Increased Shoot Dry Weight Research Articles

Seed inoculation with Pseudomonas fluorescens and Pseudomonas syringae enhanced maize growth in a compacted saline-sodic soil

Abiotic stresses like salt stress and soil compaction are responsible for increased ethylene production which may adversely affect crop growth. A field experiment was conducted to evaluate the response of seed inoculation with ACC-deaminase containing rhizobacteria (<i>Pseudomonas fluorescens</i> and <i>Pseudomonas syringae</i>) in the presence of recommended or half of a recommended rate of inorganic fertilizers at different growth stages of fodder maize in a compacted saline-sodic soil. At both fertilizer rates, seed inoculation with <i>P. fluorescens</i> and <i>P. syringae</i> significantly improved all growth parameters over the control treatment. After 30, 60 and 75 days of sowing, treatment with recommended NPK + <i>P. fluorescens</i> produced a statistically maximum increase in root length, shoot length, root fresh weight and shoot fresh weight in comparison to the control and recommended NPK only. As compared to recommended NPK only, seed inoculation with <i>P. syringae</i> + recommended NPK increased root dry weight by 4.1, 1.7 and 2.2 folds after 30, 60 and 75 days from sowing, respectively. Similarly, over the recommended NPK only, the recommended NPK + <i>P. fluorescens</i> increased shoot dry weight by 1.9, 1.5 and 1.9 folds after 30, 60 and 75 days from sowing, respectively. Conclusively, seed inoculation with <i>P. fluorescens</i> and <i>P. syringae</i> enhanced maize growth in a compacted saline-sodic soil.

Contribution of Zinc Solubilizing Bacteria in Growth Promotion and Zinc Content of Wheat.

Zinc is an imperative micronutrient required for optimum plant growth. Zinc solubilizing bacteria are potential alternatives for zinc supplementation and convert applied inorganic zinc to available forms. This study was conducted to screen zinc solubilizing rhizobacteria isolated from wheat and sugarcane, and to analyze their effect on wheat growth and development. Fourteen exo-polysaccharides producing bacterial isolates of wheat were identified and characterized biochemically as well as on the basis of 16S rRNA gene sequences. Along these, 10 identified sugarcane isolates were also screened for zinc solubilizing ability on five different insoluble zinc sources. Out of 24, five strains, i.e., EPS 1 (Pseudomonas fragi), EPS 6 (Pantoea dispersa), EPS 13 (Pantoea agglomerans), PBS 2 (E. cloacae) and LHRW1 (Rhizobium sp.) were selected (based on their zinc solubilizing and PGP activities) for pot scale plant experiments. ZnCO3 was used as zinc source and wheat seedlings were inoculated with these five strains, individually, to assess their effect on plant growth and development. The effect on plants was analyzed based on growth parameters and quantifying zinc content of shoot, root and grains using atomic absorption spectroscopy. Plant experiment was performed in two sets. For first set of plant experiments (harvested after 1 month), maximum shoot and root dry weights and shoot lengths were noted for the plants inoculated with Rhizobium sp. (LHRW1) while E. cloacae (PBS 2) increased both shoot and root lengths. Highest zinc content was found in shoots of E. cloacae (PBS 2) and in roots of P. agglomerans (EPS 13) followed by zinc supplemented control. For second set of plant experiment, when plants were harvested after three months, Pantoea dispersa (EPS 6), P. agglomerans (EPS 13) and E. cloacae (PBS 2) significantly increased shoot dry weights. However, significant increase in root dry weights and maximum zinc content was recorded for Pseudomonas fragi (EPS 1) inoculated plants, isolated from wheat rhizosphere. While maximum zinc content for roots was quantified in the control plants indicating the plant's inability to transport zinc to grains, supporting accelerated bioavailability of zinc to plant grains with zinc solubilizing rhizobacteria.

Genetic regulation of growth and nutrient content under phosphorus deficiency in the wild barley introgression library S42IL

AbstractPhosphorus (P) is an important macronutrient required for plant growth and yield formation. Since decades, breeders aim to optimize P efficiency in crops. We studied a set of 47 wild barley (Hordeum vulgare ssp. spontaneum, Hsp) introgression lines (ILs) in hydroponic culture to identify quantitative trait loci (QTLs) improving growth and nutrient content under P deficiency. Applying a mixed model analysis, a total of 91 independent QTLs were located among 39 ILs, of which 64 QTLs displayed trait‐improving Hsp effects. For example, an unknown Hsp allele on barley chromosome 4H increased shoot dry weight under P deficiency in three overlapping ILs by 25.9%. Likewise, an Hsp allele on barley chromosome 6H increased root dry weight under P deficiency in two overlapping ILs by 27.6%. In total, 31 QTLs confirmed Hsp effects already identified in previous field and glasshouse experiments with the same ILs. We conclude that wild barley contains numerous trait‐improving QTL alleles, which are active under P deficiency. In future, the underlying genes can be subjected to cloning and, simultaneously, used in elite barley breeding.

Evaluation of Shubhodoya Mycorrhizal Bio-fertilizer for Enhancing Rooting of Nursery Tea Plants.

Bio-fertilizers have not been exploited in Kenya on tea production despite benefits demonstrated in many crops. The bio-fertilizers are organisms that enrich nutrient soil quality. Plants have beneficial relationships with such organisms. Shubhodoya mycorrhizal bio-fertilizer is a consortium of three different species of Glomus mycorrhizal fungus, produced in laboratory under sterile conditions. They are cultured and used for inoculating seed or soil or both under ideal conditions to increase availability of plant nutrients. A nursery experiment was conducted to evaluate the efficacy of Shubhodaya mycorrhizal bio-fertilizer (SMB) in enhancing growth of two tea clones, TRFK 306 and EPK TN14-3. Different rates of SMB (0.6g, 0.9g, and 1.2g), standard treatment (6g diammonium phosphate) and control (no fertilizer) were laid out in randomized complete block design. Sleeved seedlings with the soil were randomly sampled from the nursery for analysis of soil pH, assessment of growth parameters and mycorrhizal colonization were conducted. Root samples were used to determine dry weight and to conduct assays for VAM infection. The SMB did not have adverse effects on soil pH in the nursery. Plants subjected to the DAP treatment all died after weeks 27. Increasing application of SMB rates and frequency increased shoot growth. SMB at 1.2 g exhibited the lowest shoots dry weight while SMB at 0.6 and 0.9g had the highest. After 62 weeks from planting, there was an abrupt increase in shoot dry weight. Successful colonization of tea roots with inoculation of SMB was also observed. SMB colonized the tea roots an indication that it has potential for exploitation.

Effects of Plant Growth-Promoting Rhizobacteria and N Source on Plant Growth and N and P Uptake by Tomato Grown on Calcareous Soils

Introducing specific microorganisms into the soil ecological system is an important strategy for improving nutrient use efficiency. Two pot experiments were conducted in the greenhouse from December 3, 2012 to January 25, 2013 (Experiment 1) and March 11 to April 23, 2013 (Experiment 2) to evaluate the effect of nitrogen (N) source and inoculation with plant growth-promoting rhizobacteria (PGPR) on plant growth and N and phosphorus (P) uptake in tomato (Lycopersicon esculentum Mill.) grown on calcareous soils from South Florida, USA. Treatments included urea, controlled release urea (a controlled release fertilizer, CRF) each at low and high N rates and with or without inoculation of PGPR. A mixture of PGPR strains Bacillus amyloliquefaciens IN937a and Bacillus pumilus T4 was applied to the soil during growing periods of tomato. Treatments with PGPR inoculation increased plant height compared to treatments without PGPR in both experiments. Inoculation with PGPR increased shoot dry weight and shoot N uptake for the same N rate and N source. In both experiments, only at high N rate, CRF and urea treatments with PGPR had significantly (P < 0.05) greater shoot biomass than those without PGPR. Only at high N rate, CRF treatment with PGPR significantly increased shoot N uptake by 39.0% and 10.3% compared to that without PGPR in Experiments 1 and 2, respectively. Meanwhile, presence of PGPR in the soil increased shoot P uptake for all treatments in Experiment 1 and for most treatments in Experiment 2. In Experiment 1, only at low N rate, CRF treatment with PGPR significantly increased shoot P uptake compared with that without PGPR. In Experiment 2, a significant increase in shoot P uptake by inoculation of PGPR was only observed in CRF treatment at high N rate. Results from this study indicate that inoculation with PGPR may increase plant growth and N and P uptake by tomato grown on calcareous soils. However, the effect of PGPR varied and was influenced by many factors such as N source, N rate, and soil fertility. Further investigations are warranted to confirm the effect of PGPR under different soil conditions.

Plant-mediated restriction of Salmonella enterica on tomato and spinach leaves colonized with Pseudomonas plant growth-promoting rhizobacteria

Reducing Salmonella enterica association with plants during crop production could reduce risks of fresh produce-borne salmonellosis. Plant growth-promoting rhizobacteria (PGPR) colonizing plant roots are capable of promoting plant growth and boosting resistance to disease, but the effects of PGPR on human pathogen-plant associations are not known. Two root-colonizing Pseudomonas strains S2 and S4 were investigated in spinach, lettuce and tomato for their plant growth-promoting properties and their influence on leaf populations of S. enterica serovar Newport. Plant roots were inoculated with Pseudomonas in the seedling stage. At four (tomato) and six (spinach and lettuce) weeks post-germination, plant growth promotion was assessed by shoot dry weight (SDW) and leaf chlorophyll content measurements. Leaf populations of S. Newport were measured after 24h of leaf inoculation with this pathogen by direct plate counts on Tryptic Soy Agar. Root inoculation of spinach cv. ‘Tyee’, with Pseudomonas strain S2 or S4 resulted in a 69% and 63% increase in SDW compared to non-inoculated controls (p<0.005 and p<0.01, respectively). Similarly, Romaine lettuce cv. ‘Parris Island Cos’ responded positively to S2 and S4 inoculation (53% and 48% SDW increase, respectively; p<0.05), and an increase in leaf chlorophyll content (p<0.001), compared to controls. Tomato cv. ‘Nyagous’ yielded significantly greater SDW (74%, p<0.01 and 54%, p<0.05 for S2 and S4, respectively), and also higher leaf chlorophyll content (19% and 29%, p<0.001, respectively) relative to controls. Leaf chlorophyll content only increased in S4-inoculated tomato cv. ‘Moneymaker’ plants (27%, p<0.001), although both S2 and S4 promoted plant growth by over 40% compared to controls (p<0.01 and p<0.05, respectively). No significant growth promotion was detected in tomato cv. ‘BHN602’, but S2-inoculated plants had elevated leaf chlorophyll content (13%, p<0.01). Root inoculation with Pseudomonas S4 restricted S. Newport populations inoculated on leaves of spinach (p<0.001) and all three tomato cultivars (p<0.05), compared to controls, 24h post Salmonella inoculation. Impairment of S. Newport leaf populations was also observed on spinach when plant roots were inoculated with S2 (p<0.01). With an initial leaf inoculum of approximately 6.0logCFU of S. Newport/plant, the significantly greater reduction of S. Newport populations on Pseudomonas-treated plants than those on non-inoculated control plants after 24h was modest with differences of one log or less. By contrast, the survival of S. Newport on the leaves of Romaine lettuce was not influenced by Pseudomonas root colonization. These findings provide evidence that root inoculation of certain specialty crops with beneficial Pseudomonas strains exhibiting PGPR properties may not only promote plant growth, but also reduce the fitness of epiphytic S. enterica in the phyllosphere. Plant-mediated effects induced by PGPR may be an effective strategy to minimize contamination of crops with S. enterica during cultivation.

Rational Water and Nitrogen Management Improves Root Growth, Increases Yield and Maintains Water Use Efficiency of Cotton under Mulch Drip Irrigation.

There is a need to optimize water-nitrogen (N) applications to increase seed cotton yield and water use efficiency (WUE) under a mulch drip irrigation system. This study evaluated the effects of four water regimes [moderate drip irrigation from the third-leaf to the boll-opening stage (W1), deficit drip irrigation from the third-leaf to the flowering stage and sufficient drip irrigation thereafter (W2), pre-sowing and moderate drip irrigation from the third-leaf to the boll-opening stage (W3), pre-sowing and deficit drip irrigation from the third-leaf to the flowering stage and sufficient drip irrigation thereafter (W4)] and N fertilizer at a rate of 520 kg ha-1 in two dressing ratios [7:3 (N1), 2:8 (N2)] on cotton root morpho-physiological attributes, yield, WUE and the relationship between root distribution and dry matter production. Previous investigations have shown a strong correlation between root activity and water consumption in the 40–120 cm soil layer. The W3 and especially W4 treatments significantly increased root length density (RLD), root volume density (RVD), root mass density (RMD), and root activity in the 40–120 cm soil layer. Cotton RLD, RVD, RMD was decreased by 13.1, 13.3, and 20.8%, respectively, in N2 compared with N1 at 70 days after planting (DAP) in the 0–40 cm soil layer. However, root activity in the 40–120 cm soil layer at 140 DAP was 31.6% higher in N2 than that in N1. Total RMD, RLD and root activity in the 40–120 cm soil were significantly and positively correlated with shoot dry weight. RLD and root activity in the 40–120 cm soil layer was highest in the W4N2 treatments. Therefore increased water consumption in the deep soil layers resulted in increased shoot dry weight, seed cotton yield and WUE. Our data can be used to develop a water-N management strategy for optimal cotton yield and high WUE.

Growth and Yield Responses of Cowpea to Inoculation and Phosphorus Fertilization in Different Environments.

Cowpea (Vigna unguiculata) is a major source of dietary protein and essential component of the cropping systems in semi-arid regions of Sub-Saharan Africa. However, yields are very low due to lack of improved cultivars, poor management practices, and limited inputs use. The objectives of this study were to assess the effects of rhizobia inoculant and P on nodulation, N accumulation and yield of two cowpea cultivars in Mozambique. Field study was conducted in three contrasting environments during the 2013/2014 and 2014/2015 seasons using randomized complete block design with four replications and four treatments. Treatments consisted of seed inoculation, application of 40 kg P2O5 ha-1, inoculation + P, and a non-inoculated control. The most probable number (MPN) technique was used to estimate the indigenous bradyrhizobia populations at the experimental sites. The rhizobia numbers at the sites varied from 5.27 × 102 to 1.07 × 103 cells g-1 soil. Inoculation increased nodule number by 34–76% and doubled nodule dry weight (78 to 160 mg plant-1). P application improved nodulation and interacted positively with the inoculant. Inoculation, P, and inoculant + P increased shoot dry weight, and shoot and grain N content across locations but increases in number of pods plant-1, seeds pod-1, and 100-seed weight were not consistent among treatments across locations. Shoot N content was consistently high for the inoculated plants and also for the inoculated + P fertilized plants, whereas the non-inoculated control plants had the lowest tissue N content. P uptake in shoot ranged from 1.72 to 3.77 g kg-1 and was higher for plants that received P fertilizer alone. Inoculation and P either alone or in combination consistently increased cowpea grain yield across locations with yields ranging from 1097 kg ha-1 for the non-inoculated control to 1674 kg ha-1 for the inoculant + P treatment. Grain protein concentration followed a similar trend as grain yield and ranged from 223 to 252 g kg-1 but a negative correlation between grain yield and protein concentration was observed. Inoculation increased net returns by $104–163 ha-1 over that for the control. The results demonstrate the potential of improving cowpea grain yield, quality and profitability using inoculant, although the cost-benefit for using P at the current fertilizer price is not attractive except when applied together with inoculant at low P site.

GROWTH, NODULATION, YIELD AND MINERAL TISSUE CONTENT OF PEANUT IN RESPONSE TO FOLIAR AND COATING APPLICATION OF HUMIC ACID AND PLANT GROWTH –PROMOTING RHIZOBACTERIA

The aim of this investigation was to study the effect of adding humic acid and plant growth promoting rhizobacteria (PGPR), as foliar and coating application on plant growth, nodulation status and yield of peanut under field conditions. Results indicate that, using microbial inoculation with Brady rhizobium as single inoculation and coinoculation with PGPR ( Azospirillum sp.+ Bacillus polymyxa+ Serratia marcescens) as mixed inocul, conjugated with humic acid at two rates 3L/fed and 5L/fed. signicantly increased shoot dry weight, nodulation status and yield of peanut plant under coating and foliar applications. Incorporation of humic acid as foliar and coating application led to highest significant for all parameters above control. Also, coating application method was higher than foliar application. Shoot mineral content of N,P and K were increased by using coinoculation and addition of humic acid

Salt Exclusion and Mycorrhizal Symbiosis Increase Tolerance to NaCl and CaCl2 Salinity in ‘Siam Queen’ Basil

A study was conducted to evaluate the effects of salinity on growth and nutrient uptake in basil (Ocimum basilicum L. ‘Siam Queen’). Plants were fertilized with a complete nutrient solution and exposed to no, low, or moderate levels of salinity using NaCl or CaCl2. The plants in control and moderate salinity treatments were also inoculated or not with the arbuscular mycorrhizal fungus (AMF), Rhizophagus irregularis (Blaszk., Wubet, Renker, &amp; Buscot) C. Walker &amp; A. Schler., to determine whether AMF mitigate the effects of salinity stress. Electrical conductivity (EC) of leachate collected from salinity treatments reached levels ≥8 dS·m−1 but had no effect on plant growth in the first 41 days of treatment. However, by 75 days, plants exposed to low and moderate levels of NaCl and CaCl2 had 20% to 38% less dry weight (DW) than controls. Reductions in DW were similar between NaCl and CaCl2 and was greater in roots than in shoots. Both NaCl and CaCl2 salinity reduced stomatal conductance (gS) within 25 days, but hastened flowering by 2–3 days, and nearly doubled the DW of flowers at 75 days. Salinity from NaCl increased uptake of Na and reduced uptake of Ca, whereas CaCl2 salinity increased uptake of Ca and reduced uptake of Mg and Mn. Both salts also increased relative uptake of N, Cu, and Zn, and reduced relative uptake of S and Fe. In general, Na was concentrated in roots and excluded from shoots, whereas Cl was concentrated primarily in leaves. Both salts reduced root colonization by AMF. However, AMF increased gS by 10% with NaCl and 22% with CaCl2, and increased shoot DW by 22% and 43%, respectively. Other than Ca and Cl, AMF did not enhance nutrient uptake under NaCl or CaCl2 salinity. ‘Siam Queen’ basil was moderately tolerant to salinity, due at least in part to exclusion of Na from the shoots, and inoculation with AMF increased tolerance to both NaCl and CaCl2 salinity. Differences in basil tolerance to NaCl and CaCl2 indicate plants may have different mechanisms for dealing with salinity and sensitivity is not solely a function of EC. This highlights the importance of understanding the source of salinity in irrigation waters and soil for predicting damage.

Far-red radiation promotes growth of seedlings by increasing leaf expansion and whole-plant net assimilation

By definition, photosynthetically active radiation (PAR) includes wavelengths between 400 and 700nm and thus, far-red radiation (FR, 700–800nm) is excluded when the photosynthetic photon flux density (PPFD) is measured and reported. However, FR radiation [and the ratio of red (R; 600–700nm) to FR] regulates phytochrome-mediated morphological and developmental plant responses to promote radiation capture and survival under shade. We postulated that the inclusion of FR in a radiation spectrum would have little effect on photosynthesis but would increase radiation capture and plant growth, while accelerating the subsequent flowering of shade-avoiding species. Geranium (Pelargonium×hortorum), petunia (Petunia×hybrida), snapdragon (Antirrhinum majus), and impatiens (Impatiens walleriana) were grown at 20°C under an 18-h photoperiod provided by sole-source lighting from light-emitting diodes that included 32μmolm−2s−1 of blue and the following intensities of R and FR radiation: R128 (128μmolm−2s−1 of R), R128+FR16, R128+FR32, R128+FR64, R96+FR32, and R64+FR64. Plant height in all species studied and total leaf area of geranium and snapdragon linearly decreased as the R:FR (or the estimated phytochrome photoequilibrium) of each treatment increased. In geranium and snapdragon, the increase in total leaf area (by 7%) with the addition of FR to the same PPFD subsequently increased shoot dry weight (DW) (by 28–50%) while the increase in total leaf area (by 30–40%) with the partial substitution of R with FR partly compensated for the reduction in PPFD (by 40%), producing a similar shoot DW. Whole-plant net assimilation of geranium, snapdragon, and impatiens increased with additional FR radiation, showing a linear relationship with the calculated yield photon flux density of each radiation treatment. In addition, inclusion of FR during seedling growth promoted flowering in the long-day plant snapdragon. We conclude that FR radiation increases plant growth indirectly through leaf expansion and directly through whole-plant net assimilation and in at least some species, promotes subsequent flowering.

Effect of Plant Growth Stimulants on Alfalfa Response to Salt Stress

Salinity is a major impediment to crop production. This study was undertaken to compare the effect of seaweed extract, humic acid, and potassium sulfate nanoparticles in alleviating salt stress in Alfalfa (Medicago sativa L.). Seeds of ten alfalfa genotypes were germinated in a growth chamber at five salt concentrations (0%, 0.5%, 1.0%, 1.5%, and 2.00%). Salt concentrations above 1% reduced seed germination by more than 70% in most genotypes. One salt tolerant genotype (Mesa-Sirsa) and one salt sensitive (Bulldog 505) were selected and planted in greenhouse pots containing 2 kg of sand and subjected to two salt levels (10 and 15 dS· m-1). Four treatments consisting of 1) control (Hoagland solution, no-salt), 2) seaweed extract at 4 Kg·ha-1, 3) humic acid at 28 L· ha-1, and 4) potassium sulfate at 300 Kg· ha-1. Plant biomass was reduced under both salt concentrations in both genotypes, with a greater magnitude in the salt sensitive genotype. Application of seaweed extract resulted in higher relative water content and proline under both salt concentrations (10 and 15 dS·m-1) in the salt sensitive genotype, and lower electrolyte leakage in both salt tolerant and salt sensitive genotypes, under both salt concentrations. Seaweed extract also resulted in higher catalase and SOD activities in both genotypes under 10 dS·m-1. Catalase and SOD activities were associated with significantly (p < 0.01) reduced electrolyte leakage and increased shoot dry weight. Overall, seaweed extract seemed to have a positive effect in alleviating salt stress in alfalfa.

Effect of nitrogen application on growth and yield of pumpkin

ABSTRACTEvaluation of any crop response to different nitrogen amounts is important for determining the amount that can be considered as optimum from economical and environmental point of view. This study was conducted to (1) evaluate the growth and yield of pumpkin (Cucurbita pepo L.) under different nitrogen rates and (2) determine the nitrogen use efficiency (NUE) of pumpkin in two growing seasons (2013 and 2014). In both growing seasons, nitrogen fertilizer (at three rates including 50, 150, and 250 kg ha−1) was band-dressed on the planted side of each furrow, coinciding with 4–6 leaves stage and flowering. Crop performance over 2 years was evaluated by measuring shoot dry matter, crop growth rate (CGR), leaf area index (LAI), leaf area duration (LAD), intercepted PAR (PARi), radiation use efficiency (RUE), shoot nitrogen uptake, water use efficiency (WUE), NUE, and fruit and seed yield. The results showed that in both growing seasons, the highest growth and yield of pumpkin were obtained by applying 250 kg N ha−1 (using urea fertilizer containing 46% nitrogen). Increased nitrogen rate from 50 to 250 kg ha−1 resulted in 87.3%, 27.0%, 62.1%, 87.5%, and 84.5% increase in shoot dry weight, RUE, WUE, fruit yield, and seed yield of pumpkin, respectively, across both growing seasons. However, higher application nitrogen rate decreased the NUE of pumpkin, i.e., the NUE decreased by 62.5% when the nitrogen rate increased from 50 to 250 kg ha−1. The effect of nitrogen applied in 2014 growing season on growth and yield of pumpkin was higher than that in 2013 growing season, which might be due to more suitable weather condition. In conclusion, the nitrogen rate of 250 kg ha−1 produced the highest amount of fruit and seed yield in pumpkin.

Effect of treated sewage effluent by different material and Levels of Organic matter on growth of Barley (Hordeum Vulgare L.)

The study was conducted at the College of Agriculture-University of Anbar during the autumn of 2013 to study the effect of treated sewage effluent by decomposed hay waste and Rock phosphate on growth of Barley. The study included four quality of irrigation water (w): fresh water (w1) sewage effluent treated by decomposed hay waste (w2), treated by Rock phosphate (w3) and untreated sewage effluent (w4). Second factor is poultry manure levels: (O0) no added, (O1) 10 mt ha-1 , (O2) 20 mt ha-1, (O3) 30 mt ha-1 with three replication using (RCBD). At end of the experiment, dry weight and plant heights were measured, in addition to concentrations of Fe, Zn, Mn, Cu, Cd and Pb for Barley seeds. Results showed a significant increase in shoot dry weight and plant heights with treated sewage by decomposed hay waste and Rock phosphate with values 50.44, 46.70 gm and 54.0, 50.58 cm respectively compared with fresh water and untreated water and increase in shoot dry weight and plant heights with levels of poultry manure. Fe, Zn, Mn, Cu, Cd, Pb concentrations decrease in Barley seeds with irrigated sewage treated by decomposed hay waste and treated by Rock phosphate, with 41.35, 31.0, 11.09, 1.31, 0.275, 0.621 mg kg-1 and 40.84, 29.5, 10.95, 1.30, 0.295, 0.635 mg.kg-1respectively. Compared with untreated sewage water and increasing of poultry manure levels resulted in increase of Fe, Zn, Mn, Cu concentration in Barley seeds giving 43.34, 33.40, 11.75, 1.63 mg kg-1 respectively compared with control , while concentration Cd, Pb decrease with poultry manure addition.

Chemical Attributes of Soil and Forage Yield of Pasture Recovered with Phosphate Fertilization and Soil Management

ABSTRACTExtensive and semi-extensive pastures are the basis of Brazilian livestock production. However, much of it is degraded or in degradation process, with low stocking rate per area. Even with this problem, this management type is 60% and 50% of Australia’s and the United States’ production costs, respectively. In order to research alternatives for Urochloa decumbens degraded pasture recovery in an Oxisol, Stylosanthes (Stylosanthes spp.) “Campo Grande” cultivar was introduced and phosphate fertilization was applied. The experimental design was of randomized blocks, 7 × 2 × 2 factorial design, with four replicates, involving seven systems to introduction (U. decumbens control; partial desiccation with 1.5 L ha−1 glyphosate, total desiccation with 3.0 L ha−1 glyphosate; direct planting; scarification, harrowing, and plowing + harrowing), phosphate fertilizer presence or absence, and two evaluation periods. “Campo Grande” Stylosanthes legume introduction increased shoot dry weight (SDW) yield, except in direct planting. Phosphorus fertilization increased SDW yield only in the first period, and Stylosanthes introduction in the pasture has not changed soil chemical properties. Phosphorus (P) fertilization also provided available P and exchangeable calcium (Ca2+) content in the soil increase, in addition to sum of bases and cation exchange capacity increase.

Effects of Phosphorus on Shoot and Root Growth, Partitioning, and Phosphorus Utilization Efficiency in Lantana

This study was undertaken to critically analyze the effects of reduced phosphorus (P) on shoot and root growth, partitioning, and phosphorus utilization efficiency (PUtE) in lantana (Lantana camara ‘New Gold’). Plants were grown in a 1:1 mixture of perlite and vermiculite with complete nutrient solutions containing a range of P concentrations considered to be deficient (1 mg·L−1), low (3 and 5 mg·L−1), adequate (10 mg·L−1), and high (20 and 30 mg·L−1). Higher P supply had most dramatic effect on increasing the number of leaves and leaf surface area, subsequently leading to a disproportionate increase in shoot biomass than root biomass. Increasing P from 1 to 30 mg·L−1 linearly (P &lt; 0.0001) increased shoot dry weight (DW) during vegetative growth, and logarithmically (P &lt; 0.0001) during reproductive growth. Regardless of plant growth stage, biomass of roots and flowers (inflorescences) logarithmically increased (P &lt; 0.0001) with increasing P concentrations. Plants grown with lower P allocated more biomass to roots than shoots, resulting in a higher root-to-shoot ratio. Increasing P concentration to 20 mg·L−1 increased the accumulation of P in all plant parts, but predominantly in shoots, whereas further increasing the concentration increased the accumulation primarily in roots and flowers. Higher P accumulation in plant tissues did not strongly contribute to the biomass production. Phosphorus utilization efficiency was higher with lower P supply in all plant tissues. P-deficient roots had the highest PUtE and specific root length (SRL), and retained higher proportion of P compared with nondeficient roots. Our results indicate that P concentration at 20 mg·L−1 is sufficient to maintain optimal vegetative growth while reproductive growth does not require P concentrations over 10 mg·L−1 as it stimulates greater level of P accumulation in plant parts with little or no effect on growth and flowering, and biomass accumulation in lantana.

RNA-seq analyses reveal insights into the function of respiratory nitrate reductase of the diazotroph Herbaspirillum seropedicae.

Herbaspirillum seropedicae is a nitrogen-fixing β-proteobacterium that associates with roots of gramineous plants. In silico analyses revealed that H. seropedicae genome has genes encoding a putative respiratory (NAR) and an assimilatory nitrate reductase (NAS). To date, little is known about nitrate metabolism in H. seropedicae, and, as this bacterium cannot respire nitrate, the function of NAR remains unknown. This study aimed to investigate the function of NAR in H. seropedicae and how it metabolizes nitrate in a low aerated-condition. RNA-seq transcriptional profiling in the presence of nitrate allowed us to pinpoint genes important for nitrate metabolism in H. seropedicae, including nitrate transporters and regulatory proteins. Additionally, both RNA-seq data and physiological characterization of a mutant in the catalytic subunit of NAR (narG mutant) showed that NAR is not required for nitrate assimilation but is required for: (i) production of high levels of nitrite, (ii) production of NO and (iii) dissipation of redox power, which in turn lead to an increase in carbon consumption. In addition, wheat plants showed an increase in shoot dry weight only when inoculated with H. seropedicae wild type, but not with the narG mutant, suggesting that NAR is important to H. seropedicae-wheat interaction.

Growth and Nutrient Uptake of Orchardgrass (Dactylis glomerata L.) and Meadow Fescue (Festuca pratensis Huds.) as Affected by Rhizobacteria

A diverse group of soil bacteria found in the rhizosphere which can colonize plant roots and improve plant growth are designated as plant growth promoting rhizobacteria. The aim of this study was isolation and screening of different rhizobacterial strains for plant growth promoting characteristics and their ability to improve growth of two grass species, orchardgrass (Dactylis glomerata L.) and meadow fescue (Festuca pratensis Huds.). The strains investigated, belonging to the genera Azotobacter, Bacillus, Pseudomonas and rhizobial bacteria, showed various plant growth promoting traits, such as phosphate solubilisation, siderophore production, and indole-3-acetic acid (IAA) production. Co-inoculation of meadow fescue with Azotobacter chroococcum A2 and Sinorhizobium meliloti or Pseudomonas sp., and A. chroococcum A5 with S. meliloti, significantly increased shoot dry weight (SDW)(25-33%), as well as total N (26-33%), P (24-31%) and K (26-28%) contents in plants (mg pot-1), compared to uninoculated control. In addition, inoculation of orchardgrass with A. chroococcum strain A1, as well as co-inoculation with B. megaterium and A. chroococcum A1 or A31, significantly increased SDW (51-59%) and total N (54-59%), P (51-74%) and K (49-55%) contents, compared to uninoculated control. Nitrogen percentage in SDW was slightly higher than sufficiency ranges, while K percentage was optimal in all treatments in both species. Phosphorous percentage was lower than sufficiency ranges as a consequence of very low soil P content. The results emphasize the potential of particular rhizobacteria to improve the growth of forage grasses.

Foliar Abscisic Acid-To-Ethylene Accumulation and Response Regulate Shoot Growth Sensitivity to Mild Drought in Wheat.

Although, plant hormones play an important role in adjusting growth in response to environmental perturbation, the relative contributions of abscisic acid (ABA) and ethylene remain elusive. Using six spring wheat genotypes differing for stress tolerance, we show that young seedlings of the drought-tolerant (DT) group maintained or increased shoot dry weight (SDW) while the drought-susceptible (DS) group decreased SDW in response to mild drought. Both the DT and DS groups increased endogenous ABA and ethylene concentrations under mild drought compared to control. The DT and DS groups exhibited different SDW response trends, whereby the DS group decreased while the DT group increased SDW, to increased concentrations of ABA and ethylene under mild drought, although both groups decreased ABA/ethylene ratio under mild drought albeit at different levels. We concluded that SDW of the DT and DS groups might be distinctly regulated by specific ABA:ethylene ratio. Further, a foliar-spray of low concentrations (0.1 μM) of ABA increased shoot relative growth rate (RGR) in the DS group while ACC (1-aminocyclopropane-1-carboxylic acid, ethylene precursor) spray increased RGR in both groups compared to control. Furthermore, the DT group accumulated a significantly higher galactose while a significantly lower maltose in the shoot compared to the DS group. Taken all together, these results suggest an impact of ABA, ethylene, and ABA:ethylene ratio on SDW of wheat seedlings that may partly underlie a genotypic variability of different shoot growth sensitivities to drought among crop species under field conditions. We propose that phenotyping based on hormone accumulation, response and hormonal ratio would be a viable, rapid, and an early–stage selection tool aiding genotype selection for stress tolerance.

Induction of systemic resistance in Chinese cabbage against black rot by plant growth-promoting rhizobacteria

Black rot, caused by Xanthomonas campestris pv. campestris, is the most important and potentially destructive disease of cabbage. The objectives of this study were to select plant growth-promoting rhizobacteria (PGPR) strains and to form strain mixtures with the capacity to elicit induced systemic resistance or to increase plant growth in Chinese cabbage. In preliminary screening, 10 of 12 tested individual PGPR strains (AP136, AP188, AP209, AP213, AP217, AP218, AP219, AP282, AP295, and AP305) reduced the number of foliar lesions, and 2 PGPR strains (AP7 and AP18) increased all tested parameters of plant growth promotion, including shoot fresh weight, shoot dry weight, root fresh weight, root dry weight and plant diameter. In advanced tests, four individual stains (AP136, AP209, AP282 and AP305) were combined into mixture-1. Mixture-2 contained all strains in mixture-1 plus three additional stains (AP7, AP18 and AP218). Both mixtures and three individual strains (AP136, AP209 and AP305) significantly reduced the number of black rot lesions, and mixture-2 increased shoot dry weight and root dry weight in greenhouse tests. In a field test, all the tested treatments significantly reduced disease incidence on whole plants at three weeks after transplanting and reduced head disease severity at harvest time. All treatments also increased marketable yield compared to the nonbacterized control. These results demonstrated that specific individual PGPR strains and strain mixtures induced systemic resistance to black rot in the greenhouse and field.