Enhancing of symbiotic efficiency and salinity tolerance of chickpea by phosphorus supply

This study aims to highlight the beneficial effect of the phosphorus on enhancing of growth plant, the efficiency of use rhizobial symbiosis and ionic partition in chickpea grown under salt stress. Exposure of plants to salt stress (0, 150 mM of NaCl) caused ionic imbalance, which resulted in increased Na⁺ and P and reduced K⁺ contents in the leaves and root. Indeed, stressed plants showed decrease of plant growth and phosphorus use efficiency. The efficiency use of rhizobial symbiosis was also affected by salinity. However, addition of two different level of phosphorus (37 and 55 mM) to saline soil increased significantly availability of P in plant organs. Specially, the (150 mM NaCl?×?37 mM P) mixture increased (33%) phosphorus use efficiency, induced better nodulation and increased plant biomass which results in the high efficiency in use of the rhizobial symbiosis. Our findings suggest that the combination of low level of P to saline soil presumably improved the tolerance of chickpea plant to salinity.

Abbreviations: phosphorus (P); phosphorus use efficiency (PUE); biological nitrogen fixation (BNF); plant dry weight (PDW); yeast extract mannitol (YEM); efficiency in use of the rhizobial symbiosis (EURS); shoot dry weight (SDW); symbiotic nitrogen fixation (SNF).     

Ameliorative Effect of Hydro Gel Substrate on Growth,Inorganic Ions,Proline, and Nitrate Contents of Bean under Salinity Stress

The effect of varying hydrogel (0, 0.5, and 1.0% w/w) supply on some agro-physiological properties, such as dry matter, nutrient contents, chlorophyll contents, proline content, and ionic balance of bean plants in different salt sources and stress due to doses were investigated. Plants were treated with eight salt sources [sodium chloride (NaCl), sodium sulfate (Na₂SO₄), calcium chloride (CaCl₂), calcium sulfate (CaSO₄), potassium chloride (KCl), potassium sulfate (K₂SO₄), magnesium chloride (MgCl₂), magnesium sulfate (MgSO₄)] and four concentrations (0, 30, 60, and 120 mM doses) for 60 days in a growth media. Salt type, doses, and hydrogel (HG) affected the soil electrical conductivity. Soil salinity affected the parameters considered, and changed the nutrient balance of plants. High salt concentration caused substantial reduction in plant growth. Different salt concentrations negatively affected plant dry weight. The highest decrease of plant root dry weight was obtained with NaCl application followed by Na₂SO₄, CaCl₂, CaSO_4, MgCl₂, MgSO₄, KCl, and K₂SO₄, and similarly NaCl, Na₂SO₄, CaCl₂, CaSO_4, KCl, K₂SO₄, MgCl₂, and MgSO₄ in root dry weight. Total chlorophyll and nitrate contents of plants decreased with increasing salt doses, and the lowest value was obtained for NaCl application. Proline contents of plants were increased with increasing salt doses, and the highest value was obtained with the NaCl application. The effects of salt concentrations in nitrogen (N), potassium (K), and phosphorus (P) content of plants were significant. The presence of salt in the growth medium induced an important decrease the macro nutrient of the root and shoot part of plant such as N, P, K, calcium (Ca), and magnesium (Mg) content, but the N and P content of root and shoot part of the plant were increased with increasing of the HG application doses. The highest N and P increases were obtained with the 1.0 HG application for all salt types for both the root and shoots of plants. The HG added to saline soil significantly improved the variables affected by high salinity and also increased plant N and P, reduced soil electricity conductivity, nitrate, proline, and electrolyte leakage of plants, enhanced plant root and shoot dry weight by allowing nutrients and water to release to the plant as needed. The results suggested that HG has great potential for use in alleviating salinity stress on plant growth and growth parameters in saline soils of arid and semi-arid areas. This HG appears to be highly effective for use as a soil conditioner in vegetable growing, to improve crop tolerance and growth in saline conditions. It is intended to confirm the results of these studies by field trials.     

INTERACTIONS BETWEEN COMMON BEAN GENOTYPES AND RHIZOBIA STRAINS ISOLATED FROM MOROCCAN SOILS FOR GROWTH,PHOSPHATASE AND PHYTASE ACTIVITIES UNDER PHOSPHORUS DEFICIENCY CONDITIONS

The improvement of common bean production requires the selection of effective rhizobia strains and Phaseolus vulgaris genotypes adapted to available soil phosphorus limitations. The interactions between bean genotypes and rhizobia were studied in hydroponic culture using six genotypes and four strains, CIAT899 as reference and three strains isolated from nodule of farmer's fields in the Marrakech region. The phosphorus (P) sub-deficiency caused a significant reduction on shoot biomass in some bean genotype-rhizobia combinations. Nodule biomass is significantly more reduced under P limitation for several combinations tested. Bean plants inoculated with these local rhizobial strains showed higher nodulation and an increase of nodules phytase and phosphatase activities under phosphorus sub-deficiency especially for RhM11 strain. It was concluded that the studied bean-rhizobia symbiosis differ in their adaptation to phosphorus sub-deficiency and the nodule phosphatases and phytases activities may constitute a strategy of nodulated bean plants to adapt their nitrogen fixation to P deficiency.     

Salicylic Acid–Induced Salinity Redressal in Hydroponically Grown Strawberry

The present study was conducted to evaluate shoot and root mineral composition of salt-stressed Selva strawberry under application timing of salicylic acid (SA). Treatments included plants sprayed with 0.5 or 1 mM SA, plants exposed to 40 mM sodium chloride (NaCl), and plants sprayed with 0.5 or 1 mM SA 1 week before, simultaneously, or after initiation of 40 mM salinity. Results indicated that under saline conditions, sodium (Na) and chloride (Cl) contents increased along with decrease in nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), and zinc (Zn) in shoot and root of plants. In plants treated with SA at 1 mM concentration, 1 week before salinity application, root Mg and shoot Ca were greater in comparison to salt-stressed plants treated with the same SA concentration 1 week after their exposure to salt stress. Thus, earlier SA application appears to be a better strategy for optimized protection against deleterious influence of salinity.     

Interactive effects of salinity and two phosphorus fertilizers on growth and grain yield of Cicer arietinum L.

Chickpea is considered among the most sensitive grain legumes to salinity. The improvement of tolerance of lines in combination with tolerant rhizobial strains depends on various environmental and cultural conditions such as soil properties. This investigation was undertaken to evaluate the effect of phosphorus fertilization (0, 90 and 200 kg ha^?1 of P₂O₅) on biomass, nodular traits and grain yield (GY) of chickpea (cv. Flip 84-79C) growing under salinity (0 and 150 mM NaCl). The trial was laid out following a randomized block design with three replicates during 2010–2012, at the experimental farm of Oued Smar (Algiers). Salinity did not significantly decrease the dry biomass of the plants but the relative shoot growth was more affected than control, P and SP1 treatments. Besides, salinity significantly reduced GY (?20%) and nodulation traits compared to the control plants while an inversely proportional relationship was found between protein, leghemoglobin and MDA content, K/Na ratio and the increase in salt concentration. Application of two P levels to saline soil enhanced growing conditions of plants. Particularly, the (90?kg?ha^–1 of P ×?150?mM?NaCl) combination significantly increased leghemoglobin (92%), reduced proline content (?69%) and protected membranes against peroxydation compared to saline conditions. A significant increase was observed in the GY (about 30%) of plants at both P doses combined with salt stress compared to other cases. Statistically, the low P level combined with salinity induced similar responses of plants and sometimes better responses to control plants. Finally, our results support the roles of phosphorus fertilizer in the alleviation of salt stress and enhancing the soil quality for better symbiosis efficiency and yield of chickpea.     

Barley response to salt stress at varied levels of phosphorus

Increasing plant phosphorus (P) supply can increase or decrease salt tolerance of many plants. Barley (Hordeum vulgare L., cv. ACSAD 176) was grown in nutrient solution under controlled conditions to determine effects of P level on detrimental effects of sodium chloride (NaCl). Increasing level of P improved tolerance of barley to NaCl. At 3, 30, and 60 μM P, the NaCl concentrations to reduce shoot dry matter (DM) by 50% were 158, 193, and 260 mM, respectively. Increased NaCl levels reduced shoot P concentrations. Plants grown with NaCl had higher Internal P requirements. When NaCl in solution was 10, 150, and 300 mM, the corresponding concentrations of P in shoots required to obtain 50% DM were 1.6, 4.2, and 4.7 mg‐g^‐1 dry weight, respectively. Increasing solution P level from 3 to 60 μM P decreased sodium (Na) and increased potassium (K) concentrations in shoots. Accumulation of mineral ions for osmotic adjustment and restriction of Na accumulation in shoots was involved in P enhancement of salt tolerance of barley.     

Growth,Mineral Composition,and Biochemical Changes of Broad Bean as Affected by Sodium Chloride and Zinc Levels and Sources

Plants grown in salt‐affected soils may suffer from limited available water, ion toxicity, and essential plant nutrient deficiency, leading to reduced growth. The present experiment was initiated to evaluate how salinity and soil zinc (Zn) fertilization would affects growth and chemical and biochemical composition of broad bean grown in a calcareous soil low in available Zn. The broad bean was subjected to five sodium chloride (NaCl) levels (0, 10, 20, 30, and 40 m mol kg^?1 soil) and three Zn rates [0, 5, and 10 mg kg^?1 as Zn sulfate (ZnSO₄) or Zn ethylenediaminetetraaceticacid (EDTA)] under greenhouse conditions. The experiment was arranged in a factorial manner in a completely randomized design with three replications. Sodium chloride significantly decreased shoot dry weight, leaf area, and chlorophyll concentration, whereas Zn treatment strongly increased these plant growth parameters. The suppressing effect of soil salinity on the shoot dry weight and leaf area were alleviated by soil Zn fertilization, but the stimulating effect became less pronounced at higher NaCl levels. Moreover, rice seedlings treated with ZnSO₄ produced more shoot dry weight and had greater leaf area and chlorophyll concentration than those treated with Zn EDTA. In the present study, plant chloride and sodium accumulations were significantly increased and those of potassium (K), calcium (Ca), and magnesium (Mg) strongly decreased as NaCl concentrations in the soil were increased. Moreover, changes in rice shoot Cl^?, Na⁺, and K⁺ concentrations were primarily affected by the changes in NaCl rate and to a lesser degree were related to Zn levels. The concentrations of Cl^? and Na⁺ associated with 50% shoot growth suppression were greater with Zn‐treated plants than untreated ones, suggesting that Zn fertilization might increase the plant tolerance to high Cl^? and Na⁺ accumulations in rice shoot. Zinc application markedly increased Zn concentration of broad bean shoots, whereas plants grown on NaCl‐treated soil contained significantly less Zn than those grown on NaCl‐untreated soil. Our study showed a consistent increase in praline content and a significant decrease in reducing sugar concentration with increasing salinity and Zn rates. However, Zn‐treated broad bean contained less proline and reducing sugars than Zn‐untreated plants, and the depressing impact of applied Zn as Zn EDTA on reducing sugar concentration was greater than that of ZnSO₄. In conclusion, it appears that when broad bean is to be grown in salt‐affected soils, it is highly advisable to supply plants with adequate available Zn.     

Growth and macronutrient contents of faba bean plants: Effects of salinity and nitrate nutrition

The effects of the interaction between sodium chloride, nitrate, and concentrations on growth and internal ion content of faba bean (Vicia faba L.) plants were studied, to understand the relationship between the above parameters and salt tolerance. Increased salinity substantially reduced the dry weight of roots and shoots and increased the root/shoot biomass ratio. Additional nitrate‐N considerably moderated the salinity effects on these parameters. The promotive effects of nitrate‐N were more pronounced on shoot dry weight. These results suggest that an exogenous supply of nitrate‐N would improve the vegetative growth of V. faba plants by moderating the suppresive effects of salinity. The evolution of the root and shoot content in potassium (K), sodium (Na), magnesium (Mg), calcium (Ca), and nitrogen (N) was monitored during vegetative growth. A high correspondence between total N and Ca content was found. The acquisition of Ca and K in response to salt and nitrate was similar in shoots and roots, whereas Mg uptake showed notable differences in the two organs. In salt‐affected plants, the roots were found to be high in accumulated Na while the shoots exhibited the lowest Na concentration. Potassium accumulation was higher in the shoots. In this way, there was an antagonistic effect between Na and K uptake. Analyses of the nutrient contents in plant organs have provided a data base on salt‐tolerance mechanisms of V. faba plants.     

Salinity effects on growth analysis and nutrient composition in four grain legumes‐rhizobium symbiosis

The effect of salinity on growth response, nitrogen (N) fixation and tissue mineral content was investigated for four legumes: faba bean (Vicia faba L), pea (Pisum sativum L), soybean (Glycine max L), and common bean (Phaseolus vulgaris L). Plants were grown in a vermiculite culture system supplied with a N‐free nutrient solution with the addition of 0, 50, and 100 mM NaCl. Plants were harvested at the beginning of the flowering period and the dry weights of shoots and roots and acetylene reduction activity (ARA) were evaluated at the same time plant tissues were analysed for N, potassium (K), calcium (Ca), magnesium (Mg), and sodium (Na) contents.

The depressive effect of saline stress on ARA of nodules was directely related to the salt induced decline in dry weight and N content in shoots. Growth inhibition by NaCl treatments was greater for the pea than for other legumes, whereas the soybean was the most salt‐tolerant Saline stress also affected the N content in shoots and roots. In general the N content accumulated in the shoot and Na in the roots of the four legumes tested, while K accumulated both organs. The acquisition of other macronutrients differed according to the legume species. The legumes most sensitive were P. sativum and V. faba which accumulated Ca in shoot and Mg both in the shoot and the roots. On the contrary, in G. max and P. vulgaris, the two most salt tolerant legumes, accumulated Mg in the roots and Ca in both vegetative organs. Our results suggest a relationship between the salt‐tolerant range in legumes and the macronutrient accumulation in vegetative organs.     

Effect of salinity on growth,nodulation and nitrogen assimilation in nodules of faba bean (Vicia faba L.)

A commercial cultivar (Alborea) of faba bean (Vicia faba L. var. minor) was inoculated with salt-tolerant Rhizobium leguminosarum biovar. viciae strain GRA19 in solution culture with different salt concentrations (0, 50, 75 and 100 mmoles l⁻¹ NaCl) added immediately at the time of inoculation. The results indicated that Rhizobium leguminosarum strain GRA19 formed an infective and effective symbiosis with faba bean under saline and nonsaline conditions. Salinity significantly decreased shoot and root dry weight, nodule weight and mean nodule weight. Roots were more sensitive than shoots, and N₂ fixation was more sensitive to salinity than was plant growth. Analyses of ammonium assimilating enzymes in the nodule showed that glutamine synthetase appeared to be more tolerant to salinity than glutamate synthase, and that it limits ammonium assimilation under saline stress.     

Nitrogen,Phosphorus, and Sulfur Nutrition in Broccoli Plants Grown Under Salinity

Broccoli (Brassica oleracea L. var. ‘Italica’) is a recognized health-promoting vegetable and shows a moderate sensitivity to salinity. As very little is known about the effect of salt stress on broccoli plants, the objective was to evaluate nitrogen (N), phosphorous (P), and sulfur (S) nutrition in plants grown under saline conditions. For this objective, the contents of nitrate, phosphate, and sulfate, and total nitrogen, phosphorus, and sulfur, as well as related metabolic enzymes, were determined for plants grown with 0, 20, 40, 60, 80, or 100 mM sodium chloride (NaCl) for two weeks. Nitrate, phosphate, and sulfate concentration in leaves and roots showed a maximum at 40–60 mM NaCl. Up to these salt levels, broccoli plants showed a normal development, but over these salt levels, broccoli plants showed a decrease of nitrate reductase and an increase of the acid phosphatase. From 60 to 100 mM NaCl, the nutritional disorders indicated that the threshold of resistance was exceeded.     

Salt tolerance and mineral relations for celery

To invertigate the relationship between salt tolerance and plant mineral status in celery (Apium graveolens L.) growth and the concentration of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sodium (Na), and chloride (Cl) in different tissues were determined in plants grown in hydroculture with nutrient solutions containing 5 (control), 50,100, and 300 mM sodium chloride (NaCl) for four weeks. At salinity levels of 50 and 100 mM NaCl, there was a moderate, albeit significantly, reduction of growth, while a drastic decrease in both fresh and dry weight was obtained at 300 mM NaCl. Regardless of the salinity level, growth resumed promptly and completely once the stress was ceased. Sodium chloride stress reduced the accumulation of nitrate (NO₃)‐N in all plant tissues, but there were no relevant effects on the concentration of reduced N and P. The concentration of K in roots and leaf petioles was unaffected by NaCl treatment, but it gradually declined with increasing salinity in leaf blades. This reduction was less pronounced in the young leaves as compared to the mature ones. Increasing the NaCl concentration decreased the concentration of Ca in all tissues, but it prevented the occurrence of black‐heart, a typical Ca‐related physiological disorder which affected severely the controls. Salt‐stressed plants absorbed large amounts of Na and Cl which accumulated in the mature leaves, particularly in the oldest leaves. These findings suggest that the relatively high salt tolerance of celery relies on the ability to maintain an adequate nutritional status and to protect the shoot meristem from salt toxicity.     

INTERACTIVE EFFECTS OF SALINITY AND PHOSPHORUS NUTRITION ON PHYSIOLOGICAL RESPONSES OF TWO BARLEY SPECIES

Salinity is one of the most important agricultural problems in Iran. The effect of different levels of salinity and phosphorus on shoot length, root and shoot fresh and dry weight, nutrient elements (sodium (Na⁺), potassium (K⁺), phosphorus (P) and chloride (Cl^?), proline and soluble sugar contents of barley were investigated. Two cultivars of barley, Hordeum murinum (wild resistant germplasm) and Hordeum vulgar, variety Afzal were treated in vegetative stage under hydroponics condition in a factorial arrangement based on completely randomized block (CRB) design with four levels of salinity [0, 100, 200 and 300 mM sodium chloride (NaCl)] and three levels of phosphorus (15, 30 and 55 μm L^?1) with three replications. By increasing salinity, all the measured parameters, except sodium (Na⁺) content were reduced. Furthermore, with increased in phosphorus levels from 15 to 55 μm, Na⁺ content of the plant shoots decreased, but length, fresh and dry weights of roots and shoots and K⁺, P, Cl^?, proline, and soluble sugars content of the shoots increased. The results indicated that accumulation of mineral ions for osmotic adjustment and restriction of Na⁺ accumulation in shoots were involved in phosphorus enhancement of the salt tolerance of barley. Thus, it seems that in saline soils, where there is no possibility for soil leaching and amending, application of phosphorus fertilizers can lead to a satisfactory growth and production in barely yield.     

Effects of salinity and nitrogen source on growth and nitrogen fixation in alfalfa

The Interaction between the effects of nitrate (NO₃) and sodium chloride (NaCl) concentration on growth) water relations, nitrogen (N) contents and N fixation were investigated in alfalfa (Medicago sativa L. cv. Magali). The plants were grown hydroponically in a growth chamber, in the presence or absence of 3 mM potassium nitrate (KNO₃) and exposed to various concentrations of NaCl. Increased salinity resulted in a significant decrease in shoot and root biomass, relative water content and water potential. Shoot growth was more inhibited by NaCl than root biomass. The plants grown in the presence of NO₃ were slightly less affected by NaCl than the plants dependent on N fixation for their N nutrition. Nitrogenase activity measured by acetylene reduction activity was substantially inhibited by NaCl, and this inhibition was significantly correlated to the inhibition of shoot growth and total N contents. The comparison of the curves of ARA response to oxygen (O₂) partial pressure showed that the salt‐induced inhibition of nitrogenase activity was associated with a significant increase in the critical O₂ pressure of the nodules exposed to NaCl. This result shows that NaCl decreases the nodule permeability to O₂ diffusion in undeterminate nodule of alfalfa, like previously shown with determinate nodules of soybean.     

Effect of salt stress on Growth and Ion accumulation of alfalfa (Medicago sativa L.) cultivars

Alfalfa (Medicago sativa L.) yield and nutrient contents may be affected under salinity condition. Thus, this experiment was conducted to determine the effect of three salinity levels (60, 120, and 180 mM NaCl) on shoot and root dry weights, and mineral contents of three alfalfa cultivars. With the increasing salinity levels sodium (Na) and magnesium (Mg) contents increased; but potassium (K), nitrogen (N), phosphorous (P), calcium (Ca), zinc (Zn), and copper (Cu) contents and root and leaf weights decreased; however, changes in these traits depended on cultivar and salinity level. However, Rehnani, a tolerant cultivar, had the lowest Na and Mg contents and the highest K, N, P, Ca, Zn, and Cu contents and dry weights under all of the salinity levels. Moreover, leaf dry weight and leaf P content had the highest correlation with salt tolerance suggesting that these traits may be used as a marker for selecting salts that are tolerant among genotypes in alfalfa.     

Brassinosteroid (BR) and arbuscular mycorrhizal (AM) fungi alleviate salinity in wheat

This study was conducted to assess the impacts of brassinosteroide (BR), arbuscular mycorrhizal (AM) fungi, Glomus mosseae and their interactions on salt stress tolerance in Triticum aestivum L. After foliar spraying of mycorrhizal and non-mycorrhizal plants by 5 µM epibrassinolide, they were subjected to 0 and 150 mM sodium chloride (NaCl) for 2 weeks. The experiment was conducted in a randomized complete block design, replicated 4 times. Our results showed a probable potential of BR and/or AM fungi in improving salt tolerance of plants. Total phenol and proline content increased in BR and/ or AM treatments. AM fungi promoted plant growth, including leaf area, shoot and root dry weights, and lengths under saline condition. Moreover, BR improved growth parameters except root dry weights and lengths. This study indicated that BR and/or AM fungi may contribute to improve salt tolerance of the plant.     

Genotypic Variation in Nodule Iron Content of Common Bean (Phaseolus Vulgaris L.) in Response to Phosphorus Deficiency

Common bean (Phaseolus vulgaris L.) can supply all of the iron that humans require for metabolism. Also, it fixes atmospheric nitrogen (N₂) in symbiosis with rhizobia. In order to analyze the relation between phosphorus (P) and iron (Fe) elements in nodules and their roles for the plant N₂-dependent growth, six common bean recombinant inbred lines (RIL) of the cross of BAT477 and DOR364 were inoculated with Rhizobium tropici CIAT 899 (originating from International Center of Tropical Agriculture, Colombia) and grown with sufficiency versus deficiency P supply in hydroaeroponic culture. Under P deficiency, the Fe content in nodules decreased in all studied genotypes and was significantly the highest for RIL 34. The nodule contents of Fe and P were significantly correlated under P deficiency. It is concluded that the regressions of nodule Fe content as a function of P content in nodules, roots and shoots, depend upon P supply and genotype.     

Pomegranate Growth Affected by Arbuscular Mycorrhizae,Phosphorus Fertilizer,and Irrigation Water Salinity

Pomegranate (Punica granatum L.) symbiosis with arbuscular mycorrhizae fungi (AMF) is a strategy in saline soils. In this study, two AMF (+AMF and –AMF), two phosphorus (P) fertilizer (+ P and –P), and three irrigation salinity (1, 4, and 8 dS m^?1) treatments were studied. The highest salinity level decreased the root colonization by hyphae. Plant growth parameters including shoot dry weight, leaf surface area, and plant height were negatively affected by salinity. However, the growth parameters improved in AMF treatments. Salinity decreased the shoot P concentration and increased the shoot chlorine (Cl). The root and shoot sodium (Na) concentrations were the greatest in unfertilized and P-fertilized treatments, respectively. AMF treatment improved the root and shoot P concentration and reduced the negative effect of salinity on shoot Cl concentrations. In conclusion, the effects of AMF symbiosis on growth and tissue elements concentration depend on irrigation water salinity and P fertilization.     

MODULATION OF PHYSIOLOGICAL AND BIOCHEMICAL METABOLITES IN SALT STRESSED RICE BY FOLIAR APPLICATION OF ZINC

An experiment was conducted to evaluate the effect of zinc (Zn) application on five rice cultivars grown under salt stress conditions. Two salinity levels of 0 and 10 dS m^?1 were created with sodium chloride (NaCl) and foliar spray of Zn (0.05%; Chelated-Zn) was applied. A decrease in growth and yield related parameters were observed under salt stress, which was ameliorated in plants that received Zn foliar spray. Similar effects of salinity and Zn foliar spray were noted on photosynthetic rate, transpiration rate, stomatal conductance, water use efficiency, and water relations of plants. Salt induced increase in sodium (Na) content and decrease in other macro- and micronutrients contents were also reversed by Zn. Other salt tolerance indicating parameters likSe total free amino acids and total soluble sugars increased under Zn spray, clearing its role in improving salt tolerance.     

EFFECTS OF PLANT GROWTH PROMOTING BACTERIA ON YIELD,GROWTH, LEAF WATER CONTENT,MEMBRANE PERMEABILITY,AND IONIC COMPOSITION OF STRAWBERRY UNDER SALINE CONDITIONS

Plant growth promoting effects of Bacillus subtilis EY2, Bacillus atrophaeus EY6, Bacillus spharicus GC subgroup B EY30, Staphylococcus kloosii EY37 and Kocuria erythromyxa EY43 were tested on strawberry cv. ‘Fern’ in terms of fruit yield, growth, chlorophyll reading value, leaf relative water content (LRWC), membrane permeability and ionic composition of leaves and roots under saline conditions. Compared with 0 mM sodium chloride (NaCl) treatment, the average decrease of yield and LRWC were 51.6% and 21.0%, respectively, when 35 mM NaCl was applied. However, EY30, EY37, and EY43 treatments under saline condition (35 mM NaCl) significantly increased fruit yield (54.4%, 51.7% and 94.9%) compared with 35 mM NaCl treatment without plant growth promoting bacteria (PGPB). The LRWC increased from 72.0% in 35 mM NaCl treatment to 88.4%, 86.6%, 84.2%, 83.5%, and 86.2% by EY2, EY6, EY30, EY37, and EY43 applications, respectively. The lowest membrane permeability among the bacterial strains was obtained from EY37 treatment (37) while it was 33 and 58 in 0 mM NaCl and 35 mM NaCl treatments, respectively. The concentration of all plant tissue nutrients investigated [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)] with the exception of root phosphorus (P) and Mg concentration significantly decreased with 35 mM salt treatment. Nitrogen content of leaves varied between 3.04 and 3.14% in bacterial treatments under saline conditions while it was 2.71% in 35 mM NaCl treatment. In contrast sodium (Na) and chloride (Cl) of leaves and Cl content of roots were significantly decreased by root inoculation with all bacterial treatments in comparison to 35 mM NaCl treatment with no inoculation. Treatment with Bacillus EY30, Staphylococcus EY37 and Kocuria EY43 to strawberry plants can ameliorative the deleterious effect of salt stress on fruit yield, growth and nutrition. These results demonstrate that PGPB treatment could be offer an economic and simple means to increased plant resistance for salinity stress.