首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
Summary Variation in nodulation and N2 fixation by the Gliricidia sepium/Rhizobium spp. symbiosis was studied in two greenhouse experiments. The first included 25 provenances of G. sepium inoculated with a mixture of three strains of Rhizobium spp. N2 fixation was measured using the 15N isotope dilution method 12 weeks after planting. On average, G. sepium derived 45% of its total N from atmospheric N2. Significant differences in fixation were observed between provenances. The percentage of N derived from atmospheric N2 ranged from 26 to 68% (equivalent to 18–62 mg N plant-1) and was correlated with total N in the plant (r=0.70; P=0.05). The second experiment included six strains of Rhizobium spp. and two methods of inoculation and the plants were harvested 14,35 and 53 weeks after planting. In the first harvest significant differences were found between the number of nodules and the percentage and amount of N2 fixed. There was also a significant correlation between the number of nodules and the amount of N2 fixed (r=0.92; P=0.05). In the final harvest no correlation was observed, although there were significant differences between the number of nodules and the percentage of N derived from the atmosphere. The amount of N2 fixed increased with time (from an average of 27% at the first harvest to 58% at the final harvest) and was influenced by the Rhizobium spp. strain and the method of inoculation. It ranged from 36% for Rhizobium sp. strain SP 14 to 71% for Rhizobium SP 44 at the last harvest. Values for the percentage of atmosphere derived N2 obtained by soil inoculation were slightly higher than those obtained by seed inoculation.  相似文献   

2.
The competitiveness of several effective winged bean Rhizobium strains for nodulation was assessed in a glass house experiment with paired and multi-strain inoculations. The strains varied in their competitive abilities when applied as mixed inocula. The strains KUL-BH, KUL-Z3, KUL-JN and KUL-GP were more competitive than the strain RRIM 56. The strain KUL-GP was more competitive than the strain KUL-JN. The strains KUL-BH and KUL-GP had relatively high competitiveness. The multi-strain inoculum consisting of Rhizobium strains RRIM 56, KUL-BH, KUL-JN, KUL-GP and KUL-Z3 was equally effective as the single strain inoculations and thus the multi-strain inoculum could be used in field practice. The broth and the peat multi-strain inocula were equally effective.  相似文献   

3.
Nitrogen (N) fixation by legume-Rhizobium symbiosis is important to agricultural productivity and is therefore of great economic interest. Growing evidence indicates that soil beneficial bacteria can positively affect symbiotic performance of rhizobia. The effect of co-inoculation with plant growth-promoting rhizobacteria (PGPR) and Rhizobium, on nodulation, nitrogen fixation, and yield of common bean (Phaseolus vulgaris L.) cultivars was investigated in two consecutive years under field conditions. The PGPR strains Pseudomonas fluorescens P-93 and Azospirillum lipoferum S-21 as well as two highly effective Rhizobium strains were used in this study. Common bean seeds of three cultivars were inoculated with Rhizobium singly or in a combination with PGPR to evaluate their effect on nodulation and nitrogen fixation. A significant variation of plant growth in response to inoculation with Rhizobium strains was observed. Treatment with PGPR significantly increased nodule number and dry weight, shoot dry weight, amount of nitrogen fixed as well as seed yield and protein content. Co-inoculation with Rhizobium and PGPR demonstrated a significant increase in the proportion of nitrogen derived from atmosphere. These results indicate that PGPR strains have potential to enhance the symbiotic potential of rhizobia.  相似文献   

4.
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.  相似文献   

5.
ABSTRACT

Common bean (Phaseolus vulgaris L.) has been shown to be a poor di-nitrogen (N2) fixer and nitrogen (N) fertilizers are usually recommended in bean production. Recent research results suggest that the success of the bean/Rhizobium symbiosis may depend, in part, on the specific bean genotype. Twelve dry bean genotypes differing in growth habit, commercial class, and maturity were evaluated for N2 fixation in field experiments. Response to inoculant application was highly influenced by environmental conditions. Genotypes differed in nodule dry mass, seed yield, seed N yield, and in amount of N2 fixed. Growth habit alone was not adequate in classifying bean genotypes for N2 fixation. The actual amount of N2 fixed was low ranging from 16 kg ha?1 to 27 kg ha?1, suggesting that the symbiotic process alone may not provide adequate N for optimum seed yield in dry environments.  相似文献   

6.
The efficiency of symbiotic dinitrogen (N2) fixation in Vicia faba L. in combination with 3 different Rhizobium leguminosarum strains was studied in a pot experiment during vegetative and reproductive growth. The objective of the experiments was to assess variability among Rhizobium strains inoculated on single legume species and determine possible reasons for observed variations. Dry matter formation, N2 fixation and the carbon (C) costs of N2 fixation were determined in comparison with nodule free plants grown with urea. Nodule number and the capacity of different respiratory chains in the nodules were also measured. The plants inoculated with the Rhizobium strain A 37 formed less dry matter and fixed less N compared to the other two Rhizobium strains (Vic 1 and A 150). This coincided with a lower number of nodules and higher C costs of N2 fixation. The C costs for N2 fixation were in all cases significantly lower during reproductive growth compared to vegetative growth. Neither the latter nor the differences in C expenditure for N2 fixation between the Rhizobium strains could be explained in terms of differences or shifts in the capacity of different respiratory chains in the nodules.  相似文献   

7.
Summary A field study carried out in a sandy, relatively acid Senegalese soil with a low soluble P content (7 ppm) and low vesicular-arbuscular mycorrhizal (VAM) populations showed that soybean responded toGlomus mosseae inoculation when the soluble P level in the soil had been raised by the addition of 22 kg P ha–1. In P-fertilized plots, N2 fixation of soybean, assessed by the A value method, was 109 kg N2 fixed hat when plants were inoculated withRhizobium alone and it reached 139 kg N2 fixed ha–1 when plants were dually inoculated withRhizobium andGlomus mosseae using an alginate bead inoculum. In addition to this N2 fixation increase (+28%),Glomus mosseae inoculation significantly improved grain yield (+13%) and total N content of grains (+16%). This success was attributed mainly to the low infection potential of the native VAM populations in the experimental site. In treatments without solubleP or with rock phosphate, no effect of VAM inoculation was observed.  相似文献   

8.
Pot and field experiments were performed to assess N2 fixation in Nicaraguan (R79 and R84) and Ecuadorian (Imba) common bean (Phaseolus vulgaris L.) cultivars, with the aim of improving their productivity by inoculating them with commercially produced Rhizobium phaseoli. With maize (Zea mays L.) as the non‐N2‐fixing control, the percentage of N2 fixed predicted by the 15N‐dilution method was significantly (P ≤ 0.05) higher than that predicted by the N‐difference method. However, the N2 amounts predicted by the two methods were not significantly different. The correlation between the two methods was significant and positive (P ≤ 0.0001, n = 36). Compared with the native rhizobial strain, symbiotic associations of the bean cultivars with UMR1073, UMR1077 and UMR1899 rhizobial inoculants did not significantly (P ≤ 0.05) influence plant dry matter (DM) and N yields, the extent of N2 fixation and uptake of soil and fertilizer N. Nevertheless, the UMR1077 and UMR1899 strains markedly increased the uptake of soil N by R84 plants, while decreasing N2 fixation. In contrast, the Imba‐UMR1899 association enhanced positive effects on all variables. About 60–70% of the total N taken up by the Imba plants was fixed N2. The R79 and R84 plants fixed about 50% of their total N uptake. N2 fixation rates were positively correlated with DM and total N yields, while being negatively correlated with soil N uptake (P ≤ 0.001, n = 36). Future research in Nicaragua should focus on selecting rhizobial strains suitable for indigenous common bean cultivars.  相似文献   

9.
Summary In an experiment performed under greenhouse conditions, four cultivars of Phaseolus vulgaris L. (Venezuela-350; Aroana; Moruna; Carioca) were inoculated with three Rhizobium leguminosarum biovar phaseoli strains (C-05; C-40 = CIAT 255; C-89 = CIAT 55) and were fertilized with an N-free mineral nutrient solution. The plants were harvested 25, 40, and 55 days after emergence and the following paramenters were evaluated: Nitrogenase activity of nodulated roots, H2 evolution by the nodules; relative efficiency of nitrogenase; respiration rates of nodulated roots and detached nodules; dry weight and total N of stems, leaves, pods, roots, and nodules. Generally the bean cultivar, Rhizobium strain, had an effect and there was an interaction effect with both symbiotic partners, on all parameters. On average, nodules represented 23% of total root respiration but the best symbiotic combinations showed lower ratios of C respired to N fixed. The maximum N-assimilation rate (between 40 and 55 days after emergence) of 11.93 mg N plant–1 day–1 occurred with the symbiotic combination of Carioca × C-05, while the poorest rate of 0.55 mg N plant–1 day–1 was recorded with Venezuela-350 × C-89. The best symbiotic combinations always showed the highest relative nitrogenase efficiency, but the differences in N2-fixation rates cannot be explained solely in terms of conservation of energy by recycling of H2. This requires further investigation.  相似文献   

10.
Although common bean (Phaseolus vulgaris L.) has a good potential for N2 fixation, poor nodulation following inoculation, principally under field conditions, has led to increased nitrogen (N) fertilizer use in this crop. In the face of the negative environmental effects of N fertilizer, alternative methods have been studied to minimize the amount to be applied. In this sense, foliar application of molybdenum (Mo) has been cited as a promising method. Several papers show that high bean yields (1,500–2,500 kg ha‐1), may be obtained in the southeasten region of Brazil, when there is an application of N as side dressing or Mo spray 25 days after plant emergence. A field experiment was carried out to verify the effect of Mo foliar application on nitrogenase and nitrate reductase activities and on bean yield. Treatments included Rhizobium inoculation (with and without), foliar application of Mo (0 and 40 g ha‐1), N at planting (0 and 20 kg ha‐1) and N applied as side dressing (0 and 30 kg ha‐1). Molybdenum and N as side dressing were used 25 days after plant emergence. Molybdenum increased greatly the nitrogenase activity and extended the period of high nitrate reductase activity, with a consequent increase in total shoot N. Increase of nitrogenase activity did not depend on inoculation, showing that soil native rhizobia may increase in effectiveness when appropriately handled. Bean yield did not differ significantly when fertilized with either Mo or N as side dressing.  相似文献   

11.
The effects of inoculation with Bradyrhizobium japonicum and Azospirillum brasilense strains on the growth of soybean were evaluated with regard to the estimation of N2 fixation using the 15N isotope dilution technique. Inoculation, in general, increased the dry mass of soybean as well as nitrogen content. Dual inoculation with a mixture of B. japonicum and A. brasilense strains was superior over single inoculation with B. japonicum. Nitrogen fixed (Ndfa) varied according to inoculant and soil conditions. Percentages of nitrogen derived from air (% Ndfa) using a non-nodulating isoline were 72% and 76% for B. japonicum and B. japonicum plus A. brasilense, respectively, in non-sterile soil. A similar but higher trend was recorded in sterilized soil, in which the percentages of N2 fixed were 81% and 86% for single and dual inoculation, respectively. The correlation coefficient between N2 fixed and N uptake (r=0.94) and dry mass (r=0.89) was significant. Application of special bacterial inoculants in agricultural systems of Egypt seems to be a promising technology and could be used for improving soybean growth as well as soil fertility, thus minimizing environmental pollution. Received: 10 January 1996  相似文献   

12.
Two winged bean Rhizobium strains, RRIM 56 and NGR 258 were tested with different selections of winged bean Psophocarpus tetragonolobus and one selection of Psophocarpus palustris under high and low sunlight intensities and long and short day photoperiods in pot experiments. Nodulation and N2 fixation by the strain RRIM 56 was not affected by light intensity and photoperiod and it showed very effective nodulation and N2 fixation. It was found to be capable of showing a N-gain of 140 kg per ha per 9 weeks and 750 kg per ha per year in winged bean selections. The strain NGR 258 was highly sensitive to light intensity and insensitive to photoperiod. High light intensity during the first two weeks after seedling emergence drastically inhibited nodulation. The light effect on this strain may relate to the reduction of tryptophan movement from shoot to root system. An experiment with tryptophan injection into the stem base indicates that the amount of tryptophan needed to produce indole – acetic acid in the root hairs plays an important role in controlling the infection and nodule initiation processes in winged bean. The conversion efficiency of tryptophan to the auxin indole-acetic acid of this strain was also lower than that of strain RRIM 56. The former converts tryptophan mostly via tryptamine, while the latter follows the pathway via indole – pyruvic acid.  相似文献   

13.
The interactions between Phaseolus vulgaris, Rhizobium spp. strains nodulating P. vulgaris, and arbuscular mycorrhizal (AM) fungi were assessed under greenhouse conditions in a nonsterilized Typic Haplustalf soil from Cauca, Colombia. Our results indicate a specific involvement of AM fungal species in nitrogen acquisition by the legume plants from symbiotic nitrogen fixation and from soil. A significant specific influence of inoculation with Glomus spp. on the 15N/14N ratio in plant shoots was dependent on the inoculated rhizobial strain, but AM fungal inoculation had no significant effect on shoot dry weight or nodule occupancy in the two different rhizobial strain treatments. The results imply that in low P soils the effects of an improved mycorrhizal symbiosis may include improved symbiotic N2 fixation efficiency and/or improved soil N uptake. Received: 11 May 1996  相似文献   

14.
 N2 fixation by leguminous crops is a relatively low-cost alternative to N fertilizer for small-holder farmers in developing countries. N2 fixation in faba bean (Vicia faba L.) as affected by P fertilization (0 and 20 kg P ha–1) and inoculation (uninoculated and inoculated) with Rhizobium leguminosarium biovar viciae (strain S-18) was studied using the 15N isotope dilution method in the southeastern Ethiopian highlands at three sites differing in soil conditions and length of growing period. Nodulation at the late flowering stage was significantly influenced by P and inoculation only at the location exhibiting the lowest soil P and pH levels. The percentage of N derived from the atmosphere ranged from 66 to 74%, 58 to 74% and 62 to 73% with a corresponding total amount of N2 fixed ranging from 169 to 210 kg N ha–1, 139 to 184 kg N ha–1 and 147 to 174 kg N ha–1 at Bekoji, Kulumsa and Asasa, respectively. The total N2 fixed was not significantly affected by P fertilizer or inoculation across all locations, and there was no interaction between the factors. However, at all three locations, N2 fixation was highly positively correlated with the dry matter production and total N yield of faba bean. Soil N balances after faba bean were positive (12–58 kg N ha–1) relative to the highly negative N balances (–9–44 kg N ha–1) following wheat (Triticum aestivum L.), highlighting the importance of rotation with faba bean in the cereal-based cropping systems of Ethiopia. Received: 13 January 2000  相似文献   

15.
Low effectiveness of native strains remains a limitation to soybean productivity in sub-Saharan Africa; while in other countries commercial inoculants are produced that provide effective strains that stimulate N fixation and growth. An experiment was set up to evaluate the response of a dual purpose promiscuous soybean variety (TGx1740-2F) and a non-promiscuous variety (Nyala) to commercial rhizobium inoculants in soils from central and coastal Kenya. Highest nodulation was observed in some of the treatments with commercial inoculants applied with nodule weights of 4.5 and 1.0 g plant−1 for TGx1740-2F and Nyala, respectively. Average biomass yields of TGx1740-2F (16 g plant−1) were twice as large as of Nyala (7.5 g plant−1) at the podding stage. Nitrogen fixation was higher in TGx1740-2F than in Nyala, and positively affected by a number of commercial inoculants with more than 50% N derived from the atmosphere. Nodule occupancy was 100% on both soybean varieties, indicating that the commercial strains were extremely infective in both of the tested soils. These results showed that commercial strains can be used to inoculate promiscuous soybean and enhance N fixation and yield.  相似文献   

16.
Abstract

Rhizobia were screened in growth chamber and greenhouse tests with the host plants: bean (Phaseolus vulgaris L.), lentil (Lens esculenta Moench.), cowpea (Vigna unguiculata (L.) Walp) and peanut (Arachis hypogaea L.). Rhizobial isolates varied in effectiveness, time to nodulation, and host plant specifities. Initial screening procedures in plastic growth pouches allowed selection of infective strains of Rhizobium. These tests enabled the selection of a small number of highly effective isolates for more critical evaluation. Highly significant correlations (p=0.01) were obtained between shoot dry weight and total nitrogen, suggesting that the technique was applying sufficient selection pressure to differentiate variation in N2 fixation among strains of Rhizobium. Results indicate that highly effective rhizobia can be efficiently selected under controlled conditions following a step‐wise procedure.  相似文献   

17.
Summary We studied the effect of three successive cuttings on N uptake and fixation and N distribution in Leucaena leucocephala. Two isolines, uninoculated or inoculated with three different Rhizobium strains, were grown for 36 weeks and cut every 12 weeks. The soil was labelled with 50 ppm KNO3 enriched with 10 atom % 15N excess soon after the first cutting. Except for the atom % 15N excess in branches of K28 at the second cutting, both the L. leucocephala isolines showed similar patterns of total N, fixed N2, and N from fertilizer distribution in different parts of the plant at each cutting. The Rhizobium strain did not influence the partitioning of 15N among the different plant parts. Significant differences in 15N enrichment occurred in different parts. Live nodules of both isolines showed the lowest atom % 15N excess values (0.087), followed by leaves (0.492), branches (0.552), stems (0.591), and roots (0.857). The roots contained about 60% of the total plant N and about 70% of the total N derived from fertilizer over the successive cuttings. The total N2 fixed in the roots was about 60% of that fixed in the whole plant, while the shoots contained only 20% of the fixed N2. We conclude that N reserves in roots and nodules constitute another N source that must be taken into account when estimating fixed N2 or the N balance after pruning or cutting plants. 15N enrichment declined up to about fivefold in the reference and the N2-fixing plants over 24 weeks following the 15N application. The proportion and the amounts of N derived from fertilizer decreased, while the amount derived from N2 fixation increased with time although its proportion remained constant.  相似文献   

18.
Limited information is available on reduced cowpea (Vigna unguiculata L. Walp.) and green gram (Vigna radiata L.Wilczek.) yields in Kenya. Declining soil fertility and absence or presence of ineffective indigenous rhizobia in soils are assumptions that have been formulated but still require to be demonstrated. In this study, soils were collected from legume growing areas of Western (Bungoma), Nyanza (Bondo), Eastern (Isiolo), Central (Meru) and Coast (Kilifi) provinces in Kenya to assess indigenous rhizobia in soils nodulating cowpea and green gram under greenhouse conditions. Our results showed that highest nodule fresh weights of 4.63 and 3.32?g plant?1 for cowpea and green gram were observed in one soil from Isiolo and another from Kilifi, respectively, suggesting the presence of significant infective indigenous strains in both soils. On the other hand, the lowest nodule fresh weights of 2.17 and 0.72?g plant?1 were observed in one soil from Bungoma for cowpea and green gram, respectively. Symbiotic nitrogen (N) fixation by cowpea and green gram was highest in Kilifi soil with values of 98% and 97%, respectively. A second greenhouse experiment was undertaken to evaluate the performance of commercial rhizobial inoculants with both legumes in Chonyi soil (also from Coast province) containing significant indigenous rhizobia [>13.5?×?103 Colony Forming Units (CFU) g?1]. Rhizobial inoculation did not significantly (P?相似文献   

19.
Low soil fertility and soil acidity are among the major bottlenecks that limit agricultural productivity in the humid tropics. Soil management systems that enhance soil fertility and biological cycling of nutrients are crucial to sustain soil productivity. This study was, therefore, conducted to determine the effects of coffee‐husk biochar (0, 2.7, 5.4, and 16.2 g biochar kg?1 soil), rhizobium inoculation (with and without), and P fertilizer application (0 and 9 mg P kg?1 soil) on arbuscular mycorrhyzal fungi (AMF) root colonization, yield, P accumulation, and N2 fixation of soybean [Glycine max (L.) Merrill cv. Clark 63‐K] grown in a tropical Nitisol in Ethiopia. ANOVA showed that integrated application of biochar and P fertilizer significantly improved soil chemical properties, P accumulation, and seed yield. Compared to the seed yield of the control (without inoculation, P, and biochar), inoculation, together with 9 and 16.2 g biochar kg?1 soil gave more than two‐fold increment of seed yield and the highest total P accumulation (4.5 g plant?1). However, the highest AMF root colonization (80%) was obtained at 16.2 g biochar kg?1 soil without P and declined with application of 9 mg P kg?1 soil. The highest total N content (4.2 g plant?1) and N2 fixed (4.6 g plant?1) were obtained with inoculation, 9 mg P kg?1, and 16.2 g biochar kg?1 soil. However, the highest %N derived from the atmosphere (%Ndfa) (> 98%) did not significantly change between 5.4 and 16.2 g kg?1 soil biochar treatments at each level of inoculation and P addition. The improved soil chemical properties, seed yield, P accumulation and N2 fixation through combined use of biochar and P fertilizer suggest the importance of integrated use of biochar with P fertilizer to ensure that soybean crops are adequately supplied with P for nodulation and N2‐fixation in tropical acid soils for sustainable soybean production in the long term.  相似文献   

20.
This study was initiated to evaluate the effect of locally isolated Rhizobium on nodulation and yield of faba bean at Haramaya, Ethiopia for three consecutive years. Ten treatments comprising of eight effective isolates of rhizobia, uninoculated, and N-fertilized (20 kg N ha?1) were laid out in a randomized complete block design with three replications. The result of the experiment indicated that all inoculation treatments increased nodule number and dry weight over the control check in all cropping seasons. The result, however, showed the non-significant effect of Rhizobium inoculation on shoot length, number of tiller per plant and 100 seed weight in all cropping season. Inoculating Haramaya University Faba Bean Rhizobium (HUFBR)-15 in 2011 and National Soil Faba Bean Rhizobium (NSFBR)-30 in 2012 and 2013 gave the highest grain yields (4330, 5267 and 4608 kg ha?1), respectively. These records were 75%, 48%, and 5% over the uninoculated treatment of respective years. Over the season, NSCBR-30 inoculation resulted in the highest nodulation and grain yield production as compared to the other treatments. In general, isolates from central Ethiopia were better than those isolated from eastern Ethiopia and Tropical Agricultural Legume (TAL)-1035 in enhancing faba bean production at Haramaya site. Therefore, NSFBR-30 is recommended as a candidate isolate for faba bean biofertilizer production in eastern Ethiopia soils.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号