Effects of Humic Acid and Fulvic Acid on some Morphological Characteristics of Geranium

Ornamental plants play a vital role in meeting the mental and spiritual needs of peoplethat considered significance from commercial point of view as well. Optimal production of agricultural products requires suitable soil and adequate and absorbable nutrients for plant. Organic materials are important because ofimproving soil physical properties and soil fertility. Soil fertility depends on the content oforganic matter as well as the quality, quantity and dynamics of these materials insoil. Organic acids are an important source of organic matter. One of the most abundant forms of organic matter in nature is humic compounds which can be found in all soil and water environment. They play an important role in cation exchange, nutrients release, phosphorus buffering capacity and metal and toxic organic molecules maintenance.
In order to evaluate the effect of humic substances on morphological characteristics of geranium, thisexperiment was conducted in research greenhouse of Ferdowsi University of Mashhad during the years 2014 and 2015. The experiment was carried out as factorial based on completely randomized design with two factors and three replications. The first factor hadfour levels of humic acid (0, 0.2, 0.5 and 1 g/l), and the second hadfour levels of fulvic acid (0, 0.2, 0.5 and 1 g/ml). Treatment was usedalong with irrigation. Morphological characteristics included the number of leaves, number of nodes, number of branches, plant height, root length, leaf area, fresh weight of shoot, fresh weight of leaf, fresh weight of root, dry weight of shoot, dry weight of leaf, dry weight of root, volume of shoots, volume of root, fresh weight of shoot were measured at the end of the experiment. Statistical analysis of the results was performed by using Jmp-8 software. Charts were drawn using Excel 2010 and difference among treatments means were compared with LSD test.
The results of means comparison showed that combined use of humic acid and fulvic acid hadpositive effects on growth traits such as height, internode length, root length, fresh weight of shoot, fresh weight of root, fresh weight of leaf, dry weight of shoot, dry weight of leaf, volume of shoot, volume of root and leaf area. Research had shown that the application of humic fertilizers increased nitrogen content in shoots of the plant. It wasreported that nitrogen compounds existed in humic acid are important factors affecting the growth of plants. Humic acid also increasedshoot growth by increasing the uptake of nitrogen, calcium, phosphorus, potassium, manganese, zinc, iron and copper as well as hormone-like properties. It wasalso found that humic acid enhancedplant growth by increasing the activity of the RuBisCO enzyme and the subsequent increase in photosynthetic activity. Furthermore, humic acid reduced the pH of alkaline soils and causedthe nitrogen to be absorbed to a greater extent. The use of humic substances increased the leaf area and thus photosynthesis, therefore leading to the production of more dry matter in plants. Humic fertilizers also had a significant effect on root growth. Researchers had suggested that the presence of oxygen groups in humic acid increased lateral root growth. Although humic acid increased the growth of both root and shoot, its effectiveness on the root system wasmore evident.
This experiment was conducted with the aims of evaluating the effect of humic organic fertilizers, reducing the harmful effects of chemical fertilizers and improving the quality of plant growth in geranium. According to the results obtained from the present research, it can be concluded that combined application of humic acid and fulvic acid had greater effects on the majority of traits compared to the sole application of aforementioned compounds.