Rhizobium Treatment Research Articles

Response of lentil under controlled conditions to co-inoculation with arbuscular mycorrhizal fungi and rhizobia varying in efficacy

This study assessed the co-inoculation response of lentil ( Lens culinaris cv. Laird) to arbuscular mycorrhizal fungi (AMF) and effective and ineffective Rhizobium leguminosarum bv. viceae strains. Plants were inoculated with the AMF species Glomus clarum NT4 or G. mosseae NT6 and/or nine Rhizobium strains varying in efficacy, and grown for 110 d in soil containing indigenous AMF and rhizobia. The effectiveness of the Rhizobium strains on the N nutrition of 6-week-old lentil grown under gnotobiotic conditions was correlated ( P<0.045; r=0.64) with the N nutrition of 110-d-old lentil grown in natural soil. The growth and yield responses of lentil to co-inoculation with AMF and Rhizobium strains depended on the particular AMF- Rhizobium strain combination. In some cases, the productivity of lentil inoculated with an effective Rhizobium strain was significantly ( P<0.05) reduced by an apparently incompatible AMF species compared to the Rhizobium treatment. In contrast, the yield of lentil inoculated with some ineffective Rhizobium strains was significantly ( P<0.05) enhanced by an apparently compatible AMF species compared to the Rhizobium treatment. However, maximum lentil productivity was achieved only in treatments with effective Rhizobium strains or co-inoculation treatments with effective Rhizobium strains and a compatible AMF species. Correlation analyses indicated that total shoot dry matter production was significantly ( P<0.05) correlated with the total shoot N ( P<0.0001; r=0.94) and P content ( P<0.0001; r=0.96), indicating that this response was mediated by enhanced N and P nutrition. Furthermore, a ( P<0.05) positive relationship between AMF colonization of roots and total shoot dry matter production ( P<0.0187; r=0.43), N ( P<0.0116; r=0.45) and P content ( P<0.0183; r=0.43) of shoots was also noted. Our results suggest that synergistic interactions between AMF and Rhizobium strains can enhance lentil productivity.

A Cluster-Based Approach to Means Separation

A plant breeder is frequently faced with analyzing a particular variable such as mean yields for a group of cultivars. Usually this follows an F test from a standard ANOVA which indicates that there are significant differences among cultivars. Many breeders then employ one of the large variety of available range tests to aid in digesting the experimental results. Most of the tests construct groups which may have substantial overlaps. An example of one such analysis was cited by Steel and Torrie (1980), beginning on page 140 with the data and continuing on page 176 with Duncan's multiple comparison procedure. The original experiment measured nitrogen content of red clover plants inoculated with six different rhizobium treatments. Duncan s procedure produced three groups. Group 1 contained four of the treatments and Group 2 contained three of the treatments. The disconcerting part of this analysis was that two of the treatments in Group 1 were also two of the treatments in Group 2. In the same way, the third treatment in Group 2 was also one of the two treatments in Group 3. This situation presents a problem since it gives rise to ambiguous interpretations. The proposed procedure eliminates that problem and simulation results indicate that the procedure is quite good when compared with several others. In the statistics literature, there are many types of multiple range or multiple comparison techniques as well as other approaches that are neither multiple range tests nor multiple comparisons. Examples include Fisher's Least Significant Difference (Fisher 1935), Tukey's Honestly Significant Difference (Tukey 1953), Student-Newman-Keuls (Student 1927; Newman 1939; Keuls 1952), Waller and Duncan (Waller and Duncan 1969), Duncan's New Multiple Range Test (Duncan 1955), Scheff6s method (Scheff6 1959),

PERFORMANCE OF DIFFERENT RHIZOBIAL CULTURES IN GROUNDNUT

The results of a field experiment conducted for three consecutive years during summer 1990, 1991 and 1992 revealed that rhizobial inoculation significantly increased groundnut pod yield and returns under irrigated condition. Performance of rhizobial cultures TNAU 14, IGR 40 and IGR 40 6 was superior to other cultures tried. Though there was a response to rhizobial ioculation even at 100 per cent recommended dose of nitrogen (15 kg/ha), application of 7.5 kg N/ha along with seed treatment of Rhizobium resulted in higher benefit cost ratio. Groundnut variety VRI.1 performed better than Co.2

Physiological and morphological aspects of interactions between Rhizobium meliloti and alfalfa (Medicago sativa) in association with Azospirillum brasilense

In a 50-L pot experiment with Medicago sativa grown under nonsterile conditions, a combined treatment of Azospirillum and Rhizobium was measured against soil inoculated with Rhizobium or Azospirillum alone or a control with a low background level of autochthonous rhizobia. The combined treatment significantly increased the shoot length and weight at 6 weeks and the regrowth shoot weight at 14 weeks when compared with the treatment with Rhizobium alone. In 1.5-L pots in which gnotobiotic conditions were maintained, the combined treatment led to more nodules on the main root at intermediate Rhizobium concentrations, and a greater root surface area at intermediate and high Rhizobium concentrations after 2 weeks but not after 4 weeks. In pouch-grown seedlings, plants were inoculated with either Rhizobium alone or in combination with Azospirillum or applied together with a flavonoid, luteolin (a nodulation gene inducer), or with a cytokinin, benzyl adenine. Luteolin had similar effects to those of Azospirillum in increasing the main root nodule number and the total nodule number. With Fahraeus slides, a significant increase was observed in the number of root hairs and the root diameter in the presence of Azospirillum as compared with the control and Rhizobium alone. There was no increase in the total number of infection threads; however, the combined treatment caused a significant decrease in the percentage of infected root hairs.Key words: Rhizobium, Azospirillum, Medicago, flavonoid, inoculation.

Release of periplasmic enzymes fromRhizobium leguminosarum bvphaseoli bacteroids by lysozyme is enhanced by pretreatment of cells at low pH

Treatment ofRhizobium leguminosarum bvphaseoli bacteroids with 25 mM citrate buffer, pH 4.0, prior to treatment with 50 mM Tris, pH 8.0, containing 1 mM EDTA, 20% (wt/vol) sucrose, and 1 mg lysozyme/mL increased by two- to three-fold the release of the periplasmic marker enzymes phosphodiesterase and pyrophosphatase. Release of malate dehydrogenase, a cytoplasmic marker, was largely unaffected by the citrate pretreatment. The pretreatment was shown to be a pH effect, with a narrow optimum pH range. Above pH 4.0 the enhancement of release of periplasmic enzymes decreased sharply to almost no effect at pH ≥ 5.5, and below pH 4.0 release of malate dehydrogenase increased sharply. The effectiveness of pretreatment with low pH did not appear to be owing to increased entry of lysozyme into the periplasmic space, and an effect of low pH on the suceptibility of the peptidoglycan layer to hydrolysis is suggested.

Interaction between Rhizobium leguminosarum and Meloidogyne javanica nematode in broad bean under nematicide application

Summary The interaction between Rhizobium leguminosarum and Meloidogyne javanica nematode in broad bean root-knot infection under a nematicide, Vydate 10G, application was investigated. Results indicate that Meloidogyne javanica population was high in a nematode + Rhizobium treatment. Moreover, nematode egg-masses were noticed only in the same treatment. While no nematode infection was observed by nematode + Vydate 10G treatment, this infection occurred with nematode treatment alone. In addition, the nematode population was highly decreased at nematode + Rhizobium + Vydate 10G treatment. Whereas the average numbers of Rhizobium nodules were highly noticed by Rhizobium alone and Rhizobium + Vydate 10G treatment, the lowest ones were detected with nematode + Rhizobium treatment. Intermediate status between the 2 mentioned levels was observed in a Rhizobium + nematode + Vydate 10 G treatment.

Genetic Variation for Acetylene Reduction Rate and Other Characters in Alfalfa

The objective of this study was to determine the general (GCA) and specific (SCA) combining abilities of alfalfa (Medicago sativa L.) for rate of acetylene reduction, plant dry weight, N content (%), total plant N and nodule score. The parental clones were selected from the commercial cultivars ‘Beaver,’ ‘Roamer,’ ‘Saranac,’ and ‘Rambler.’ Five strains of Rhizobium meliloti Dang., including four single strains and one commercial inoculant ‘Balsac’ were used. The most effective strain of Rhizobium was NRG61, while RM110 was the poorest. Diallel analysis of the six‐parent half diallel cross revealed that mean squares of both GCA and SCA were highly significant for all characters except the SCA mean square for nodule score. The highly significant interactions of GCA and SCA with Rhizobium strains suggested differential expressions of gene effects for alfalfa genotypes with different strains of Rhizobium. The GCA variance components were higher than SCA for total plant dry weight, total plant N and nodule score. This suggested that the major portion of the total genetic variation was additive. Recurrent selection for these characters should be possible. However, the additive and non‐additive gene effects were equally important for acetylene reduction rate with Rhizobium strains NRG43, NRG61, and NRG118. Reciprocal recurrent selection method might be necessary to improve this character with these single Rhizobium strains. Combining ability analysis for each of the parental clones indicated that Clone 4 had consistently high and positive GCA effects over all Rhizobium treatments. Clone 2 was on the other extreme with negative GCA effects in all cases. None of the other parental clones produced consistently positive GCA effects across all the Rhizobium strains.

Increase in Internode Length of Phaseolus lunatus L. Caused by Inoculation with a Nitrate Reductase-deficient Strain of Rhizobium sp.

Dramatic differences in the height of lima beans (Phaseolus lunatus L.) treated with two different Rhizobium strains were studied. Lima beans were grown in Perlite in the greenhouse or in a minus-N culture solution in the growth chamber. The plants were inoculated with either Rhizobium sp. (lima bean) strain 127E15, which contains the constitutive nitrate reductase activity, or strain 127E14, which lacks that activity. For up to 3 weeks, no growth differences were observed in the plants inoculated with either strain. Five weeks after inoculation, however, those plants inoculated with strain 127E14 were significantly taller and had a larger number of leaves than those inoculated with strain 127E15. The difference in plant height was the result of increased internode elongation caused by inoculation with Rhizobium sp. 127E14. This response was observed with all lima bean cultivars tested, including Henderson, Fordhook, Allgreen, and Early Thorogreen. The growth difference occurred in plants cultured in the greenhouse or in the growth chamber.No differences were observed in fresh weights of nodules, roots, axes, leaves, or flowers. The number of nodules, pods, or flowers also did not differ. Acetylene reduction rates and total N content were equal in plants inoculated with strains 127E14 or 127E15.Inasmuch as only internode length and leaf number differed between Rhizobium treatments, the response appeared to be hormone-mediated. Application of gibberellic acid to the apex of plants inoculated with strain 127E15 caused an increase in plant height similar to that observed in untreated plants inoculated with strain 127E14. Conversely, the height of plants infected with strain 127E14 was decreased by application of gibberellin synthesis inhibitors to the root system. These data suggest that the increased growth caused by inoculation with strain 127E14 could be the result of increased gibberellin synthesis in lima bean nodules infected with that strain. Whether this response was related to the absence of nitrate reductase activity in strain 127E14 is unknown.

Symbiotic variability in Vicia faba. 2. genetic variation in Vicia faba

Eight varieties of Vicia faba were examined in association with a standard strain of Rhizobium leguminosarum and also with the application of mineral nitrogen. Large differences in dry matter yield, nitrogen percentage and total nitrogen uptake were apparent between varieties and between rhizobium and mineral nitrogen treatments; the interaction was also significant. Genotypic differences in both the effectiveness of the symbiosis with this strain of rhizobium and the efficiency of utilization of nitrogen were thus demonstrated. The implications of this variability on the assessment of varieties and the possiblity of exploiting it by plant breeding techniques are discussed.

Effect of nitrogen, Rhizobium inoculation and simazine on yield and quality of Bengal gram (Cicer arietinum L.)

A field experiment was conducted to study the effect of Rhizobium inoculation, nitrogen and simazine application, individually and in combination, on yield and quality of Bengal gram. Application of nitrogen and simazine, and seed inoculation with Rhizobium increased the grain yield significantly. The combined treatment of Rhizobium, simazine and nitrogen increased the grain yield to the extent of 70 per cent over control. Application of simazine increased the methionine content. re]19760609

Effect of Certain Pesticides on Nodulation and Nitrogen Fixation by Rhizobium sp. in Groundnut

Treatment of Rhizobium inoculated groundnut sced with wet ceresin (1000 opm) did not appreciably after the dry matter weight, total nitrogen content, nodulation and leghemoglobin content of nodules of the plants Although sail application of brassicol at 11 ppm (field rate) d'd not appreciably alter the efficiency of the groundnut Rhizobium symbiosis, higher concentrations of 50 and 100 ppm proved to be harmful. Foliar appli- cation of Dithane Z-78 and copper oxychlorids at the recommended levels of 0.2 and 03 per cent, respectively, did not affect the symbiotic relationship in plants. Seil application of disysson and DDT at field rates increased significantly the dry weight, total nitrogen content. nodulation and leghemoglobin content. However, at 200 ppm. these insecticides exerted a harmful effect on the symbiosis Foliar applica- tion of endrin (at 0.02 and 0.04 %) and parathion (0.025%) crused a significant increase in the dry weight. total nitrogen, nodulation and leghemoglobin content of nodules of plants. Pro-sowing soil application of Lasso and TOK E.25 at field rates caused n significant reduction in dry waight, total nitrogen, nodulation and leghemoglobin content of nodules. At 200 ppm these two herbicides have completely inhibited the nodule formation.

Effect of Seed Fumigation on the Symbiosis of Rhizobium sp. with Arachis hypogaea Linn

To minimize the loss due to insect pests during storage, the fumigation of the seeds is advocated. However, no information is available on the subject how these fumigants, if such fumigated seeds are treated with Rhizobium , will interact with the Rhizobium legume symbiosis. Hence, groundnut seeds treated with ethylene dibromide, ethylene dichloride carbon tetrachloride mixture (EDCT), chloropicrin, and phosphine were treated with Rhizobium and sown. Observations were made on the number, fresh weight and leghaemoglobin content of the nodules, and on the yield, dry weight and nitrogen content of the plants. The results indicated that all the four fumigants adversely affected the nodulation status and the yield of groundnut treated with Rhizobium , and hence the use of fumigated seeds for Rhizobium treatment is not advisable. The insecticide malathion is also used in store houses to protect groundnut seeds from insect pests. When the malathion-treated seeds were inoculated with Rhizobium and sown, no adverse effect on nodulation and yield was recorded. Die Begasung von Saatgut wird häufig als Mittel gegen Verluste durch Insekten angewendet. Es sind keine Angaben vorhanden, auf welche Art und Weise diese Begasung die Symbiose von Rhizobium mit der Pflanze beeinflußt. Darum wurde Erdnuß mit Athylenbromid, einem Äthylendichlorid-Kohlenstofftetrachlorid-Gemisch (EDCT), Chlorpikrin und Phosphin behandelt und angebaut. Die Zahl und die Masse der frischen Knöllchen, der Gehalt an Leghämoglobin der Knöllchen sowie Ertrag und Stickstoffgehalt der Pflanzen wurden ermittelt. Alle angewandten Mittel beeinflußten die Knöllchenbildung und den Ertrag nachteilig. Es ist daher nicht empfehlenswert, sie anzuwenden. Dagegen hatte das Insektizid Melathion keine Nachwirkung, wenn es während der Lagerung des Saatgutes angewandt wurde.