Mycorrhiza and soil fertility effects with growth,nodulation and nitrogen fixation of leucaena grown on a typic eutrustox

Abstract

The rapidly growing, woody perennial legume, Leucaena (Leucaena leucocephala (Lam.) de Wit), is adaptable to a wide range of neotropical soil conditions. Effective Rhizobium inoculation and endophyte mycorrhizal colonization are essential for high levels of production and symbiotic N₂ fixation. The objective of this study was to determine growth, nodulation, nitrogenase activity and nodule composition of inoculated Leucaena as affected by mycorrhizal colonization and factorial soil fertility treatments of a Typic Eutrustox. Highly significant increases in top growth, nodule fresh wt. and nitrogenase activity resulted with Glomus fasciculatum colonization, soil K and linear increases with low‐soluble P fertilization to 300 mg P kg^‐1 soil. Highly significant interactions for increased nodulation and nitrogenase activity resulted with K × mycorrhiza. Interactions of all three factors P, K and mycorrhiza were highly significant for nodule fresh wt. However, responses comparing inoculation with G. fasciculatum and with combined G. fasciculatum, G. microcarpus and G. clavium were not significant. Highly significant increases with applied K levels to 300 mg K kg^‐1 soil resulted with top and root growth, nodulation and nitrogenase when applied with soluble P at 100 mg kg^‐1 soil and 500 mg Ca kg^‐1 soil. Significant and highly significant interactions of P, Ca and K level resulted for all parameters. Plant nutrient element composition of nodules increased with the fertilization treatments for P, Ca and increased K levels. A highly significant inverse relation was apparent with decreased Na resulting with increased K levels. Half or more of total nodule K, P and Mg but less than 20% of Ca and Na were within the nodule cytosol. Sodium, Mg, P, and Ca decreased in the cytosol fraction with increased K content.     

Soil fertility effects on growth,nitrogen fixation,nodule enzyme activity and xylem exudates of lablab purpureus (L.) sweet,grown on a typic eutrustox

Abstract

The Lablab or Hyacinth bean, Lablab purpureus (L.) Sweet, is a drought tolerant grain‐forage legume widely grown within a wide range of neotropical regions of the world. It has been an important cultivated food grain crop for many centuries within extensive warm humid‐subhumid climatic areas and grown on widely different Ultisol and Oxisol soil types. The objective of these studies was to determine soil fertility effects of Ca, P, and K factorial combinations applied to a Typic Eutrustox on growth, nodulation, and nitrogen fixation of Lablab bean. Stem and nodule xylem components were determined along with soil pH and nitrification within the nodule rhizosphere. Highly significant increases resulted with P fertilization for stem, leaf, seed, nodulation, and nitrogenase activity. With the exception of nitrogenase, all were also increased with K additions. Both stem and seed were significantly increased with Ca treatments. Highly significant increases for total plant N content resulted with P, K, Ca, and P x K interaction. Allantoinates were initially dominant components of stem xylem exudate following decapitation but were not detected after 5 days. Amino‐amide composition remained relatively constant. Nitrates increased from 1.6 to 81.8 ug N ml^‐1 exudate during the 8 day collection period. Soil nitrate levels adjunct to decomposing nodules increased from 4.2 to 1661.1 ug g^‐1 soil. Initial high levels of ureide transforming enzymes ALTN, ALTC, and URC were not detected after 4 days. Amine‐amide enzymes AST, GS, GOGAT, and GDH were relatively constant with nitrate reductase increasing from 0.12 to 9.35 IU ml^‐1 xylem exudate during the 8 d period. Nodule xylem export components were dominated by ureides, 429.8 umol, and amines 30.3 umol ml^‐1. Enzyme activity levels were highest for AST 22.17 and GS 13.25 IU ml^‐1 with the ureide enzymes URC 2.24, ALTN 0.26, and ALTC 0.15 IU ml^‐1 . Nodule exudate composition was K 422.0, P 63.4, Ca 53.8, Mg 42.8, and Na 25.6 ug ml^‐1.     

Perennial winged bean yield and nitrogen fixation improvement with soil fertility treatments of a typic eutrustox

The perennial legume, Winged Bean (Psophocarpus tetragonolobus (L) DC), has potential as a high protein food crop for the humid, tropical regions of the world. Edible seed pods, oil seed grain, leaves, flowers, and unique high protein tubers provide abundant nutritious components desirable for improved human diets. However, soil characteristics and fertility levels influence plant growth, yields and nitrogen fixation capability of this legume. Objectives of this study were to determine soil‐plant nutrient influences on vigorous regrowth, pod and tuber yields, nitrogenase (C₂H₂ red.) activity levels, and nodule cytosol components of the perennial Siempre cultivar grown on a Typic Eutrustox during three years, 1978–1980.

Available soil phosphorus was a first limiting plant nutrient during all three years of plant age. Effects of combined 100 mg P with 200 mg K/kg soil were highly significant for every parameter and plant age. Pod and seed yields more than doubled with PK addition compared to the check. Tuber growth, nodule mass and nitrogenase activity levels more than trebled with PK treatments as compared to the check. Both elemental P and K were significantly increased within the nodule cytosol of fertilized plants. Cytosol Na was significantly decreased with soil K additions. The best fit multiple regression was: nitrogenase = 1.99 nodule wt. + 6.34 tuber wt. + 0.39 tuber % N + 5.08 cytosol P + 1.55 cytosol K ‐ 0.45 cytosol Na, R² = 95.5, C.V. = 11.2%. The dominant nodule cytosol enzymes, aspartate aminotransferase (AST) and glutamine synthetase (GS), significantly increased with soil K additions regardless of P treatments. Glutamate dehydrogenase (GDH) and glutamate synthase (GOGAT) also contributed significantly with multiple regression for nitrogenase = 1.07 GS + 2.1 AST + 1.74 GOGAT ‐ 1.76 GDH + 12.89 Ureide, R² = .89, C.V. = 17.3%. Highly significant increases in nodule cytosol ureide composition with K soil additions has interest because of the role as a nitrogenous nonprotein component for many legumes. Increases in growth, nodulation and nitrogenase activity levels resulted with increased K levels of 0, 100, 200 and 300 mg K/kg soil when soil P and Ca were not limiting.     

Soil fertility effects on nodulation,nitrogen fixation,and yields of guar, (Cyamopsis tetragonoloba (L.) Taub.), grown on a typic eutrustox

Guar (Cyamopsis tetragonoloba (L.) Taub.) is a legume of unusual industrial importance due to increased utilization of Guar gum, ‘Guran,’ in numerous modern manufacturing and food processes. Guar has high tolerance of drought and inhibitory soil characteristics and has been utilized for many centuries within the subhumid regions of the Indo‐Pakistan subcontinent. Nodulation, nitrogen fixation, and yields of high protein seed with desirable Guran content are improved by favorable soil fertility. Plant growth, seed yields, and nodulation are influenced by plant population density.

Top Growth quadratically increased with plant population densities of 10, 25, and 50 plants per meter² for P and P+K treatments. Highest seed yield and nodule development resulted for all soil fertility treatments with 25 plant per meter². Ontogenetic response from anthesis to full seed maturity resulted with increased nodulation significantly correlated (r = 0.67) with top growth. However, nitrogenase activity levels plant‘¹ declined significantly with plant maturity. Nodule cytosol enzyme activity levels at anthesis were: allantoinase (ALTN) 29.5 IU, aspartate transaminase (AST) 19.3 IU, glutamine synthase 12.5 IU, uricase (URC) 2.25 IU, and allantoicase (ALTC) 0.14 IU g^‐1 fresh nodule. Cytosol composition included ureidoglycolates (ureides) 425.8 μmol, amine‐amide content 29.5 μmol, nitrate 1.95 μmol, pyruvate 0.21 μimol, and oketoglutarate 0.09 μmol g‘¹ fresh nodule. Plant nutrient composition of nodule cytosol was K 394.9 jig, P 59.4 μg, Ca 48.9 μg, Mg 39. μg, and Na 19.0 μg g^‐1 fresh nodule. Precise histology with Giemsa and PAS procedures were essential for microscopy with cellular compartmentalization of purine enzymatic transformations governing nitrogenase activity and nodule development.     

Soil fertility effects on growth,yield, nodulation and nitrogenase activity of Austrian winter pea

Austrian winter pea (Pisum sativum subspecies arvense (L.) Poir) is grown as a cool season annual to produce high protein seed and forage as well as for soil fertility improvement. This legume is grown on a wide range of soil types with many different cropping systems. The objective of these studies was to determine the influence of K levels, with and without P and Ca fertilization, for increased growth, yield, nodulation and nitrogenase activity. Results were from 3 years’ field and greenhouse experiments with a Psammentic Paleustalf (Eufaula series) utilizing Rhizobium leguminosarum (Frank), ATCC 10314 as inoculum. Soil fertility effects on composition and histology of field‐grown nodules are presented.

Available soil P was a limiting plant nutrient in field studies with significant response to K resulting with PK combinations for top growth, tillers, pods, seed yield, nodule mass, and nitrogenase activity levels (C₂H₂, red.). Multiple regression for nitrogenase (umol C₂H₄ h^‐1) = 1.09 tiller number + 3.37 nodule weight + 2.29 pod number, R² = 0.837, C.V. = 29.9%. Results from the greenhouse experiments indicated significant responses with increased K application levels when combined with P and Ca fertilization for top growth, nodule weight, number of nodules and nitro‐genase activity. Highly significant correlations resulted with nitrogenase x nodule weight (r=0.538) and nitrogenase x top growth (r=0.359) with multiple regression of treatment effects for nitrogenase (μmol C₂H₄ h^‐1) = 2.73 P + 1.04 K + 4.92 Ca, R² = 0.797 and C.V. = 48.8%. Soil addition of plant nutrients resulted in significantly increased concentrations of those elements within nodules. Magnesium content was not consistently influenced by P, Ca, and K amendments. Sodium decreased with increased K fertilization. Multiple regression of elemental composition (mg g^‐1 nodule) for nitrogenase (pmol C₂H₄ h^‐1) = 0.21 P + 0.86 K + 2.35 Ca ‐ 2.01 Na, R² = 0.772, C.V. = 55.6%. The proportion of plant nutrients in nodules contained within the nodule cytosol was highest for K (56.2%) and lowest for Ca (21.4%) with intermediate levels of Mg (50.2%), P (45.4%), and Na (37.2%).

Practical application from these data include the requirement of adequate available soil K for increased yield and nitrogen fixation with favorable P and Ca soil levels in Austrian winter pea production.     

Effects of changes in applied nitrogen concentrations on nodulation,nitrogen fixation and nitrogen accumulation during the soybean growth period

ABSTRACT

The specific mechanism by which nitrogen application affects nodulation and nitrogen fixation in legume crops remains uncertain. To further study the effects of nitrogen application on soybean nodulation and nitrogen accumulation, three consecutive tests were performed during the VC-V4, V4-R1 (10 days), and R1-R2 (10 days) growth periods of soybean. In a dual-root soybean system, seedlings on one side were watered with a nutrient solution containing NH₄⁺ or NO₃^? as the N source (N+ side), and those on the other side were watered with a nitrogen-free nutrient solution (N- side). During the VC-R2 period, on the N+ side, high nitrogen treatment inhibited nodule growth and nitrogenase activity (EC 1.18.6.1), and the inhibition was significantly increased with increasing high nitrogen supply time (10 days, 20 days). When the high nitrogen treatment time reached 20 days, the specific nitrogenase activity (C₂H₄ μmol^?1 g^?1 nodule dry mass h^?1) was similar to that in the low nitrogen treatment, indicating that the nitrogen fixation capacity per gram of dry mass nodules was almost the same. Therefore, it is assumed that long-term high nitrogen treatment mainly reduces nitrogen fixation by reducing the nodule number. The effect of nitrogen concentration on the roots on the N+ side was greater than that on the N- side. Taken together, these results indicate that nitrogen application affects a contact-dependent local inhibition of root nodule growth, nitrogenase activity, and nitrogen accumulation. The whole plant systematically regulates specific nitrogenase activity, and high nitrogen inhibition is recoverable.     

Rhizobiophage effects on nodulation,nitrogen fixation,and yield of field-grown soybeans (Glycine max L. Merr.)

Summary Previous laboratory and greenhouse studies have shown that phages significantly reduce soil populations of homologous rhizobia. Reductions in nodulation and N₂ fixation have also been observed. The purpose of the current study was to examine the effect of a phage specific ofBradyrhizobium japonicum USDA 117 on nodulation, nodule occupancy, N₂ fixation and soybean growth and yield under field conditions. The phage was inoculated in combination withB. japonicum USDA 117 and/orB. japonicum USDA 110 (resistant strain) into a rhizobia-free sandy loam soil and planted toGlycine max (L.) Merr. Williams. When the phage was applied to soil inoculated withB. japonicum USDA 117 alone, significant reductions in nodule weight and number, shoot weight, foliar N, nitrogenase activity, and seed index were observed. When, however, the soil also contained the non-homologous strain,B. japonicum USDA 110, no significant effects on any of these parameters were found. Nodule occupancy by competing strains ofB. japonicum USDA 110 and USDA 117 was also affected by the phage. In soil which did not contain the phage, 46% and 44% of the identified nodules were occupied by USDA 110 and 117, respectively. When the phage was present in the soil, nodule occupancy byB. japonicum USDA 117 was reduced to 23%, while occupancy byB. japonicum USDA 110 was increased to 71%. These results suggest that nodulation by selected strains of rhizobia can be restricted and nodulation by more effective, inoculated strains can be increased through the introduction of a homologous phage to soils.     

Soil fertility effects with tripartite symbiosis for growth,nodulation and nitrogenase activity of vicia faba L

Fababean (Vicia faba L.) is one of the oldest known important grain legume food crops grown within the temperate and subtropical regions of the world. This species is adapted for both forage and food grain production as a cool season annual crop on a wide range of soil and climatic conditions with effective tripartite symbiosis. Both Rhizobium and endophyte mycorrhiza are essential for high levels of production and symbiotic N₂ fixation. The objective of these greenhouse and field studies was to determine effects of Glomus fasciculatum colonization with soil fertility treatments to a Psammentic Paleustalf (Eufaula series) on growth, nodulation, nitrogenase activity and nodule composition for V. faba, var. Major, fuh Rumi (Nile) inoculated with R. leguminosarum Frank.

Top growth and nodule mass were increased approximately 10 fold and nitrogenase activity about 7 fold with the highly significant effect of mycorrhiza and response to low soluble Ca₃(PO₄)₂ fertilization in greenhouse studies. With both effective mycorrhiza and Rhizobium inoculation in the field experiments, seed yields were correlated with top growth (r = 0.841). Phosphorus and Ca fertilization resulted in highly significant increases in seed yields. Nitrogenase activity was correlated with nodule wt. (r = 0.958) and highly significant increases resulted with P and Ca soil amendment. Plant nutrient element composition of nodules increased with the fertilization treatments for P, Ca and increased K levels. Sodium content decreased significantly with increased K fertilization (r = ‐0.846). Potassium composition increased significantly with P content (r = 0.523). Enhanced N₂‐fixation along with increased high protein forage and food grain production with Fababeans have much potential. However, soil fertility and management techniques for improved production include effective mycor‐rhizal colonization.     

The inorganic N requirement,nodulation and yield of common bean (Phaseolus vulgaris L.) as influenced by inherent soil fertility of eastern Ethiopia

Though mineral N application impaired nodulation initiation and function, it improves the productivity of common bean. The effect of inorganic application on common bean productivity, however, is dependent on the availability of plant nutrients including nitrogen (N) in the soils. Therefore, multilocation field experiments were conducted at Babillae, Fedis, Haramaya, and Hirna to evaluate the effect of inherent soil fertility status on responsiveness of common bean to different rates of N fertilizer application and its effect on nodulation, yield, and yield components of common bean. The treatments were six levels of N fertilizer (0, 20, 40, 60, 80, and 100 kg N ha^?1) laid out in randomized completed block design with three replications. The result revealed that 20 kg N ha^?1 application significantly improved the nodule number (NN) and nodule dry weight (NDW) except Hirna site, in which reduction of NN and NDW was observed. Although the remaining investigated yield and yield components were significantly improved due to N fertilizer in all study sites, 40 kg N ha^?1 application resulted in significantly increased GY of common bean at Fedis, Haramaya, and Hirna site, while 60 kg N ha^?1 at Babillae site. The highest total biomass yield (7011.6 kg ha^?1) and GY (2475.28 kg ha^?1) of common bean were recorded at Hirna and Haramaya sites, respectively, indicating the importance of better fertile soil for good common bean production. Hence, it can be concluded that the effect of inorganic N on common bean was irrespective of soil fertility rather the total amount of N in soil would affect the need of different rate of inorganic N.     

氮肥对大豆结瘤固氮、籽粒产量和蛋白质含量的影响

【目的】合理施用氮肥不仅可提高大豆结瘤固氮能力,还可减少农业污染,实现大豆生产的高产优质高效。研究施氮时期和施氮量对大豆结瘤固氮、产量及蛋白质含量的影响,为大豆高产优质提供理论基础及科学依据。【方法】采用盆栽试验,供试大豆品种为‘东生35’,试验设2个氮肥施用时期(V2期和R1期)和3个氮肥施用量[N 0、5、100 mg/(kg,土)],表示为N0、N5和N100。在大豆R2期(盛花期)和R5期(鼓粒期)取样分析了地上部干物质积累量、根瘤数量、根瘤干重和固氮酶活性。在R8期(成熟期)调查了大豆籽粒产量和蛋白质含量。【结果】施氮时期和施氮量对大豆地上干物质积累、结瘤和固氮能力均有显著影响。不论是V2期还是R1期施氮,大豆地上部干物质积累量均随着施氮量的增加而增加,而根瘤干重、数量则呈降低的趋势。R1期施氮条件下,N100处理的大豆盛花期根瘤数量和根瘤干重比N0分别下降了42.3%和32.8%,而固氮酶活性则均以N5处理最高;V2期施氮条件下,N5处理的大豆固氮酶活性在R2期和R5期较N0处理分别增加15.3%和27.1%。大豆籽粒产量和蛋白质含量均以N5处理最高,籽粒蛋白质含量较N0处...     

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.     

Effect of organic matter on the growth,nodulation, and nitrogen fixation of soybean grown under acid and saline conditions

Abstract

A field experiment was conducted to examine the effects of two organic materials (Bark and Tenporon composts) on the growth, nodulation and nitrogen fixation (measured as acetylene-reducing activity) of soybean plants (Glycine max L.) under acid and saline conditions. These organic materials were incorporated into acid and saline (induced by irrigating the soil with a NaCl solution) soils at 4% rate of application.

These composts tended to improve nodule formation in soybean under acid and saline conditions, especially in the plants treated with Bark compost. Acetylene-reducing activity was significantly (P<0.05) increased by these composts under acid condition.

These composts also tended to improve shoot growth under acid and saline conditions, presumably due to the improvement of the soil moisture status of the soils and nutrient uptake. These results suggest that the growth of soybean could be improved by the application of organic matter under acid and saline conditions.     

Effects of hairy vetch foliage application on nodulation and nitrogen fixation in soybean cultivated in three soil types

We investigated the effects of applying hairy vetch foliage on nodulation and atmospheric nitrogen (N₂) fixation in soybean cultivated in three soil types in pot experiments. Soybean plants were grown in Gley Lowland soil (GLS), Non-allophanic Andosol (NAS), and Sand-dune Regosol (SDR) with hairy vetch foliage application in a greenhouse for 45 days. In GLS, the nodule number was not influenced by the application, however, nodule dry weight and N₂ fixation activity tended to increase. In NAS and SDR, nodule formation was depressed by foliage application. Soybean plant growth was promoted in GLS and SDR but not in NAS. These promotive effects of hairy vetch foliage application on soybean plant growth in GLS were considered to be mainly caused by the increase in N₂ fixation activity of the nodules, whereas it was considered to be mainly caused by the increase in nitrogen uptake activity of the roots in SDR. The varying effects of hairy vetch foliage application on soybean nodulation may be due to soil chemical properties such as pH and cation exchange capacity, which are related to soil texture. Therefore, we conclude that it is important to use hairy vetch for soybean cultivation based on the different effects of hairy vetch on soybean plant growth in different soil types.     

The role of potassium fertilizer in nodulation and nitrogen fixation of faba bean (Vicia faba L.) plants under drought stress

Three-week-old nodulated faba bean plants were subjected to different levels of drought stress (onehalf, one-quarter, or one-eighth field capacity) for 5 weeks. Half the stressed plants were treated with KCl at 10 mg kg^-1 soil or 150 mg kg^-1 soil at the beginning of the drought stress. Nodulation and nitrogenase activity were significantly decreased by increasing drought stress. Leghaemoglobin and protein contents of nodule cytosol were also severely inhibited by drought sttess. This decline was attributed to the induction of protease activity. However, carbohydrate contents of the nodule cytosol increased significantly. This accumulation was attributed to a sharp decline in invertase activity and low use of sugar by the bacteroids We conclude that harmful effects of water deficits can be alleviated by increasing K⁺ supplementation.     

Effect of Mycorrhiza,Organic Sources,Lime, Secondary and Micro-nutrients on Soil Microbial Activities and Yield Performance of Yam Bean (Pachyrhizus erosus L.) in Alfisols

Effect of integrated use of mycorrhiza, lime, inorganic fertilizers, and organic manures on microbial activities and yield performance of yam bean (Pachyrhizus erosus L.) was studied for two consecutive kharif (rainy) seasons during 2013–14 and 2014–15 in an acid Alfisol. The experiment was laid out with 16 treatments consisting of graded doses of soil test–based nitrogen, phosphors, and potassium (NPK); lime; mycorrhiza; organic sources, that is, farmyard manure (FYM), vermicompost, and green manure; secondary magnesium sulfate (MgSO₄) and micronutrients zinc sulfate (ZnSO₄ and borax). Significantly highest mean tuber yield (29.61 t ha^?1) was recorded due to integrated application of lime + FYM + NPK + ZnSO₄. Graded doses of NPK showed a mean yield response of 65%, 134%, and 191% due to addition of 50%, 100%, and 150% of NPK over control, respectively. Inoculation of vesicular–arbuscular mycorrhiza (VAM) combined with NPK and FYM recorded a mean tuber yield of 25.14 t ha^?1. Highest mean dry matter (18.85%) was recorded due to application of 150% NPK, whereas highest starch content on fresh weight basis was recorded due to integrated use of lime + FYM + NPK + MgSO₄ (11.11%). Application of 150% NPK has recorded highest dehydrogenase activity (2.018 µg TPF h^?1 g^?1) and fluorescein diacetate hydrolysis assay (2.012 µg g^?1 h^?1). Fungal inoculation of VAM in combination with lime + FYM + NPK recorded highest acid and alkaline phosphatase activities (82.20 and 67.02 µg PNP g^?1 soil h^?1, respectively). Soil biological activities and phosphatase activities had highly significant relationship with tuber yield and biochemical constituents of yam bean. The study emphasized the conjunctive use of soil test–based inorganic fertilizers, lime, and organic manures to enhance the enzymatic activities and to realize higher crop yields of yam bean in acid Alfisols.     

Effect of several Rhizobium strains on nodulation,nitrogen uptake and yield of chickpeas (Cicer arietinum L.)

The effect of soil sterilization, and seed inoculation with three Rhizobium strains (3889, CP5b and IC 26) were studied on 5 chickpea (Cicer arietinum L.) genotypes (Jordan local, ILC 72 from Spain, ILC 484 from Turkey, C 235 from India, and ILC 1272 from U.S.A.). The main objective of the work was to investigate the effect of inoculation with different Rhizobium strains on yield, nodulation and other agronomic characteristics of different chickpea genotypes. Inoculation with Rhizobium resulted in a significant increase in grain yield for all genotypes tested. The average increase due to inoculation was 110% over the uninoculated control. Inoculation resulted in more nodules, greater nodule fresh weight and higher nitrogen uptake. The various Rhizobium strains differed in their effects. Genotypes responded differently to inoculation.     

Effects of arbuscular mycorrhizal inoculation on growth,yield, nitrogen,and phosphorus nutrition of nodulating bean varieties in two soil substrates of contrasting fertility

A pot experiment was conducted to study the response of nodulated bean (Phaseolus vulgaris L.), vars. Ceca and Montalbán, to inoculation with the arbuscular‐mycorrhizae (AM) Glomus spurcum strain IES‐3 and G. mosseae strain IES‐8 in two non‐sterilized non‐amended soil substrates (S‐l and S‐2) of contrasting fertility. S‐l was an acid soil (pH 5.0) with 77% exchangeable aluminum (Al), low available phosphorus (P) (3.5 ug g^‐1 dry soil) and 1.8% organic matter. S‐2 was a soil with pH 7.0, 7.9 μg P g^‐1 dry soil, 9.6% organic matter and no exchangeable Al. Plants growing in S‐1 (S‐1 plants) and S‐2 (S‐2 plants) soils were sampled at the beginning of the flowering stage. S‐1 and S‐2 plants were nodulated by the rhizobial populations native of each soil. S‐1 plants of both varieties did not respond to AM inoculation in term of shoot and root mass, P content, relative abundance of ureides (RAU) and seed yields. Only the total chlorophyll, chlorophyll‐a, chlrophyll‐a/b ratio and nodule mass were significantly enhanced in AM‐inoculated plants. Increased total reducing sugars concentration was detected in roots of S‐1 plants inoculated with G. mosseae. S‐2 plants displayed significantly higher shoot and nodule mass as well as increased total chlorophyll, chlorophyll‐a, chlorophyll‐a/b ratio and P content than S‐1 plants, regardless of the variety and AM inoculation. S‐2 plants of the var Ceca showed a two fold increase in seed yields but similar RAU values (>60%) when compared to S‐1 plants of the same variety. In contrast, the significant increase in RAU detected in S‐2 plants of the var Montalban was not translated into higher seed yields. In S‐2, the productivity of plants of the var Ceca doubled that of the var Montalban. For both bean varieties the highest significant P content and seed yield were observed exclusively in S‐2 plants inoculated with G. mosseae. This Glomelean strain enhanced the sink‐source ratio of the S‐2 plants as evidenced by the higher total reducing sugar concentration in the root mass. Arbuscular‐mycorrhizae inoculation significantly decreased the acid phosphatase activity in the rhizosphere of S‐1 and S‐2 plants, respectively, pointing toward a negative effect of foreign AM on the native microbial biomass. The effectiveness of the rhizobial populations native of each soil type and the weak response elicited by G. mosseae in S‐2 plants do not justify, at present, the inclusion of foreign inocula in the bean crops carried out at S‐1 and S‐2 soils of the Sucre State of Venezuela. Results also indicated the higher adaptability of var Ceca to conditions prevailing in S‐1 and S‐2.     

添加秸秆对水稻产量和土壤碳氮及微生物群落的影响

为探究添加秸秆对黄筋泥田水稻产量和土壤碳、氮含量和微生物学特性的影响,设计了5个处理,即不添加秸秆和生物炭（CK）、添加秸秆（ST）、添加秸秆和腐熟剂1号（SB1）、添加秸秆和腐熟剂2号（SB2）和添加秸秆生物炭（SC）的水稻盆栽试验,分析水稻产量和土壤全碳、全氮、腐殖质含量和磷脂脂肪酸含量。结果表明：与CK相比,ST、SB1、SB2和SC均能提高水稻产量（P<0.05）,其中SB2增产55.73%;ST、SB1、SB2和SC也提高土壤全碳、全氮、腐殖质含量、细菌磷脂脂肪酸含量、真菌磷脂脂肪酸含量和总磷脂脂肪酸含量（P<0.05）,其中SC土壤全碳提高31.36%,SB2土壤全氮提高40%,SB1腐殖质含量增加50.01%,而SB1和SB2的细菌磷脂脂肪酸含量、真菌磷脂脂肪酸含量和总磷脂脂肪酸含量增加86.49%～401.59%。因此,添加秸秆可以增加水稻产量,提高土壤全碳、全氮和腐殖质的含量,改善土壤微生物群落结构。     

Dynamics of nodulation,nitrogen fixation,nitrogen use and biomass yield over time in pot-grown Leucaena leucocephala (Lam.) de Wit

The dynamics of nodulation, N₂-fixation and N use in Leucaena leucocephala cv. K28 over time was investigated in a screenhouse at 4, 8, 12 and 16 months after planting (MAP) using the ¹⁵N-labelling method. Leucaena had a consistently increasing pattern of nodulation, dry biomass and nitrogen yield. A sharp rise in nodulation was observed between 12 and 16 MAP, whereas for biomass, N accumulation and N₂-fixation, and N₂-fixation, an upward surge occurred between 4 and 12 months. Nodulation, N accumulation, N₂-fixation and biomass yield all peaked at 16 MAP. Along with the steady increase in N₂-fixation throughout the 16-month growth period, the % N derived from the atmosphere rose from 17.9% to 61.5%, 70.1% and 74%, equivalent to 191, 1623, 2395 and 3385 mg N₂ fixed plant^-1 at 4, 8, 12 and 16 MAP, respectively. Nitrogen assimilation from soil and fertilizer decreased inversely to the increase in symbiotic nitrogen fixation with time.