ofCajanus Cajan Research Articles

Assessment of PGP traits of Bacillus cereus NDRMN001 and its influence on Cajanus cajan (L.) Millsp. phytoremediation potential on metal-polluted soil under controlled conditions.

The current study looked at the plant growth-promoting (PGP) traits of the pre-isolated and metal-tolerant Bacillus cereus NDRMN001 as well as their stimulatory effect on the physiology, biomolecule content, and phytoremediation potential of Cajanus cajan (L.) Millsp. on metal-polluted soil. The bauxite mine, which is surrounded by farmland (1 km away), has been severely polluted by metals such as Cd (31.24 ± 1.68), Zn (769.57 ± 3.46), Pb (326.85 ± 3.43), Mn (2519.6 ± 5.71), and Cr (302.34 ± 1.62 mg kg−1) that exceeded Indian standards. The metal-tolerant B. cereus NDRMN001 had excellent PGP activities such as synthesis of hydrogen cyanide (HCN), siderophore, indole acetic acid (IAA), N2 fixation, and P solubilization. Furthermore, the optimal growth conditions (temperature of 30°C, pH 6.5, 6% glucose, 9% tryptophan, and 1.5% tricalcium phosphate) for effective synthesis and expression of PGP traits in B. cereus NDRMN001 were determined. Such metal-tolerant B. cereus NDRMN001 traits can significantly reduce metals in polluted soil, and their PGP traits significantly improve plant growth in polluted soil. Hence, this strain (B. cereus NDRMN001) significantly improved the growth and phytoremediation potential of C. cajan (L.) Millsp on metal-polluted soil without [study I: 2 kg of sieved and autoclaved metal-polluted soil seeded with bacterium-free C. cajan (L.) Millsp. seeds] and with [study II: 2 kg of sieved and autoclaved metal-polluted soil seeded with B. cereus NDRMN001-coated C. cajan (L.) Millsp. seeds] B. cereus NDRMN001 amalgamation. Fertile soil was used as control. The physiological parameters, biomolecule contents, and the phytoremediation (Cr: 7.74, Cd: 12.15, Zn: 16.72, Pb: 11.47, and Mn: 14.52 mg g−1) potential of C. cajan (L.) Millsp. were significantly effective in study II due to the metal-solubilizing and PGP traits of B. cereus NDRMN001. These results conclude that the test bacteria B. cereus NDRMN001 considerably improved the phytoremediation competence of C. cajan (L.) Millsp. on metal-polluted soil in a greenhouse study.

Morphological and anatomical variations ofCajanus cajan (Linn.) huth raised in cadmium-rich soil

Different concentrations of cadmium in the growing media affected morphological parameters ofCajanus cajan. Over time, the amount of increase in shoot and root lengths, number of branches and leaves per plant, single and total leaf areas, and dry mass of leaves, was significantly lower for treated plants compared with controls. The root-shoot length ratio, which varied little over time, was relatively low for the treated plants. Although dry mass of both stems and roots increased, the rates were considerably low under Cd stress. The root-shoot dry mass ratio in the controls was highest during flowering and lowest in the post-flowering stage, but continually declined over time for the stressed plants. Compared with the controls, treated plants had fewer pods, with the number decreasing as the Cd concentration increased. Cd content was greater in roots than in stems or leaves, and leaves had greater amounts than did stems at higher doses. For all plants, the width and density of vessel elements and the length of fibers in the wood of stems and roots increased with plant age. However, the rate of increase was generally lower in the treated plants, the difference being more pronounced with higher doses of Cd. This indicated a reduced ascent of sap and, hence, less available water for tissues in treated plants.

Studies in the pollen morphology of Cajanus cajan(L.) Millsp. and its wild ally Atylosia W. & A.

Studies in the pollen morphology of 13 cultivars ofCajanus cajan, a cultivated legume of Africa and Asia,and six species of Atylosia, a wild ally ofC. cajan, were conducted with light microscope andscanning electron microscope, with a view to assess interrelationship betweenthe wild and cultivated species. There is a striking resemblance among thepollen features of Cajanus cajan and fiveAtylosia species, namelyA. albicans, A. lineata,A. platycarpa, A. scarabaeoidesand A. volubilis. Pollen grains in all these species are3-zonocolporate with thickened colpi margins, and the exine surface isreticulate with circular, slightly elongated or irregular lumina. The mergerof these Atylosia species into the genusCajanus finds support also in pollen features. However,A. marmorata (an Australian species) shows distinctlydifferent pollen features from all of the above species by having smallerpollen grains, by the absence of thickened colpi margins and by havingreticulation with elongated large brochi with narrow muri. Interestingly,A. scarabaeoides, another Australian species but alsowidely distributed in Africa and Asia, does not show pollen morphologicalaffinity with A. marmorata, and is closer toCajanus cajan.

Multipurpose tree prunings as a source of nitrogen to maize under semiarid conditions in Zimbabwe

When multipurpose-tree (MPT) prunings are used as a source of nitrogen to annual corps in agroforestry systems, it is important that high levels of N recovery are attained. In order to test the effect of pruning quality and method of pruning application on N-recovery rates, a field experiment was conducted using prunings of five MPT species and two methods of application (surface versus incorporation). There was an interaction of pruning quality and method of pruning application on N recovery and maize grain yield. For most MPT species used, incorporated prunings gave high nitrogen recovery compared to surface applied prunings. In order to achieve synchrony between N supply from prunings and N demand by a maize crop, relatively large amounts of N should be released into the soil before peak N demand by the maize crop. This could be achieved by incorporating adequate quantities of high quality prunings such as those ofCajanus cajan andLeucaena leucocephala.

Variability in nuclear DNA content within pigeonpea,Cajanus cajan (Fabaceae)

4C DNA values have been estimated in 16 cultivars ofCajanus cajan by cytophotometry. The values range between 6.19 pg to 7.97 pg, a 23.6% variation. The cultivars form four groups which differ significantly from each other but have insignificant difference within them. The implications of this variability with respect to the heterogeneity and origin of this legume crop are discussed.

Nitrogen distribution index ofCajanus cajan L. during drought and rehydration

Relative competition among various plant parts for N during water stress,i.e. nitrogen distribution index (NDI) was determined in relation to specific nitrogenase activity (SNA) and nodule and soil nitrogen in both indeterminate (H-77-216) and determinate (ICPL-151) types of pigeonpea (Cajanus cajan L.) under greenhouse conditions. Two levels of water stress,i.e. moderate (soil Ψw) -0.77 MPa) and severe (soilΨw -1.34 MPa) were created by witholding the irrigation at vegetative (40 DAS) and flowering (70 DAS) stages. At vegetative stage under moderate stress the highest NDI was in nodules of cv. H-77-216 and in leaf of cv. ICPL-151. Under severe stress both the cultivars showed negative values of NDI, with maximum loss of N from root and nodules. Cultivar ICPL-151 behaved differently at flowering and vegetative stages. Very high loss of N from different plant parts was seen at flowering under severe stress. All the plant parts showed gain in N during rehydration. Loss and gain in N at both the stages under stress and rehydration respectively, correlated with available N in soil. Specific nitrogenase activity (SNA) and nodule N were maximum at moderate stress and related with NDI values of leaf and nodules.

Symbiotic effectiveness of Hup+ Rhizobium, VAM fungi and phosphorus levels in relation to nitrogen fixation and plant growth ofCajanus cajan

Effect of hydrogen uptake positive (Hup+) strain ofRhizobium sp. (pigeon pea) and VAM fungus (Glomus fasciculatum) was studied on the symbiotic parameters of pigeon pea (Cajanus cajan) cv. AL-15 at various levels of phosphorus. The Hup+ Rhizobium strain showed more nodulation, plant biomass and plant nitrogen content than its Hup− counterpart. VAM infection in pigeon pea roots helped in translocating phosphorus from the soil and improved nitrogen fixation. Similarly, addition of phosphorus was found to play a positive role in enhancing all these parameters. Dual inoculation of Hup+ Rhizobium strain and VAM significantly increased nodulation, nitrogenase activity, plant nitrogen and phosphorus content and plant biomass compared to single inoculation of either organism and dual inoculation with Hup− and VAM fungus.

Urease purification from the seeds ofCajanus Cajan and its application in a biosensor construction

Urease has been purified from the seeds of Cajanus Cajan. The purification process involves three solvent extraction steps followed by DEAE-cellulose column chromatography. The specific activity of the purified enzyme is found to be 1920 U/mg with the recovery of 8%. The application of the purified enzyme in a biosensor construction is discussed.

Parasitoid-host relationship betweenTrioxys (Binodoxys) Indicus [Hymenoptera: Aphidiidae] andAphis Craccivora [Hemiptera: Aphididae]. VI. Impact of males on the number of progeny of the parasitoid reared on certain host plants

The present paper elucidates the impact of males on the reproductive rate ofTrioxys (Binodoxys) indicus reared on the aphids ofCajanus cajan, Dolichos lablab andSolanum melongena host plants. The F1 offspring increases with the increase of parasitoid number. This increase is maximum inC. cajan followed byD. lablab andS. melongena reared aphids. The presence of male parasitoids caused a significant decrease in the emergence of F1 generation.

Seed and Seedling anatomy ofCajanus cajan (L.) Millsp.

Seed structure and seedling anatomy ofCajanus cajan are investigated. Seeds are non-endospermic. Initially ovules are anatropous but later they become campylotropous. The epidermis and the hypodermis of the seed coat consist of macrosclereids and osteosclereids respectively. Macrosclereids have fluted wall thickenings. The “tracheid island” has cells with lignified reticulate wall thickenings. Vascular interrelationship between the radicle, epicotyl and first pair of leaves have been described.

Rhizosphere microflora ofCajanus cajan in relation to Fusarium wilt resistance

Studies were made to find out the factors responsible for resistance inCajanus cajan (L.) Millsp. variety C-11-6 against wilt caused byFusarium udum Butl. It was thought to be either due to associated antagonistic microflora in the rhizosphere or due to biochemical constituents in the plant itself. Screening of the rhizosphere isolates revealed the absence of any potent antagonists againstF. udum suggesting that the resistance in C-11-6 variety is not due to antagonistic organisms in the rhizosphere.

Seed globulins of Cajanus cajan

Seed globulins ofCajanus cajan a widely cultivated legume were purified and characterised. About 78% of the seed proteins were salt soluble, out of which 61% were globulins which were further separated into three fractions. The ∞ fraction was insoluble at pH 4.7 and consisted of two subfractions. Fraction β and γ were soluble at pH 4.7. All the fractions were characterised as glycoproteins by cesium chloride centrifugation. The proteins consisted of subunits which were not held together by covalent disulphide linkages. Amino acid analysis of the different globulin fractions showed that the γ fraction was comparatively rich in sulphur amino acids.

Diallel Analysis of Genetic Variation in Pigeon Pea (Cajanus cajan)

SUMMARYA diallel analysis of flowering time, pod number, 100-seed weight and yield of six cultivars ofCajanus cajan(L.) Millsp. was studied. Additive inheritance was important in determining flowering time, but the dominance component was higher than the additive component, and over-dominance was observed for pod number, 100-seed weight and yield. Heritability estimates for all the traits except flowering time were quite low, and the bulk population method of breeding was suggested for early segregating generations. The graphical analysis of the diallel cross was in close agreement with the findings from variance component analysis. It is suggested that the best cross would be that between two parents chosen on the basis of their low g.c.a. for flowering time and their high g.c.a. for other traits.

Anatomical anomalies in tissue culture-induced roots ofCajanus cajan (L.) Mills P

Structural peculiarities of roots developed from tissue culture of gamma-irradiated seeds ofCajanus cajan have been compared with unirradiated roots, based on anatomy. Internal perturbation as a result of irradiation was marked in 10 kR-treated roots in which each xylem group was reduced to a single metaxylem vessel with fewer or no protoxylem elements, secondary growth was absent consequent on loss of cambium and the phloem was transformed into fibrous tissue.

Foliar sprays of growth regulators and rhizosphere effect inCajanus cajan Millsp.

Foliar sprays of growth regulators affected the per cent distribution of individual species of the dominant group of Aspergilli in the rhizosphere ofCajanus cajan Millsp. Generally, physiological groups occurred in the order of starch hydrolyzing > nitrifiers > denitrifiers. A shift in the balance in favour of denitrifiers and a parallel increase in the incidence ofAzotobacter in the rhizosphere of NAA- and IAA-treated plants was observed. Sprays of 2,4-D, NAA and IAA promoted starch-hydrolyzing group. On the other hand, with sprays of MH and gibberellin, their incidence was considerably reduced. It is suggested that transport and accumulation of carbohydrates in the roots might limit the incidence of this group of bacteria in MH- and gibberellintrated plants. 2,4-D and NAA sprays stimulated amino-acid requiring bacteria while MH treatment tended to preferentially stimulate group-V organisms. These results are discussed with reference to metabolic changes in the plant.

Genetical studies inCajanus cajan (L.) Millsp.

From three sets of crosses involving the phenotypes chocolate, red oxide, green with chocolate streaks and green with red oxide streaks, the action of the genes governing the phenotypes of the pods ofCajanus cajan (L.) Millsp. has been proposed. GeneL controls production of chocolate colour,L (r) an allelomorph ofL hitherto unreported, controls production of red oxide colour and geneD controls distribution of this colour. As regards inheritance of these two genes, the relationships betweenL andL (r) isL>L (r) andD is incompletely dominant overd. The genotypes of the different phenotypes have been presented.

Bio-assay of heavy metals byAspergillus niger—sensitivity of a new strain

The standard ‘M’ strain ofAspergillus niger van Tiegh. which is being used in many laboratories as a biological test to detect the presence of some heavy metals in minute traces has been compared with a new strain of the same fungus, isolated in this laboratory, from the rhizosphere ofCajanus cajan, and designated as M.U.B.L. 1.