Abstract
Humic acids are the most active components of soil organic matter and have been shown to have an hormone-like activity thus stimulating plant growth. The objective of this work was to verify the quantitative and qualitative yield responses of the table grape cv. Italia after the application of a humic acid at various phenological stages. The humic acid used in this study has been extracted from a clay soil of the Apulia region and was applied at a concentration of 100 mg L–1 in four different times: pre-bloom (I), full-bloom (II), fruit set (III) and veraison (IV) and in two years, 2007 and 2008. The following parameters were measured at harvesting: berry size, °Brix, pH and titratable acidity. Finally, the °Brix/titratable acidity ratio has been calculated. Soil Plant Analysis Development (SPAD) readings were performed every 30 days up to harvesting time on the leaves of the middle shoots. No statistical differences were observed between the two years for all the parameters examined. The humic acid applied at full-bloom (II) induced a significant increase of berry size (width and weight) and a significant improvement of the other quality parameters (titratable acidity and °Brix/titratable acidity) with respect to the control. This study confirmed that humic acids, if applied at full-bloom, can induce significant increase of qualitative and quantitative parameters in table grape and can find a positive application in an organic and sustainable viticulture.
Highlights
Humic acids (HAs) are the main fractions of humic substances (HS) and the most active components of soil and compost organic matter
Indirect effects are mainly exerted through properties such as: enrichment in soil nutrients, increase of microbial population, higher cation exchange capacity (CEC), improvement of soil structure; whereas direct effects are various biochemical actions exerted at the cell wall, membrane or cytoplasm and mainly of hormonal nature (Varanini and Pinton, 2001; Chen et al, 2004)
These results are in agreement with previous results (Ferrara and Brunetti, 2008) using two HAs, from a soil and a olive pomace compost, when various foliar applications were performed
Summary
Humic acids (HAs) are the main fractions of humic substances (HS) and the most active components of soil and compost organic matter. HAs have been shown to stimulate plant growth and yield by acting on mechanisms involved in: cell respiration, photosynthesis, protein synthesis, water and nutrient uptake, enzyme activities (Vaughan and Malcolm, 1985; Albuzio et al, 1986; Chen and Aviad, 1990; Concheri et al, 1994; Nardi et al, 1996; Chen et al, 2004). This action of HAs has been demonstrated to be dose dependent and effective in a low concentration range (Chen and Aviad, 1990). The hormonelike activities of HAs is well documented in various papers, in particular auxin-, cytokinin- and gibberellinlike effects (O’Donnell, 1973; Cacco and Dell’Agnola, 1984; Casenave de Sanfilippo et al, 1990; Piccolo et al, 1992; Pizzeghello et al, 2002) and, further, the presence of plant hormone-like substances in HAs has been recently demonstrated, in particular the high content of indolacetic acid in a humic fraction isolated from forest soils (Muscolo et al, 1998; Nardi et al, 2000)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
