Griffin, D. 2000. Modelling the effect of humic substances on the transport of europium through porous media a comparison of equilibrium and equilibrium/kinetic models. Journal of Contaminant Hydrology, 42, 19-34. 

Haitzer, M., G. Abbt-Braun, W. Traunspurger, and C. E. W. Steinberg, Effects of humic substances on the bioconcentation of polycyclic aromatic hydrocarbons Correlations with spectroscopic and chemical properties of humic substances , Environ. Toxicol. Chem., 18, 2782-2788 (1999). 

Morimoto K, Kenji T (1995) Effect of Humic Substances on the Enzymatic Formation of OCDD from PCP. Organohalogen Compds 23 387... 

Voelker, B. M., F. M. M. Morel, and B. Sulzberger. 1997. Iron redox cycling in surface waters Effects of humic substances and light. Environmental Science Technology 31 1004-1011. 

The DEMI model also accounts for the amphitrophic effects of humic substances observed across systems by assuming that populations vary in... 

Chen, Y., and Aviad, T. (1990). Effects of humic substances on plant growth. In Elumic Substances in Soil and Crop Science, MacCarthy P, ed., ASA, SSA, Madison, WI, pp. 161-186. 

Chen, Y., De Nobili, M., and Aviad,T. (2004). Stimulatory effects of humic substances on plant growth. In Soil Organic Matter in Sustainable Agriculture, Magdoff, F. R., and Weil, R. R., eds., CRC Press, New York, pp. 103-129. 

Effects of Humic Substances on Biochemical Pathways and Processes 323... 

The positive effects of humic substances often occur when the plants are grown in nutrient solution under anexic conditions in thin film isolators. This shows that the beneficial effects are due to the humic substances per se, rather than being mediated by microbial breakdown products. 

A beneficial effect of humic substances on the nutrient uptake and contents of plants has been reported for the major inorganic elements, such as nitrogen, phosphorus, potassium (Mylonas and McCants, 1980), and sulfur (Guminski, 1968). In addition, the uptake and contents of nutrients such as calcium, magnesium (Mylonas and McCants, 1980), sodium (Vaughan and McDonald, 1976) and copper (Rauthan and Schnitzer, 1981) are also enhanced by humic substances. Most of these reports on the effects of HS on the nutrient contents of plants are purely descriptive, and little attempt has been made to elucidate the mechanisms of the action of the humic material. The authors proposed both an indirect and a direct effect of HS on plant nutrition. In the former case HS may, for example, chelate a cation, thus changing... 

EFFECTS OF HUMIC SUBSTANCES ON BIOCHEMICAL PATHWAYS AND PROCESSES... 

Albuzio, A., Ferrari, G., and Nardi, S. (1986). Effects of humic substances on nitrate uptake and assimilation in barley seedlings. Can. J. Soil Sci. 66,731-736. 

Merlo, L., Ghisi, R., Rascio, N., and Passera, C. (1991). Effects of humic substances on carbohydrate metabolism of maize leaves. Can. J Plant Sci. 71,419 425. 

Muscolo, A., Felici, M., Concheri, G, and Nardi, S. (1993). Effect of humic substances on peroxidase and esterase patterns during growth of leaf explants of Nicotiana plumbagini-folia. Biol. Fertil. Soils 15,127-131. 

Muscolo, A., Panuccio, M. R., Sidari, M., and Nardi, S. (2005).The effects of humic substances on Pinus callus are reversed by 2,4-dichlorophenoxy acetic acid. J. Chem. Ecol. 31(3), 577-590. 

Nardi, S., Pizzeghello, D., Muscolo, A., and Vianello, A. (2002). Physiological effects of humic substances on higher plants. Soil Biol. Biochem. 34,1527-1536. 

Visser, S. A. (1987). Effect of humic substances on mitochondrial respiration and oxidative phosphorylation. Sci. Total Environ. 62, 347-354. 

Kamiya, M., and Kameyama, K. (1998). Photochemical effects of humic substances on the degradation of organophosphorus pesticides. Chemosphere 36(10), 2337-2344. 

Si, Y., Zhou, J., Chen, H., Zhou, D., and Yue, Y. (2004). Effects of humic substances on photodegradation of bensulfuron-methyl on dry soil surfaces. Chemosphere 56, 967-972. Siesler, H. W., Ozaki,Y., Kawata, S., and Heise,H. M., editors. (2002). Near-Infrared Spectroscopy Principles, Instruments, Applications, Wilcy-VCI I, Wcinhcim. 

Voelker, B.M. and Kogut, B. (2001) Interpretation of metal speciation data in coastal waters the effects of humic substances on copper binding as a test case, Marine Chemistry 74, 303-318. 

---