Foliar Humic Acid Research Articles

Influence of row density and foliar humic acid application on growth parameters, yield and yield components of Niger (Guizotia abyssinica Cass.) in Erbil

Influence of row density and foliar humic acid application on growth parameters, yield and yield components of Niger (Guizotia abyssinica Cass.) in Erbil

Effect of Foliar Application of Potassium Silicate on Growth Attributes of Jamun (Syzygium cumini (L.) Skeels.) cv. Goma Priyanka

A field experiment was carried out on the Instructional Farm, which finds its location intricately linked to the Department of Fruit Science at the esteemed College of Horticulture and Forestry in Jhalarapatan, a prominent site within the Jhalawar region. during (2021-22 and 2022-23) with the object of assessing the response of foliar humic acid on growth attributes of Jamun (Syzygium cumini (L.) Skeels) cv. Goma Priyanka. Four doses of Potassium silicate (KS) 0, 1000, 2000 and 3000 ppm were tried in 4 treatments in a factorial randomized block design. The foliar response of Potassium silicate KS3 (3000 ppm) treatment registered relatively better plant growth parameters viz. rootstock girth, scion girth, plant height, canopy volume, canopy spread E-W, N-S, of Jamun cv. Goma Priyanka plants.

Soybean (Glycine max L.) Yield and Yield Component Under Different Planting Time and Foliar Application of Humic Acid

A triplicate field experiment laid out in randomized complete block design was conducted to evaluate the effect of foliar application of humic acid rates (HAR) at Bakrajo, Sulaimani which is (located at 35°32'52.8"N and 45°21'16.6"E) belongs to Kurdistan region of Iraq with the silty clay soil type. Five different Humic Acid rates (HAR) which were (0 (control), 2,4,6,8 g/L) and two cultivation period (CP) which were cultivation Period 1 (CP1) on 15 May 2022 and cultivation Period 2 (CP2) on 1st of June 2022. The effect of foliar Humic acid rates application methods was highly significant on the Pod No./ Plant, Empty Pod/Plant, Seed Weight / Plant (g) and yield (kg/ha) and significant on the 1000 Seed Weight (g). While, the effect of cultivation period (CP) was highly significant only for the Pod No./ Plant and the insignificantly affected the other parameters including Empty Pod/Plant, Seed No./ Pod, 1000 Seed Weight (g), Weight / Plant (g) and yield (kg/ha). The maximum Pod No./ Plant, Empty Pod/Plant, Seed Weight / Plant (g) and yield (kg/ha) and significant on the 1000 Seed Weight (g) were observed under foliar application of HAR of 6 g/L and the best cultivation period for sowing humic acid was (CP1) which was on 15 May.

Effect of Foliar Humic Acid on Water Productivity: Biochemical Parameters and Biotic Stress on Geranium Yield

During the 2017/2018 and 2018/2019 seasons, a study was conducted on the effect of humic acid at 1.0, 1.5, and 2.0 ml L-1 and water productivity on essential oils and proline content, biotic stress caused by Cucumber Mosaic Virus (CMV) and yield of geranium plants. The study was conducted in El Kanater El Khairia of Qalubia Governorate. It was aimed at determining the appropriate concentration of humic acid that attains the highest water productivity (WP), the highest production of essential oils, and highest proline content as well as reducing the symptoms of CMV. Results indicate that the highest fresh yield was obtained with a foliar application of 2.0 ml L-1 humic acid and 120% evapotranspiration (ETo). Applied irrigation water was 15155, 12168, and 9334 m3 ha-1 in the first growing season and 15218, 12298, and 9678 m3 ha-1 in the second growing season with 120, 100, and 80% ETo in both seasons. The highest average of WP 9.31 kg ha-1 both seasons was attained with 80% ETo and, 2.0 ml L-1 humic acid. While, the highest percentage of geranium essential oils and proline content, 68.16 and 3.73%, respectively were found with 2.0 ml L-1 humic. On the contrary, there was a significant reduction in CMV symptoms in plants treated with 2.0 ml L-1 humic acid compared to untreated controls. Thus, it is recommended that geraniums be irrigated with 80% ETo and application of 2.0 ml L-1 humic acid. Additionally, these treatments increased WP and resulted in the highest production of essential oils. It also increased the concentration of proline which acts as an endogenous osmoprotectants, against CMV.

Foliar humic acid and salicylic acid application stimulates physiological responses and antioxidant systems to improve maize yield under water limitations

AbstractBackgroundHumic acid (HA) is an organic acid that is naturally present in soil organic matter and improves nutrient availability and the mechanisms involved in plant growth and development. Likewise, salicylic acid (SA) is an important plant hormone involved in the regulation of plant growth and development. A pot experiment was carried out to determine the effects of individual or combined HA and SA application on growth and yield of maize (Zea mays L.) under drought stress conditions. Two maize hybrids, namely, 30T60 (drought tolerant) and 75S75 (drought sensitive), were grown in semi‐controlled conditions and foliar applied with SA (1 mM), HA (100 mg L−1) and their combination (HA + SA). The plants were exposed to drought stress at the tasseling stage (R1, 60 days after sowing) for 2 weeks, while control plants were given normal irrigation.ResultsThe results showed that HA and SA applications significantly enhanced the gas exchange characteristics (photosynthetic rate, transpiration rate, and stomatal conductance), and antioxidant activity (catalase, guaiacol peroxidase, and superoxide dismutase) of water stressed maize plants. Foliar SA spray significantly increased the photosynthetic efficiency and activity of enzymatic antioxidants closely followed by HA + SA application that ultimately improved the yield and net benefit cost ratio of maize under water deficit conditions.ConclusionOur findings suggest that foliar spraying of SA at the initiation of the reproductive stage is a cost‐effective strategy to obtain a high maize yield under limited water conditions.

Effect of Humic Acid, Nitrogen Concentrations and Application Method on the Morphological, Yield and Biochemical Characteristics of Strawberry ‘Paros’

ABSTRACT The current study investigates the effects of humic acid concentration, its application methods as well as nitrogen ratios on the morphological, yield and biochemical characteristics of strawberry cv. Paros, during 2014–2015 in Ardabil Province, Iran. The study has been conducted within the framework of a double split plot randomized complete block design with three replications and density of 10 plants per replications. Different nitrogen levels (50, 100 and 150 kg ha−1) were examined in the main plots while application methods of humic acid (foliar and soil) and its different concentrations (0, 2, 4 and 6 kg ha−1) were considered in the subplots and sub-sub plots, respectively. The results of the analysis of variance (ANOVA) indicated that the interaction effects of different concentrations of nitrogen, humic acid and its application methods are significant on most of the measured variables at 5% probability level. Mean comparisons showed that the highest values for the leaf area, fruit yield, chlorophyll a, carotenoids and titratable acidity are associated with the combined treatments of nitrogen and humic acid with concentrations of 100 kg ha−1 and 4 kg ha−1, respectively. In three-way interactions, the highest shoot and root biomass and total chlorophyll content were obtained from the application of 100 kg ha−1nitrogen and 4 kg ha−1 foliar humic acid, while the highest nitrogen and protein contents of leaf and root were achieved upon applying 2 kg ha−1 foliar humic acid and 150 kg ha−1 nitrogen. Moreover, the highest amounts of ascorbic acid and total soluble solids were found at a concentration level of 100 kg ha−1 nitrogen along with applying 2 and 6 kg ha−1 foliar and soil humic acids, respectively. Finally, the best results of most of the studied traits were observed at 100 kg ha−1 nitrogen and 4 kg ha−1 foliar humic acid application.

Improving Phytoremediation Efficiency of Copper-spiked Calcareous Soils by Humic Acid Applications

In current study, the enhanced efficiency of copper (Cu) phytoremediation potential of Calendula officinalis L. was investigated in a Cu-spiked calcareous soil, using foliar and soil application of humic acid. For this purpose, in a greenhouse experiment, seedlings of C. officinalis were transferred to Cu-spiked soils (0, 250 and 500 mg/kg) and treated separately with soil (soil drench) and foliar (spraying plant leaves) humic acid applications at different levels (0, 10, 20 μM). The humic acid treatments were applied 2 weeks after transferring plant, and eventually the various biochemical-physiological traits and phytoremediation indices of Cu in C. officinalis were measured at (specific) time points. According to the results, C. officinalis grew normally without any toxicity signs in Cu-spiked soils, however with increasing the Cu levels, the dry weight biomass decreased and antioxidant enzymes activities increased. Both foliar and soil humic acid application in Cu-spiked soils increased dry weight biomass, photosynthetic pigment contents, Cu concentration, and bioconcentration factor (BCF). Furthermore, the application of this organic substance, obviously moderated the Cu stress since the antioxidant enzymes activities reduced compared to the control. Based on the results, the obtained translocation factor (TF) and BCF values of Cu, which were >1, indicated that this plant is a Cu-hyperaccumulator, which could extract Cu via phytoextraction mechanism. Generally, the results of this study showed that, among the humic acid treatments, application of 20 μM (especially soil drench application) had the best effect on increasing Cu phytoremediation efficiency in the studied soil and it recommended to enhance the efficiency of Cu phytoremediation in calcareous soils.

Effect of Humic Acid Application on Growth and Productivity of Sunflower Under Saline Soil Conditions

A field experiment was conducted at El-bostan Farm, Faculty of Agriculture, Damanhur University in the two successive summer seasons of 2018 and 2019. The aim of this study was to investigate the effect of humic acid application on sunflower (Helianthus annuus L.) growth, yield & its components and some chemical constituents grown under saline soil conditions.The experiment was laid out in a split plot design in four replicates. The main plots were occupied by three sunflower genotypes Sakha 53, Giza 102 and Line 120. While subplots contained four treatments of humic acid (HA) i.e.; without HA (control), HA soil application, foliar HA spray and a combination of both foliar spray and soil addition of HA. The results showed that, different genotypes did not perform similarly under salinity stress conditions. Line 120 had the highest leaf area/plant, head diameter, seed yield/ plant and seed yield/ha. With regard to humic acid application, it caused improvement for most growth, physiological parameters, yield and its components compared to control. Obtained results also, showed that humic acid application as both soil and foliar spray on Line 120 and Sakha 53 led to obtain the highest values of most studied parameters in the two growing seasons. Finally, it could be concluded that humic acid application can ameliorate negative effects of salinity on sunflower.

Ionic responses of bean (Phaseolus vulgaris L.) plants under salinity stress and humic acid applications

This study aimed to investigate the effects of different humic acid application methods (control, soil, foliar and soil + foliar) on chlorophyll content, dry matter weight of shoots and roots, concentrations of potassium (K), calcium (Ca) and sodium (Na), and K/Na and Ca/Na ratios of bean plants exposed to increasing salinity levels (0, 50, 100 and 150 mM). The effects of salt damage on shoots and roots of bean plants were significantly differed in humic acid application methods. Chlorophyll content decreased with the increase in salt doses at control and soil application of humic acid, while the decrease in chlorophyll content was lower in foliar application of humic acid. Shoot dry weight was not affected by humic acid applications, while root dry weight increased in soil + foliar application method. Soil + foliar humic acid application caused the highest shoot and root Na concentrations. Shoot Ca (2.61%) concentration in soil + foliar application was significantly higher compared to the other treatments, while the highest Ca concentration in roots (1.55%) was recorded in soil humic acid application method. The highest K concentration in roots was obtained in the control treatment (2.50%) followed by soil + foliar humic acid application (2.48%). The ratios of K/Na and Ca/Na in shoots decreased with the increase in salt application rates. The highest shoot K/Na (1456.1%) and Ca/Na (1274.1%) ratio in humic acid x salt interactions was found in soil application of humic acid without salt treatment. The root and shoot dry matter yield and K and Ca concentrations of the plants indicated that soil+foliar application method has a preventive effect for the plants against the 50 mM salt damage. The results showed that soil+foliar humic acid application in addition to the mineral fertilization required for beans can contribute to the growth and mineral nutrition of the plants under moderate salt stress (50 mM NaCl).

Effect of foliar application of humic acid on fodder and grain yield of oat (Avena sativa L.)

An experiment was carried out at the farm of Field Crops Department, Agriculture College, University of Basrah, Iraq during two winter seasons of 2016–17 and 2017–18 to study the effect of spraying humic acids (0, 3, 6 and 9 g/l) at two growth stages (Tillering and 50% flowering stage) on the fodder and grain yield of oat cv. Shaffaa. Split plot design arranged by RCBD was used with three replications, stage of spraying was placed in the main plots, while foliar humic acid concentrations in the sub-plots. The best concentration of humic acid was 6 g/l which achieved the highest green fodder yield (50.6 and 54.4 t/ha), dry fodder yield (16.9 and 18.6 t/ha) and grain yield (6.19 and 5.97 t/ha) for both the growing seasons. Spraying at tillering stage was more efficient for increasing fodder and grain yield as compared to spraying at 50% flowering stage. The interaction was significant, plants that sprayed at tillering stage with concentration of 6 g/l of the humic acid were more potential for most studied characteristics. Therefore, humic acid @ 6 g/l during tillering growth stage proved most suitable for obtaining optimum yield of oat.

Yield, berry quality and physiological response of grapevine to foliar humic acid application

ABSTRACT Environmentally friendly grape growing is an important objective of modern viticulture. The aim of the study was to examine the response of two grapevine Vitis vinifera L. cultivars to humic acids (HA) foliar application as biostimulant in order to provide sustainable viticultural practices for farmers. The experiment was carried out under field conditions and repeated in two consecutive years. In order to evaluate the effect of humic acids application, the grapevines were treated with three concentrations: 30 ml.L-1 (HAT1), 40 ml∙L-1 (HAT2) and 50 ml∙L-1 (HAT3). The grapevines were represented by two grape varieties: cv. Feteasca Regala (cv. FR) and cv. Riesling Italian (cv. RI). Foliar sprays with humic acid derived from vermicompost at a concentration of 50 ml∙L-1 induced a significant increase in the total leaf area, yield and total soluble solids. For several measurements performed in plants we found no significant difference between grapevines treated with HAT2 and those with HAT3. The experimental results in the present study confirm that foliar application with humic acid may improve growth, yield, and berry quality attributes of grapevine.

EFFECT OF GROWTH STIMULANT SUBSTANCES ON THE PRODUCTIVITY AND QUALITY OF SOME EGYPTIAN CLOVER (TRIFOLIUM ALEXANDRINUM, L.) VARIETIES

Two field experiments were carried out at the Experimental Farm, faculty of Agriculture, Menoufia University, Shebin El-Kom, Egyptduring 2015/2016 and 2016/2017 seasons to investigate the effect of some plant stimulant substances(control,ascorbic acid 1 g/L, citric acid 1 g/L, humic acid 2 g/L and salicylic acid 0.5 g/L)as foliar application on vegetative growth performance(plant height, number of leaves and stems/m2,stems and leaves dry weight/m2,total dry weight/m2 , leaf area/ m2, specific leaf area and specific leaf weight/ m2 and leaf/stem ratio),photosynthetic pigments(total chlorophyll), plant chemical composition(N,P and K%) and nutritive value(P and DP%), forage yield( fresh and dry forage/fed) and seed yields and its components (number of heads/ m2, number of seeds/head, 1000-seed weight, seed weight/head and seed yield/fed) of some Egyptian clover varieties (Serw1, Sakha4, Helaly, Gemmeiza1 and Giza 6).The results obtained could be summarized as follows: 1-The Data indicated thatHelaly variety surpassed the other varieties in most growth characters (plant height, number of leaves/ m2, stems, leaves and total dry weight/m2 and leaf area/ m2), photosynthetic pigment (total chlorophyll),Chemical composition(N %) and nutritive values(crude protein and digestible protein percentage),forage yield(total fresh and dry forage yields/fed)and seed yield and its components(number of seeds/head, seed weight/head and seed yield /fed). However, Gemmeiza 1 variety surpassed the other varieties in number of stems/ m2 and number of heads/ m2.On the other hand, the highest values ofP% and K% were recorded by Sakha4.Serw1variety gave the highest value of 1000-seed weight in both seasons. 2- Foliar application of humic acid was superior to the other rest stimulant substances in most characters studied of growth characters and forage yield. However, Salicylic acid produced generally the highest values of chemical composition and nutritive values and seed yield and its components. On the other hand, unsprayed clover plants gave the lowest values of most characters studied. 3-The interactions between Egyptian clover varieties and stimulant substances were found to be significant for most characters under study.It could be concluded that Helaly variety treated with foliar humic acid being the most effective combined treatment for maximizing fresh forage yield/fed, while the same variety when treated with foliar salicylic acid produced the highest values of seed yield/fed of Egyptian clover under the experiment conditions. 4-Seasonal fresh and dry forage yields were significantly and positively correlated with characters studied except number of stems/m2, number of seeds/head and seed weight/head in the first season and 1000-seed weight in the two seasons. Also seed yield/fed was significantly positively associated with all characters studied except 1000-seed weight in both seasons.

Response of Maize Intercropping with Soybean to Nitrogen Fertilizer and Humic Acid Application.

Two field experiments were conducted at Zarzoura Experimental Station in Etay El-Baroud El-Behira Governorate, during 2013 and 2014 seasons, to study the effect of nitrogen fertilizer with humic acid (for maize), i. e. 120 Kg N/faddan, soil humic acid (5Kg/ fad.), foliar application humic acid (5g/litter), soil and foliar application humic acid, 60 Kg N/faddan plus soil humic acid, 60 Kg N/faddan in combination with foliar humic acid, 60 Kg N/faddan plus soil and foliar humic acid on growth, yield and chemical constituents under one intercropping system 2 : 2 row maize/soybean, as well as maize sole and soybean sole.Results indicated that: 1-Maize: growth, yield and its components had significant effect for nitrogen fertilizer with humic acid except ear position %, ear diameter and rows number/ear, sole maize, 120 Kg N/faddan and 60 Kg N/faddan with soil and foliar humic treatments had the highest values, while the lowest values were obtained with foliar humic, soil humic as well as soil and humic application in both seasons. 2-Soybean: growth and yield and its components characters did not significantly affected by nitrogen fertilizer with humic acid except shoot dry weight, number of pods/plant, seed weight/plant and seed yield/faddan, the highest values were obtained in sole soybean.3- The results verified that chemical characters of maize and soybean were significantly affected by nitrogen fertilizer with humic acid except protein% and oil% in maize as well as carbohydrates% and oil% in soybean the highest values were obtained with sole treatments followed by the combination between soil application on nitrogen and soil or foliar humic acid, while the lowest values were obtained with foliar humic, soil humic as well as soil and foliar humic acid application. 4- The data of competitive relationships indicated that all the imposed treatments showed yield advantage compared with solid planting. Maximum values LER and K were obtained when applied 120 Kg N/faddan followed by 60 Kg N/faddan plus soil and foliar humic acid application. Aggressivity, maize was dominated in 120 Kg N/faddan and 60 Kg N/faddan with soil and foliar humic acid, while soybean was dominated in foliar humic and soil and foliar humic acid application.

Antioxidant compounds and activity in cucumber fruit in response to foliar and soil humic acid application

Summary Humic acid (HA), with its hormon-like activity influences yield and quality of fruits and vegetables. This study was performed to determine the influence of foliar and soil HA fertilization on antioxidant properties of cucumber fruit. Cucumber plants were treated with soil and foliar HA at various concentrations (0 mL L-1, 10 mL L-1, 20 mL L-1, 30 mL L-1 and 40 mL L-1) via spraying or drenching to the plant root area. Fruits were harvested at commercial maturity and their antioxidant activities in the hydrophilic (HAA) and lipophilic (LAA) fractions, lycopene, beta carotene, xanthophylls, total phenolics and chlorogenic acid contents were determined. The results demonstrated that HA application significantly improved both HAA and LAA activities in cucumber fruit. Moreover, HA also significantly enhanced total carotenes and xanthophylls, beta carotene, lycopene and chlorogenic acid contents. The data suggested that HA could be used to significantly improve cucumber fruit quality by enhancing its content of antioxidant compounds.

Effects of humic acid derived from sediments on the postharvest vase life extension in cut chrysanthemum flowers

Previous research has shown that humic acid can extend the vase life of cut flowers. However, the mechanisms responsible for this effect are unclear. In this study, the physiological mechanisms of foliar humic acid fertilizer on cut chrysanthemum flower postharvest vase life were investigated. Seedlings of chrysanthemum were sprayed with the same volume of distilled H2O, inorganic NPK fertilizer and organic foliar humic acid fertilizer every 15 days (15, 30, 45, 60 days after transplanting).The results showed that foliar application of humic acid improved the chlorophyll content, the net photosynthetic rate (Pn), contents of soluble sugars and soluble protein in the leaves of chrysanthemum, and increased the flower size, fresh weight, vase life, activities of antioxidant enzymes, and decreased the malondialdehyde (MDA) content in cut chrysanthemum flowers.It was concluded that the responses of the foliar humic acid fertilizer on postharvest vase life extension of cut chrysanthemum flowers could be related with the higher chlorophyll content, Pn, contents of soluble sugars and soluble protein in the leaves, the greater flower size, fresh weight, activities of antioxidant enzymes, and the lower MDA content in cut chrysanthemum flowers.

Effects of humic acid derived from sediments on growth, photosynthesis and chloroplast ultrastructure in chrysanthemum

Humic acid (HA) is natural biological organic fertilizer derived from organic waste materials, which shows a highly promoting effect on plant growth and development. However, the mechanisms responsible for the promoting effect of humic acid on the growth and development are poorly understood. In this study, the physiological mechanisms of foliar humic acid (FHA) fertilizer on chrysanthemum growth and development from the viewpoint of photosynthesis and chloroplast ultrastructure were investigated. Seedlings of chrysanthemum were sprayed with the same volume of distilled H2O (control), inorganic NPK fertilizer and organic foliar humic acid fertilizer every 15 days (15, 30, 45, 60 days after transplanting). The results showed that the morphological indices (stem diameter, fresh weights of shoots and roots, the root to shoot ratios, dry weights of shoots and roots, leaf area, flower diameter), the net photosynthesis rate, the chlorophyll fluorescence, the content of chlorophyll and the chloroplast ultrastructure of chrysanthemum improved obviously after foliar application of humic acid compared with those of the control and the NPK fertilizer. The promoting effect of the humic acid fertilizer showed an obvious dose-effect. The results from correlation analysis indicated that the responses of the foliar humic acid fertilizer on growth and development of chrysanthemum could be related with a constitutive increased net photosynthetic rate due to the high content of chlorophyll and the improved chloroplast ultrastructure.

Effect of foliar Humic acid application and Mulching of soil on character of Growth and Yield of strawberry Fragaria ananassa D.

The experiment was conducted in Alamria-Fallujah at Anbar proviance during spring season of 2010-2011 to study the effect of foliar application with humic acid and soil mulching and their interaction on some features of vegetative and rooting growth and yield of strawberry Rubygem &Fern variety. The foliar application of humic acid with 0, 1,2and4 ml/L where tow minds mulching with straw , black plastic in addition to control treatment without mulching were used. Factorial experiment with Randomized Complete Block Design RCBD in three replicates .The best result in total leaves area/plant, the percent of fruit set and total yield and root content of dry matter were obtained in Fern which get (1879.9cm2,, 62.83%, 166.08gm and 41.87gm)respectively. Mulching soil also had a significant effect on plant growth and yield and the treatment mulching straw the best result in mention characters which get (1592.3cm2, 40.92gm, 68.48%, 168.04gm) respectively. Foliar application with humic acid had a significant effect on average total leaves area/plant, root content of dry matter, the percent of fruit set and yield/plant which get (1968.2cm2, 44.42gm, 67.09%, 189.19gm) respectively. The interaction between mulching and foliar application had a significant effect in both varieties all mention of features.

Effects of bio, mineral nitrogen fertilizer management, under humic acid foliar spraying on fruit yield and several traits of eggplant (Solanum melongena L.)

To study the effect of nitrogen fertilizer and foliar spraying of humic acid on yield and yield components of eggplant, an experiment was conducted in factorial format based on randomized complete block design with three replications in Astaneh Ashrafiyeh (north of Iran) during 2011 farming year. Factors of experiment consist of humic acid foliar spraying in three levels; H1: control (without humic acid spraying), H2: 25 mg/L and H3: 50 mg/L, and nitrogen fertilizer management with six levels; N1: control (no nitrogen and no nitroxin), N2: 40 kg/ha pure nitrogen, N3: 80 kg/ha pure nitrogen, N4: roots inoculation with nitroxin, N5: 20 kg/ha pure nitrogen +roots inoculation with nitroxin and N6: 40 kg/ha pure nitrogen + roots inoculation with nitroxin. At maturity, fruit yield, number of fruits per square meter, number of branches per plant, plant height, fruit length and fruit width were measured. Results showed that, the effect of foliar humic acid spraying on all measured traits had significant differences at 1% probability level. Also, effect of nitrogen fertilizer management on fruit yield, number of fruit per square meter, plant height, fruit length and fruit width at 1% and on number of branches per plant at 5% was significant. Interaction effect of foliar humic acid spraying and nitrogen fertilizer management on fruit yield at 1% and on number of fruit per square meter, plant height, fruit length and fruit width at 5% was significant and on number of branches per plant was non significant. The highest fruit yield was obtained from use of 50 mg/L humic acid spraying and also from 80 kg/ha nitrogen fertilizer. Key words: Eggplant, nitrogen, humic acid, yield, Iran.

Changes in fruit yield and quality in response to foliar and soil humic acid application in cucumber

This study was designed to determine the influence of foliar and soil humic acid (HA) treatment on fruit quality and yield of cucumber grown under soil conditions in a greenhouse. Different concentrations of HA (0, 10, 20, 30 and 40 ml/L) were applied to cucumber plants through either foliar spraying or drenching in the root area. Foliar and soil HA applications led to significantly higher mean fruit weight, early and total yield than the control. HA treatments had no significant effect on skin chlorophyll b, mesocarp chlorophyll a, b and total chlorophyll contents, fruit length and diameter. Both soil and foliar HA treatments significantly increased total and reducing sugar contents. Moreover, HA application significantly influenced fruit skin total chlorophyll content and this effect was mainly on chlorophyll a content. The study shows that cucumber fruit yield and quality can significantly be improved with soil and foliar HA application. Key words: Cucumber, humic acid, quality, yield.

The influence of foliar and soil fertilization of humic acid on yield and quality of pepper

Humic acid (HA) is the result of organic matter decomposition and is beneficial to plant growth and development. The objective of the study was to find the influence of foliar and soil HA application on fruit quality and yield of organically grown pepper. Pepper plants were treated with soil and foliar HA applications at various concentrations (0 ml/l, 10 ml/l, 20 ml/l, 30 ml/l, and 40 ml/l). Starting four weeks after planting, HA was applied via spraying and/or drenching to the plant root area three times during the growth period at 15-day intervals. HA treatments had no significant effect on fruit firmness, fruit length, or diameter. Total and reducing sugar contents significantly increased in response to both foliar and soil HA treatments. Moreover, HA application significantly influenced total chlorophyll content and this effect was mainly on chlorophyll b content. Foliar 20 ml/l and soil 20 ml/l HA application resulted in the highest total chlorophyll content. Foliar and soil HA applications also led to significantly higher mean fruit weight, and early and total yield than for control. The study demonstrates that both soil and foliar HA treatment might successfully be used to obtain higher fruit yield and can significantly enhance fruit quality in organically grown pepper.