Plant growth promoting bacteria increases biomass,effective constituent,and modifies rhizosphere bacterial communities of Panax ginseng

Purpose: The main aim of this study was to introduce and explore plant growth-promoting bacteria (PGPB) indigenous to ginseng, and to evaluate their ability to improve production and quality, and effect on rhizosphere niche in ginseng.

Materials and methods: Endophytic bacteria were isolated from root, stem, and leaf of ginseng from different sites and genotype in China and Korea, screened based on their beneficial properties as PGPB. Nine bacterial isolates were selected according to their plant growth properties including soluble phosphate and potassium, ammonia, auxin and siderophore producing, ACC deaminase, and antagonistic pathogen as well. Changes in ginseng after PGPB inoculation were evaluated with respect to the non-inoculated control.

Results and Conclusions: The PGPB isolates were identified as genera Bacillus, Lysinibacillus, Rhizobium, Stenotrophomonas, Erwinia, Ochrobactrum, Enterobacter and Pantoea based on 16S rRNA sequences. Inoculation of G209 and G119 increased not only plant height, root length, fresh weight, and dry weight, but also root activity and the amount of ginsenosides significantly. In particular, using the Illumina Miseq platform, the native bacterial community of rhizospheric soil maintained high community diversity and increased abundance of specific bacteria. Therefore, they may be play a crucial role in sustainable ginseng cultivating in farmland.     

Quantification of Aspergillus fumigatus and enteric bacteria in European compost and biochar

Although most potential human pathogens (PHPs) can be inactivated during composting, the risk that such substrates represent for human health remains largely unknown due to the shortage of information on presence and abundance of PHPs in finished composts. This study focused on the assessment of Salmonella spp., Listeria monocytogenes, Shiga toxin-producing Escherichia coli (STEC), and the opportunistic fungal pathogen Aspergillus fumigatus in different compost commodities. A total of fifteen European composts, made from different waste types and processes, were evaluated for the occurrence of the selected PHPs using molecular and traditional techniques. The analyses were extended to five biochar because of their growing application in agriculture, horticulture, floriculture, and private gardening.

Enteric bacteria were detected by molecular methods in eight out of fifteen composts; however, viable propagules were confirmed for L. monocytogenes only in two composts, and for STEC in three more composts. No bacterial pathogens were found in biochar. Living A. fumigatus was present in eleven composts and two biochars. None of the eighteen isolates contained single nucleotide polymorphisms (SNPs) relevant for resistance to azole fungicides. The role of compost and biochar as a source of PHPs in the environment and the risk for human health is discussed.     

Assessing the impact of soil amendments made of processed biowaste digestate on soil macrofauna using two different earthworm species

Fermentation in combination with subsequent composting of biowaste is a preferred method for municipalities to recycle organic byproducts and transform them into useful end products for soil amelioration or plant fertilization. These compost products, especially if obtained from household wastes, can be a source of hazardous components, e.g. heavy metals, pathogens, synthetic chemicals or toxic organic compounds. An avoidance test with two earthworm species (Eisenia fetida and Aporrectodea caliginosa) was conducted to assess the impact of differently processed biowaste based digestate products on soil invertebrates. Body weight changes were recorded, as well as differences in effects on adult versus juvenile earthworms.

While E. fetida showed no avoidance towards the digestate products (negative avoidance, meaning that the tested products were preferred, of 80 to 100 %), A. caliginosa rejected the crude biowaste digestate compost in higher concentrations (avoidance of 45 %), but not the agglomerated or pelletized variants. A clear weight gain of up to 25 % was observed only for individuals of E. fetida. The developmental stages of the worms were not crucial for the outcome of the avoidance test.

Based on the results of this study the application of biowaste products on arable land cannot be recommended without constraints.     

Apple rootstocks may become infected by Neonectria ditissima during propagation

Introduction and purpose: The ability of apple rootstocks to become infected by Neonectria ditissima, the cause of European canker, was studied over two years.

Materials and methods: Rootstocks B9 and M9 with a size suitable for grafting (6-10 mm stem diameter, termed rootstocks), and smaller sized rootstocks (<5 mm stem diameter, termed transplants) of B9, M9, M26, MM106 and Antonovka were inoculated with N. ditissima at different times, either with contaminated map pins or with spore suspensions. In addition, the rootstocks were either defeathered (side shoots removed), topped (top shoot headed) or both, to create wounds that would normally occur during propagation, while wounds on transplants were made by removing leaves.

Results and discussion: One month after inoculation, slightly sunken canker lesions had developed around the inoculation points of the map pins or wounds. No lesions developed on the non-inoculated controls. Map pin inoculation resulted in 30% to 89% infection and spore suspension sprayed on wounds from 5% to 45% infection. When the cankered areas were split open, brown lesions with necrotic tissue due to infection by N. ditissima appeared. The transplants of M9, M26 and MM106 inoculated with contaminated map pins in 2014 developed necrosis on 40% to 67% of the plants, but there were no differences in the incidence or severity among the different types. On the transplants of B9, Antonovka and M9 inoculated in 2015, there was more necrosis on B9 (42%) than on Antonovka (11%) and more sporulating lesions on B9 (29%) than on M9 (9%) or on Antonovka (4%).

Conclusion: It can be concluded that rootstocks used for apple trees may become infected by N. ditissima, and wounds should thus be protected during propagation.     

Nutrient Uptake and Leaching from Soil Amended with Cattle Manure and Nitrapyrin

We investigated whether nitrification inhibitor nitrapyrin can reduce nutrient leaching and increase nutrient uptake by corn (Zea mays L.) in cattle manure amended soil. Amendments included non-amended check (CK), urea (Urea), REG (manure from cattle fed barley grain), and DDGS (manure from cattle fed 60% dried distillers grains with solubles), co-applied with or without nitrapyrin and leached or unleached with water. Nitrapyrin reduced (P < 0.01) leaching of nitrate by 56, 32, and 24% from DDGS, REG, and Urea treatments, respectively, and also reduced (P < 0.05) leaching of phosphate (58%), potassium (39%), calcium (39%), and magnesium (39%) from DDGS treatment. While nitrapyrin reduces the rate of ammonium conversion to nitrate, higher magnesium and phosphate levels in DDGS-amended soil favor struvite formation and reduce their leaching. Corn biomass and nutrient uptake were higher (P < 0.01) in DDGS and Urea than CK and REG treatments, but remained unaffected by nitrapyrin. The benefits of nitrapyrin should be further investigated under field conditions.

Abbreviations: DCD, dicyandiamide; DDGS, dried distillers grains with solubles; NI, nitrification inhibitor; TP, total P; TN, total N.     

Resistance breeding and biocontrol of Striga asiatica (L.) Kuntze in maize: a review

Purpose: The aims of this article are to highlight pre-breeding procedures for identifying primary sources of Striga-resistance genes and to summarize complimentary breeding techniques that enhance partial resistance of maize varieties against Striga species.

Materials and methods: The paper presented a comprehensive account of Striga screening and controlling techniques and highlighted the potential of integrating partial resistance with FOS to boost maize production and productivity in SSA.

Results: Striga infestation is a major constraint to maize production and productivity in Sub-Saharan Africa (SSA). A lack of Striga-resistant maize varieties and the limited adoption of other control methods hinder effective and integrated control of the parasitic weed in maize and related cereal crops globally. Genetic resistance of maize should be complemented with the use of Fusarium oxysporum f.sp. strigea (FOS), a biocontrol agent known to suppress Striga.

Conclusions: A combined use of genetic resistance and FOS has remained largely unutilized in controlling Striga in Africa. A combination of conventional and molecular Striga-resistance breeding tools as well as the use of FOS are promising methods to effectively control Striga in SSA.     

Sulfur nutrition effects on dinitrogen fixation of seedling alfalfa

Greenhouse experiments with alfalfa (Medicago sativa L. cv. ‘Apollo') were performed to evaluate the effect of varied nutrient solution concentrations of S on the yield, nodulation, dinitrogen fixation, N and S concentration, and the partitioning of N and S into shoots and roots.

Sulfur treatments consisted of four levels (0, 1, 2.5, and 25 mg S/L) of added S. The experimental design was a randomized complete block, with three replications. Seeds were inoculated with commercial inoculum, planted in plastic containers of acid‐washed sand, and irrigated with nutrient solution for one minute, at 2 h intervals.

Sulfur application increased the yield of all treatments. The results demonstrated that the addition of 2.5 mg S/L to the nutrient solution, besides providing the highest total dry matter yield (12 g/72 plants), showed the highest percent yield increase (19%), acetylene reduction rate (0.426 umole ethylene/mg nodule dry wt/h), total N content (306 mg/72 plants), percent recovery of S (3.8%), and percent increase in N due to dinitrogen fixation (32%).

N:S ratios obtained were different for shoots and roots, with S application decreasing the N:S ratios. The N:S ratios of 16:1 (shoots), and 9:1 (roots) obtained in the 2.5 mg S/L treatment were found to be adequate for normal growth and development.

These data indicated that the 2.5 mg S/L treatment (2.7 mg total S/L) was optimal for alfalfa seedling development.     

Isolation and characterisation of phages against Pseudomonas syringae pv. actinidiae

Purpose: Pseudomonas syringae pv. actinidiae causes bacterial canker of kiwifruit and is responsible for severe economic losses and emergence of drug-resistant bacteria. Bacteriophages are viruses that infect target bacterial hosts and may be the best strategy to prevent and control kiwifruit canker disease. The objective of this experiment was to monitor the prevalence of Pseudomonas syringae pv. actinidiae and provide insight for the use of phages in biological control.

Materials and methods: In this study, 52 strains of Pseudomonas syringae pv. actinidiae were isolated from 68 stem samples of kiwi plant (cv. Hongyang & Jinkui). Following polymerase chain reaction (PCR) analysis, 15 isolates belonging to biovar 3 were identified, one of which was named XWY0007 and used as the target strain to isolate the phages. Thirty-six phages were isolated and purified from a total of 51 surface water samples collected in Shanghai. All phages were identified by transmission electron microscopy (TEM) and their host ranges were evaluated. Three phages, designated φXWY0013, φXWY0014 and φXWY0026 were selected and further characterised using one-step growth curve and stability at different temperatures and pH.

Results and conclusions: The isolated phages are promising for use as antimicrobials against bacterial canker in kiwi. This report is regarding Pseudomonas syringae pv. actinidiae and its phages from major areas of kiwifruit cultivation.     

Mineral oil barrier is an effective alternative for suppression of damage by white snails

Purpose: Citrus white snail, Helicella candeharica Pfeiffer (Panpulmonata: Helicidae) is one of the most important orchard pests. In this study, the effectiveness of mineral oil was compared with molluscicide baits such as metaldehyde, ferricole (iron phosphate) and a snail-repellent paint in a commercial citrus orchard in northern Iran to reduce access of citrus white snails to citrus trees.

Materials and methods: The number of snails on citrus trees was monitored and counted 10 days after the application of the treatments, and at an interval of 6–8 days up to harvest time.

Results: In the first study, the mineral oil and repellent paint treatments reduced a number of snails best. In the second study, using metaldehyde and mineral oil barrier, again the mineral oil barrier reduced snails best. The cost of each treatment during one season per hectare was calculated at 55, 153, 124 and 120?$/ha for mineral oil, iron phosphate, snail-repellent paint and metaldehyde, respectively.

Conclusions: Mineral oil is an effective alternative for chemical compounds for reducing access by H. candeharica to citrus trees.     

Volatile losses of sulfur by intact alfalfa plants

An apparatus was developed for the quantitative collection of volatile sulfur compounds released by intact plants and was used to study the effects of leaf temperature and stomatal aperture on the amount and pattern of release.

An air stream sweeps volatiles released by the plants through a water‐cooled condenser system in which the air is dried prior to trapping the volatile sulfur compounds on activated carbon. Tests with ³⁵S‐labelled 1‐butanethiol gave a mean recovery of 95.8 ± 4.3%.

The yield of volatile sulfur compounds increased greatly when air flow rate increased from 1 to 2 1 min^‐1 , but was independent of flow rate over the range 2 to 6 1 min^‐1. About 93% of the trapped activity originated from plant shoots, about 1% from stem bases and roots and about 4% from culture solutions.

Release of volatile sulfur compounds from intact plants followed a diurnal pattern, maximum rates occurring around midday and minimum rates overnight. Maximum rates of release ranged from 30 to 41 ng S g dry weight of shoots^‐1 2 hr ^‐1, while minimum rates ranged from 1.5 to 2.1 ng S g dry weight of shoots^‐1 2hr^‐1. Leaf temperature rather than stomatal aperture seemed to be the major factor controlling rate of release of volatile sulfur compounds. The rate of release was almost doubled by an increase of 7–9°C in leaf temperature.     

Arbuscular mycorrhizal colonization of selected herbaceous plants under arid protected area in Tunisia

Arbuscular mycorrhizal fungi (AMF) play an important role in plants growth and soils dynamic in all most ecosystems. The main objective of the present study was to evaluate the plant-AMF interactions on soil functions under arid protected area ‘Zarat-Gabès’ in Tunisia.

AMF colonization was evaluated by visual observation of AMF in fine roots of eight herbaceous plants. The level of mycorrhizal colonization varied between plants. Astragalus corrugatus and Hippocrepis areolata showed the highest mycorrhizal performance. The relative spore number was significantly different across rhizosphere soils. Statistical analysis showed a clearly positive correlation between the number of spores and plant-mycorrhizal intensity.

For microbiological parameters, our results showed that mycorrhizal plants improved significantly the various microbiological parameters. Rhizosphere soils of Astragalus corrugatus and Hippocrepis areolata presented the necessary microbial densities and microorganisms more stable compared to unplanted soil. This study allowed obtaining a new result that challenges us about the need for efficient management of natural resources in the objective of nature conservation.     

Nitrogen Fertility Island Stability around Prosopis glandulosa Sprouts after Mechanical Shrub Control in a Degraded Grassland

We examined the effects of mechanical chopping to reduce shrub cover for grassland restoration in a semi-desert environment near Douglas, Arizona, USA. Specifically, soils were sampled to determine spatial and treatment differences, after 10 years, in soil-N fertility islands associated with undisturbed honey mesquite shrubs (Prosopis glandulosa Torr. var. glandulosa) compared with resprouted mesquite shrubs. Honey mesquite is the dominant shrub of this degraded grassland community.

One decade after mechanical crushing of shrubs for grassland restoration, soil amino sugar nitrogen (N) values and patterns for resprouted honey mesquite and undisturbed shrubs did not differ from one another according to a repeated measures analysis of variance. However, the concentrations in samples of the surficial 30-cm of soil around undisturbed and resprouted shrubs combined differed statistically at 161 parts per million (ppm) at trunk, 100 ppm midway between trunk and dripline, 78 ppm at the dripline, and 46 ppm beyond the dripline.

The results indicate that soil N fertility remained stable, but with decreasing levels at regular, radial sample points extending from the trunk to beyond the dripline, around mesquite shrubs that resprouted 10 years after mechanical crushing of tops for grassland restoration.     

Estimation of synergistic effect of humic fertilizer and Bacillus subtilis on lettuce plants by reflectance measurements

Previous research showed that the use of plant growth promoting rhizobacteria helped to increase nutrient use efficiency. The individual and combined effects of combined action of humic fertilizer and rhizobacteria Bacillus subtilis No. 2 on the lettuce yield, chlorophyll, total nitrogen and nitrate-(N) contents in lettuce leaves was studied. Traditional biochemical analysis and crop reflectance method were compared. Vegetation Indices and key spectrum characteristics - a median of frequency spectrum and bandwidth of frequency spectrum were used to estimate chlorophyll content in plant leaves.

The synergistic effect of bacteria and humic fertilizer was evidenced by increase in N and chlorophyll contents and in decreased nitrates content in lettuce leaves. Humic fertilizer resulted in decreased nitrates concentration in plants, whereas bacillus (B). subtilis No. 2 increased total N and chlorophyll contents. Results indicated that the application rate of humic fertilizer may be reduced when B. subtilis No. 2 is also applied.     

Differential Tolerances of Amaranthus Strains to High Levels of Aluminum and Manganese in Acid Soils

Species of Amaranthus are grown extensively as leafy green vegetables in tropical Africa and Asia and as high yielding grain crops in Western South America, Central America, Northern India, Western Nepal, and Pakistan. The crop is often grown on acid, marginal soils, under subsistence conditions, where liming even the soil plow layer may not be economically feasible. Hence, the identification or development of strains with high tolerance to acid soils would be beneficial. Aluminum and Mn toxicities are the most important growth‐limiting factors in many acid soils. The objective of our research was to determine the tolerances of selected Amaranthus strains to high levels of these elements in acid soils.

Fifteen strains, representing five species, were grown in greenhouse pots of an acid, Al‐toxic Tatum soil limed to pH 4.8 and 5.8. Strains differed significantly in tolerance to the acid soil. Relative yields (pH 4.8/pH 5.8%) ranged from 50.1 to 6.3% for tops and from 54.5 to 5.7% for roots. Four strains of A. tricolor L. (vegetable type) were significantly more tolerant than six strains of A. cruentus L. (seed and vegetable type). Strains of A. hypochondriacus L. and A. caudatus L. studied were intermediate in tolerance.

Twelve strains, representing four species, were grown on an acid, Mn‐toxic Zanesville soil at pH 4.6 and 6.3. Strains also differed significantly in tolerance to this acid soil; however, overall growth was better and strain differences were smaller than on Al‐toxic Tatum soil at pH 4.8. On Zanesville soil the relative top yields (pH 4.6/pH 6.3%) ranged from 74.1 to 18.6%. The most tolerant group included three strains of A. tricolor and one strain of A. hypochondriacus, but four strains of A. cruentus were also fairly tolerant. The sensitive end of the scale included one strain of A. cruentus and two strains of A. hypochondriacus.

In general, strains that were most tolerant to the Al‐toxic Tatum soil were also among the most tolerant to the Mn‐toxic Zanesville soil. Likewise, those most sensitive to the high Al soil were most sensitive to the high Mn soil. But some strains that were sensitive to excess Al in Tatum soil were fairly tolerant to high Mn in Zanesville soil.

Results suggest that superior strains of Amaranthus can be selected or developed for use on acid soils.     

Evaluation of Two Products Recently Introduced as Nitrification Inhibitors

This study compared the relative effectiveness of two products recently introduced as nitrification inhibitors with other materials used to inhibit nitrification. Four soils were treated with 0, 0.2, 1, 5, and 25 mg kg^?1 of nitrapyrin (NP), a new microencapsulated nitrapyrin product (ENP), dicyandiamide (DCD), a new maleic-itaconic polymer product (MIP), and ammonium thiosulfate (ATS). The soils were also treated with 200 mg N kg^?1 as urea, and percent inhibition of nitrification determined after 2 or 4 weeks of incubation. After 4 weeks, similar levels of nitrification inhibition were provided by 1 mg kg^?1 of NP (72%), 5 mg kg^?1 of ENP (79%), and 25 mg kg^?1 of DCD (73%), averaged across soil. After 4 weeks with a sandy soil, the highest rate of MIP and ATS provided 15 and 36% inhibition, respectively. MIP and ATS were ineffective at inhibiting nitrification when added to the other three soils.

Abbreviations: ATS: ammonium thiosulfate; DCD: dicyandiamide; ENP: encapsulated nitrapyrin; MIP: maleic-itaconic polymer; NP: nitrapyrin; UAN: urea-ammonium nitrate liquid fertilizer     

Effect of Boron on Antioxidant Response of Two Lentil (Lens culinaris) Cultivars

Boron (B) is an essential micronutrient for plants through paticipating key reactions such as reproduction, development, and regeneration. Similar to its deficiency, its over-concentations possess toxic effects on plant growth. In this work, possible boron toxicity was researched through evaluating alaterations in antioxidant enzymes, oxidative stress biomarkers, and chlorophyll contents for two types of lentil species as red (native) and green (winter flake 11) lentil (Lens culinaris L.cv) cultivars, which are indigenous to Turkey. Ten days old seedling lentil plants were subjected to low as 0.5, 1.0 mM and high 2.0 and 5.0 mM boric acid treatments for 7 days. B worked as a growth-promoting nutrient for 0.5, 1.0, and 2.0 mM concentration by enhancing length and weight of both shoot and root tissues, while it started showed its suppression effect on these tissues at 5-mM cocentration, which were obtained more dramatic for green lentil in comparison to red lentil. In contrast to this, oxidative stress markers such as MDA, H₂O₂, and proline concentrations showed increasing trend for 0.5, 1.0, 2.0, and 5.0 mM B treatment, accompanied with a change in photosynthetic pigment concentrations (p < 0.01). MDA in red lentil shoot control was 30,3871 (μmol/gFW) and it was significantly increased to 36,5806 and 51,7414 by the 2.0 and 5.0 B rates, respectively. However, enzymes in anti-oxidation metabolism include superoxide dismutase (SOD), guaiacol peroxidase (GPX), lipoxygenase (LOX), glutathione peroxidase (GSH-Px) activities were obtained higher in high-B-treated groups, while decreased and stable activities were obtained for catalase (CAT) and ascorbate peroxidase (APX) enzymes. CAT and APX activities were higher than those were obtained for 2.0 and 5.0 mM B treatments in both root and shoot tissues. The lentil species manipulated their metabolism to suppress B-stress, and enhanced growth in shoot and root tissues up to 5-mM B stress even though oxidative stress markers showed increasing trend from low B concentrations, 1.0 mM. Therefore, B stress can be claimed as “doubled edge sword” for these lentil species.

Abbreviations

AOS, active oxygen species; APX, ascorbate peroxidase; CAT, catalase; DAB, diamino-benzidine tetrahydrochloride; DMSO, dimethyl sulfoxide DW, dry weight; EDTA, ethylenediamine-N,N,N₀,N₀-tetraacetic acid; FW, fresh weight GPX, guaiacol peroxidase; GSH-P_x, glutathione peroxidase; LOX, lipoxygenase; MDA, malondialdehyde; NBT, nitroblue tetrazolium; PEG, polyethylene glycol; ROS, reactive oxygen species; SOD, superoxide dismutase; H₂O_2, Hydrogen peroxide;     

Comparative response of poppy (Papaver somniferum L.) and eight crop and vegetable species to manganese excess in solution culture

The relative response of poppy (Papaver somniferum L.) and eight crop and vegetable species to excess manganese was investigated in a glasshouse, solution culture experiment. Plant yields and manganese concentrations were measured after two and six weeks growth at five levels of manganese (10–800 μM).

Poppies were highly sensitive to manganese toxicity in solution culture and reductions in shoot yield occurred at lower manganese levels in solution and at lower shoot manganese concentrations than that for the following sensitive species, ranked in order of increasing tolerance : brussels sprout, barley, green beans, lucerne and grean pea. In contrast lupins, oats and sugar beet were relatively tolerant producing about 80% or more of maximum shoot yield at the highest solution manganese level (800 μM Mn).

In this study the sensitivity of poppy, and brussels sprout, to manganese excess was attributed to their low shoot manganese “toxicity threshold values”; and their capacity to partition a high proportion of total plant manganese and dry matter to the shoot at solution manganese levels ≥ 100 μM.

The application of these results to field grown poppy is discussed in relation to interactions between manganese and other elements which modify plant tolerance to manganese excess.     

Manganese toxicity in bush bean as affected by concentration of manganese and iron in the nutrient solution

An experiment was conducted to clarify the relationship between Mn toxicity and Fe deficiency in bush snap bean (Phaseolus vulgaris L. cv. ‘Wonder Crop No. 2'). Seedlings were grown in full strength Hoagland No. 2 solution at pH 6.0 for ten days. Six concentrations of Mn as MnCl₂.4H₂O were used in combination with three concentrations of Fe as FeEDTA.

Toxicity symptoms, induced by low levels of Mn (0.1 ppm and above), included: small brown necrotic spots and veinal necrosis on primary leaves; necrosis on primary leaf petioles; interveinal chlorosis, with or without brown necrotic spots, on trifoliate leaves; and brown necrotic spots on stipules. Manganese toxicity symptoms were alleviated or prevented by increasing Fe concentration in the nutrient solution.

Manganese concentration in the leaves increased with increasing Mn and decreased with increasing Fe concentration in the nutrient solution, Iron concentration in the roots increased with increasing Fe concentration in the nutrient solution; however, Fe concentration in the leaves was not significantly affected by increasing Mn concentration in the solution culture. Manganese toxicity symptoms developed when Mn concentration in the leaves reached about 120 ppm.

A decrease in the Fe/Mn ratio in the nutrient solution resulted in a proportionate decrease in that of the leaves. Manganese toxicity symptoms occurred when the Fe/Mn ratio in the solution was 10.0 and below, or when the ratio in the leaves was less than 1.5. The ratio of Fe/Mn in the solution required for optimum growth of ‘Wonder Crop No. 2’ bean, without Mn toxicity symptoms, was in the range of 20.0 to 25.0.

Results indicate that the chlorosis on bush bean leaves induced by excessive Mn in the nutrient solution was due to excessive accumulation of Mn and not to Fe deficiency.     

Animal-based organic nutrition can substitute inorganic fertigation in soilless-grown grape tomato

Purpose: In recent years, interest in plant nutrition research has arisen with a strong focus on organic forms. The aim of this study was to determine the effect of different organic fertilizers on growth, yield, fruit quality and polyphenol content in soilless grown grape tomatoes under greenhouse conditions.

Materials and methods: Tomato plants were subjected to three organic nutrient solutions, which consisted of different mixtures of several OMRI (Organic Materials Review Institute) certified nitrogen fertilizers of industrially processed residues: Treatment I: solid and soluble liquid fertilizers of animal raw materials, natural potassium sulphate-non-synthetic, and calcium chloride; Treatment II: solid and soluble liquid fertilizers of animal raw materials, by-product of marine raw material (soluble liquid), natural potassium sulphate-non-synthetic, and calcium chloride; and Treatment III: solid fertilizers of animal raw materials, natural potassium sulphate-non-synthetic, and calcium chloride to 100% [0-30 days after transplanting (DAT)], 125% [31-80 DAT], and 150% [>81 DAT]. The Steiner solution (SS) was used as a control (Treatment IV).

Results: Yield did not differ between organic and conventional treatments, ranging from 3.04 to 3.35 kg m^-2 while fresh weight in organic treatments was 3.14 compared to 3.2 kg m^-2 in plants fed with the SS. No significant differences in plant height or fruit quality were found. The application of organic fertilizers positively affected the total hydrolysable and condensed polyphenols of tomato fruits compared to the control. Twelve phenolic compounds were identified, highlighting 3-Caffeoylquinic acid, salvianolic acid and 5,6-Dihydroxy-7,8,3’,4’-tetramethoxyflavone (Treatment I) and Medioresinol (Lignan) (Treatment II).

Conclusions: The results indicated that organic fertilization through animal-based fertilizer application is a feasible alternative for grape tomato production under greenhouse conditions.     

Grain yield increases in wheat and barley to nitrogen applied after transient waterlogging in the high rainfall cropping zone of western Australia

Nitrogen (N) is a major factor limiting grain production in the high rainfall zone (HRZ, 450–700 mm annual average rainfall of southwestern Australia (SWA). Transient waterlogging and leaching of applied N fertilizer are hazards faced in most years by crop producers. The major crops are wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), canola (Brassica napus L.) and lupin (Lupinus angustifiolius L.) grown in rotation. Two series of experiments involving, levels and timing of N fertilizer application and levels of plant population were done. The first series, in 2003–2004, consisted of 3 experiments in 3 growing seasons (early May to late-October) to measure the grain yield (GY) increase (response) of wheat and barley to various methods of N fertilizer application (methods of split N application were compared to N applied at sowing). The aim of the experiments was to determine the optimal N fertilizer application strategy for maximum GY and quality in situations where transient waterlogging was a frequent occurrence. The second series of four experiments, from 2007–2009, measured the GY of wheat sown at three levels of plant population to 4 levels of N applied after transient waterlogging (taken to be rainfall events in which >25 mm of rain was recorded in 24 to 48 hours).

Applying the N fertilizer after high rainfall and transient waterlogging (tactical N application) increased GY and protein percentage of grain compared to applying all of the N fertilizer at sowing. Where transient waterlogging was not frequent, applying the N after waterlogging was not always better than applying part of the N according to growth stage of the crop or according to fixed times after sowing. When the crop was water-logged three or more times, N uptake by the crop at anthesis and apparent fertilizer N recovery in the crop was substantially increased by applying the N after waterlogging compared to applying the entire N at sowing. This study found that a tactical N management strategy for the HRZ of SWA is to apply some N at sowing with subsequent applications made after heavy rainfall that leads to transient waterlogging. Split N fertilizer applied either according to time after sowing or to growth stage of the crop was equally effective for increasing GY in situations where waterlogging was less frequent.

The observation from these experiments, that grain yield increases due to splitting the N dose were associated with increases in ear numbers, lead to a further set of experiments where plant population was increased in conjunction with N applied after waterlogging events. The combined strategy of increased plant population with strategic N application decreased the amount of N required for maximum GY where more than 3 heavy rainfall events occurred in a growing season.

One practical outcome of this research is to indicate that farmers can withhold applications of N fertilizer after sowing in seasons when transient waterlogging does not occur.