Sown In Pots Research Articles

Biochemical properties of phytase immobilized and its effect on growth parameters of tomato

AbstractBackgroundPhosphorus (P) is one of the nonrenewable resources of critical importance in agricultural production. P is present in soil in organic and inorganic forms. Phytate constitutes the majority of organic P in soil. Phytate binds strongly to the solid phase of the soil and becomes unavailable for use by plants. Therefore, the soluble phytate‐P ratio in soil is mostly at very low levels. Plants and associated microorganisms secrete organic acids and hydrolyzing enzymes such as phytase to dissolve phytate in the soil. Both the solubility of phytate and phytase activity are limiting properties for the uptake of phytate‐P by plants.AimsOur aim was to evaluate the effects of phytase immobilized on zinc oxide nanoparticles (ZnO Np) on tomato plant (Solanum lycopersicum) growth parameters. In this study, seedling period was analyzed.MethodsIn the study, phytase activity of 13 different bacteria was investigated, and phytase was purified from Lactobacillus kefiri, showing the highest activity, and its biochemical properties were determined. Phytase was immobilized on zinc oxide (ZnO) nanoparticles and characterized by X‐ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopes analysis. The effects of ZnONps, immobilized phytase, and free phytase on the growth parameters of tomato plant were investigated. Tomato seeds were soaked with ZnONps, immobilized and free phytase for 30 min at room temperature and sown in pots containing suitable growing medium. Vegetative development of tomato plant, plant height, number of lateral branches, main stem diameter, distance between nodes, number of nodes, main root, and shoot length were determined.ResultsPhytase was partially purified with 7.60% recovery and specific activity of 1758.5 (EU mg−1 protein). Molecular mass of partially purified phytase was approx.72 kD, optimum pH and temperature values were determined as pH 5.0 and 70–80°C, respectively. Immobilized phytase caused a significant increase of 41.1% in plant height, 64.1% in main root, and 36.1% in shoot length in tomato plants compared to the control. In addition, a significant increase was observed in the number of side branches, main stem diameter, distance between nodes, number of nodes, and vegetative growth of the plant.ConclusionsThe results showed that the immobilized phytase enzyme has a positive effect on seedling growth in tomato and can be used in tomato cultivation in the future.

Biotechnological potential of growth-promoting bacteria in cotton (Gossypium hirsutum L.) crop

Studies involving plant growth-promoting bacteria are attracting increasing attention in the agricultural sector due to their potential to improve growth and production, and to protect plants from biotic and abiotic stresses. The present study aimed to evaluate the effects of three species of plant growth-promoting bacteria (Bacillus subtilis, Priestia megaterium, and Priestia aryabhattai) on the growth and morphological and biochemical aspects of Gossypium hirsutum L. (cotton) seedlings. The experiment was conducted in a greenhouse with four treatments (one control and three inoculations) and five replications per treatment. The seeds were inoculated by immersion in bacterial suspensions (109CFU/mL) and then sown in pots. The plants were monitored for 60 days. During collection, the plants were measured for the fresh mass of roots and shoots, the height of the shoots, stem diameter, and number of leaves. Leaf samples were collected and used for biochemical analyses. The results obtained showed that seeds treated with P. aryabhattaihad significant improvements in the parameters of fresh mass, plant height, stem diameter, and number of leaves, and in the contents of chlorophyll (a, b, and total), nitrogen, and proteins concerning plants in the control treatment. Plants treated with P. megaterium also achieved improvements in fresh mass, stem diameter, nitrogen, and protein contents. These results indicate the potential of these plant growth-promoting bacteria for use in cotton crops and can be employed in the preparation of biostimulants and biofertilizers.

Free amino acid profiling and quantification of 4-hydroxyisoleucine in Trigonella foenum-graecum (fenugreek) seeds treated with Trichoderma viride and rhizobium

Fenugreek is a legume but regarded as a poor nitrogen fixer. The present study deals with the marked effect of Trichoderma viride and rhizobium on quantification of 4-hydroxyisoleucine content and free amino acid composition of fenugreek seeds. 4-hydroxyisoleucine is regarded as an antidiabetic compound present specifically in fenugreek plants. Fenugreek seeds treated with both T.viride and rhizobium boosted free amino acid concentration and 4-hydroxyisoleucine content compared to control and positive control (NPK treated). Seeds were treated with T.viride suspension (107 spores/seed), rhizobium suspension (108 cells/seed) , combination of T.viride and rhizobium suspension in equal amounts (0.5ml of T.viride  0.5ml of rhizobium suspension /seed), NPK suspension ( 1ml NPK suspension / seed) and untreated seeds (1 ml distilled water/ seed) serving as control sown in pots filled with potting soil and also in a randomized plot ( 55 feet) in the field. In free amino acid composition, isoleucine is the precursor for 4-hydroxyisoleucine compound and its concentration was enhanced by 47.79 % (potted plants) and 26.46 % (field plants) over control and by 27.02 % (potted plants) and 13.03 % (field plants) over positive control. 4-hydroxyisoleucine content was quantified using LCMS method in both potted and field plants. An increase of 37.02 % (potted plants) and 23.61 % (field plants) in 4-hydroxyisoleucine concentration in dual treated plants over control and positive control was observed.

Synergic mitigation of saline-alkaline stress in wheat plant by silicon and Enterobacter sp. FN0603.

Although microorganisms and silicon are well documented as factors that mitigate salt stress, their effect mitigating saline-alkaline stress in plants remains unknown. In this study, wheat plant seeds were treated with silicon, Enterobacter sp. FN0603 alone and in combination of both. Wheat seeds were soaked in silicon and bacterial solutions and sown in pots containing artificial saline-alkaline soils to compare the effects among all treatments. The results showed that the treatments with silicon and FN0603 alone significantly changed plant morphology, enhanced the rhizosphere soil nutrient content and enzyme activities, improved some important antioxidant enzyme activities (e.g., superoxide dismutase) and the contents of small molecules (e.g., proline) that affected osmotic conditions in the top second leaves. However, treatment with silicon and FN0603 in combination significantly further increased these stress tolerance indexes and eventually promoted the plant growth dramatically compared to the treatments with silicon or FN0603 alone (p < 0.01), indicating a synergic plant growth-promoting effect. High relative abundance of strain FN0603 was detected in the treated plants roots, and silicon further improved the colonization of FN0603 in stressed wheat roots. Strain FN0603 particularly when present in combination with silicon changed the root endophytic bacterial and fungal communities rather than the rhizosphere communities. Bipartite network analysis, variation partitioning analysis and structure equation model further showed that strain FN0603 indirectly shaped root endophytic bacterial and fungal communities and improved plant physiology, rhizosphere soil properties and plant growth through significantly and positively directing FN0603-specific biomarkers (p < 0.05). This synergetic effect of silicon and plant growth-promoting microorganism in the mitigation of saline-alkaline stress in plants via shaping root endophyte community may provide a promising approach for sustainable agriculture in saline-alkaline soils.

Attenuating the toxicity of isoproturon to maize by priming in ascorbate, glutathione or thiourea

Maize grains were primed in ascorbate (AsA), glutathione (GSH) or thiourea (TU) for 24 h, sown in pots for 10 days and then treated with Ipu whose residues persisted in shoots from the next day and increased over 8 days and then decreased continuously. The herbicide significantly reduced growth parameters, pigments, photosynthetic activity parameters, AsA, GSH and GSH/oxidized glutathione (GSSG) ratio and inhibited the activities of δ-aminolevulinate dehydratase (ALA-D), ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), phosphoenolpyruvate carboxylase (PEP-C), malate dehydrogenase (MDH), pyruvate phosphate dikinase (PPDK), superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) but significantly increased malondialdehyde (MDA), H 2 O 2 , superoxide radicals (O 2 ∙−) and GSSG. The priming mostly improved the tested parameters and overcame the deficiency in enzymatic and non-enzymatic antioxidants as well as in the photosynthetic parameters and enzyme activities; AsA or GSH were more efficient than TU. Besides, in vitro tests showed that the inhibition constant (IC50) for Ipu was lowest for CAT but highest for PPDK indicating that CAT was the most inhibited but PPDK was the least while the others were moderate. Furthermore, calculations showed that Ipu competitively inhibited ALA-D, Rubisco, APX, PEP-C, MDH and PPDK but caused non-competitive inhibition of APX, CAT and SOD. These findings reveal that maize was prone to suffering from Ipu; however, priming attenuated the toxicity of Ipu and overcame the herbicide impacts by repairing, maintaining and improving antioxidants and photosynthetic activities .

Effect of Parental Components and Pollination Frequency on the Setting and Germination of Chrysanthemum Seeds

The chrysanthemum is one of the most economically important ornamental plants in the Asteraceae family. Unfortunately, the efficacy of breeding through the traditional crossing in this species is highly limited due to inefficient seed setting. Therefore, this study aimed to investigate the effect of parental components and crossing frequency on the set and germination of chrysanthemum seeds. For this purpose, seven chrysanthemum cultivars were used as parental components in 10 crossing combinations. The crossing was performed either once or twice a week, for three successive weeks, starting from November. Next, the obtained chrysanthemum seeds were collected, sown in pots in a greenhouse, and seedling growth was observed. The efficacy of the seed set, germination rate, and plant development was evaluated. The plants of the F1 generation were brought to flowering and evaluated phenotypically in the three successive vegetative propagation cycles. Both the arrangement of parental components and pollination frequency affected the production of seeds. More seeds were obtained if pollination was performed twice a week and if the ‘Wda’ cultivar was used as the maternal component. Approximately 50–100% of the seeds were able to germinate in the greenhouse, depending on the parental components, which also affected the developmental pace of the seedlings. Nearly all of the seedlings (80–100%) developed into properly growing plants. Out of 10 parental combinations tested, 7 produced the F1 offspring. The obtained plants varied in the shape, size, and color of their flowers. A total of eight new phenotypes were found, among which six new cultivars granted plant breeders’ rights, so far. The present research expands knowledge on how effective crossing should be performed.

Phytochemical and Nutritional Composition of Three Varieties of Cowpea (Vigna Unguiculata) Pre-Treated with Salicylic Acid Under Arsenic Stress

Abiotic stress is one of the major factors limiting production and utilization of cowpea in developing nation of the world. Salicylic acid serve to promote and regulate plant growth. The work was design to examine the impacts of Salicylic acid on phytochemicals and nutritional composition of cowpea under arsenic stress. Three varieties of clean seeds of cowpea each were soaked in 0,75 and 150mg/L of salicylic acid for five hours. They were air-dried and sown in pots of soil containing 0, 250 and 500mg/L of sodium arsenate in a completely randomized design and were replicated thrice. The seeds were harvested at maturity and analyzed for phytochemical composition (total phenolic and flavonoid), Proximate composition (Crude protein, fat, ash, moisture, crude fibre and carbohydrate) and elemental composition (As, Ca, K, P, Mo, Mg and Zn). Data were analysed using ANOVA at α0.05. By comparing treatments with the control, crude protein, fat, phosphorus, calcium, magnesium and molybdenum were by increased by 2 folds among the three cultivars, total phenolic, flavonoid were increased by 4 and 2 folds in ART98-12, 5 and 3 folds in Ife brown and ITOK-568-18 in 250mg/L sodium arsenate-treated soil with SA (150mg/L). The result shows that 150mg/L of salicylic acid could be appropriate concentration to alleviate arsenic stress in cowpea .

Silicon Seed Priming Combined with Foliar Spray of Sulfur Regulates Photosynthetic and Antioxidant Systems to Confer Drought Tolerance in Maize (Zea mays L.)

The present study evaluated the effect of silicon (Si) seed priming and sulfur (S) foliar spray on drought tolerance of two contrasting maize hybrids viz. drought tolerant Hi-Corn 11 and susceptible P-1574. The maize seeds were primed with (3 mM Na2SiO3) or without Si (hydropriming) and later sown in pots filled with sandy loam soil. Drought stress (25–30% water holding capacity or WHC) was initiated at cob development stage (V5) for two weeks, whereas the well-watered plants were grown at 65–70% WHC. On appearance of drought symptoms, foliar spray of S was done using 0.5% and 1.0% (NH4)2SO4, whereas water spray was used as a control. The drought-stressed plants were grown for further two weeks at 25–30% WHC before the final harvest. The results showed a marked effect of Si seed priming and foliar S spray on biomass, physiological and enzymatic processes as well as macronutrient concentrations of maize. In comparison to control, the highest increase in leaf relative water content (25%), chlorophyll a content (56%), carotenoids (26%), photosynthetic rate (64%), stomatal conductance (56%) and intercellular CO2 concentration (48%) was observed by Si seed priming + S foliar spray (Si + S) under water deficit conditions. Also, Si + S application stimulated the activity of catalase (45%), guaiacol peroxidase (38%) and superoxide dismutase (55%), and improved NPK concentrations (40–63%) under water limitations. Our results suggest that Si seed priming + foliar spray of S is more effective than the individual application of these nutrients to enhance drought tolerance in maize.

Enhancement of 4-Hydroxyisoleucine Content of Trigonella Foenum-Graecum (Fenugreek) by Trichoderma viride

Trigonella foenum- graecum (fenugreek) is a leguminous plant with poor nitrogen fixing ability. The current study deals with the effects of T.viride on growth, yield and 4-hydroxyisoleucine content in fenugreek. 4-hydroxyisoleucine is an antidiabetic compound present only in plants particularly in fenugreek. Treatment of fenugreek seeds with T.viride enhanced the growth, yield and 4-hydroxyisoleucine content significantly compared to control. Seeds were treated with T.viride suspension (107spores/seed) and untreated seeds (1 ml distilled water/ seed) served as control sown in pots filled with potting soil. Several growth parameters like root length and lateral root expansion, shoot length, yield, chlorophyll and nitrogen were estimated. 4-hydroxyisoleucine content in fenugreek seeds was estimated by ninhydrin method. A significant increase of 25 % in root length and 128 % in lateral root expansion and 50 % in shoot length was observed in treated plants over control. The total yield increased by 95 % in treated one. The total chlorophyll content exceeded by 21.86 % and total plant nitrogen by 121.73 %. An increase of 27 % of 4-hydroxyisoleucine content is observed in treated fenugreek plants over control.

English

Fungi in the genus Trichoderma are widely used as biological control agents because they can suppress plant pathogens and activate plant defense systems. In the present study, efficacy of microbial antagonists viz., T. harzianum and T. viride or their combination was evaluated against the pathogenic fungus Macrophomina phaseolina and their effect on enzymatic activities and phenol content of soybean [Glycine max (L.) Merr.] plants. Soybean seeds were inoculated with T. harzianum and T. viride separately or in combination, and sown in pots under green house and under field conditions. Host enzymatic activities and phenol levels were measured at 14, 28 and 42 days after sowing (DAS) in both field and greenhouse experiments. Seed treatments with T. harzianum, T. viride or their combination increased peroxidase, polyphenol oxidase and β-1, 3-glucanase activities, and also the total phenol content in soybean leaves as compared to a non-treated control treatment. Concentration of peroxidase and β-1, 3-glucanasepeaked at 14 DAS and decreased thereafter in all the treatments under greenhouse and field conditions. All the treatments showed the highest levels of total phenols and polyphenol-oxidase at 28 DAS under both greenhouse and field conditions. At 14 DAS in both trials, the combination of T. viride + T. harzianum resulted in the highest level of peroxidase and β-1, 3-glucanase activities. This combination also resulted in the highest levels of total phenols and polyphenol oxidase content at 28 DAS. Our findings demonstrated that application of Trichoderma species as seed treatment has potential to trigger key mechanisms of systemically acquired resistance in soybean, and thereby enhanced efficacy of disease management tactics. © 2021 Friends Science Publishers

English

The menadione sodium bisulphite (MSB) is hydrophilic and has been suggested a defensive molecule against different biotic and abiotic stresses. Cadmium (Cd) is a highly mobile element and even its minute amount causes toxicity in different organisms including plants. This experiment was conducted to elucidate whether seed priming with MSB could induce Cd tolerance in summer squash. The seed were primed with 0, 10 and 20 mM MSB and sown in pots filled with clean and dried sand saturated with Hoagland’s nutrients solution supplemented with different Cd concentrations (0 and 0.1 mM). The Cd stress reduced growth and contents of chlorophyll (Chl), osmoprotectants (soluble sugars, free amino acids, soluble proteins) and yield while increased oxidants such as hydrogen peroxide (H2O2) and malondialdehyde (MDA) and secondary metabolites (total phenolics and flavonoids). The Cd stress increased root and shoot Fe (4−18%, respectively) and Ca2+ (24−93%, respectively) concentration while decreased root and shoot Mg2+ concentration (31−39%, respectively). The summer squash transported Cd to shoot and compartmentalized it in the cells to avoid Cd toxicity. However, the plants raised from seed primed with MSB had higher contents of photosynthetic pigments (17−23% total Chl), secondary metabolites and osmoprotectants when grown under Cd stress. Further, MSB-priming attenuated the toxicity of Cd on nutrients acquisition and increased growth and yield in the summer squash. The MSB-priming reduced Cd uptake (84%) and also altered Cd compartmentalization at sub-cellular level, and mediated its accumulation in the cell wall and soluble fraction (vacuole) rather than in the chloroplasts and cell membranes. Overall, MSB-priming (10 mM) was much more effective and increased growth and yield of summer squash under Cd stress. © 2021 Friends Science Publishers

Effect of sodium azide on Bambara groundnut (Vigna subterranean (L.) verdc.) as revealed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (sds-page)

This study investigated the mutagenic effects of Sodium Azide (NaN3) on the agromorphological and protein content of eight Bambara groundnut genotypes. The seeds of six genotypes; TVSu-86, TVSu-91, TVSu-186, TVSu-235, TVSu-242, TVSu-350 were collected fromthe International Institute of Tropical Agriculture (IITA) and two landraces from Abia State and Enugu State North East, Nigeria local markets. The seeds were treated with five concentrations: 0.00%(control), 0.01%, 0.03%, 0.05% and 0.07% of NaN3 after pre-soakingfor 6hrs in distilled water and sown in pots arranged in a Complete Randomized Design with three replicates. There was reduction in germination percentage and growth characters as concentrations of NaN3 increases. Early flowering was recorded at 37 days mutated with 0.07% of NaN3 compared to control which flowered late at 42 days. NaN3 (0.07%) caused lethal effect on Abia and Enugu landraces. There was no significant (P&gt;0.05) difference in yield traits among mutants and control. Mutant seeds significantly (P&lt;0.05) increased protein content (19.12%) at 0.05% of NaN3 compared to control (18.5%). The number of seeds (0.99), seed yield (0.89) and pod yield (0.96) strongly correlated with seeds per pod (0.85). The SDS-PAGE revealed the presence of polypeptide bands in mutants compared to control. TVSu-235 and TVSu-350 genotypes had higher tolerance and yield traits to 0.01% concentration of NaN3, thuscould be further improved in subsequent breeding.&#x0D; Keywords: Bambara groundnut, Sodium azide, SDS-PAGE, polypeptide bands.

Enhancement of physiological and biochemical attributes of okra by application of salicylic acid under drought stress

Horticultural crops especially vegetables are most vulnerable to drought due to their higher irrigation needs. Hence, this study was undertaken to evaluate the adverse effects of drought stress and the beneficial effects of salicylic acid (SA) on physiological and biochemical attributes of okra plants under drought stress. For this purpose, a pot experiment was laid out in Complete Randomized Design (CRD) design. Okra seeds were primed with four different SA treatments i.e., 0 (control), 1, 2 and 3 mM and sown in pots (Ø 20 cm). After 14 days of germination, the plants were subjected to two drought levels i.e., 25% and 50% field capacity (FC) and after 20 days of germination regular foliar sprays of SA at 7 days interval were performed with aforementioned SA levels. Physiological parameters like fresh weight, dry weight, and length of plants along with biochemical attributes like chlorophyll (‘a’, ‘b’ and total), total carotenoids, total protein and proline contents, and electrolyte leakage were recorded. Results revealed that drought stress (25% FC) significantly reduced all the studied parameters and resulted in the lowest values of fresh weight (5.04 g), dry weight (1.33 g), length of plants (11.68 cm), chlorophyll ‘a’ content (5.97 mg/g FW), chlorophyll ‘b’ content (8.86 mg/g FW), total chlorophyll (14.84 mg/g FW), total carotenoids (4.96 mg/g FW) and total protein (1.05 mg/g FW), except proline content (6.81 mg/g FW) and electrolyte leakage (77.31%) which was increased. Application of SA under drought stress reduced the harmful effects of drought and application of 2 mM SA produced the maximum fresh weight (8.60 g), dry weight (2.51 g), length of plants (16.23 cm), chlorophyll ‘b’ content (14.47 mg/g FW), total protein (3.73 mg/g FW) and proline content (5.11 mg/g FW); whereas application of 3 mM SA showed the highest values of chlorophyll ‘a’ (8.91 mg/g FW), total chlorophyll content (23.20 mg/g FW) and carotenoids (7.93 mg/g FW), and the lowest value for electrolyte leakage (62.00%).

Integration of Seed Priming and Biochar Application Improves Drought Tolerance in Cowpea

Cowpea is a highly nutritious grain legume crop, cultivated mostly in a semi-arid environment and frequently confronts sporadic dry periods during different stages of plant growth, which drastically reduce its productivity. The current study was enacted to evaluate the biochar application and seed priming induced drought tolerance in cowpea. The seeds of cowpea were primed with CaCl2 (1% solution), water (hydropriming) (positive control), and dry seeds (absolute control), sown in pots with and without mango wood biochar. The water holding capacity (WHC) in well-watered and drought-stressed pots was maintained at 70% and 35%, respectively. Drought stress caused a delay in germination and reduced plant growth. Osmopriming enhanced seed germination, seedling growth, dry biomass production, chlorophyll contents, leaf area, soluble sugar contents, CO2 assimilation, water use efficiency (WUE), and leaf K+ concentration and inhibited the oxidative damage in cowpea under drought. The addition of biochar was effectively recuperated by the drought-induced growth reduction in cowpea. Osmopriming + biochar application increased the biomass production (115%), α-amylase activity (81%), chlorophyll contents (76%), total soluble sugars (60%), WUE (95%), leaf osmotic potential (25%), and leaf sap K + concentration (25%), and decreased the MDA content and total antioxidant activity by 34 and 28%, respectively, than non-primed control without biochar application under drought. Osmopriming supplemented with biochar amendment augmented the performance of cowpea under normal and water-deficit conditions through synchronized seedling emergence and better growth, chlorophyll synthesis, CO2 assimilation, osmolyte accumulation, and nutrient uptake with minimal oxidative damage, which lead to better cowpea performance in drought stress condition. Osmopriming and biochar application may prove effective in improving cowpea performance under changing climate.

Effect of seed priming on growth, flowering and cut flower quality of carnation

Carnation is one of the most important commercially grown flowers in the world. It has wide variations inshape and colours as well as good keeping quality. The present experiment was conducted to study the effectsof seed priming through various chemicals such as salicylic acid, glycine betaine, potassium nitrate, ascorbicacid and hydropriming on growth and floral quality attributes of carnation. The seeds were pre-treated withdifferent priming agents (salicylic acid 100 mg/L, glycine betaine 1536 mg/L, potassium nitrate 10 g/L, ascorbicacid 50 mg/L, and water) for 24 hours and then sown in clay pots. Seeds without treatment were served ascontrol. Sowing was done on 21-10-2014 during year 1 and on 20-10-15 during year 2. Seeds were sown inpots and after two months of sowing, seedlings were transplanted into clay pots till flowering. Hydropriming(water treatment) resulted in the maximum seed germination (43.04%) and took minimum days to initiate firstflower bud (87 days). Salicylic acid treated seeds resulted in the plants with delayed flower bud initiation andhad maximum flower stalk length (3.08 cm), root length (21.89 cm), fresh weight of foliage (54.35 g), dry weightof foliage (16.66 g), fresh weight of roots (3.97 g), dry weight of roots (1.64 g), total biomass per plant (52.84g), and longer length of growth cycle (177.5 days). Potassium nitrate treatment showed the maximum freshweight per flower (4.24 g), dry weight per flower (0.95 g) and flower stalk diameter (10.44 mm). The minimumfresh and dry weights per flower were recorded (2.750, 68 g respectively) in unprimed seeds.

Burkholderia phytofirmans PsJN and tree twigs derived biochar together retrieved Pb-induced growth, physiological and biochemical disturbances by minimizing its uptake and translocation in mung bean (Vigna radiata L.)

Anthropogenic activities like industrial mining, refining and smelting release substantial amounts of lead (Pb) into the soil causing potential ecological menaces to environment, soil productivity and food security. Present pot scale study was undertaken to investigate the effects of tree twigs-derived biochar and a bacterium Burkholderia phytofirmans PsJN on Pb accumulation, growth, physiological, biochemical and antioxidative defense responses of mung bean grown in Pb spiked soil. The original soil was spiked with Pb (600 mg kg−1) and amended with biochar (1% w/w). Upon screening in laboratory, B. phytofirmans PsJN exhibited high Pb tolerance and was able to grow at high Pb concentrations. Surface-disinfected seeds of mung bean were inoculated with B. phytofirmans PsJN and sown in pots along with un-inoculated seeds. Data were collected for various growth, physiological and biochemical parameters from fully matured harvested plants. Application of biochar and B. phytofirmans PsJN ameliorated Pb induced negative impacts in mung bean both individually and in combination, but better growth, physiological and seed quality responses were observed with their combined use. Compared with respective controls, their combined use increased the following parameters in normal and Pb spiked soils, respectively: plant height (69% and 159%), root dry weight (97% and 130%), shoot dry weight (42% and 104%), number of pods (70% and 210%), grains weight (58% and 194%) and number of root nodules (71% and 255%). Moreover, combined use increased chlorophyll contents (27% and 37%), photosynthetic rate (93% and 204%), transpiration rate (42% and 132%), stomatal conductance (70% and 218%), sub-stomatal conductance (93% and 148%) and water use efficiency (35% and 43%). In addition, combined application of biochar and B. phytofirmans PsJN retarded Pb-induced oxidative stress by intensifying antioxidant enzyme activities and reducing activities of reactive oxygen species. Similarly, considerable reduction in Pb uptake, translocation and bioaccumulation in mung bean was noticed in Pb spiked soil due to applied amendments. Furthermore, their combined use resulted in considerable increase in grain quality parameters (protein, fat, ash) both in normal and Pb-spiked soils. Therefore, it can be inferred that interactive use of biochar and B. phytofirmans PsJN provides an efficient innovative strategy to repossess Pb induced growth, physiological, biochemical and oxidative disturbances in mung bean.

Are Cowpea-Nodulating Bradyrhizobial Communities Influenced by Biochar Amendments in Soils? Genetic Diversity and Symbiotic Effectiveness Assessment of Two Agricultural Soils of Brazilian Drylands

The objective of this study was to evaluate the influence of biochar amendment on the bacterial genetic diversity and symbiosis in cowpea-nodulating rhizobial communities in two agricultural soils of Brazilian drylands. Vertisol and Ultisol surface layer soil samples were collected in the Brazilian semiarid region. The soils were mixed with biochar and cowpea seeds (BRS Marataoa) and sown in pots. Forty-five days after plant emergence, the nodule bacteria were isolated. The genetic variability of the nodule bacteria was evaluated by means of restriction fragment length polymorphism of 16S-23S rRNA intergenic spacer region (IGS-RFLP), and those that shared identical IGS-RFLP profiles were fingerprinted by BOX-PCR. By selecting of representative isolates in the genetic clusters, 27 bacteria were identified by 16S-23S IGS sequencing and symbiotically assessed. The IGS-RFLP dendrogram of the 73 isolates had 20 clusters; the multivariate correspondence analysis grouped both Vertisol treatments, and the Ultisol treatments were placed far away in the biplot. Ultisol showed higher bradyrhizobial diversity than the Vertisol. The fingerprinting indicated the presence of only three clonal colonies, showing high intraspecific diversity. The 16S-23S IGS sequences indicated the prevalence of bacteria related to Bradyrhizobium guangxiense in the Vertisol and Bradyrhizobium zhanjiangense in the Ultisol, in addition to the presence of three putative Microvirga spp. in the Ultisol. The symbiotic efficiency of 22 out of 27 bacteria was comparable with that of the inoculant strain Bradyrhizobium yuanmingense BR 3267. The genetic diversity of the cowpea-nodulating bradyrhizobia was not primarily affected by the biochar application in two agricultural soils of Brazilian drylands. Both soils harbored symbiotically efficient bacteria, without the influence of biochar amendment .

Efecto de herbicidas pre-emergentes sobre la siembra directa de semillas pregerminadas de Gmelina arborea Roxb. y Gliricidia sepium (Jacq.) Kunth ex Walp. para el establecimiento de plantaciones dendroenergéticas

This study addresses the need to find preemergence herbicides for the direct sowing of seeds of forest species dedicated to the establishment of energy plantations. Twelve different preemergence herbicides were evaluated on the direct sowing of two forest species with great potential for biomass production for bioenergy. One of the limiting aspects of the plantations energy is the high cost of establishment by concept of acquisition of plants, so we looked for the best options for direct sowing of pregerminated seeds of Gmelina arborea (Melina) and Gliricidia sepium (Black Madero), and offer an alternative in lowering costs. The experiment was carried out in a greenhouse (ITCR, Cartago), for 10 weeks, analyzing each species separately. A randomized complete block experimental design was used. The seeds were subjected to the best pre germination treatment and sown in pots, they were immediately atomized by the different pre-emergent herbicides following the protocol described in the methodology. At the end of the experiment it was determined that pre-emergent herbicides with the active ingredient of Linuron and Oxyfluorfen can be used in the direct sowing of Melina, as they did not cause damage to plant yields, in addition to obtaining most of the parameters with statistically superior results. In the case of black Madero the pre-emergent Linuron obtained the best results, concluding that it can be useful for use in direct sowing. The pre-emergent herbicide with the active ingredient of Pendimethalin obtained the lowest yield results in almost all the parameters analyzed; For both species it produced the total death of the weeds before week 7.

Response of Cratylia argentea (Desvaux) O. Kuntzeto inoculation with Rhizobium sp. and Bradyrhizobium sp. strains

'Cratylia argentea' is a neotropical leguminous shrub that exhibits symbiosis with nitrogen (N) fixing bacteria and high levels of protein. Thus, it has potential for animal feed and green manure. In spite of its potential, few cultivars are registered for the species and there is little information in regard to its interaction with N-fixing microorganisms. The aim of this study was to evaluate the effect of inoculation with rhizobium strains on the growth and concentration of N in 'Cratylia argentea'. Seeds were inoculated with two strains of 'Rhizobium' sp.,CR 33 (BR10243) and CR42 (BR10244), and four strains of 'Bradyrhizobium' sp., CR52 (BR10257), CPAC-B10, SEMIA 6464 (BR3262), and SEMIA 6462 (BR3267), and sown in pots filled with sand and vermiculite in a greenhouse. After 150 days we evaluated the number of nodules, shoot and nodules dry matter, total nitrogen and crude protein contents for the shoots. The plants inoculated with CR 52 exhibited nodulation, with nodular efficiency of 0.189 and relative efficiency of 66.14%; it is possible to observe the effect of nodulation as of 85 days after sowing. Based on the obtained results it was identified the strain that showed symbiosis with 'C. argentea' and presents potential to be used as a commercial inoculant.

Effects of the inoculations using bacteria producing ACC deaminase on ethylene metabolism and growth of wheat grown under different soil water contents

Crop growth and productivity are often impacted by the increased ethylene content induced by adverse environmental conditions such drought. Inoculations with bacteria producing ACC deaminase is considered as a potential biological approach to improve the growth and tolerance of stressed plants by lowering endogenous ethylene level. In this study, germinated wheat seeds were inoculated using three species of the rhizobacteria, which were isolated from the rhizosphere of wheat growing in dryland, and sown in pots. After three weeks, wheat seedlings were exposed to non-limiting water condition, medium drought and severe drought, respectively, for six weeks. The results showed that, irrespective of rhizobacterial inoculations, decreased soil water contents stimulated wheat ethylene metabolism, which was reflected by the significantly increased activity of ACC synthetase and ACC oxidase, besides an increased content of ACC both in the roots and leaves, and an enhanced capacity of leaves to release ethylene, concomitant with a significant decline in shoot and roots biomass. The inoculations of all three rhizobacterial species under each water condition reduced ACC content in wheat leaves, but effects of the inoculations on ACC synthase and ACC oxidase activity in the leaves and roots, ACC content in the roots, the capacity of leaves to release ethylene, and wheat growth varied with water conditions and bacterial species. Hence, both soil water conditions and rhizobacterial inoculations acted on all the processes of ethylene metabolism, with the former being dominant. The inoculations under non-limiting water condition and medium drought promoted shoot and root growth of wheat plants.