Query: role of humic acid in plants

title: Discriminating the Short Term Action of Root and Foliar Application of Humic Acids on Plant Growth: Emerging Role of Jasmonic Acid
abstract: Humic substances (HS, fulvic and humic acids) are widely used as fertilizers or plant growth stimulants, although their mechanism of action still remains partially unknown. Humic substances may be applied either directly to the soil or as foliar sprays. Despite both kind of application are commonly used in agricultural practices, most of the studies regarding the elicited response in plants induced by HS are based on the root application of these substances. The present work aimed at discriminating between the mechanisms of action of foliar application versus root application of a sedimentary humic acid (SHA) on plant development. For this purpose, six markers related to plant phenotype, plant morphology, hormonal balance and root plasma membrane H+ ATPase were selected. Both application strategies improved the shoot and root growth. Foliar applied and root applied SHA shared the capacity to increase the concentration of indole 3 acetic acid in roots and cytokinins in shoots. However, foliar application did not lead to short term increases in either abscisic acid root concentration or root plasma membrane H+ ATPase activity which are, however, two crucial effects triggered by SHA root application. Both application modes increased the root concentrations of jasmonic acid and jasmonoyl isoleucine. These hormonal changes caused by foliar application could be a stress related symptom and connected to the loss of leaves trichomes and the diminution of chloroplasts size seen by scanning electron microscopy. These results support the hypothesis that the beneficial effects of SHA applied to roots or leaves may result from plant adaptation to a mild transient stress caused by SHA application.

title: Physiological Role of Humic Acid, Amino Acids and Nitrogen Fertilizer on Growth of Wheat under Reclaimed Sandy Soil
abstract: In order to evaluate productivity of some wheat cultivars grown in sandy, saline soil under foliar spraying with humic acid, amino acids and nitrogen fertilizer levels. Highest chlorophyll b and carotenoid content, percentage of sodium and calcium, tallest plants and higher number of tillers/plant were achieved from Gemiza 9 cultivar. The highest relative growth rate (RGR) and net assimilation rate (NAR) chlorophyll and total chlorophyll values, higher flag leaf area and stem diameter were resulted from Giza 168 cultivar. While, higher percentages of proline, total phenols and potassium percentages were found from Shaka 93 cultivar. The earlier for a number of days to heading and flowering were resulted from Shaka 93 cultivar. Application of humic and amino acid mixture significantly enhanced total leaf area/plant, plant dry weight after 75 and 95 days from sowing (DFS) RGR, NAR, photosynthetic pigments, i.e. chlorophyll a, chlorophyll b and carotenoids and proline contents. In addition, highest total phenols, potassium and calcium percentages, height flag leaf area, tallest plants, highest stem diameter and number of tillers/plant compared with other foliar spraying treatments. Accordingly, it could be recommended that foliar spraying wheat plants Giza 168 cultivar with the mixture of humic acid and Amino acids with addition, mineral fertilizing with 262 kg N/ha to obtain the best growth characters of wheat under newly reclaimed sandy saline soil conditions.

title: Humic acid's (HA) role in NDMA formation from daminozide (DMNZD) during ozonation
abstract: Daminozide (DMNZD) has been found to be an important ozone reactive N nitrosodimethylamine (NDMA) precursor; however, the influence of humic acid (HA) on NDMA formation from daminozide during ozonation is unclear. In this study, the impacts of HA on NDMA formation from daminozide at various oxidation conditions (ozone dosages, pH) and other water components (bicarbonate ion (HCO3 sulfate ion (SO42 were investigated. In addition, its implications for water treatment plants are discussed. The results indicated that low levels of HA =0.6 mg L 1) facilitated NDMA formation and its molar yield was maximized at 0.1 mg L 1 HA (8.5% while a high concentration of HA >0.6 mg L 1) had an inhibition role. The NDMA amount increased with increasing pH and showed a peak at pH 8. With 0.1 mg L 1 HA, NDMA was raised from 3.0% to 23.1% with ozone increasing from 0.5 to 4 mg L 1; HCO3 competed with daminozide for ozone and cut down NDMA formation, whereby 160 mM HCO3 reduced NDMA conversion from 8.5% to 6.5% however, with the increase in SO42 from 0 to 20 mM, NDMA conversion was augmented from 8.5% to 17.8% Based on the results of LC/MS/MS and GC/MS analyses, NDMA transformation pathways with/without HA are proposed.

title: Physiological Role of Humic Acid and Nicotinamide on Improving Plant Growth, Yield, and Mineral Nutrient of Wheat (Triticum durum) Grown under Newly Reclaimed Sandy Soil
abstract: Humic acid is not a fertilizer as it does not directly provide nutrients to plants, but is a compliment to fertilizer. Nicotinamide (Vitamin pp) is a stress associated compound that can induce and regulate secondary metabolic accumulation and/or the manifestation of defense metabolism in plants. A field experiment was conducted at the experimental station of National Research center at El Nubaria region, Egypt, to study the role of foliar application of humic acid (as soil conditioner 13 cm/l) and/or priming grains in nicotinamide (vitamin pp 5 mg/l) in saving irrigation water, decreasing fertilizer dose of NPK and at the same time increasing durum wheat (Triticum durum) cultivars' (Beni Sweif 1 and Beni Sweif 3) productivity grown under newly reclaimed sandy soil exposed to drought for three weeks continuously. The results showed that plant treated with humic acid or nicotinamide increased significantly all morphological criteria (plant height, leaves number, fresh and dry weights of shoots) metabolism (photosynthetic pigment, total soluble sugar, total carbohydrates, total amino acids and proline) mineral contents (N, P, K, Ca and Mg) and yield (grain, straw and biology) of both cultivars amended with either recommended or half recommended doses of NPK. Foliar application of humic acid to plant priming in Vitamin pp induced significant increases in all studied parameters (morphology, chemical and yield) of plants amended with recommended or half recommended doses of NPK as compared with control plants. The maximum yields of grain, straw and biology of both cultivars were obtained in response to triple treatment (humic acid nicotinamide recommended dose of NPK) or (humic acid nicotinamide half recommended dose of NPK) respectively.

title: Culturable Bacterial Endophytes From Sedimentary Humic Acid Treated Plants
abstract: The global decrease in soil fertility leads to a new agricultural scenario where eco friendly solutions play an important role. The plant growth promotion through the use of microbes, especially endophytes and rhizosphere microbiota, has been proposed as a useful solution. Several studies have shown that humic substances are suitable vehicles for the inoculation of plant growth promoting bacteria, and that this combination has an enhanced effect on the stimulation of plant development. In this work, cucumber plants grown hydroponically have been pre treated with a sedimentary humic acid (SHA) with known plant growth enhancing effects, and culturable bacterial endophytes have been isolated from these plants. The hypothesis was that this pre treatment with SHA could lead to the isolation of certain endophytic taxa whose proliferation within the plant could have been promoted as a result of the effects of the treatment with SHA, and that could eventually reinforce a potential synergistic effect of a combined application of those endophytic bacteria and SHA. The culturable endophytes that have been isolated from humic acid treated cucumber plants have been identified as members of four main phyla: Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes. Isolates were characterized according to the following plant growth promoting traits: nitrogen fixation/scavenging, phosphate solubilization, siderophore production and plant hormone production. Most of the isolates were able to fix/scavenge nitrogen and to produce plant hormones (indole 3 acetic acid and several cytokinins) whereas few isolates were able to solubilize phosphate and/or produce siderophores. The most promising endophyte isolates for its use in futures investigations as plant growth promoting bacterial inocula were Pseudomonas sp. strains (that showed all traits) Sphingomonas sp. Stenotrophomonas sp. strains, or some Arthrobacter sp. and Microbacterium sp. isolates.

title: Improvement of Vegetative and Reproductive Growth of 'Camarosa' Strawberry: Role of Humic Acid, Zn, and B
abstract: This experiment was conducted with the aim to improve vegetative and reproductive growth of strawberry (Fragaria x ananassa Duch. cv. 'Camarosa' using humic acid, zinc sulfate (ZnSO4) and boric acid. We evaluated applications of humic acid at 0, 20 and 40 mg*L 1, ZnSO4 at 0, 50 and 100 mg*L 1, and boric acid at 0, 50 and 100 mg*L 1 at 30 days after planting and blooming stage on growth of strawberry cv. 'Camarosa' Results indicated that humic acid, ZnSo4, and boric acid application improved reproductive and vegetative characteristics compared to control treatment. The results showed, that plants treated with humic acid, ZnSO4, and boric acid at higher their concentrations exhibited generally higher dry weight of roots and shoots, number of flowers and inflorescences, leaf area, length of roots and shoots, length of flowering period, yield, weight of primary and secondary fruits and number of their achenes. Total yield was significantly increased by all treatments compared to control treatment at both stages of application, especially at blooming stage. Moreover, conclusion showed that the mentioned materials could have impact on vegetative and reproductive growth of strawberry generally. In this study humic acid at 40 mg L 1 at blooming stage resulted in best effects on development of strawberry cv. 'Camarosa'

title: Effect of humic acid enriched cotton waste on growth, nutritional and chemical composition of oyster mushrooms (Pluerotus ostreatus and Lentinus sajor caju)
abstract: Humic acid (HA) is natural product obtained by plant decomposition. It improves systematic resistance in plants and the shelf life of food products. Oyster mushrooms occupy important place in human food due to their palatability and nutritional enrichment. Little is known about the impacts of HA on mushrooms yield. Therefore, a trial was conducted to study the role of HA improving growth, nutritional and chemical composition of two oyster mushroom strains (Pleurotus ostreatus, Lentinus sajor caju) Pure cotton waste amalgamated with five levels of HA, i.e. 2, 4, 6, 8 and 10 mM/L was used as growth media. The responses of oyster mushroom to HA were recorded in various traits i.e. time to spawn initiation, time to mycelium growth initiation, time to maturity of flushes, time to initiation of pinheads, yield, biological efficiency (BE) minerals (N, P, K, and ascorbic acid, Zn, Cu, Mg, Mn, Fe, Na and Ca) sugars (total sugars, reducing and non reducing sugars) proximate, total soluble solids (TSS) acidity, and Fourier transform infrared spectroscopy (FTIR) The HA amalgation notably improved the growth, nutritional and chemical composition of oyster mushroom; however, strains differences were non significant >0.05) to various level of HA on dry weight basis TSS ranged from 6 to 6.8 degBrix, total sugar was 5.8 11.9% reducing sugar was 2.6 3% non reducing sugar was 9.2 9.6% ascorbic acid was 35.9 43 mg/100 g, carbohydrates were 68 74% crude protein was 62 69% crude fiber was 22 37% fat contents were 2.5 17% ash content was 9 11% These results suggest that HA is an innovative substrate for valuable and high quality production of the oyster mushroom.

title: Abiotic Stress Tolerance in Plants: Exploring the Role of Nitric Oxide and Humic Substances
abstract: A number of studies have demonstrated the key role of nitric oxide in the regulation of many fundamental physiological processes that includes plant responses to abiotic and biotic stresses. On the other hand, beneficial action of humic substances on plant growth has been well corroborated, particularly when plants are subjected to abiotic stresses. Furthermore, several recent works have reported the functional links between the plant growth promoting action of humic substances and nitric oxide production and function in plants. In this article, we try to briefly review and discuss the main results showing the relationships between nitric oxide function and humic substances action on plants, also stressing the nitric oxide dependent involvement of other plant growth regulators, such as auxin, ethylene, abscisic acid, and cytokinins.

title: Protective Effect of Humic acid and Chitosan on Radish (Raphanus sativus, L. var. sativus) Plants Subjected to Cadmium Stress
abstract: Humic acid or chitosan has been shown to increase plant growth, yield and improving physiological processes in plant, but its roles on alleviating the harmful effect of cadmium on plant growth and some physiological processes in plants is very rare. Pot experiments were conducted to study the role of 100 and 200 mg/kg dry soil from either humic acid or chitosan on counteracted the harmful effects of cadmium levels (100 and 150 mg/kg dry soil) on radish plant growth and some physiological characters Results Cadmium at 100 and 150 mg kg 1 soil decreased significantly length, fresh and dry weights of shoot and root systems as well as leaf number per plant in both seasons. Chlorophyll, total sugars, nitrogen, phosphorus, potassium, relative water content, water deficit percentage and soluble proteins as well as total amino acids contents were also decreased. Meanwhile, cadmium concentration in plants was increased. On the other hand, application of chitosan or humic acid as soil addition at the concentration of 100 or 200 mg kg 1 increased all the above mentioned parameters and decreased cadmium concentrations in plant tissues. Chitosan at 200 mg kg 1 was the most effective than humic acid at both concentrations in counteracting the harmful effect of cadmium stress on radish plant growth.  In conclusion, both natural chelators, in particular, chitosan at 200 mg/kg dry soil can increase the capacity of radish plant to survive under cadmium stress due to chelating the Cd in the soil, and then reduced Cd bio availability.

title: THE ROLE OF HUMIC AND AMINO ACIDS IN IMPROVING GROWTH AND QUALITY OF PASPALUM TURF
abstract: 20/12/2016 Accepted: 10/1/2017  A field experiment was conducted at the nursery of Hort.  2014 and 2015 seasons to study the effect of spraying with humic acid at 0, 5 and 10 ml/l and adding mixture of amino acids as soil drench at 0, 1 and 2 g/pot individually or in combinations on growth, covering rate and chemical composition of seashore paspalum (Paspalum vaginatum, Swartz. plants grown in 40 cm diameter plastic pots filled with sand medium. The obtained results showed that all treatments caused improvement in plant height, covering rate, number of plants/pot and herb fresh and dry weights compared with control, also, chemical results of chlorophyll a, b and carotenoids content in the leaves and total sugars content in the herb. The best treatments used resulted from the combining between humic acid at 10 ml/l and mixture of amino acids at 2 g/pot which recorded the highest means. Hence, in order to get the best growth and quality of paspalum plants, it could be recommended to spray with humic acid at 10 ml/l and adding a mixture of amino acids as soil drench at 2 g/pot six times with one month interval.