Groundnut Plants Research Articles

Induced systemic resistance in groundnut by foliar application of Headline (Pyraclostrobin 20% WG)

Plant’s own defence mechanisms can be stimulated by the application of elicitors for its protection. We evaluated the ability of Headline (Pyraclostrobin 20% WG) to induce systemic resistance in 40-day-old field-grown groundnut plants by foliar application. Elevated levels of defence-related enzymes such as phenylalanine ammonia lyase, peroxidase, β 1,3 glucanase, nitrate and nitrite reductase and other biochemical parameters such as total phenol, total protein, total carbohydrate and total chlorophyll content were found highest in Headline treated plants on fourth day after treatment in comparison with untreated plants. The treated plants showed enhanced growth and development as well as increased yield up to 16%. About 10% mortality rate was found in groundnut seeds treated with Headline when grown on Sclerotium rolfsii-infested soil than control. These results indicate that foliar application of Headline can be successfully developed the broad-spectrum resistance against pathogens in groundnut.

Plant Growth Promoting Activity, Induction of Systemic Resistance and Control of Collar Rot Disease in Arachis hypogaea L. by a Novel Pseudomonas species.

Induction of systemic resistance in Arachis hypogaea L. by an agriculturally useful bacteria was studied. 25 bacteria were isolated from rhizospheric soil of groundnut plants grown in Junagadh region of Gujarat. The plant growth promoting and antagonistic activity (against A. niger) of all these bacteria were compared and a bacterium with high level of siderophore, GA3, IAA, ammonia and ACC deaminase producing and phosphate, zinc and potassium solubilizing ability was selected to study its effect on plants. This bacterium promotes the germination of seedlings from 65-88 % to 82-94 %. It could also recover the A. niger infected seedlings. The generation of ISR was evident as its treatment increased Phenyl alanine ammonia lyase, peroxidase, lipoxygenase, jasmonic acid, β-1,3-glucanase and chitinase activities in GG20 and GG2 varieties of A. hypogaea L. seedlings. The bacterized seeds sowed in field, reduced the disease incidence significantly in the plants challenged with A. niger. Field survivability was found to be 15 days. To identify this bacteria, 16s rRNA gene was isolated, sequenced and subjected to BLAST, which showed 99% analogy with P. plecoglossicida, P. monteilii, P. putida and P. mosselii. Results of biochemical and FAME analysis differed from P. plecoglossicida, P. monteilii, P. putida and P. mosselii, which showed that this is a novel bacteria. The bacterium was found to promote plant growth in field studies and could be useful.

Selection criteria for grain yield and stability in bambara groundnut (Vigna subterranean (L) Verdc) landraces

The potential of bambara groundnut as a crop-based approach for the sustainable reduction of protein–energy malnutrition prevalent in Nigeria is still being explored. However, one of the limitations to sustainable production of this adapted species is low and unstable yield. Here, we employed multiple statistical analyses to determine traits that could be useful in predicting grain yield. Furthermore, additive main effect and multiplicative interaction and genotype × genotype × environment models were used to identify high yielding and stable landraces. Twenty-four bambara landraces were evaluated in two contrasting dry land growing seasons at four environments. Based on the results of correlation, path coefficient values and stepwise multiple regression analysis, it is reasonable to assume that seed growth rate would be effective as indirect selection criteria for grain yield improvement in this set of breeding materials under early and late planting environment. However, optimizing biomass growth rate, pod fill period, 100-seed weight, number of pods per plant and time to flowering may have important role in the improvement of grain yield in bambara groundnut. Due consideration should be given to 100-seed weight and time to flowering in the early dry and late planting environment. The possibility of successful cultivation of bambara groundnut in forest–savannah transition agricultural zone of Nigeria, particularly when planting is done around early August has been established in this study. However, based on the strong association between seed yield and its related characters in early and late planting environments, selection for higher seed growth rate combined with large number of pods appears to be the best indirect traits when selecting bambara groundnut plants to enhance grain yield under early and late planting environments. While landraces TVSu 1520 and 1578 were considered the best adapted landraces, TVSu 1670 and 1518 are promising landraces that could contribute to increasing grain yield stability.

A Pseudomonas guariconensis strain capable of promoting growth and controlling collar rot disease in Arachis hypogaea L

Background and aim Collar rot disease due to A. niger in ground nut plants causes a great loss in yield. Using a PGPR isolated from the field of same plants, we aimed to study effect on control of this disease as well as to study effect on seed germination and development of Induced systemic resistance in germinated seedlings.

Isolation and Screening of Indigenous Bambara Groundnut (Vigna Subterranea) Nodulating Bacteria for their Tolerance to Some Environmental Stresses

Environmental stresses are important limiting factors for crops production. The aim of this experiment is to isolate Legume Nodulating Bacteria (LNB) obtained from root nodules of bambara groundnut (Vigna subterranea L.) plants and evaluate their performance under some environmental constraints. Samples were collected in Cameroon from three location sites of the Humid-forest zone: Logbessou in the Littoral region; Mfoua in the South and Boga in the Centre region. Nodulation of bambara groundnut was examined in plastic bags and root nodules were collected from seedling. After their isolation, the bacteria were confirmed as LNB by re-nodulating Macroptilium atropurpureum. The morphological, cultural and phenotypic characteristics (utilization of carbon, tolerance to salt, pH, aluminium) of isolates were determined. The results obtained were analyzed statistically by ANOVA using the software SPSS analysis version 11.5. Duncan test was used to measure the difference among the means at a level of p<0.05. A collection of 18 isolates was obtained on Yeast Extract Mannitol Agar medium. Authentication experiments, confirmed that the majority of the isolates (66.67%) were LNB due to their ability to infect the host plant. Bambara groundnut isolates are different morphologically. Dendrogram of the phenotypic characteristics showed that, below the boundary level of 50% average similarity, isolates fell into at least three distinct groups. All isolates showed fast-growing capacity. Most isolates (66.67%) were able to grow in a medium with pH as low as and Al concentration of 50 µM (58.33 %). Some isolates (50%) showed weak growth capacity at 4% NaCl. The bambara groundnut isolates tested were able to use a broad range of carbohydrates as sole source of carbon. The isolates from the present study may be useful to increase the symbiotic nitrogen fixation in legume.

Impact of plant development on the rhizobacterial population of Arachis hypogaea: a multifactorial analysis.

Present study investigates the impact of plant development on the structure and composition of root-associated bacterial community of groundnut (Arachis hypogaea) plant, an economically important oilseed legume. Relative abundance of total and active bacteria were studied in bulk soil and rhizosphere samples collected from different growth stages of groundnut plant by sequencing PCR-amplified 16S rRNA gene fragments from soil genomic DNA and reverse-transcribed soil community RNA. Plant growth promoting potential of cultivable rhizobacteria was evaluated using assays for inorganic phosphate solubilization and production of indole acetic acid, siderophores, biofilm, 1-amino-cyclopropane-1-carboxylate deaminase, laccase, and anti-fungal chemicals. Our study demonstrates that groundnut plant rhizosphere harbors a core microbiome populated by Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, and Acidobacteria. A distinct bacterial assemblage at nodulation stage due to predominance of Flavobacteria and Actinobacteria in DNA and RNA derived libraries respectively was also observed. Majority of cultivable isolates exhibiting plant growth promoting activities belonged to Proteobacteria and Firmicutes. Of them, Pseudomonas indica and Bacillus megaterium were detected in the rhizosphere samples from all the developmental stages of groundnut plant. This polyphasic study establishes the impact of plant development on rhizobacterial population of groundnut and underscores the applicability of soil isolates as a reliable component in sustainable agriculture.

Photosynthesis of some drought resistant groundnut cultivars

The groundnuts have not only a high economy value but also they are very useful in improving the soil. We carried out a study of the photosynthesis of three groundnut cultivars TQ6, V79 and L05 at different growth periods and the change in drought conditions. According to the results measured by the Ultra compact photosynthesis system LCi, the photosynthetic intensity of these groundnut cultivars is different at the stages of the young and overmature nuts. The cultivar TQ6 always has higher photosynthetic intensity than the cultivars V79 and L05 . The drought conditions have a great influence on the photosynthesis of the groundnut plants at the flowering stage. Also, the photosynthetic intensity of the higher drought resistant cultivars reduces at least in the drought conditions.

Effects of Glomus fasciculatum and Trichoderma asperelloides in Roots of Groundnut (Cv. Western-51) Against Pathogen Sclerotium rolfsii

Sclerotium rolfsii (Sacc.) is the causal agent of stem-rot of groundnut plants which is an important damaging soil-borne root pathogen worldwide. Arbuscular mycorrhizal (AM) fungi (Glomus fasciculatum) and Trichoderma asperelloides have shown potential bio-control agent properties against several soil-borne plant pathogens. Interactions between G. fasciculatum, T. asperelloides and soil-borne pathogen S. rolfsii were investigated in this present pot culture experiment. The inoculation of G. fasciculatum and T. asperelloides reduced the severity of disease but their combinations were most effective in reducing harmful effects of S. rolfsii. The arbuscule percentage of AM fungi was affected by presence of T. asperelloides but chlorophyll content got increased by AM fungi or T. asperelloides treatments during S. rolfsii attack. The defense related physiological, biochemical and anti-oxidant activities observed in roots of groundnut plant significantly increased by single inoculation of AM fungi or Trichoderma. But, the combined inoculations of AM fungi and Trichoderma species showed the highest defense related activities. Moreover, single application of either AM fungi or Trichoderma species showed potential for the biocontrol of soil-borne plant pathogen but their combined application attributed most substantial inhibition in development of pathogen

First evidence on phloem transport of nanoscale calcium oxide in groundnut using solution culture technique

Nanoscale materials, whose size typically falls below 100 nm, exhibit novel chemical, physical and biological properties which are different from their bulk counterparts. In the present investigation, we demonstrated that nanoscale calcium oxide particles (n-CaO) could transport through phloem tissue of groundnut unlike the corresponding bulk materials. n-CaO particles are prepared using sol–gel method. The size of the as prepared n-CaO measured (69.9 nm) using transmission electron microscopic technique (TEM). Results of the hydroponics experiment using solution culture technique revealed that foliar application of n-CaO at different concentrations (10, 50, 100, 500, 1,000 ppm) on groundnut plants confirmed the entry of calcium into leaves and stems through phloem compared to bulk source of calcium sprayed (CaO and CaNO3). After spraying of n-CaO, calcium content in roots, shoots and leaves significantly increased. Based on visual scoring of calcium deficiency correction and calcium content in plant parts, we may establish the fact that nanoscale calcium oxide particles (size 69.9 nm) could move through phloem tissue in groundnut. This is the first report on phloem transport of nanoscale calcium oxide particles in plants and this result points to the use of nanoscale calcium oxide particles as calcium source to the plants through foliar application, agricultural crops in particular, as bulk calcium application through foliar nutrition is restricted due to its non-mobility in phloem.

Transport via xylem and accumulation of aflatoxin in seeds of groundnut plant

Aflatoxin contamination in groundnut seeds in the absence of any aflatoxigenic fungi leads to a hypothesis that aflatoxins are present naturally in soil and is transferred to seeds through uptake by roots. A survey was conducted on the natural occurrence of aflatoxins in agricultural soils, among nine main groundnut-growing regions of Karnataka state, India. All 71 soil samples collected in this survey were contaminated with aflatoxins esp. AFB1. An in vitro xylem sap experiment proved the ability of groundnut plant roots to absorb AFB1, and transport to aerial plant parts via the xylem. Hydroponics experiment also proved the uptake of AFB1 by the roots and their translocation to shoot. Uptake was affected by the initial concentration of toxin and pH of the medium. Among the 14 varieties screened, GPBD4 and MLT.K.107 (III) recorded highest and least AFB1 uptake, respectively. The above results were validated using a greenhouse experiment. Here, the aflatoxin absorbed by root gradually transferred to shoot that was later found in seeds towards the end of experiment. Thus, the groundnut seeds can also get contaminated with aflatoxin by direct uptake of aflatoxin through conducting tissue in addition to fungal infection. The present study revealed the novel mode of aflatoxin contamination in groundnut seeds without fungal infection.

Assessment of ecological diversity of rhizobacterial communities in vermicompost and analysis of their potential to improve plant growth

AbstractPresent study was designed to determine the microbial diversity from three distinctive sites (amended with vermicompost) of Gujarat, India. A set of 76 strains were screened from total of 438 strains that exhibit plant growthpromoting (PGP) and antagonistic potential isolated from sites PS1 (Mehsana district), BS2 (Dantiwada district) and VS3 (Gandhinagar district). Their diversity indices were studied for determining the species richness and evenness of screened isolates. Results revealed that site BS2 showed the most significant diversity indices in terms of Shannon (H′ 1.525) and Simpson (1/D 5.120) than other two samples. Principal component analysis showed that bacterial diversity (H′) was correlated with the soil characteristics. Chickpea and groundnut plants inoculated with MBCU1 and MBCU3 isolates showed an increase in the vegetative growth parameters that evaluate plant growth when compared to uninoculated controls. Strains MBCU1 and MBCU3 were identified as Pseudomonas stutzeri and Pseudomonas mosselii, respectively, according to sequence analysis of the 16S rRNA gene. These both isolates belong to site BS2 and they showed specific PGP traits suggesting that these isolates can promote plant growth by more than one mechanism with respect to their higher diversity index.

Siderophore as a potential plant growth-promoting agent produced by Pseudomonas aeruginosa JAS-25.

Siderophores scavenges Fe(+3) from the vicinity of the roots of plants, and thus limit the amount of iron required for the growth of pathogens such as Fusarium oxysporum, Pythium ultimum, and Fusarium udum, which cause wilt and root rot disease in crops. The ability of Pseudomonas to grow and to produce siderophore depends upon the iron content, pH, and temperature. Maximum yield of siderophore of 130 μM was observed at pH 7.0 ± 0.2 and temperature of 30 °C at 30 h. The threshold level of iron was 50 μM, which increases up to 150 μM, favoring growth but drastically affecting the production of siderophore by Pseudomonas aeruginosa JAS-25. The seeds of agricultural crops like Cicer arietinum (chick pea), Cajanus cajan (pigeon pea), and Arachis hypogaea (ground nut) were treated with P. aeruginosa JAS-25, which enhanced the seed germination, root length, shoot length, and dry weight of chick pea, pigeon pea, and ground nut plants under pot studies. The efficient growth of the plants was not only due to the biocontrol activity of the siderophore produced by P. aeruginosa JAS-25 but also may be by the production of indole acetic acid (IAA), which influences the growth of the plants as phytohormones.

Excess Nickel Modulates Oxidative Stress Responsive Enzymes in Groundnut

Groundnut plants exposed to excess nickel (Ni) produced visual symptoms of toxicity that intensified with increasing level and duration of metal supply. Decreased concentrations of pigments along with a marked increase in the activities of anti-oxidative enzymes such as superoxide dismutase, ascorbate peroxidase, and peroxidase suggest strong induction of oxidative stress due to excess Ni. The decreased activity of catalase may suggest interference of excess nickel in iron metabolism of plants. The appearance of metal specific toxicity is a likely result of damage predominantly due to enhanced generation of reactive oxygen species (ROS) at higher (300–400 μM) nickel supply. The threshold of toxicity (10% growth reduction) and toxicity (33% growth reduction) values of Ni in groundnut were 26 and 72 μg g−1 in leaves, 17 and 94 μg g−1 in stem and 45 and 240 μg g−1 in roots respectively.

Induced resistance to Helicoverpa armigera through exogenous application of jasmonic acid and salicylic acid in groundnut, Arachis hypogaea.

Induced resistance to Helicoverpa armigera through exogenous application of jasmonic acid (JA) and salicylic acid (SA) was studied in groundnut genotypes (ICGV 86699, ICGV 86031, ICG 2271 and ICG 1697) with different levels of resistance to insects and the susceptible check JL 24 under greenhouse conditions. Activities of oxidative enzymes and the amounts of secondary metabolites and proteins were quantified at 6 days after JA and SA application/insect infestation. Data were also recorded on plant damage and H. armigera larval weights and survival. Higher levels of enzymatic activities and amounts of secondary metabolites were observed in the insect-resistant genotypes pretreated with JA and then infested with H. armigera than in JL 24. The insect-resistant genotypes suffered lower insect damage and resulted in poor survival and lower weights of H. armigera larvae than JL 24. In some cases, JA and SA showed similar effects. JA and SA induced the activity of antioxidative enzymes in groundnut plants against H. armigera, and reduced its growth and development. However, induced response to application of JA was greater than to SA, and resulted in reduced plant damage, and larval weights and survival, suggesting that induced resistance can be used as a component of pest management in groundnut.

English

Strain EGB3 was isolated from the gut of earthworm fed with sterile soil and identified as Pseudomonas stutzeri on the basis of biochemical tests and by comparison of 16S rDNA sequences. This bacterium exhibits a broad-spectrum antifungal activity towards soil borne phytopathogenic fungi (Fusarium oxysporum, Fusarium solani, Fusarium moniliformae, Fusarium udum, Macrophomena phaseolina, Rhizoctonia solani, Colletotrichum capsicii, Aspergillus flavus, and Aspergillus niger). The antifungal metabolite produced by EGB3 was extracted and characterized to determine the nature of the active molecules (volatile and non-volatile). The bioactive compound was thermostable upto 80&deg;C for 10 min. The zone of inhibition was observed after 6 h of incubation and increased up to 36 h and there was no change in zone of inhibition after 36 h of incubation. EGB3 was an antagonist against a range of phytopathogenic fungi that infect groundnut plants. Key words: phytopathogenic fungi, EGB3, Pseudomonas stutzeri, antifungal metabolites.

Variability in Reactions of Groundnuts Varieties to Groundnut Rosette Virus Isolates from Uganda

Aims: The study was conductedto assessthe variability in reactions of groundnut varieties to groundnut rosette virus isolates from Uganda (Please correct the yellow highlighted sentence). Study Design:The experimental design was randomized complete block design arranged as a split plot with three replications. The main plots were the groundnut varieties while the sub-plot were the groundnut rosette virus isolates collected from central, western and eastern Uganda. Place and Duration of Study:The studywas conducted at the screen house, Kyambogo University, Kampala during 2011 and 2012, respectively Materials andMethods: Non-viliferous aphids obtained from Mukono zonal agricultural research and development institute (MUZARDI) fed on infected groundnut plants collected from central, western and eastern Uganda were used to infect 3 week old groundnut seedlings in a screen house. Results: There were significant variation in reactions (P<0.05) among the groundnut varietiesto groundnut rosette virus isolate s. Similarly, significant variety x isolate interactions were observed for incidence, leaf area index and plant height. Conclusion: This study has shown that there were significant variations in reactions of groundnut varieties to groundnut rosette virus i solates. In general, two groundnut rosette

Nodulation, Nitrogen Yield and Fixation by Bambara Groundnut (Vigna Subterranea (L.)Verdc.) Landraces Intercropped with Cowpea and Maize in Southern Guinea Savanna of Nigeria

Two separate field experiments were undertaken during the rainy seasons (August – December) of 2010 and 2011 at the Teaching and Research Farm of the Federal University of Agriculture, Makurdi, Nigeria. The objective of the study was to evaluate some landraces of bambara groundnut intercropped separately with cowpea and maize at varying planting densities for nodulation, nitrogen (N) yield and fixation. Each experiment was a 2 x 3 x 3 split-split plot set out in a randomized complete block design with three replications. Intercropping decreased the number and weight of nodules; nitrogen derived from the atmosphere and fixed in both bambara groundnut/maize and bambara groundnut/cowpea intercropping systems. No significant differences were noticed between the landraces in N content of shoot and roots, but ‘Okirikiri’ had significantly higher N content (3.11 %) of pod with seed than the other two landraces. ‘Okirikiri’ and ‘Adikpo’ landraces fixed more N than ‘Karo’. N fixed increased with decline in bambara groundnut planting density. Mean percentage of plant N derived from atmosphere varied from 49.80 in the bambara groundnut/maize systems to 56.80 in the bambara groundnut/cowpea intercrops, while N fixed was 11.27 kg/ha and 34.90 kg/ha in the respective intercrop systems. The expectation of enormous contribution of nitrogen fixation to bambrara groundnut yields and its residual effects on soil medium for ensuing crops may be an illusion with the use of the landraces tested in this work, except, probably when inoculated with the appropriate rhizobia?

Very low dose gamma irradiation stimulates gaseous exchange and carboxylation efficiency, but inhibits vascular sap flow in groundnut (Arachis hypogaea L.)

Purpose: An experiment was carried out to determine the effect of low dose gamma radiation on germination, plant growth, nitrogen and carbon fixation and carbon flow and release characteristics of groundnut.Materials and methods: Dry seeds of groundnut variety Trombay groundnut 37A (TG 37A), a radio mutant type developed by Bhabha Atomic Research Centre (BARC), Mumbai, India, were subjected to the pre-sowing treatment of gamma radiation within low to high dose physiological range, i.e., 0.0, 0.0082, 0.0164. 0.0328, 0.0656, 0.1312, 5, 25, 100, 500 Gray (Gy) from a cobalt source (60Co). Observations were recorded for the radiation effect on percentage germination, vigour, gas exchange attributes such as photosynthetic rate, stomatal conductance and transpiration rate, chlorophyll content, root exudation in terms of 14C release, vascular sap flow rate and activities of rate defining carbon and nitrogen assimilating enzymes such as ribulose-1,5-bisphosphate carboxylase (rubisco) and nitrate reductase (NR).Results: Seed germination was increased by 10–25% at the lower doses up to 5 Gy while the improvement in plant vigour in the same dose range was much higher (22–84%) than the unirradiated control. For radiation exposure above 5 Gy, a dose-dependent decline in germination and plant vigour was measured. No significant effect was observed on the photosynthesis at radiation exposure below 5 Gy but above 5 Gy dose there was a decline in the photosynthetic rate. Stomatal conductance and transpiration rate, however, were only inhibited at a high dose of 500 Gy. Leaf rubisco activity and NR activities remained unaffected at all the investigated doses of gamma irradiation. Mean root exudation and sap flow rate of the irradiated plants, irrespective of the dose, was reduced over the unirradiated control more so in a dose-dependent manner.Conclusions: Results indicated that a very low dose of gamma radiation, in centigray to gray range, did not pose any threat and in fact stimulated metabolic functions in such a way to aid growth and development of groundnut plants. It further showed that the radiation threshold for the gas exchange traits and rubisco activity, which ultimately determine the plant health and yield, were higher than compared to the other metabolic attributes and were well beyond 500 Gy and that the dose range above 500 Gy should be targeted to measure lethal effects of radiation on carbon assimilation attributes in leguminous crops, in general, and groundnut in particular.

Symbiotic N nutrition, C assimilation, and plant water use efficiency in Bambara groundnut (Vigna subterranea L. Verdc) grown in farmers’ fields in South Africa, measured using 15N and 13C natural abundance

Bambara groundnut (Vigna subterranea L. Verdc) is the second most important indigenous food legume in Africa. The aim of this study was to evaluate plant growth, N2 fixation, N contribution, C accumulation, and plant water relations of Bambara groundnut grown in 26 farmers’ fields in Mpumalanga Province of South Africa. The data revealed marked (p ≤ 0.05) differences in plant dry matter (DM) yield, N concentration and content, δ15N, the proportion of N derived from symbiotic fixation (%Ndfa), and actual amounts of N-fixed between and among the 26 farms surveyed. Bambara groundnut plants obtained 33–98 % (mean = 72 %) of their N nutrition from symbiotic fixation and contributed 4–200 kg N-fixed ha−1 (mean = 102 kg N-fixed ha−1). Plant density correlated positively with %N (r = 0.31***), δ15N (r = 0.126***), and amount of N-fixed (r = 0.15*), indicating that the high %Ndfa values obtained for Bambara groundnut in this study and the low symbiotic N yield associated with some farms were due to low plant density rather than poor symbiotic functioning. Bambara groundnut obtained more N from soil (e.g., 173 kg N ha−1) than from symbiosis (e.g., 135 kg N-fixed ha−1) in some fields, implying that the N2-fixing efficacy of the microsymbionts nodulating Bambara groundnut was low at some locations in South Africa. The data from this study showed δ13C values ranging from −28.01 to −26.20 ‰, which indicates differences in plant water use efficiency on the different fields studied. Furthermore, the positive correlations between δ13C and N-fixed (r = 0.15*) and between δ13C and N content (r = 0.14*) suggest a functional relationship between water use efficiency and N2 fixation, just as the positively significant correlations between δ15N and DM yield (r = 0.24***), N-fixed and DM weight (r = 0.76**), and N content and DM yield (r = 0.99*), as well as N-fixed and C content (r = 0.76**) also indicate a functional relationship between N2 fixation and photosynthesis. In the same way, the positive correlation between δ13C and DM weight (r = 0.14*), or δ13C and C content (r = 0.15*), also implies a functional link between water use efficiency and plant growth. Thus, an increase in water use efficiency in Bambara groundnut, whenever it occurs, seems to functionally enhance plant growth, symbiotic N2 fixation, and photosynthetic activity, just as N2 fixation in nodules also seems to stimulate leaf photosynthesis.

Management of Stem-rot of Groundnut (Arachis hypogaea L.) Cultivar in Field

The present experiment was conducted at University of Pune for biocontrol of soil-borne plant pathogen Sclerotium rolfsii by incorporating arbuscular mycorrhizal fungi (Glomus fasciculatum) and conventional system of cultivation with different spacing pattern (15 and 30 cm) in field. Both mycorrhizal inoculation and 30 cm spacing pattern significantly increased growth and yield as compared to control or 15 cm spacing pattern. The pathogenic mycorrhizal groundnut plants in 30 as well as 15 cm spacing pattern showed better growth in terms of plant height, leaf and pod number, fresh and dry weight of whole groundnut plant in comparison to non-mycorrhizal pathogenic ones and the plant growth was better in 30 spacing than 15 cm. The colonization by AM fungi in both spacing pattern was higher in absence of pathogen S. rolfsii. However, pathogen’s presence decreased the mycorrhizal colonization considerably in 30 and 15 cm. The disease severity and incidence were recorded to be lowered when inoculated with mycorrhiza in pathogenic groundnut plants as compared to non-mycorrhizal pathogenic ones in both spacing pattern and incidence and severity was significantly lower in 30 cm as compared to 15 cm. Therefore, it was observed from our results that for management of soil-borne pathogens inoculation of AM fungi and spacing patterns are necessary.