Effects of Salinity and Water Stress on Growth and Macro Nutrients Concentration of Pomegranate (Punica granatum L.)

In order to study the effects of salinity and water stress on growth and macronutrients concentration of pomegranate plant leaves, a factorial experiment was conducted based on completely randomized design with 0, 30, and 60 mM of salinity levels of sodium chloride and calcium chloride (1:1) and three irrigation intervals (2, 4, and 6 days) with 3 replications on ‘Rabab’ and ‘Shishegap’ cultivars of pomegranate. The results of the shoot and root analysis indicated that the salinity and drought affected the concentration and distribution of sodium (Na⁺), potassium (K⁺), chloride (Cl^?), calcium (Ca²⁺), magnesium (Mg²⁺), and phosphorus (P⁺) in pomegranate leaves. Mineral concentrations of sodium (Na⁺), chloride (Cl^-), potassium (K⁺), in shoots and roots were increased with increasing salinity. Drought treatments increased the concentration of Cl^?, Na⁺, and Mg²⁺ in the shoot. Both cultivars showed significant differences in the concentrations of elements, however the most accumulation of Na⁺ and Cl^? was observed in ‘Rabab,’ while the ‘Shishegap’ cultivar had the most absorption of K⁺. ‘Shishegap’ cultivar showed higher tolerance to salinity than ‘Rabab’ through maintaining the vegetative growth and lower chloride transport to the shoot, and improvement of potassium transport to shoot.     

Foliar-applied trehalose modulates growth,mineral nutrition,photosynthetic ability,and oxidative defense system of rice (Oryza sativa L.) under saline stress

A tub experiment was conducted to assess the effect of exogenously applied trehalose (0, 10, and 20 mM) on various attributes of two rice cultivars (Bas-385 and Bas-2000) under salt stress (0, 50, 100, and 150 mM). Salinity decreased growth, gas exchange characteristics, shoot and root potassium (K⁺) ions, hydrogen peroxide (H₂O₂), total soluble proteins, activity of catalase (CAT), and yield attributes, while it increased chlorophyll contents, shoot and root sodium (Na⁺) and calcium (Ca²⁺), malondialdehyde (MDA), glycinebetain (GB), free proline, and peroxidase (POD) activity. Foliar-applied trehalose improved growth attributes, net photosynthetic rate, GB, total soluble proteins, superoxide dismutase (SOD) and yield. Yield was not obtained at 150 mM salt stress. The rice cultivar Bas-2000 showed better performance with respect to gas exchange attributes and activities of enzymatic antioxidants. Overall, varying levels of foliar-applied trehalose proved to be effective in ameliorating adverse effects of salt stress on rice.     

Evaluating the effectiveness of biofertilizer on salt tolerance of cotton (Gossypium hirsutum L.)

In the present study, the effectiveness of biofertilizer containing plant growth promoting rhizobacteria was evaluated on growth and physiology of cotton under saline conditions. Cotton plants were exposed to different levels of NPK (50%, 75%, and 100% of recommended levels) along with coating with biofertilizer under saline (15 dS m^?1) and non-saline conditions. It was observed that the biofertilizer seed coating improved growth, physiological (relative water content and chlorophyll content index), and ionic (K⁺/Na⁺) characteristics under saline and non-saline conditions. However, shoot growth (shoot fresh and dry weight) and leaf gas exchange characteristics (CO₂ assimilation rate, A; intercellular CO₂ concentration, C_i; transpiration rate, E; stomatal conductance, g_s) were decreased by biofertilizer coating under saline condition. Increasing levels of NPK fertilizer increased shoot growth, whereas root growth was maximum at 75% NPK level under saline conditions. The results of the study indicate that the biofertilizer application was very effective for cotton plant in non-saline conditions but not very effective in saline conditions.     

Calcium and humic acid affect seed germination,growth, and nutrient content of tomato (Lycopersicon esculentum L.) seedlings under saline soil conditions

The effects of calcium and humic acid on seed germination, growth and macro- and micro-nutrient contents of tomato (Lycopersicon esculentum L.) seedlings in saline soil conditions were evaluated. Different levels of humic acid (0, 500, 1000 and 2000 mg kg^?1) and calcium (0, 100, 200 and 400 mg kg^?1) were applied to growth media treated with 50 mg NaCl kg^?1 before sowing seeds. Seed germination, hypocotyl length, cotyledon width and length, root size, shoot length, leaf number, shoot and root fresh weights, and shoot and root dry weights of the plant seedlings were determined. Macro- and micro-nutrient (N, P, K, Ca, Mg, S, Cu, Fe, Mn and Zn) contents of shoot and root of seedlings were also measured. Humic acid applied to the plant growth medium at 1000 mg kg^?1 concentration increased seedling growth and nutrient contents of plants. Humic acid not only increased macro-nutrient contents, but also enhanced micro-nutrient contents of plant organs. However, high levels of humic acid arrested plant growth or decreased nutrient contents. Levels of 100 and 200 mg kg^?1 Ca²⁺ application significantly increased N, Ca and S contents of shoot, and N and K contents of root.     

Neotyphodium endophytes trigger salt resistance in tall and meadow fescues

Infection with Neotyphodium spp. endophytes increases resistance to drought stress and soil mineral imbalances in tall fescue (Festuca arundinacea Schreb. = Lolium arundinaceum (Schreb.) S. J. Darbysh.) and meadow fescue (Festuca pratensis Huds. = Lolium pratense (Huds.) Darbysh.). We hypothesized that resistance of these grasses to salinity stress may also be attributed to endophyte infection. Two tall fescue genotypes, Fa75 and Fa83, and one meadow fescue genotype, Fp60, infected (E+) with their endophytic fungi, Neotyphodium coenophialum (Glenn, Bacon and Hanlin) and N. uncinatum (Glenn, Bacon and Hanlin), respectively, and their noninfected counterparts (E–) were cultured in nutrient solution at three salinity levels of 0, 85, and 170 mM NaCl. Except for genotype Fa75, E+ plants exhibited higher leaf survival rates than E– clones at a high salinity level (170 mM). Root dry matter was higher in E+ than in E– plants, but shoot dry matter was not affected by endophyte infection. This resulted in a lower shoot‐to‐root ratio in E+ plants (1.63) compared with E– plants (2.40). Sodium (Na⁺) and chloride (Cl^–) concentrations were greater in roots of E– than in E+ clones. In shoots, Na⁺ and Cl^– concentrations were not affected by the endophyte. In contrast, E+ plants accumulated more potassium (K⁺), which resulted in a greater K⁺ : Na⁺ ratio in shoots of E+ than in those of E– plants. Our results show that endophyte infection reduced Na⁺ and Cl^– concentrations in tall fescue and meadow fescue roots but increased K⁺ concentrations in the shoots. Based on these results, we conclude that endophyte‐infected grasses may thrive better in salinity‐stress environments.     

Growth of Tropical Legume Cover Crops as Influenced by Nitrogen Fertilization and Rhizobia

Tropical legume cover crops are important components in cropping systems because of their role in improving soil quality. Information is limited on the influence of nitrogen (N) fertilization on growth of tropical legume cover crops grown on Oxisols. A greenhouse experiment was conducted to evaluate the influence of N fertilization with or without rhizobial inoculation on growth and shoot efficiency index of 10 important tropical cover crops. Nitrogen treatment were (i) 0 mg N kg^?1 (control or N₀), (ii) 0 mg N kg^?1 + inoculation with Bradyrhizobial strains (N₁), (iii) 100 mg N kg^?1 + inoculation with Bradyrhizobial strains (N₂), and (iv) 200 mg N kg^?1 of soil (N₃). The N?×?cover crops interactions were significant for shoot dry weight, root dry weight, maximal root length, and specific root length, indicating that cover crop performance varied with varying N rates and inoculation treatments. Shoot dry weight is considered an important growth trait in cover crops and, overall, maximal shoot dry weight was produced at 100 mg N kg^?1 + inoculation treatment. Based on shoot dry-weight efficiency index, cover crops were classified as efficient, moderately efficient, and inefficient in N-use efficiency. Overall, the efficient cover crops were lablab, gray velvet bean, jack bean, and black velvet bean and inefficient cover crops were pueraria, calopo, crotalaria, smooth crotalaria, and showy crotalaria. Pigeonpea was classified as moderately efficient in producing shoot dry weight.     

Growth and ion accumulation responses of four grass species to salinity

Ion inclusion or ion exclusion are the two main strategies developed by plants to tolerate saline environments. Shoot sodium (Na⁺), potassium (K⁺), and calcium (Ca²⁺) in four perennial grass species (tall wheatgrass, Nuttall's alkaligrass, creeping foxtail, and switchgrass) treated with nutrient solution salinity levels ranging from 2 to 32 dS m^?1 were measured. As the nutrient solution salinity was increased from 2 to 10 dS m^?1, tall wheatgrass, creeping foxtail and Nuttall's alkali grass had increased shoot Na⁺ and decreased Ca²⁺ concentration while maintaining growth suggesting that these species tolerated these changes in shoot ion concentration. In contrast, switchgrass excluded Na⁺ from the shoot and maintained K⁺ and Ca²⁺ concentrations but suffered dramatic shoot dry weight reduction. Thus, the Na⁺ exclusion mechanisms present in switchgrass were less efficient in maintaining growth under the 10 dS m^?1 nutrient solution treatment than the Na⁺ inclusion mechanisms used by the other three species.     

Stimulatory effect on pea of Typha Angustifolia L. extracts and their chemical composition

In this study, the influence of aqueous and organic extracts of different plant parts (flowers, leaves, and stems) of Typha angustifolia on the germination and early seedling growth of field pea (Pisum sativum L.) was evaluated. Chemical composition of extracts of different plant parts of Typha was also determined. Aqueous (20, 40, 60, 80, and 100 g L^?1) and organic extracts (at 0.5, 1, and 2 mg mL^?1) were applied to the seeds of two pea cultivars, Douce de Provence and Lincoln, placed in Petri dishes. Application of extracts had a beneficial effect on germination and early seedling growth of both pea cultivars. However, aqueous extract of leaves showed the most beneficial effect at 60 and 40 g L^?1 for the cultivars Douce de Provence and Lincoln, respectively. The effect could be attributed to the allelochemicals present in the aqueous extracts. Petroleum ether and chloroform extracts of leaves had the most stimulating effect on the germination and early seedling growth of pea. Analysis of Typha extracts indicated the presence of vitamin E in leaves, which could be responsible forthis stimulation. Moreover, Typha leaves also had substantial amount of flavonoids. In conclusion, the allelopathic activity of of Typha was dependent on the plant part, the solvent nature, the concentration of the extracts tested, and on the pea cultivar. Application of leaf extract was the most effective in improving the germination rate and early seedling growth of pea.     

Adaptive attributes of tropical forage species to acid soils II. Differences in shoot and root growth responses to varying phosphorus supply and soil type

Identification of plant attributes that improve the performance of tropical forage ecotypes when grown as monocultures or as grass+legume associations in low fertility acid soils will assist the development of improved forage plants and pasture management technology. The present work compared the shoot and root growth responses of four tropical forages: one grass and three legumes. The forages were grown in monoculture or in grass+legume associations at different levels of soil phosphate. Two infertile acid soils, both Oxisols, were used: one sandy loam and one clay loam. They were amended with soluble phosphate at rates ranging from 0 to 50 kg ha^‐1. The forages, Brachiaria dictyoneura (grass), Arachis pintoi, Stylosanthes capitata and Centrosema acutifolium (legumes), were grown in large plastic containers (40 kg of soil per container) in the glasshouse. After 80 days of growth, shoot and root biomass production, dry matter partitioning, leaf area production, total chlorophyll content in leaves, soluble protein in leaves, root length, and proportion of legume roots in grass+legume associations were determined. The grass, grown either in monoculture or in association responded more to phosphorus supply than did the three legumes in terms of both shoot and root production. At 50 kg ha^‐1 of phosphorus, the grass's yield per plant in association was greatly enhanced, compared with that of grass in monoculture. The increase in size of grass plants in association compared with that in monoculture may have been caused by reduced competition from the legumes. These differences in shoot and root growth responses to phosphorus supply in acid soils between the grass and the three legumes may have important implications for improving legume persistence in grass+legume associations.     

Effects of Graphene Oxide and/or Cd<Superscript>2+</Superscript> on Seed Germination,Seedling Growth,and Uptake to Cd<Superscript>2+</Superscript> in Solution Culture

With increasing graphene oxide (GO) applications in industry and biomedicine, effects of GO on microorganisms, animals, and human health have been frequently studied; however, direct and indirect effects of GO on plants are seldom concerned. In this study, effects of GO and/or Cd²⁺ on seed germination, seedling growth, and uptake to Cd²⁺ were investigated in solution culture. The results showed that GO could quickly adsorb Cd²⁺ in solution, and the higher the GO concentration was, the lower the residual Cd²⁺ concentration was in solution. Rice seed germination, seminal root length, and bud length decreased with increasing GO and Cd²⁺ concentrations respectively, while the presence of GO could alleviate the inhibitive effects of Cd²⁺ on seminal root and bud growth compared with the single Cd²⁺ treatment. In maize seedling, fresh weights of shoot and root showed similar responses to the presence of Cd²⁺ and/or GO. Compared with the single Cd²⁺ treatment, root Cd concentrations were generally increased by GO in high Cd²⁺ solution (20 mg/L), while were slightly affected by GO in low Cd²⁺ solution (5 mg/L) independent of GO concentrations except for 100 mg/L GO. Shoot Cd concentrations were decreased by low GO (100 mg/L) while were increased by high GO (>?500 mg/L) independent of Cd²⁺ concentrations in solution. Moreover, significant interactive effects of GO and Cd²⁺ on root and shoot Cd concentrations were observed. This study indicates that GO can change the effects of Cd²⁺ on seed germination, seedling growth, and uptake to Cd²⁺ in solution through its adsorption on Cd²⁺.     

Effects of cadmium stress on seedlings of various rangeland plant species (Avena fatua L., Lathyrus sativus L., and Lolium temulentum L.): Growth,physiological traits,and cadmium accumulation

A pot culture experiment was performed to study the effect of cadmium stress (Cd stress) on seedling growth, physiological traits, and remediation potency of Avena fatua, Lathyrus sativus, and Lolium temulentum. The seedlings of these native rangeland plant species were treated with 0, 2, 4, and 6 mM cadmium nitrate concentrations. Based on the results of analysis of variance (p < 0.05), the shoot height, shoot dry weight, root length, root dry weight, root: shoot ratio, total chlorophyll content, soluble sugars, and protein contentof A. fatua, L. sativus, and L. temulentum significantly decreased with increased cadmium concentrations. Generally, translocation factor (TF) and tolerance index (TI) decreased significantly as the concentration of cadmium increased. The maximum TF and TI of studied plants in various concentrations of Cd were observed in L. temulentum followed by L. sativus and A. fatua. The root concentration factor (RCF) values of all studied plants were higher than 1 under different cadmium concentrations. Our results indicate that Lolium temulentum could be labeled as an accumulator of Cd asthe values of TF and RCF are greater than 1. A. fatua and L. sativus showed a potential to be used in the phytoremediation of Cd-contaminated soils.     

Is the salt tolerance of maize related to sodium exclusion? I. Preliminary screening of seven cultivars

Maize (Zea mays L.) plants in the early stage of development were treated with 80 mM sodium chloride (NaCl) with or without supplemental calcium (Ca²⁺) (8.75 mM) for a seven day period. The effects of salinity on dry matter production and shoot and root concentrations of sodium (Na⁺), Ca²⁺, and potassium (K⁺) were measured for seven Pioneer maize cultivars. Salinity significantly reduced total dry weight, leaf area, and shoot and root dry weight below control levels. For all seven cultivars, Na⁺concentrations were reduced and leaf area was significantly increased by supplementing salinized nutrient solutions with 8.75 mM calcium chloride (CaCl₂). The two cultivars with the lowest shoot and root Na⁺ concentrations under NaCl‐salinity showed the greatest increases in total, shoot and root dry weights with the addition of supplemental Ca. Shoot fresh weight/dry weight ratios for all cultivars were decreased significantly by both salinity treatments, but supplemental Ca²⁺ increased the ratio relative to salinity treatments without supplemental Ca. Root fresh weight/dry weight ratios were decreased only by salinity treatments with supplemental Ca. With NaCl‐salinity, cultivars which had lower shoot and root Na⁺ concentrations were found to be more salt sensitive and had significantly lower amounts of dry matter production than those cultivars which had higher shoot and root Na⁺ concentrations. It was concluded that Na⁺ exclusion from the shoot was not correlated with and was an unreliable indicator of salt tolerance for maize.     

Neotyphodium coenophialum‐endophyte infection affects the ability of tall fescue to use sparingly available phosphorus

Neotyphodium coenophialum, (Morgan‐Jones & Gams) Glenn, Bacon & Hanlin, infected tall fescue (Festuca arundinacea Schreb.) plants perform better than non‐infected isolines on phosphorus (P)‐deficient soils. Our objective was to characterize growth and P uptake dynamics of tall fescue in response to endophyte infection and P source at low P availability in soil. Two tall fescue genotypes (DN2 and DN4) infected with their naturally occurring N. coenophialum strains (E+), and in noninfected (E‐) forms were grown in Lily soil (fine loamy siliceous, mesic Typic Hapludult) in a greenhouse for 20 weeks. Three soil P treatments were imposed: no P supplied (control) and P supplied as commercial fertilizer (PF) or as phosphate rock (PR) at the level of 25 mg P kg^‐1 soil. Interaction of tall fescue genotype and endophyte status had a significant influence on mineral element uptake suggesting high specificity of endophyte‐tall fescue associations. Endophyte infection did not affect root dry matter (DM) when no P was supplied but shoot DM was reduced by 20%. More biomass was produced and greater P uptake rate occurred in PR than PF treatment. Root DM was greater in E+ DN4 than E‐DN4 when supplied with either PF or PR. In contrast, endophyte infection did not affect root DM of DN2, regardless of P source. Relative growth rate (RGR) of E+ plants grown with PR was 16% greater than that of E‐plants. Endophyte infection did not improve growth or P uptake in PF treatment. When PR was supplied, P uptake rate was 24% greater in E+ DN2 than E‐ DN2, but endophyte infection did not benefit DN4. Phosphorus‐use efficiency was 6% less in E+ DN2 but 16% greater in E+ DN4 compared to E‐ plants, regardless of P source. Root exudates of E+ DN2, but not E+ DN4 solubilized more P from PR than those of E‐ plants. The correlation between root RGR and P uptake rate was relatively high for E‐ plants (r=0.76), but low for E+ plants (r=0.27) grown with PR. Results suggest that P uptake by E+ tall fescue might rely on mechanisms other than an increase in root biomass (surface area). Endophyte infection modified tall fescue responses to P source. This phenomenon was associated with modes of P acquisition which included enhanced activity of root exudates in releasing P from PR in E+ plants (DN2), and increased root biomass (DN4). The dominant means of P acquisition may be determined by a specific association of endophyte and tall fescue genomes. Endophyte‐tall fescue association plasticity contributes to widespread success of symbiotic in marginal resource conditions.     

Effect of nitrogen source and salinity level on salt accumulation of two chickpea genotypes

This study aimed at investigating mechanisms of salt tolerance and ionic relations of chickpea (Cicer arietinum L.) cultivars with different nitrogen (N) sources. Two resistant genotypes, ILC‐205 and ILC‐1919, were subjected to four levels of salinity (0.5, 3.0, 6.0, and 9.0 dS m^‐1). Nitrogen sources consisted of inoculation with two resistant Rhizobium strains, CP‐29 and CP‐32, mineral N additions, and no N application. Data was collected on root and shoot contents of sodium (Na⁺) chlorine, (Cl^‐,) and potassium (K⁺), and shoot to root Na⁺ratio, as well as shoot K⁺ to Na⁺ ratio. Salinity affected shoot Na⁺ and Cl^‐contents, but nodulating plants had higher shoot Na⁺ contents than plants supplied with mineral N. Shoot to root Na⁺ ratios were lower in the mineral N treatment than in nodulating treatments at 3.0 dS m^‐1, indicating that root compartmentalization and shoot exclusion were only possible at low salinities. Potassium levels of nodulating plant shoots were lower than those of non‐nodulating plants only at low salinities. N‐source significantly affected shoot K⁺/Na⁺ ratio, with nodulating plants having lower ratios than non‐nodulating plants, indicating that rhizobial infection or nodule formation may lead to salt entry curtailing the selective ability of chickpea roots.     

Effects of vermicompost and salinity stress on growth and physiological traits of Medicago rigidula L.

The use of vermicompost as a biological fertilizer under salinity stress conditions was tested in this research. Accordingly, the seeds of Medicago rigidula were grown in the greenhouse. The experiment was performed based on factorial arrangement in a completely randomized design using 5 replications. Application rates of vermicompost were 0, 10, 20 and 30%. Salinity stress was conducted in three levels (0, 50 and 100 mM sodium chloride (NaCl)). The highest and the lowest values of the plant survival capacity (%), shoot dry weight (g), leaf relative water content (LRWC) (%), total chlorophyll content (%), leaf area (cm²), total nitrogen content (TNC) (%) and potassium (K) content (%) of the plant tissues were found in VC4 × SL1 and VC1 × SL3 treatments, respectively. Whereas, the maximum and minimum values of root dry weight and root:shoot ratio were seen in VC1 × SL3 and VC4 × SL1 treatments, respectively.     

Alleviation of cadmium phytotoxicity by magnesium in Japanese mustard spinach

Abstract

To clarify the mechanism of Magnesium (Mg) in alleviating cadmium (Cd) phytotoxicity, Japanese mustard spinach (Brassica rapa L. var. pervirdis) was grown for 10 days after treatment in hydroponics in a growth chamber under natural light. The treatments were: (1) nutrient solution alone (Control), (2) 10 mmol L^?1 Mg (High-Mg), (3) 2.5 µmol L^?1 Cd (Cd-toxic), (4) 2.5 µmol L^?1 Cd plus 10 mmol L^?1 Mg (Mg-alleviated). The Cd-toxic treatment showed substantial growth retardation and chlorosis of young leaves, such symptoms were not observed in Mg-alleviated plants. Magnesium-alleviated plants showed higher shoot growth, more than twofold, and decreased shoot Cd concentration, approximately 40%, compared with Cd-toxic plants. This increase in shoot growth and simultaneous decrease in shoot Cd concentration may explain the alleviation of Cd toxicity with Mg in Japanese mustard spinach. In Cd-toxic plants, concentrations of K in shoots and Zn in both shoots and roots increased compared with the other three treatments. Concentrations and accumulations of Fe and Mn in shoots decreased significantly in the Cd-treated (Cd-toxic and Mg-alleviated) plants compared with the control and High-Mg plants. Thus, the application of high amounts of Mg in the nutrient solution can alleviate Cd toxicity in plants.     

Effects of Salinity and Water Stress on Echophysiological Parameters and Micronutrients Concentration of Pomegranate (Punica granatum L.)

In order to study the effects of salinity and drought stress on echophysiological parameters and micronutrients concentration of pomegranate leaves, a factorial experiment was conducted based on completely randomized design with 0, 30, and 60 mM of salinity levels of sodium chloride and calcium chloride (1:1) and three irrigation intervals (2, 4, and 6 days) with three replications on ‘Rabab’ and ‘Shishegap’ cultivars of pomegranate. The results analysis of shoot and root indicated that the water salinity and drought affected the concentration of iron (Fe²⁺), zinc (Zn²⁺), copper (Cu²⁺) and manganese (Mn²⁺) in pomegranate leaves and roots. Mineral concentration of zinc (Zn²⁺), copper (Cu²⁺) and manganese (Mn²⁺) in roots and manganese (Mn²⁺) in shoot was increased with increasing salinity. Drought treatments decreased the concentration of Zn²⁺ in the shoot and increased Zn²⁺ in roots. Both cultivars showed significant differences in the Fe²⁺ concentrations of shoot, however the most accumulation of Fe²⁺ was observed in ‘Shishegap’ cultivar.     

Phosphorus source,organic matter,and arbuscular mycorrhiza effects on growth and mineral acquisition of chickpea grown in acidic soil

Abstract

Plants grown in acidic soil usually require relatively high amounts of available phosphorus (P) to optimize growth and productivity, and sources of available P are often added to meet these requirements. Phosphorus may also be made available at relatively high rates in native soil when roots are colonized with arbuscular mycorrhizal fungi (AMF). Addition of P to soil usually reduces root‐AMF colonization and decreases beneficial effects ofAMF to plants. In glasshouse experiments, soil treatments of P [0 P (Control), 50 mg soluble‐P kg^?1 as KH₂PO₄ (SP), and 200 mg P kg^?1 as phosphate rock (PR)], organic matter (OM) at 12.5 g kg^?1, AMF (Glomus darum), and various combinations of these (OM+SP, OM+PR, AMF+SP, AMF+PR, AMF+OM, AMF+OM+SP, and AMF+OM+PR) were added to steam treated acidic Lily soil (Typic Hapludult, pH_w=5.8) to determine treatment effects on growth and mineral acquisition by chickpea (Cicer areitinum L.). The various treatment applications increased shoot dry matter (DM) above the Control, but not root DM. Percentage AMF‐root colonization increased 2‐fold or more when mycorrhizal plants were grown with AMF, OM+SP, and OM+PR. Regardless of P source, plant acquisition of P, sulfur (S), magnesium (Mg), calcium (Ca), and potassium (K) was enhanced compared to the Control, and mineral enhancement was greater in PR compared to SP plants. Mycorrhizal plants also had enhanced acquisition of macronutrients. OM+SP and OM+PR enhanced acquisition of P, K, and Mg, but not Ca. Concentrations of Fe, Mn, Cu, and Al were generally lower than Controls in SP, RP, AMF+PR, AMF+SP, and OM plants, and mycorrhizal plants especially had enhanced micronutrients. Relative agronomic effectiveness values for shoot DM and shoot P, Ca, and Mg contents were considerably higher for PR, including OM+PR, AMF+PR, and AMF+OM+PR, than for SP. PR and OM applications to AMF plants are low‐cost attractive and ecologically sound alternatives to intensive use of P fertilizers for crops grown in acidic soils.     

Metabolite profiling of shoot extract,root extract,and root exudate of rice under nitrogen and phosphorus deficiency

ABSTRACT

Root exudate is derived from plant metabolites and its composition is affected by plant nutrient status. A deficiency of mineral nutrients, such as nitrogen (N) and phosphorus (P), strongly affects the type and amount of plant metabolites. We applied a metabolite profiling technique to investigate root exudates of rice plants under N and P deficiency. Oryza sativa was grown in culture solution containing two N levels (0 and 60 mg N L^?1) or two P levels (0 and 8 mg P L^?1). Shoot extracts, root extracts, and root exudates were obtained from the rice plants 5 and 15 days after transplanting and their metabolites were determined by capillary electrophoresis/time-of-flight mass spectrometry. Shoot N concentration and dry weight of rice plants grown at ?N level were lower than those of plants grown at +N level. Shoot P concentration and dry weight of rice plants grown at ?P level were lower than those of plants grown at +P level. One hundred and thirty-two, 127, and 98 metabolites were identified in shoot extracts, root extracts, and root exudates, respectively, at the two N levels. One hundred and thirty-two, 128, and 99 metabolites were identified in shoot extracts, root extracts, and root exudates, respectively, at the two P levels. Seventy-seven percent of the metabolites were exuded to the rhizosphere. The concentrations of betaine, gamma-aminobutyric acid, and glutarate in root exudates were higher at both ?N and ?P levels than at their respective high levels. The concentration of spermidine in root exudates was lower at both ?N and ?P levels than at their respective high levels. The concentrations of the other metabolites in root exudates were affected differently by plant N or P status. These results suggest that rice roots actively release many metabolites in response to N and P deficiency.     

Combination of different marine algal extracts as biostimulant and biofungicide

This study investigates the efficiency of seaweed liquid fertilizer (SLF) prepared from combinations of different seaweeds (Sargassum polyphyllum, Turbinaria ornata, Gelidiopsis sp., Padina tetrastomatica, Gracilaria corticata) as a stimulant for the growth of Vigna radiata (Mung) as well as its antagonistic activity against fungal pathogens (Alternaria solani, Rhizoctonia solani., Sarocladium oryzae). 100% SLF was prepared, which was further diluted to 60%, 40%, and 20%. Seeds were soaked in four different concentrations of the SLF (20%, 40%, 60%, and 100%) for 12 hr and planted. After 60 d, the root and shoot length were increased by 14% and 16%, respectively, with SLF (100%). The carbohydrate and protein concentrations were also increased by 70% and 86%, respectively, at 100% SLF. The concentration of chlorophyll a, chlorophyll b, and carotenoids were found to be increased by 20%, 43%, and 28%, respectively, with 100% SLF. Further, the SLF (60% and 100%) successfully inhibited the growth of fungal pathogen A. solani but the other tested strains were found to be resistant. The present study indicates that 100% SLF concentration acts as both biostimulant and biofungicide for A. solani and thus, this SLF could be used as a potential alternative to the chemical fertilizers.