Fulvic acid in foliar spray is more effective than humic acid via soil in improving coffee seedlings growth

ABSTRACT

Humic (HA) and fulvic (FA) acids improve the nutrient availability and uptake by plants but some aspects of their agronomic use still need to be clarified. The effects of HA soil application and FA foliar application on the growth, Zn and B uptake by coffee seedlings were evaluated. HA was added to an Oxisol at concentrations 0, 10, 25, 50, 75 and 100 mg kg^?1 (C-HA), in both limed (pH 6.2) and overlimed (pH 7.2) conditions. FA (0, 0.2, 0.5 and 1 g L^?1 C-FA) was applied to coffee leaves in three different application modes (M): with 0.3% Zn and 0.6% B supplied via foliar (M₁), 0.6% B and 1.2% Zn supplied via foliar (M₂) and 1.2 mg kg^?1 B and 6 mg kg^?1 Zn supplied via soil (M₃). HA addition in soil significantly (p < 0.05) reduced leaf B and Zn accumulation and coffee growth in both pH conditions. In the M₁ and M₂, FA application significantly (p < 0.05) increased the shoot growth at 0.59 and 0.45 g L^?1 and B accumulation at 0.96 and 0.45 g L^?1 C-FA. Foliar application of C-FA, instead soil application of C-HA, is a suitable practice to improve coffee seedlings growth and nutrition on Oxisol.     

Effect of Iron Deficiency on Gas Exchange and Catalase and Peroxidase Activity in Citrus

Abstract

The effects of iron (Fe) deficiency on catalase and peroxidase activity, net photosynthesis (Pn), stomatal conductance (g _s ), plant water relations, and specific leaf weight, were studied under greenhouse conditions in two sweet orange (C. sinensis) cultivars grafted on sour orange (Citrus aurantium) and Swingle citrumelo (C. paradisi × P. trifoliata). Iron deficiency caused by the absence of Fe in the Hoagland nutrient solution reduced significantly catalase and peroxidase activity, photosynthesis (Pn), osmotic potential (Ψ _π ), turgor potential (Ψ _p ), and specific leaf weight, but did not influence g _s and leaf water potential (Ψ _L ). Iron deficiency caused by increasing concentrations of bicarbonate supplied as NaHCO₃ (10 and 40 mM) in the nutrient solution reduced significantly g _s , Pn, and Ψ _p and increased Ψ _L and Ψ _π . Furthermore, remarkable differences were recorded between the various cultivars/rootstocks combinations.     

Effects of Foliar Application of FeSO4 and NaCl Salinity on Vegetative Growth,Antioxidant Enzymes Activity,and Malondialdehyde Content of Tanacetum balsamita L.

Salinity is one of the major environmental stressors which has deleterious effects on the growth, development, and yield of crops. Because of the gradual increase in soil and water salinity in the East Azarbaijan, Iran, Tanacetum balsamita L. cultivation in this region has always been associated with many problems. To study the effect of foliar spray of iron sulfate (FeSO₄) (0, 750, and 1500 mg L^?1) under sodium chloride (NaCl) salinity (0, 50, and 100 mM) on some physiological characteristics of Tanacetum balsamita L. plants, an experiment was conducted as a factorial based on complete randomized block design with three replications. Total soluble solids (TSS) and essential oil contents were significantly affected by the interaction effects of FeSO₄ foliar application and salinity levels. The highest TSS and essential oil content were found in the plants under NaCl₀ × FeSO₄ 1500 mg L^?1 treatment combination. Leaf length, leaf fresh and dry weights were influenced by both Fe foliar application and salinity levels. Foliar application of iron (Fe) positively affected leaf length, leaves fresh and dry weights, root fresh and dry weights and peroxidase (POD) content, especially at ₁₅₀₀ mg L^?1. Other traits such as leaf length, leaf fresh and dry weights, malondialdehyde (MDA), POD and catalase (CAT) contents were influenced by salinity levels. For POD, MDA, and CAT contents, the highest values were recorded with NaCl 50 and 100. The highest values of leaf length, leaf fresh and dry weights were found in the control plants.     

Effect of applying calcium chloride and three milk supplements to poinsettia ‘Prestige Red’

Some poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) cultivars are susceptible to bract calcium (Ca) deficiency in developing bracts. In this study, we evaluated the efficacy of foliar uptake of Ca from milk-based products plus calcium chloride (CaCl₂) as a potential Ca source. Weekly foliar applications of 237 mL L^?1 whole milk, 80 mL L^?1 powdered milk, 30 mL L^?1 condensed milk, 0.94 g L^?1 CaCl₂, or distilled water (used as a control) were applied to runoff of ‘Prestige Red’ for four weeks. The four largest bracts with petioles on three different inflorescences and three leaves with petioles below the transitional leaf per inflorescence were collected per pot. None of the treatments affected bract or leaf Ca concentration. Powdered milk treatments resulted in a higher concentration of zinc (Zn) in bracts and aluminum (Al) in bracts and leaves. White residue remained on the bracts and leaves after treatment with powdered milk, which would reduce marketability.     

ACC deaminase-producing bacteria mediated drought and salt tolerance in Capsicum annuum

Influence of drought and salt stress on different morphological and physiological growth parameters in Capsicum annuum inoculated with our isolates was estimated during the present study. Bulkhorderia cepacia was reported to possess the maximal, whereas Citrobacter feurendii the least plant growth promoting efficacy under salt and drought stress. ACC Deaminase activity of purified B. cepacia, C. feurendii and Serratia marcescens was 12.8 ± 0.44, 12.3 ± 0.56 and 11.7 ± 0.53 μM αKB mg^?1 min^?1 respectively. Under drought stress, B. cepacia showed maximum tolerance as it produced 4.893 ± 0.06 mg/mg protein of exopolysaccharide followed by C. feurendii and S. marcescens that produced 4.23 ± 0.03 and 3.46 ± 0.05 mg/mg protein, respectively. Chlorophyll “a” concentration was recorded 5.7 gm L^?1 in B. cepacia inoculated plant (without stress) and was sustained till 2.9 gm L^?1 even under the highest tested drought period. Chlorophyll “a” concentration in the B. cepacia inoculated plant under the highest tested NaCl concentration was 3.2 gm L^?1. Thus, bacterial inoculation mitigates the effects of salinity by the proliferation of root system, increasing plant biomass proving to be potential bioinoculum for alleviating abiotic stress.     

Evaluation of nanosilicon dioxide and chitosan on tissue culture of apple under agar-induced osmotic stress

In vitro, applications of nanosilicon dioxide (SiO₂) and chitosan were investigated for their effects on growth and proliferation of apple (Malus domestica Borkh. ‘Gala’) explants under osmotic stress induced by agar to simulate drought stress and under non-stressed conditions. The experiment included five levels of SiO₂ (0, 25, 50, 100, and 200 mg L^?1), two levels of chitosan (0 and 40 mg L^?1), and two levels of agar (7 g L^?1 and 9 g L^?1) added to Murashige and Skoog medium. Under non-stressed conditions (7 g L^?1 agar), application of SiO₂ at 50 or 100 mg ^?1 increased proliferation of apple explants. Use of 50 or 100 mg L^?1 SiO₂ or 40 mg L^?1 chitosan increased growth of apple explants under osmotic stress (9 g L^?1 agar). This research suggests that use of SiO₂ or chitosan may improve plant growth and tolerance to stress.     

Improving drought tolerance in maize by foliar application of boron: water status,antioxidative defense and photosynthetic capacity

Boron (B) plays a vital role in cell division and elongation in apical meristem. Drought stress (DS) severely reduced the B-uptake and thus growth and crop-productivity of plants. The aims of this study were to evaluate whether foliar application of B corrects physiological-disorders under DS in two contrasting maize genotypes i.e. Dekalb-6525 (drought-tolerant) and Yousafwala-hybrid (drought-sensitive). Initially, foliar rate of B (0, 2, 4 and 6 mg L^?1) was optimized in terms of improved plant growth under drought-stress. Then, optimized rate of B (4 mg L^?1) was applied to assess the physiological and biochemical basis of B-induced improved growth of maize under deficit-moisture supply. Drought-stress reduced the growth of plants by lowering in water-status (leaf water-relations), photosynthetic capacity (gas-exchange aspects, photosynthetic-pigments), membrane permeability, imbalance in redox potential (oxidative-stress, antioxidant-defense system) and tissue-B concentration. Application of B considerably improved maize growth by improving water-status, photosynthetic capacity, tissue-B concentration as well as up-regulation of antioxidative defense-system. Moreover, ameliorative effects of B on maize was also evident from stress relieving indicators such as slight decrease in accumulation of proline, total free amino-acids, total soluble-sugars and MDA content under water-deficit conditions. In addition, cultivar Dekalb-6525 showed considerable improving response to B application over Yousafwala-hybrid.     

Selenium in lemon balm plants: Productivity,phytotoxicity and drought alleviation

Since studies on the effects of selenium (Se) supplementation in water-stressed plants have mainly focused on cereal crops, the specific reports regarding Se-mediated adaptation to drought stress in medicinal vegetables are scant. Thus, we investigated the responses of Melissa officinalis to Se supplementation. Selenium contents were increased in leaves and grains by supplemental Se. Selenium foliar application at 1 mg l^?1 could be useful to increase the vegetative and reproductive growth of Se-enriched plants under well-watered conditions but at 20 mg l^?1 led to toxicity and caused damage to shoots. Drought stress significantly inhibited plant growth by chlorophyll degradation and reduced net carbon dioxide (CO₂) assimilation rate. Although Se at 1 mg l^?1 could increase biomass production under well-watered conditions in addition to the stimulation of antioxidant system under water stress, it could not ameliorate the negative effect of drought on productivity.     

Modulation in growth,development, and yield of Camelina sativa by nitrogen application under water stress conditions

Camelina sativa has rejuvenated as a successful oilseed crop in the recent years. It is a low-input-requiring crop with an unusual fatty acid composition. A pot experiment was conducted in rain-out shelter to investigate the effect of different nitrogen levels (N₀ = 0, N₁ = 50, N₂ = 100, and N₃ = 150 kg ha^?1) on the growth and yield of two C. sativa genotypes (Australian and Canadian) under normal [100% field capacity (FC)] and water stressed (60% FC) conditions. The experiment was laid out in a completely randomized design with factorial arrangement having three replicates in the Department of Crop Physiology, University of Agriculture, Faisalabad. The results indicated that nitrogen doses and water stress levels significantly affected the growth and yield of C. sativa. Maximum values for growth indices like leaf area index (LAI), crop growth rate (CGR), leaf area duration (LAD), net assimilation rate (NAR), and yield attributes were observed under N₂ treatment (100 kg ha^?1) followed by the treatment in which nitrogen was applied at the rate of 50 kg ha^?1. However, growth and yield components significantly reduced under water stress conditions (60% FC). Of both the genotypes, Australian Camelina performed better as compared to Canadian Camelina under both non-stress and drought stress conditions.     

NUTRITIONAL DIAGNOSIS AND CORRECTION OF SHOOT DIEBACK OF RED BAYBERRY (MYRICA RUBRA SIEB. ET ZUCA)

Shoot dieback characterized by leaflet, rosette shoots, and dieback of shoot tips is one of the most important problems in red bayberry production in south China. However, the causes of shoot dieback have not been determined. The results of leaf analysis and correction experiment showed that leaf boron (B) concentrations were highly correlated with leaf area (P < 0.01), spring shoot length (P < 0.01), and spring shoot numbers sprouting from one old shoot (P < 0.05). Foliar application of B at 2.0 g L^–1 of borax was more effective on correcting shoot dieback than foliar application of Zn at 2.0 g L^–1 of zinc sulfate and of molybdenum (Mo) at 2.0 g L^–1 of ammonium molybdate. Boron application increased fruit yields by 1.23–2.15 times compared with the control. Shoot dieback resulted mainly from B deficiency in the red bayberry trees.     

Boron fertilization improves seed yield and harvest index of Camelina sativa L. by affecting source-sink

The impact of soil (1, 2 kg ha^?1) and foliar (100, 200 mg L^?1) boron (B) with control (no B) was evaluated on phenology and yield formation of Camelina each applied at stem elongation and flowering stages. Foliar (200 mg L^?1) or soil B (2 kg ha^?1) resulted in earlier flowering and maturity, increased fruit bearing branches (19.68%), number of siliqua, seeds per siliqua (4.6%), biological yield (15%), seed yield (24%), harvest index (11.4%) and oil contents (23%) than no B. Increased fruit bearing branches, seed filled siliqua or seed numbers, harvest index and oil quality can be attributed to changes in dry matter accumulated of stem with simultaneous increase in siliqua dry weight with foliar or soil applied B. In crux, foliar (200 mg L^?1) or soil applied (2 kg ha^?1) B seems promising to improve seed and oil yield, harvest index of Camelina sativa under B deficient condition.     

Combined effect of deficit irrigation and foliar-applied salicylic acid on physiological responses,yield, and water-use efficiency of onion plants in saline calcareous soil

Field-applied salicylic acid (SA) could provide a potential protection against drought stress in onion large-scale production. Two-season field experiments were consecutively conducted in 2013/2014 and 2014/2015 to study the effect of 1 and 2 mM SA on growth, yield, plant water relations, chlorophyll a fluorescence, osmoprotectants, and water-use efficiency (WUE) in onion plants under four levels of irrigation (I₁₂₀ = 120%, I₁₀₀ = 100%, I₈₀ = 80%, and I₆₀ = 60% of crop evapotranspiration). Foliar application of SA enhanced drought stress tolerance in onion plants by improving photosynthetic efficiency and plant water status as evaluated by membrane stability index and relative water content. These results were positively reflected by improving plant growth, productivity, and WUE under drought stress conditions. Therefore, SA application may, in future, find application as a potential growth regulator for improving plant growth and yield under deficit irrigation by 20–40%.     

Effects of weed control and fertilization at early establishment on tree nitrogen and water use in an exotic F1 hybrid pine of subtropical Australia

Purpose

We investigated the effects of weed control and fertilization at early establishment on foliar stable carbon (δ¹³C) and nitrogen (N) isotope (δ¹⁵N) compositions, foliar N concentration, tree growth and biomass, relative weed cover and other physiological traits in a 2-year old F₁ hybrid (Pinus elliottii var. elliottii (Engelm) × Pinus caribaea var. hondurensis (Barr. ex Golf.)) plantation grown on a yellow earth in southeast Queensland of subtropical Australia.

Materials and methods

Treatments included routine weed control, luxury weed control, intermediate weed control, mechanical weed control, nil weed control, and routine and luxury fertilization in a randomised complete block design. Initial soil nutrition and soil fertility parameters included (hot water extractable organic carbon (C) and total nitrogen (N), total C and N, C/N ratio, labile N pools (nitrate (NO₃ ^?) and ammonium (NH₄ ⁺)), extractable potassium (K⁺)), soil δ¹⁵N and δ¹³C. Relative weed cover, foliar N concentrations, tree growth rate and physiological parameters including photosynthesis, stomatal conductance, photosynthetic nitrogen use efficiency, foliar δ¹⁵N and foliar δ¹³C were also measured at early establishment.

Results and discussion

Foliar N concentration at 1.25 years was significantly different amongst the weed control treatments and was negatively correlated to the relative weed cover at 1.1 years. Foliar N concentration was also positively correlated to foliar δ¹⁵N and foliar δ¹³C, tree height, height growth rates and tree biomass. Foliar δ¹⁵N was negatively correlated to the relative weed cover at 0.8 and 1.1 years. The physiological measurements indicated that luxury fertilization and increasing weed competition on these soils decreased leaf xylem pressure potential (Ψ_xpp) when compared to the other treatments.

Conclusions

These results indicate how increasing N resources and weed competition have implications for tree N and water use at establishment in F₁ hybrid plantations of southeast Queensland, Australia. These results suggest the desirability of weed control, in the inter-planting row, in the first year to maximise site N and water resources available for seedling growth. It also showed the need to avoid over-fertilisation, which interfered with the balance between available N and water on these soils.     

EXOGENOUS APPLICATION OF POTASSIUM DIHYDROGEN PHOSPHATE CAN ALLEVIATE THE ADVERSE EFFECTS OF SALT STRESS ON SUNFLOWER

A greenhouse experiment was conducted to examine whether foliarly applied potassium + phosphorus (K + P) in the form of monopotassium phosphate (KH₂PO₄) could mitigate the adverse effects of salt stress on sunflower plants. There were two levels of root-applied salt [0 and 150 mM of sodium chloride (NaCl)], and varying levels of KH₂PO₄ [(NS (no spray), WS (spray of water), 5 + 4, 10 + 8, 15 + 12, and 20 + 16 mg g^?1 K + P, pH 6.5] applied foliarly to 18-day old non-stressed and salt stressed sunflower plants. Salt stress adversely affected the growth, yield, photosynthetic capacity, and accumulation of mineral nutrients in the sunflower plants. However, varying levels of foliar applied KH₂PO₄ proved to be effective in improving growth and yield of sunflower under salt stress. The KH₂PO₄ induced growth in sunflower was found to be associated with enhanced photosynthetic capacity, water use efficiency and relative water contents.     

Effect of Foliar Applications of Humic Acid on Growth,Visual Quality,Nutrients Content and Root Parameters of Perennial Ryegrass (Lolium Perenne L.)

In recent years, applying humic acid (HA) has been common in turfgrass management. A series of experiments were conducted to evaluate the effect of HA on qualitative and quantitative characteristics of “Speedygreen” perennial ryegrass (Lolium perenne L.). Different concentrations of HA (0, 100, 400, and 1000 mg L^?1) were applied monthly as foliar application. Results showed that leaf phosphorus (P), potassium (K), and zinc (Zn) content, fresh and dry weight, chlorophyll content, and root fresh weights were not affected by HA. Meanwhile, HA improved the root and shoot development, except for root fresh weight. While just 100 mg L^?1 improved height, visual quality, nitrogen (N) content, roots length, and surface of roots, all of HA concentrations were effective on iron content. These results suggest that HA foliar application might be of benefit to enhance some nutrients uptake and root development of ryegrass possibly leading to improved drought resistance.     

Amelioration of Drought in Sorghum (Sorghum bicolor L.) by Silicon

The purpose of this study was to analyze the effects of silicon (Si) nutrition on sorghum growth under drought. The present study investigated the distribution of Si in plant parts under stress conditions and its effects on physiological and growth traits. The study was conducted during 2 years (2007–2009) at PMAS Arid Agriculture University, Rawalpindi, Pakistan. Polyethylene glycol (PEG) 6000 (–4.0, –6.0, –8.0, and –10.0 Mpa) solution was used to screen drought-tolerant (Johar1) and drought-susceptible (SPV462) sorghum (Sorghum bicolor L.) cultivars, which were replicated three times with Si sources of potassium silicate (K₂SiO₃) (Si₃₀₀: 300 ml L^?1) and control (Si₀) treatments. The results showed that drought-tolerant cultivars accumulated maximum Si under Si treatment versus Si absence, which resulted increased leaf water potential, leaf area index, Soil Plant Analysis Development (SPAD) chlorophyll, net assimilation, and relative growth rate over SPV462. Similarly, Si accumulation in leaves conserved transpiration and leaf water potential, verifying Si nutrition as a defense for plants under drought.     

Non-destructive estimation of sunflower leaf area and leaf area index under different water regime managements

Leaf area (LA) is a valuable parameter in many agronomic and plant physiological studies. Its measurement is time consuming and involves leaf destruction. Therefore, there is a tendency in using simple, fast, non-destructive, and electronic devices methods to estimate LA. The aim of this study was to estimate LA across different water regime treatments using a combination of leaf mass and leaf dimensions of sunflower (Helianthus annuus L.). For this purpose, different leaf sizes were collected from plants during the growing season on different time intervals. Experiment was conducted during 2012 summer time in Sari Agriculture Sciences and Natural Resources University, Iran. On field leaf dimension measurements were carried out, and leaves sketches were put on paper, scanned and then areas were measured using AutoCAD software. Multivariate linear and non-linear regression models were constructed between LA and other leaf components measured. All constructed models provided highly significant correlations (r = 0.90–0.99) between LA and different leaf components. The exponential model [LA = 0.619 [(L × W)^0.5]^2.019] provided the best estimation of sunflower LA (R² = 0.993). In conclusion, the simple and quick models developed in this study could predict the sunflower LA and leaf area index (LAI) with high precision.     

Boron Foliar Application in Nutrition and Yield of Beet and Tomato

The objective of this work was to evaluate the effect of the application of boron (B) by foliar spraying for the yield of beet (Beta vulgaris L.) and tomato (Solanum lycopersicum L.) crops. An experiment for each crop was done in a greenhouse at the São Paulo State University (UNESP), Jaboticabal campus, in Brazil. The experiments evaluated the B concentrations of 0, 0.085, 0.170, 0.255, and 0.340 g L^?1; applied in the 20, 35, and 50 days after the transplant (DAT) of beet cv. ‘Tall Top Early Wonder’, and in the 20, 40, and 60 DAT for the tomato cv. ‘Raisa N’. The plants were cultivated in pots with washed sand with 5 dm³ for the beet crop and 10 dm³ for the tomato crop. The beet and tomato crops were harvested 58 and 154 DAT, respectively. The leaves and fruits numbers; the foliar area; the dry matter of leaves, bark and roots; the fresh and dry matter of the fruits and the tuberous root; the dry matter of the total plant and the B foliar content were evaluated. The total dry matter of beet and tomato the plant were influenced by the concentration of the foliar B spray. The highest yield of the tuberous root and the total plant dry matter of beet occurred with B foliar concentration of 0.065 g L^?1 and it was associated with the B foliar content of 26 mg kg^?1. The highest yield of fruit and total plant dry matter of tomato occurred with the B foliar spraying of 0.340 g L^?1 and it was associated with the B foliar content of 72 mg kg^?1.     

Growth and photosynthesis of salt‐stressed sunflower (Helianthus annuus) plants as affected by foliar‐applied different potassium salts

In order to assess the effectiveness of foliar‐applied potassium (K⁺, 1.25%) using different salts (KCl, KOH, K₂CO₃, KNO₃, KH₂PO₄, and K₂SO₄) in ameliorating the inhibitory effect of salt stress on sunflower plants, a greenhouse experiment was conducted. Sodium chloride (150 mM) was applied through the rooting medium to 18 d–old plants and after 1 week of salt treatment; different K⁺‐containing salts were applied twice in 1‐week interval as a foliar spray. Salt stress adversely affected the growth, yield components, gas exchange, and water relations, and also caused nutrient imbalance in sunflower plants. However, foliar‐applied different sources of potassium improved shoot and root fresh and shoot dry weights, achene yield, 100‐achene weight, photosynthetic rate, transpiration rate, stomatal conductance, water‐use efficiency, relative water content, and leaf and root K⁺ concentrations of sunflower plants grown under saline conditions. Under nonsaline conditions, improvement in shoot fresh weight, achene yield, 100‐achene weight, photosynthetic and transpiration rates, and root Na⁺ concentration was observed due to foliar‐applied different K sources. Of the different salts, K₂SO₄, KH₂PO₄, KNO₃, and K₂CO₃ were more effective than KCl and KOH in improving growth and some key physiological processes of sunflower plants.     

Roles of glycine betaine in mitigating deleterious effect of salt stress on lettuce (Lactuca sativa L.)

This study was conducted to evaluate the roles of glycine betaine (GB) in mitigating deleterious effect of salt stress on lettuce. Lettuce plants were subjected to two salinity (0 and 100 mmol l^?1 NaCl) and four GB levels (0, 5, 10, 25 mmol l^?1). Salinity resulted in a remarkable decrease in growth parameters, relative leaf water content and stomatal conductance. Plants subjected to salt stress exhibited an increase in membrane permeability (MP), lipid peroxidation (MDA), leaf chlorophyll reading value, H₂O₂ and sugar content. Exogenous foliar applications of GB reduced MP, MDA and H₂O₂ content in salt-stressed lettuce plants. Salt stress increased Na and generally decreased other nutrient elements. GB reduced Na accumulation, but significantly increased other element contents under salinity conditions. The study showed that gibberellic acid (GA) and salicylic acid (SA) content in salt-stressed plants were lower than those of nonstressed plants. However, salinity conditions generally increased the abscisic acid content. GB treatments elevated the concentrations of GA, SA and indole acetic acid (IAA) at especially 10 and 25 mmol l^?1 GB under salt stress conditions. It could be concluded that exogenous GB applications could ameliorate the harmful effects of salt stress in lettuce.