Nodule Leghemoglobin Content Research Articles

N-compound accumulation and carbohydrate shortage on N2 fixation in drought-stressed and rewatered cowpea plants

In this study nodulated cowpea plants were exposed to a progressive drought-stress followed by rewatering in orderto establish mechanisms related to the nodule sensitivity to N2 fixation. Water stress caused a prominent decreasein the dry matter of leaf and nodule in contrast to the root growth that was stimulated. The drought-stressed plantsshowed a great decline in the ureide concentration of xylem sap whilst the concentration of the nodule leghaemoglobindecreased slightly. The stressed-nodules had significant accumulation of soluble carbohydrates in parallel to intenseincrease in the concentration of ureide, total amino acid and proline. After two days rewatering, the leaf growthshowed a significant enhancement whereas in nodules a poor recovery was observed. In addition, the nodule N2 fixationcapacity did not improve after rehydration whereas the sap ureide experienced only a slight recovery and surprisinglythe content of nodule soluble protein continued to drop. In contrast, a significant recovery in the nodule leghaemoglobincontent was observed. Rewatering greatly induced depletion of both sucrose and total soluble sugarcontents of nodules that were associated to a great decrease in the concentration of ureide, proline and amino acids,especially in leaves. Conversely the poor recovery of cowpea nodules after rehydration was apparently related to a carbohydrateshortage.

Studies on the effect of salinity, drought stress and soil type on nodule activities of Lablab purpureus (L.) sweet (Kashrangeeg)

Lablab purpureus (50 cultivars throughout the world) is a drought-tolerant legume widely grown as a high-protein grain food and forage legume within a wide range of neotropical regions with extensive production in India and similar climatic areas of Asia, Africa, Central and South America. The objective of this work was to study the nitrogen-fixing potentialities of L. purpureus under the effects of the extreme environmental conditions prevailing in the southern part of Egypt aiming at the recommendation of its propagation in areas of the National giant projects. L. purpureusinoculated with Rhizobium sp. Strain I 4 (21 days after planting) grown on Nile valley and Wadi Allaqi soils was relatively tolerant to mild levels of salinity, but the nodule number was reduced to about 35% of the control plants when subjected to a high salt level (120mM NaCl). Lablab plants were similarly affected by different rates of water deficits. This legume was tolerant to moderate levels of drought. The nodule number and weight at 50% of field capacity was about 70% of the control. These values were reduced to 45–55% at a field capacity of 16·5%. Absolute nitrogenase activity, leghaemoglobin content of nodules and protein content of bacteroids and cytosol were moderately affected by mild levels of NaCl and drought but significantly reduced to about 25–35% of the control treatments. The results also indicate that plants grown on the soil of Nile Valley exhibited slightly higher values (nitrogenase, protein, etc.) than those grown on Wadi Allaqi soil. This would encourage the possibility of propagating L. purpureus in the newly reclaimed areas of southern Egypt.

Nodule Structure and Functioning in Chickpea (Cicer Arietinum) as Affected by Salt Stress

Cicer arietinum L. plants raised in sand culture under natural light were subjected to salinity stress induced by mixture of NaCl, CaCl2, MgCl2 and MgSO4 (40, 60 or 80 meq dm-3). Acetylene reduction activity (ARA) of nodules, leghemoglobin content and nodule structure were followed 55, 75 and 85 d after sowing. ARA declined significantly under salt treatments and the lowest ARA was observed at day 85 after sowing. Decrease in ARA was consistent with decreased nodule leghemoglobin content. The leghemoglobin content of control plants decreased by 50 % at day 85 indicating senescence of nodules. This senescence was further accelerated by salt treatment after which the leghemoglobin content fell to negligible levels. The structural changes associated with salt stress were mainly reduction in size of the nodules, decreased meristematic zone, reduced number and degradation of symbiosomes, reduced intercellalar spaces and deposition of electron dense material in the intercellular spaces in the cortex of nodules.

Effect of Glyphosate on Growth, Chlorophyll, and Nodulation in Glyphosate-Resistant and Susceptible Soybean (Glycine max) Varieties

ABSTRACT Greenhouse and growth chamber experiments were conducted to examine glyphosate [isopropylamine salt of N-(phosphono-methyl) glycine] effects on growth, chlorophyll content, nodulation, and nodule leghemoglobin content of glyphosate-resistant and susceptible soybean (Glycine max[L.] Merr.) varieties. In susceptible soybean, a single application of 0.28 kg/ha reduced chlorophyll content (49%), and shoot and root dry weight (50 and 57%, respectively) at 2 wk after treatment. In glyphosate-resistant soybean, there were no significant effects on these parameters by single application up to 1.12 kg/ha, but 2.24 kg/ha reduced shoot and root dry weight by 25 to 30%. Application of glyphosate 1.12 kg/ha, followed by sequential applications at 0.56 or 1.12 kg/ha, did not affect plant growth and chlorophyll content, but application of 2.24 kg/ha followed by sequential application of 2.24 kg/ha reduced root growth. In glyphosate-resistant soybean, an application of 1.12 kg/ha 3 wk after planting did not affe...

Salinity Induced Changes in Plant Water Status, Nodule Functioning and Ionic Distribution in Phenotypically Differing Genotypes of Vigna radiata L.

Summary Two phenotypically differing mungbean genotypes, i.e. K-851 (trifoliate) and a mutant (pentafoliate), were raised in earthen pots containing dune sand under natural conditions of a screen-house. At vegetative stage (30–35 DAS), plants were exposed to salinity levels of 0, 2.5, 5.0 and 10 dSm−1 for the duration of 3, 6, and 9 days with the objective to test their tolerance on the basis of plant water status, N2 fixation and mineral distribution. The water potential (ψw) of leaves and osmotic potential (ψs) of leaves, roots and nodules became more ‹−ve› with increasing salt stress. Relative water content (RWC %) of leaves, roots and nodules decreased significantly, while a sharp rise in proline content was observed. In a mutant (Code No. 97003), the values of ψw of leaves and ψs of leaves, roots and nodules were more negative than with K-851, while the reverse was true for RWC(%), showing better osmoregulation in the mutant than in K-851. A conspicuous increase in ethylene evolution was noticed from nodulated roots under salt stress, and genotype K-851 showed higher ethylene production than the mutant. A sharp decline in ARA and leghemoglobin content of nodules was recorded and K-851 was more sensitive than the mutant. The mutant maintained a better N-status in different plant parts than K-851, though N content of leaves, roots and nodules declined under stress. The Na+/K+ ratio in leaves, roots and nodules was enhanced significantly, being highest in roots. The mutant exhibited a low value of Na+/K+ ratio in plant parts. Cl− concentration was significantly higher in roots of the mutant than K-851, whereas the reverse was true for leaves and nodules. Dry weight of nodules plant−1 decreased more in genotype K-851. The better plant water status in the mutant, based upon ψw, ψs, RWC, proline and Na+/K+ ratio, resulted in a relatively better nodule dry weight, ARA and leghemoglobin content of nodules, and moreover less ethylene production. Hence, the mechanism of salt tolerance was better in the mutant than in K-851, as found from the physiological traits studied.

Effects of exogenous application and stem infusion of ascorbate on soybean (Glycine max) root nodules

Numerous biochemical and physiological studies have demonstrated the importance of ascorbate (ASC) as a reducing agent and antioxidant in higher plant metabolism. Of special note is the capacity of ASC to eliminate damaging activated oxygen species (AOS) including O2−· and H2O2. N2‐fixing legume nodules are especially vulnerable to oxidative damage because they contain large amounts of leghaemoglobin which produces AOS through spontaneous autoxidation; thus, ASC and other components of the ascorbate–reduced glutathione (ASC–GSH) pathway are critical antioxidants in nodules. In order to establish a meaningful correlation between concentrations of ASC and capacity for N2 fixation in legume root nodules, soybean (Glycine max) plants were treated with excess ASC via exogenous irrigation or continuous intravascular infusion through needles inserted directly into plant stems. Treatment with ASC led to striking increases in nitrogenase activity (acetylene reduction), nodule leghaemoglobin content, and activity of ASC peroxidase, a key antioxidant enzyme. The concentration of lipid peroxides, which are indicators of oxidative damage and onset of senescence, was decreased in ASC‐treated nodules. These results support the conclusion that ASC is critical for N2 fixation and that elevated ASC allows nodules to maintain a greater capacity to fix N2 over longer periods.

Efficiency of the nodulating Rhizobium leguminosarum bv. viciae population under the influence of slurry deposition and slope position

In a three year study (1993, 1994 and 1995) the effect of slurry deposition, landscape position and slope exposure in a grass-covered arid region on the leghemoglobin content (Lb) of pea nodules was studied. Until 1990 this region was used for the deposition of bovine slurry over a period of five years. The leghemoglobin content of legume nodules is, at different stages of plant development, correlated with the activity of nitrogenase measured by acetylene reduction assay. The total leghemoglobin concentration (Lb/mg nodule) was used to measure the physiological activity of the nodulating Rhizobium leguminosarum bv. viciae population. A simple spectroscopic method was adapted to determine the content of leghemoglobin in the nodules of two varieties of Pisum sativum. The effect of slurry on the nodule leghemoglobin content was more pronounced at the northern exposed slope, where significant different leghemoglobin contents at nonpolluted and polluted sites could be determined in the first two years of sampling. At the southern slope no effect of slurry on the leghemoglobin content of the nodulating population was found, whereas significant differences were determined between slope position and year of sampling. The leghemoglobin content/mg nodule was higher at the southern slope in all three years compared to the northern slope and in 1995 the nodules from all sites had a significant higher leghemoglobin content compared to 1993 and 1994. The relative differences between the individual positions, measured in one year, were reproducible in every year.

Water relations and nitrogen fixation in potassium fedVigna radiata nodules

Drought created by withholding the irrigation at 30 and 45 d after sowing significantly decreased relative water content (RWC) and osmotic potential (ψs) ofVigna radiata (L.) Wilczek cv. MH-83-30 nodules. Potassium fed plants showed higher RWC, whereas ψs was further declined irrespective of soil moisture levels. The nitrogenase activity and leghemoglobin content of nodules markedly decreased under drought and nodules of potassium fed plants showed better recovery after rehydration. The proline content significantly increased under drought but declined upon reirrigation. Also, the C, N and K contents of nodules significantly declined under drought.

Interaction response ofglomus albidusandcicer rhizobiumstrains on iron uptake and symbiotic N2fixation in calcareous soil

Abstract A field experiment was conducted in calcareous soil (pH 8.4, free CaCO3, 34.2% and DTPA‐extractable Fe, 4.2 ppm) to assess the role of G. albidus in iron nutrition and N2 fixation of Cicer arietinum Fe‐efficient (Pant G 114) and Fe‐inefficient (BR‐77) genotypes with and without Rhizobium strains IC‐76 and RG‐3. Application of G. albidus with Rhizobium strains to the genotypes produced significant differences in N2ase activity, leghaemoglobin content of nodules and active and total iron contents of nodules, roots and shoots compared with the uninoculated control. Interaction between Pant G 114 X IC‐76 X G. albidus showed the highest active iron content and N2ase activity of nodules while low content of total iron was noted in this combination.

Influence of Meloidogyne Incognita On Nodulation and Growth of Pea and Black Bean

Meloidogyne incognita invaded aseptic roots of Pisum sativum and Phaseolus vulgaris and developed to adult females in about 19 days. Males were occasionally observed. Juvenile nematodes invaded nodules initiated by Rhizobium; nodules formed also on galls initiated by nematodes. M. incognita suppressed root and nodule growth. However, M. incognita stimulated the initiation of nodules which remained undeveloped. Effective nodules had more nitrogenase activity/g on plants with M. incognita than on those without nematodes. M. incognita increased the leghaemoglobin content of nodules on Pisum and decreased it on Phaseolus. All the effects of the nematode invasion were transient and 7d difference in invasion date altered the degree of effect recorded at different harvest dates.

Influence of seed treatment and foliar nutrition of molybdenum on green gram and black gram

SummaryIn two separate field experiments with green gram (Vigna radiata L. Wilczek) and black gram (Vigna mungo L. Wilczek), the effect of seed treatment of molybdenum at 4, 8 and 12 g of sodium molybdate/kg seeds as well as foliar nutrition of sodium molybdate at 0·4, 0·8 and 1·2 kg/ha was evaluated on the nodulation characteristics and leghaemoglobin content of nodules and growth and yield of crops. Both seed treatment and foliar application of sodium molybdate were found to be superior to controls in respect of the number of nodules per plant and dry weight of nodules. The leghaemoglobin content of nodules in both crops was maximal in the treatments with the highest dose of seed treatment followed by the highest dose of molybdenum for foliar sprays. Molybdenum favourably influenced the growth of green gram and black gram by increasing the number of branches and leaves and by nearly doubling the leaf area index. This resulted in increased D.M. and yield of pods.

Dark treatment effects on symbiotic nitrogen fixation and related processes in Cicer arietinum L. (Chickpea)

Seven-week-old chickpea plants grown in earthenware pots were given dark treatment by shifting them to a dark room after they had received a 9 hr exposure to natural day light. The plants were retained in the dark till the end of the experimental period, while a set of plants growing under natural daylength (average 10–11 hr) served as control. A dark period of 18 hr was sufficient to result in a 69% decrease in the rate of nitrogen fixation as determined by an acetylene reduction bioassay. With prolongation of the dark period to 48 hr, the nitrogenase activity was decreased to 10% of the control value. However, the decrease in nodule respiration was not correspondingly sharp. Dark treatment of 18–66 hr resulted in 34–68% decrease in nodule respiration, respectively. During the same period nodule carbohydrates decreased only by 25–40%. Dark treatments led to an accumulation of free amino acids in the nodules. This accumulation appeared to be mainly due to protein hydrolysis. A dark period of 18 hr resulted in a small decrease in the nodule leghemoglobin content, which, however, remained unaffected with further prolongation of the dark period. It appears that the metabolic factors investigated are unable to explain such a sharp decline in the rate of N-fixation. It appears that some other critical and faster acting factor(s) is (are) involved.

Lysis of bacterioids in the vicinity of the host cell nucleus in an ineffective (fix-) root nodule of soybean (Glycine max)

In nodules of Glycine max cv. Mandarin infected with a nod (+)fix(-) mutant of Rhizobium japonicum (RH 31-Marburg), lysis of bacteroids was observed 20 d after infection, but occurred in the region around the host cell nucleus, where lytic compartments were formed. Bacteroids, and peribacteroid membranes in other parts of the host cell remained stable until senescence (40d after infection). With two other nod(+) fix(-) mutants of R. japonicum either stable bacteroids and peribacteroid membranes were observed throughout the cell (strain 61-A-165) or a rapid degeneration of bacteroids without an apparent lysis (strain USDA 24) occurred. The size distribution of RH 31-Marburg-infected nodules exhibited only two maxima compared with four in wild-type nodules and nodule leghaemoglobin content was found to be reduced to about one half that of the wild type. The RH 31-Marburg-nodule type is discussed in relation to the stability of the bacteroids and the peribacteroid membrane system in soybean.

Effect of zinc on nodulation and nitrogen fixation in chickpea (Cicer arietinumL.)

SUMMARYNumber of nodules and leghaemoglobin content of nodules increased with increasing Zn application up to 7·5 μg/g soil. Dry-matter yield and N fixation increased with Zn up to 10 μg/g soil. Both nodulation and N fixation decreased at higher levels. Soil N content showed an initial depletion but increased during the late season. Critical lower and upper levels for maximum N fixation were 1·75–2·5, and 10–14 μg of DTPA extractable Zn/g soil, respectively. In the present studies 5–10 μg Zn/g soil was sufficient for maximum N fixation in chickpea.

Effect of phosphorus and zinc on nodulation and nitrogen fixation in chickpea (Cicer arietinum L.)

A green house study was conducted on the effect of P and Zn on nodulation and N fixation in chickpea (Cicer arietinum L.) in a loamy sand (Typic Torripsamments) using treatment combinations of five levels of P (0, 25, 50, 100 and 250 ppm), and six levels of Zn (0, 5, 10, 20, 40 and 100 ppm). The number, dry matter and leghaemoglobin content of nodules, and amount of N fixed generally increased with Zn alone upto 19 ppm and P alone upto 50 ppm, and decreased with their higher levels. Application of 25 to 50 ppm P and 5 to 10 ppm Zn counteracted to a greater extent the adverse effect of 40 and 100 ppm Zn, and 250 ppm P, resp. Maximum nodulation and N fixation (91 to 145% over zero P and Zn, at maturity) was recorded with 25 to 50 ppm P applied along with 5 to 10 ppm Zn. At 64 days, depletion in soil-N was noted, particularly when P was applied, whereas at maturity there was a gain in soil-N, ranging from 10.5 to 44.5 kg/2×106 kg soil depending upon P and Zn treatments. The increase in nodulation and N fixation with balanced P and Zn nutrition might be attributed to an increase in leghaemoglobin, and K and Fe concentration in nodules, and increased plant growth, resulting into enhanced activity of N fixing organisms. The results showed that balanced P and Zn nutrition is essential not only for plant growth but also for maximum activity of Rhizobium for N fixation.

Response of strains of Rhizobium on nodulation, grain yield, protein and amino acids content of chick pea (Cicer arietinum Linn.)

SummaryNine strains of Rhizobium sp. were studied in vivo for their nodulation capacity, leghaemoglobin content, grain yield, crude protein and 16 amino acids content, in the chick pea variety C 235 grown on a calcareous saline alkali soil. There was no significant correlation between grain yield and number of nodules (r = 0·37) or dry weight of nodules (r = 0·29), but grain yield was significantly correlated with leghaemoglobin content of nodules (r = 0·95). Of the 16 amino acids analysed in seed samples, aspartic, glutamic, proline and histidine were greatest with strain H 45; glycine, leucine and arginine with strain F 6; norleucine, tyrosine and phenylalanine with strain KG 38; and alanine and valine were greatest with strain KG 41. Strain KG 38 led to significantly higher grain yield than the other strains.

Interaction between chick peas (Cicar arietinum Linn.) genotypes and strains of Rhizobium sp.

SummaryFive strains of Rhizobium sp. were studied in vivo for their nodulation capacity, leghaemoglobin content of nodules, crude protein and four amino acids content in five genotypes of chick pea in calcareous soil. Inoculation with Rhizobium led to a significant increase in grain yield compared with the uninoculated control. Genotype C 235 gave significantly higher grain yield than the others. The interactions between strains and genotypes were significant. Genotype C 235 gave maximum grain yield (2·2 t/ha) when treated with strain KG 41. Genotype C 235 exhibited maximum leghaemoglobin content and amino acids.

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.

Comparisons of nitrogen fixation estimates in soybeans by nodule weight, leghemoglobin content, and acetylene reduction.

Nodule leghemoglobin content, acetylene reduction rates, and nodule weight determinations were made during an entire growth period of soybean (Glycine max (L.) Merr. cv. Altona) plants grown under field conditions. High correlations within most sampling dates were found between each pair of possible comparisons of these indicators of nitrogen fixation.Rates of conversion of acetylene to ethylene per milligram leghemoglobin constantly decreased during the growing season, whereas leghemoglobin content per gram nodule fresh weight remained relatively constant. These results indicate that leghemoglobin content of nodules could be used to compare rates of nitrogen fixation in plants of a soybean cultivar at similar stages of development but should not be used to compare fixation rates in plants at different stages in ontogeny.

Effect of dichloro diphenyl trichloro-ethane (DDT) on symbiosis ofRhizobium sp. withPhaseolus aureus (green gram)

The effect of varying concentrations of DDT was studied on growth, nodulation, yield, leghaemoglobin content of nodules and nitrogen uptake ofPhaseolus aureus inoculated withRhizobium sp. Normal doses and even ten times more than those were not deleterious to any of the above characters but 40 ppm and higher levels were significantly harmful. Addition of 1 per cent organic matter appreciably reduced the toxic action of the insecticide.