Effect of inoculation withGlomus mosseae on nitrogen fixation by field grown soybeans

Summary This field study was undertaken to determine the effect of inoculation withGlomus mosseae on N₂ fixation and P uptake by soybean. The inoculation withGlomus mosseae was achieved using a new type of inoculant, alginate-entrapped (AE) endomycorrhizal fungus. N₂ fixation was assessed using the A value method. In P-fertilized plots, inoculation with AEGlomus mosseae increased the harvest index based on dry weight (+20%) and N content of seeds (+17%), the A value (+31%) and %N derived from fixation (+75%). Inoculation with AEGlomus mosseae decreased the coefficient of variation for the A value and for the dry weights of the different plant parts.     

Mutual shading and the photosynthetic capacity of exposed leaves of field grown soybeans

Light-saturated photosynthetic rates at air levels of carbon dioxide were measured about weekly in upper canopy leaves of two soybean cultivars grown at stand densities of 40 and 100 plants per square meter. Early in the season, when leaf area indices differed between stand densities, plants of both cultivars grown at high stand density had photosynthetic rates which averaged 23% lower than plants at low stand density. Later in the season, when there were no differences in leaf area index between stand densities, there were no differences in photosynthetic rates in the cultivar Kent, but rate differences of about 14% persisted in the cultivar Williams. In Williams mainstem leaves emerged into full sunlight later in their development at high than at low stand density. In both cultivars the oldest fully exposed leaves were photosynthetically immature for much of the season, as higher rates could be achieved by lower leaves which were shaded in situ. The results identify shading of young developing leaves and photosynthetic immaturity of fully exposed leaves as factors limiting canopy photosynthesis in soybeans, and indicate cultivar differences in how much high stand density reduces photosynthetic capacity.     

Effects of phosphate fertilization,lime amendments and inoculation with VA-mycorrhizal fungi on soybeans in an acid soil

Soybeans [Glycine max (L.) Merr. cv. Essex] were grown in nonsterile acid (pH. 5.2) infertile Wynnville silt loam (Glossic Fragiudult) in a glasshouse. The effects of P fertilization and lime were determined by inoculation with two VAM-fungi (VAMF): Glomus fasciculatum (Gf) and Glomus etunicatum (Ge). An important factor affected by the interaction between applied lime (soil acidity), applied P, and VAMF inoculation was the soil Al. Five application rates of P as KH₂PO₄ and three rates of lime were tested. Potassium was equalized with KCl (muriate of potash). P-efficiency (g seed/mg P kg^-1 soil) by vesicular-arbuscular mycorrhiza (VAM) was maximal at 20 mg P kg^-1 soil at all lime and VAMF treatments. VAMF inoculation increased plant survival and protected the soybeans from leaf scorch, thereby substituting for the effects of lime and P. The Ge inoculum was superior in ameliorating leaf scorch in the nonlimed soil. The Gf inoculum required more lime and P than the Ge inoculum to increase seed yield relative to the noninoculated controls containing only native VAMF. Both inocula increased root Al uptake and extractable soil Al in the acid soil without apparent adverse effects on root or shoot. The ability of the VAMF inocula to enhance the efficiency of applied P and decrease seed Cl concentration was increased by lime. Seed yield (Y) was negatively related to seed Cl concentration (X) where Y=aX^-b. Both VAMF inoculation and lime application reduced this negative relationship and may have increased the tolerance to both Cl and soil Al.     

Suppression of nodulation in soybeans by superoptimal inoculation with Bradyrhizobium japonicum

Symbiotic nodulation of the primary roots of soybeans ( Glycine max L. Merrill cv. Pride 216) is regulated by the plant, and is suppressed in response to a high inoculum dose of Bradyrhizobium japonicum USDA strain I–110 (ARS)⁺ applied at one time to the root. If an optimal dose is followed 10 h later by a superoptimal dose, nodules from the first inoculum near the base of the primary root are suppressed in a dose-dependent way similar to that observed after single inoculations. The nodules which appear are probably derived from infections initiated by the bacteria in both inocula.     

The genetic diversity of annual wild soybeans grown in China

Annual wild soybeans (Glycine soja), the ancestors of cultivated soybeans (G. max), are important sources of major genes for resistance to pests, diseases and environmental stresses. The study of their genetic diversity is invaluable for efficient utilization, conservation and management of germplasm collections. In this paper, the number of accessions, the variation of traits, the genetic diversity indexes (Shannon index) and the coefficient of variation were employed to study the geographical distribution of accessions, genetic diversity of characters and genetic diversity centers of annual wild soybean by statistical analysis of the database from the National Germplasm Evaluation Program of China. Most annual wild soybeans are distributed in Northeast China, and the number of accessions decreases from the Northeast to other directions in China. The genetic diversity indexes (Shannon index) were 0.49, 0.74, 0.02, 0.55, 1.45, 2.41, 1.27 and 1.89 for flower color, sootiness of seed coat, cotyledon color, pubescence color, hilum color, leaf shape, stem type and seed color, respectively. Coefficients of variation were 7.1%, 28.7%, 76.43% and 18.2% for protein content, oil content, 100-seed weight and days to maturity, respectively. Three genetic diversity centers, the Northeast, the Yellow River Valley and the Southeast Coasts of China, are proposed based on the geographical distribution of the number of accessions, genetic diversity and the multivariate variation coefficient. Based on these results and Vavilov’s theory of crop origination, two opposing possible models for the formation of the three centers are proposed, either these centers are independent of each other and the annual wild soybeans in these centers originated separately, or the Northeast center was the primary center for annual wild soybeans in China, while the Yellow River Valley center was derived from this primary center and served as the origin for the Southeast Coast center. Received: 25 June 2000 / Accepted: 18 October 2000     

Effect of inoculation on element uptake by plants grown on saline soils

A relationship between inoculation and elemental uptake ofMedicago sativa inoculated withRhizobia meliloti (isolated from a saline area) was found. The plant uptake of the elements with atomic number between 19 and 42 was significantly higher in plants grown on inoculated soils, with the exception of molybdenum. Preliminary evidence shows that the concentration of some elements was affected by inoculation.     

Effects of inoculation of phosphate-solubilizing microorganisms and an arbuscular mycorrhizal fungus on mungbean grown under natural soil conditions

 The effect of inoculation of the phosphate-solubilizing microorganisms (PSM) Bacillus circulans and Cladosporium herbarum and the arbuscular mycorrhizal (AM) fungus Glomus fasciculatum with or without Mussoorie rockphosphate (MRP) was studied in a P-deficient natural non-disinfected sandy soil on mungbean (Vigna radiata). The AM levels increased following the addition of MRP or inoculation with PSM or G. fasciculatum. Both grain and straw yield of mungbean increased following inoculation with PSM or the AM fungus. In general, the increase in yield was higher in the presence of MRP and inoculation with a combination of PSM and AM fungus. Highest N and P uptake by mungbean was recorded after treatment with a combination of B. circulans, C. herbarum and G. fasciculatum in the presence of MRP. Generally the PSM population increased after AM fungus inoculation. Accepted: 13 October 1997     

Effects of Open-Top Chambers on physiological and yield attributes of field grown grapevines

Touriga Franca grapevines were grown in Open-Top Chamber (OTC) and in outside plot (Exterior) for 3 years (2004–2006) to investigate the impact of these structures on climatic conditions and, consequently, on physiological and yield attributes. In general, CO₂ assimilation, stomatal conductance, carbohydrate concentration, maximum bulk modulus of elasticity, palisade parenchyma thickness, leaf mass per unit area and values of red/far-red ratio transmitted by leaves were lower, whereas intrinsic water use efficiency, SPAD-readings and osmotic potential at full turgor were higher in OTC leaves. However, OTC did not affect leaf water potential, maximum PSII photochemical efficiency, stomatal density and soluble proteins concentration. Also, there were no significant differences in C, P, Ca and Fe between treatments. Meanwhile, N and Mg were higher, whereas K concentration was lower in OTC leaves. The environmental conditions inside OTC provided a significant reduction in yield and Ravaz index of 2004, mainly due to a decrease in clusters weight. Regarding the vegetative growth parameters, OTC did not influence the pruning weight, but in 2006 the weight/shoot was significantly lower in OTC vines. In conclusion, the use OTC facility to study the impact of CO₂ enrichment was very expedite, but the extrapolation of results to the open-field environment must be prudent due to the OTC effect.     

Effects of N-serve on soybeans and soil nitrogen transformations

Summary Plant dry weight, total N, and total Ca was increased at 0.1 and 1 ppm N-serve. At greater 10 ppm the plants showed visual symptoms of a stunted growth, stem elongation, flowers, and pods failed to form or were aborted, young leaves were curled, and roots were club shaped with many branches. These symptoms were increasingly evident with increasing N-serve application rates. The reason was attributed to an auxin effect. Dry wt and total N in the plant was less than the control at the higher N-serve applications. There was little effect on nitrogenase activity at less than 10 ppm N-serve. Nodulation tended to increase at 0.1 and 1 ppm N-serve.Nitrification was inhibited up to 104 days at 20 ppm N-serve. The soil pH of the high N-serve rates was decreased at 104 days probably due to nitrification. Generally there were little detectable differences among treatments in soil organic N. The average soil organic N from 0 to 104 days decreased by 0.01%. Average increase in total N within each pot at harvest was equivalent to about 138 kg N/ha.     

Dinitrogen fixation by field grown soybeans: statistical analysis of variations in δ15N and proposed sampling procedureand proposed sampling procedure

Summary This paper reports a field study for the assessment of the variation in¹⁵N natural abundance method to estimate nitrogen fixation. For two successive years (1979 and 1980) at the same site, distribution of the variable δ¹⁵N in populations of nodulating and non-nodulating soybeans (Glycine max) has been studied. In 1980, the population structure was studied in order to detect a neighbour effect which could explain bimodal trend observed in the distribution. There was no evidence for such an effect. A sampling procedure is proposed: with 15 to 30 nodulating plants chosen randomly, a confidence interval of ±0.5δ can be obtained, while less than 10 non-nodulating plants are sufficient to achieve a very good precision. Some other aspects are studied: effect of pooling plants which considerably reduce the experimental work; the use of a non leguminous reference plant is possible. All our results show that fixing capacity introduces major variability in the δ¹⁵N measured in the plants, while the absence of fixation leads to a homogenous population, so the percentage of fixed N can be evaluated with a rather good precision. The higher the reference value, the better the accuracy of this evaluation, for a given precision of a δ¹⁵N measurement.     

Effects of plant trichomes on herbivores and predators on soybeans

Abstract Tritrophic interaction in soybean system has received increasing attention recently. However, few studies have investigated the influence of plant trichomes on the population dynamics of soybean herbivores and their natural enemies. We conducted a field survey to investigate whether soybean trichomes affected the abundance of herbivores and their predators. The results of this study show that moderately or densely pubescent trichomes have positive influences on the abundance of some herbivores (e.g., Stollia guttiger) and predators (e.g., Propylaea japonica and Orius similes) although the influence may change over time, while trichome types do not affect the density of soybean aphid, Aphis glycines.     

Effect ofRhizobium inoculation and the application of phosphate on the growth,yield and nitrogen fixation of soybeans

Summary Application of phosphate at 60, 90 and 120 kg P ha^–1 to the Bragg variety of soybeans inoculated with a mixture of three strains ofRhizobium japonicum (TAL 102 + TAL 377 + TAL 379) and grown in silty loam soil in a pot experiments, significantly improved the number of nodules per plant and increased production of shoots and roots by 65, 36 and 17%, the yield of pods by 38, 12 and 3% and N₂-fixing capacity by 57, 29 and 20%, respectively. Rhizobium inoculation alone with the test strains caused a positive but poor nodulation of the crop and increased its dry-matter production of shoots and roots by 22%, pods yield by 7% and N₂-fixing capacity by 6%. Soybean plants from uninoculated treatments were without nodules indicating that indigenous rhizobia associated with this crop are absent in the test soil. Phosphate concentration in the total dry matter of mature crop exhibited an increasing tendency as a result of all the applied levels of phosphorus.

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Resumen La adición de fosfato (60, 90, y 120Kg P ha^–1) a plantas de soja de la variedad Bragg inoculadas con una mezcla de tres cepas deRhizobium japonicum (TAL 102 + TAL 377 + TAL 379) cultivada en contenedores en un suelo arcillo-limoso, mejoró significativamente el número de nódulos por planta, aumentó la producción de tallos y raíces en un 65, 36 y 17%, el rendimiento de la cosecha en un 38, 12 y 3%, y la capacidad fijadora de N₂ en un 57, 29 y 20% respectivamente. La sola inoculación con las cepas deRhizobium ya mencionadas produjo una nodulación positiva aunque pobre del cultivo, incremetando la producción de tallos y raíces en un 22%, el rendimiento de la cosecha en un 7% y la capacidad fijadora de nitrógeno en un 6%. Las plantas de soja de los tratamientos no inoculados no tenían nódulos lo que indica que no habían rizobios específicos para esta planta en el suelo ensayado. La concentración de fosfato en la materia seca de las plantas maduras mostraba una tendencia a incrementarse como resultado de la aplicación de los distintos niveles de fosfato.

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Résumé L'application du phosphate à raison de 60, 90 et 120 kg en phosphore par hectare à la variété Bragg de soja inoculée avec un mélange de 3 souches deRhizobium japonicum (TAL 102, TAL 377 et TAL 379) et cultivée sur un sol gras limoneux dans des expériences en jarre de croissance, a augmenté de manière significative le nombre de nodules par plant et a augmenté la production des pousses et racines respectivement de 65, 36 et 17%, le rendement des cosses respectivement de 38, 12 et 3% ainsi que la capacité de fixer l'azote, respectivement de 57, 29 et 20%. L'inoculation seule avec les souches testées de Rhizobium a causé une nodulation positive mais faible de la plante, et a augmenté la production en matière sèche des racines et pousses de 22%, le rendement en cosses de 7% et la capacité de fixer l'azote de 6%. Les plants de soja dans les expériences sans inoculation ne présentaient pas de nodules, indiquant par là que les rhizobia endogènes associés avec cette plante étaient absents dans le sol expérimental. La concentation en phosphate dans la matière sèche totale de la plante mûre a marqué une tendance à l'augmentation comme suite aux applications du phosphore à tous les niveaux.

     

Effects of nutritional stress on the storage proteins of soybeans

The effects of sulfur deficiency on the complement of proteins laid down in developing seeds of soybean (Glycine max L. Merr) have been examined. Sulfur deficiency caused a 40% decrease in the level of glycinins and a contrasting elevation in the level of β-conglycinins. The subunit composition of these proteins was also affected. There was in particular a 3-fold increase in the β-subunit of β-conglycinins in the sulfur-deficient seeds, and this accumulated largely as the B₀-isomer of β-conglycinins, a protein which while virtually devoid of methionine and cysteine retains the physical properties of a normal 7S storage protein. These data demonstrate that a high degree of selectivity can be exerted by environmental stress over the accumulation of proteins in developing seeds.     

Effects of arbuscular mycorrhizal inoculation on the growth,zinc distribution and photosynthesis of two citrus cultivars grown in low-zinc soil

Key message

‘Newhall’ and ‘Ponkan’ citrus cultivars grafted on trifoliate orange with mycorrhization by Glomus intraradices displayed different responses to low-Zn, and the optimal growth of ‘Newhall’ was more fungal inoculation dependent.

Abstract

The effects of arbuscular mycorrhizal (AM) fungus, Glomus intraradices, on plant growth, zinc (Zn) concentration and distribution, and photosynthesis were investigated in ‘Newhall’ navel orange (Citrus Sinensis) and ‘Ponkan’ tangerine (Citrus reticulata) grafted on the rootstock trifoliate orange (Poncirus trifoliata) exposed to low-Zn soil. Under the Zn-poor condition, the two cultivars showed similar decreases in growth, levels of leaf chlorophyll, gas exchange parameters, root soluble sugar, and Zn levels in various plant parts; however, the Zn percentage in the roots of ‘Ponkan’ was increased while in ‘Newhall’ it remained stable, indicating ‘Newhall’ may have a higher Zn translocation efficiency from the roots to the scion’s shoots. AM inoculation improved growth, Zn concentrations and photosynthesis in the two cultivars. AM-infected seedlings had lower minimal fluorescence values but higher maximal fluorescence values than non-infected seedlings. In addition, they were more efficient in terms of photosystem II’s (PS II’s) maximal and potential photochemistry. The greater changes appeared in ‘Newhall’, implying AM symbioses could alleviate the negative effects of low-Zn on the PS II reaction center. In addition, AM-infected ‘Newhall’ and ‘Ponkan’ seedlings had higher Zn percentages in the leaves but lower Zn ratios in the roots than non-AM-infected seedlings, especially in the former cultivar. These results indicate that G. intraradices has the potential to enhance the growth and Zn distribution in ‘Newhall’ grafted on trifoliate orange seedlings grown in low-Zn soil in a greenhouse.     

Effects of Cu,Pb and Zn on two Potamogeton species grown under field conditions

Two common macrophyte species, Potamogeton perfoliatus L. and Potamogeton pectinatus L. were grown for 12 weeks at shallow depths in sediments contaminated with 1250 or 2500 g Pb or Cu and/or Zn (gDW sediment)^-1. Control experiments were run at background levels of 4, 13, and 38 g Pb, Cu and Zn (gDW sediment)^-1, respectively. Effects of heavy metals on biomass production and metal uptake and distribution in plants are presented in relation to total amount and plant-available fraction of metals in the sediment.All three studied metals gave reduced biomass production, and the toxicity of the metals decreased in the order Zn>Cu>Pb. The root/shoot biomass ratio increased for P. pectinatus, but decreased for P. perfoliatus with metal treatment. The content of any single metal was higher in shoots than in roots of plants grown on sediments not contaminated with that specific metal, but addition of that metal increased the proportion in roots. The uptake by plants of any of the heavy metals increased with increased metal addition. The magnitude of the plant-available fraction of metals of untreated sediment was Zn>Cu>Pb, and increased in contaminated sediments. Addition of Cu decreased both the plant-available fraction and the total concentration of Zn in the sediment, while increased the uptake of Zn by the plants. The opposite was found for Cu when Zn was added. P. pectinatus accumulated about twice as much Cu as P. perfoliatus. On the other hand, the concentration of Pb was higher in P. perfoliatus than in P. pectinatus, and was negligible in P. pectinatus when cultivated in untreated sediments.     

Effect of mycorrhizal inoculation on ecophysiological responses of pistachio plants grown under different water regimes

In a greenhouse experiment, the influence of arbuscular mycorrhizal fungi (Glomus mosseae and Glomus intraradices) and water stress [100% field capacity (FC), 75% FC, 50% FC and 25% FC] on maximal quantum yield of photosystem II (PSII) photochemistry (F_v/F_m) and some other ecophysiological characteristics of two pistachio cultivar (Pistacia vera cv. Badami-Riz-Zarand and Pistacia vera cv. Qazvini) were investigated.     

Effects of weed management systems on canopy insects in herbicide-resistant soybeans

The effects of transgenic herbicide-resistant soybean varieties and their corresponding weed management strategies on canopy insects were examined in studies at two locations in Iowa in 1997 and 1998. Weed management systems that allowed more weed escapes typically had higher insect population densities. However, systems with fewer weeds seemingly were preferred by potato leafhoppers. Bean leaf beetles and potato leafhoppers showed preferences for certain soybean varieties, but these effects were attributed to soybean plant height. These findings indicate that although the transgenic soybean varieties did not strongly affect insect populations, weed management systems can affect insect populations in soybean. However, this impact is likely related more to weed suppression effectiveness than to a direct effect of the herbicides on the insects.     

Chloroplast structure in normal and pigment-deficient soybeans grown in continuous red or far-red light

Clark L1, a normal green soybean [ Glycine max (L.) Merrill] and Clark y₉y₉, a backross-developed isoline exhibiting pigment deficiency, were grown under continuous red (11 W m⁻² and far-red (9 W m⁻²) light. Chloroplast thylakoids from the unifoliolate leaf (9–10 days old) were isolated and analyzed for pigments, pigment-protein, membrane polypeptides, electron transport and ultrastructural differences. Chloroplasts of soybean plants grown under far-red light have decreased chlorophyll a to chlorophyll b ratio, increased light-harvesting complexes, and grana structure with few stroma-type thylakoids. Photosystem II/photosystem I ratios (PSII/PSI) are higher in far-red due to decreased synthesis of PSI reaction center and/or less antenna associated with PSI.