Pot Culture Experiment Research Articles

Optimization of integrated phytoremediation system (IPS) for enhanced lead removal and restoration of soil microbial activities

Improving phytoremediation efficiency in lead (Pb) contaminated soil through either bacterial or fungal inoculants have extensively been studied with different successes and limitations. In this study, co-application of bacteria and fungi have been investigated for development of an integrated phytoremediation system (IPS) for efficient Pb removal and restoration of soil microbial and enzymatic activities in degraded soil. For this purpose, Pb tolerant bacterial and fungal strains were firstly analyzed for antifungal and antibacterial activities through disc diffusion method. Afterwards, the co-inoculation studies were performed to investigate the effects on phytoavailability and uptake of Pb by Pelargonium hortorum through soil incubation and pot culture experiments, respectively. Results indicated significant (p < 0.05) antibacterial activity of Mucor spp. against bacterial species (Klebsiella variicola and K. quasipneumoniae). The highest significant increase in extractable Pb fraction (5.0–folds) was observed when soil was co-inoculated with Aspergillus flavus + Microbacterium paraoxydans compared to the control soil (un-inoculated soil) at 2000 mg Pb kg−1 concentration. Similarly, uptake results also indicated significantly higher Pb uptake in plants inoculated with A. flavus + M. paraoxydans. Soil microbial results indicated significant decrease in microbial health indicators and enzymatic activities with increasing Pb concentration and exposure time, as compared to control soil. A relatively severe decline was observed in soil respiration and dehydrogenase (DEH) activities by 2.8– and 2.5–folds, respectively at 2000 mg Pb kg−1 of soil. The optimized IPS was effective for restoring enzymatic activities in Pb contaminated soil and could be applied for sustainable restoration of Pb contaminated soil.

Effects of arbuscular mycorrhizal fungi and P-solubilizing Pseudomonas fluorescence (ATCC-17400) on morphological traits and mineral content of sesame.

Sesame (Sesamum indicum L.) is an important staple crop of the family Pedaliaceae. The commercial production of sesame is still dependent on the applications of chemical fertilizers. Mycorrhiza inoculum resulted in better morphological and biochemical traits in vegetables. Thus, here the outcome of arbuscular mycorrhizal fungi (AMF) and Pseudomonas fluorescence (ATCC-17400) inoculation was studied in the pot culture experiment. Primarily, there seems to be a promising opportunity of AMF in sesame under pot and field trials because of enhanced morphological parameters, especially root weight, and disparities in nutrients and metabolites. The AMF appears to be an option to boost plant growth, mineral content, and sesame yield. The AMF treatment with Pseudomonas fluorescence strain (ATCC-17400) determined the maximum values for the morphological traits and mineral content. Overall, our study highlights mycorrhizal fungi and other microbes efficacy in achieving a successful sesame production.

Critical Level of Magnesium for Cowpea [Vigna unguiculata (L.) Walp.] in Ultisols of Kerala

Background: Ultisols are characterized by low pH, low cation exchange capacity and low base saturation due to dominance of kaolinite and oxides and hydrous oxides of iron and aluminium. Among the basic cations, magnesium has smaller ionic size and larger hydrated radius which limits binding of Mg to soil exchange sites. As a result the deficiency of magnesium is a common nutritional disorder in these soils due to leaching of bases under humid tropical conditions. The determination of critical level of magnesium in soil and plant helps to manage the nutrient deficiency and will help to avoid crop loss.Methods: A pot culture experiment was conducted to determine the critical level of magnesium for cowpea in Ultisols of Kerala during January 2019. Graded doses of magnesium were applied @ 5 mg kg-1 to 80 mg kg-1 of soil as magnesium carbonate along with recommended dose of fertilizers to evaluate the effect of applied magnesium on soil pH, available magnesium in soil, magnesium content in plant, crop uptake and yield.Result: Soil pH and available magnesium in soil recorded at flowering and harvest was highest where magnesium was applied @ 80 mg kg-1 of soil. Magnesium content in stem and leaves was found to increase with the levels of magnesium added. No significant variation in the content of magnesium in pods was recorded. Crop uptake (66.62 mg g-1) of magnesium and yield per plant (79.33 g plant-1) was highest in the treatment (T5) where magnesium was applied @ 10 mg kg-1 of soil. The critical level of magnesium determined by Cate and Nelson graphical method was found to be 75 mg kg-1 of available magnesium in soil and 0.38% in leaves of cowpea during flowering.

Growth Responses and Accumulation Characteristics of Three Ornamental Plants to Sn Contamination in Soil

Decorative ornamental plants have been applied as hyperaccumulators/phytoremediators to a wide spectrum of heavy metal contaminants. In this study, pot culture experiments were conducted to investigate the Sn tolerance and accumulation in Impatiens balsamina L., Mirabilis jalapa L. and Tagetes erecta L., in order to assess the possibility of these three ornamental plants to be used as phytoremediators of Sn-contaminated soil. Results show that all three plants exhibited strong tolerance to Sn contamination, and no significant visual toxicity was observed for all three plants grown under most of the Sn treatments. The amount of Sn accumulated in the three plants was positively correlated with the Sn concentration in the soil. The order of the Sn accumulative capacity was Impatiens balsamina &gt; Mirabilis jalapa &gt; Tagetes erecta. Impatiens balsamina and Tagetes erecta showed a low translocation ability (TF) (&lt;1), and the roots accumulated the highest Sn concentration, but Impatiens balsamina showed a relatively high bioconcentration factor (BCF, Sn concentration in each part &gt; 100 mg/kg after Sn treatment of 500 mg/kg). Meanwhile, the TF of Mirabilis jalapa was &gt;1, and the fluorescence accumulated the most Sn. In combination with the adaptation to high concentrations of various heavy metals, these three ornamental plants are potential candidates for Sn mining tailings or contaminated soil.

Evaluation of plant beneficial microbes for bio-hardening of in-vitro raised pomegranate saplings

Five beneficial microbial agents either alone or in combinations were used to inoculate one year old in-vitro raised pomegranate plants of cv. Bhagawa for further utilization of these microbes as bio-hardening agents. A pot culture experiment was initiated comprising 15 treatments each having three replications. The growth, physiological and biochemical parameters of the inoculated and control plants were recorded at 90 days after inoculation. Microbes and microbial formulations were evaluated for their further utilization as bio-priming agents in in-vitro raised pomegranate plants. Plants inoculated with Aspergillus niger strain AN27 (Asp) + Penicillium pinophilum registered significant increase in plant height (225.00 cm) and plant spread E-W (198.33 cm) as compared to control. Asp + Pseudomonas fluorescens inoculated plants performed significantly better with respect to total chlorophyll (1.84 mg/g FW), SPAD value (41.23) and total phenol content (0.81 mg/g FW) as compared to non-inoculated plants. Plants inoculated with AMF (Glomus intraradices) + T. viridae and T. harzianum was at par with Asp + P. fluorescens in total chlorophyll content (1.71 mg/g FW) and SPAD value of leaves (36.10). Plants inoculated with AMF in combination with P. pinophilum (T10), P. fluorescens (T11) and T. viridae and T. harzianum (T12) registered higher photosynthesis as compared to control and many other treatments. Microbial treatments were found effective in improving most of the morphological, physiological and biochemical attributes of inoculated pomegranate plants.

Response of soybean genotypes to iron limiting stress in calcareous vertisol under ambient and elevated CO2 and temperature conditions

Aim: To compare the relative performance of two contrasting genotypes of soybean to iron limiting conditions under ambient and elevated CO2 and temperature conditions. Methodology: A pot culture experiment was performed using calcareous vertisol soil. The environmental factors viz. CO2 and temperature were combined and applied as a single factor with two levels: a-[CO2+T] (400±10 µmol mol-1, day/night temperature 30oC/22oC) and e-[CO2+T] (610±10 µmol mol-1, day/night temperature 34oC/26oC). Soybean genotype that differed in iron use efficiency was used as another factor and two contrasting genotypes were used as two levels viz. iron efficient and responsive (FeER) and iron inefficient and responsive (FeIR). Results: The higher partial pressure of CO2 under elevated carbon dioxide and temperature condition (Pco2 = 61.8 Pa) dissolved the native CaCO3 from calcareous vertisol soil and thereby resulted in higher HCO3- ion concentration. The antagonistic interaction between Fe2+ with HCO3- ion resulted in greater iron stress. As compared to ambient condition, seed yield was significantly reduced under more stressed e-[CO2+T] condition and resulted in ~1.4 and ~1.9 times drop in FeER and FeIR genotypes, respectively. Iron efficient and responsive (FeER) genotype recorded an impressive performance, as compared to the iron inefficient and responsive (FeIR) genotype, in counteracting iron deficiency stress, both under ambient and elevated conditions. Interpretation: The intra-specific variability between soybean genotypes and their response to elevated CO2 and temperature can be exploited to remediate the emerging iron deficiency stress in soybean plants and suggest ways to structure the future breeding programmes to adapt to the climate change. Key words: Calcareous vertisol, Chlorosis, Climate change, CO2, Soybean

Photosynthetic Nutrient and Water Use Efficiency of Cucumis sativus under Contrasting Soil Nutrient and Lignosulfonate Levels.

To reduce the use of commercial conventional inorganic fertilizers, the possibility of using pulp and paper industry wastes in agriculture as an alternative source of nutrients is recently under study and discussion. This work aimed to evaluate the effect of sodium lignosulfonate application to soil on photosynthetic leaf nutrient (N, P, K, Ca, Mg, Fe, Mn, and Na) and water use efficiency. A pot culture experiment was conducted with cucumber seedlings, using five lignosulfonate concentrations (0, 1, 2.5, 5, and 10 vol. %) in sandy soil under sufficient or low nutrient availability for plants. The impact of nutrient availability on the plants’ physiological traits was stronger than the lignosulfonate impact. Under sufficient nutrient availability, the lignosulfonate application resulted in decreased photosynthetic N, P, K, Ca, Mg, Fe, and Na use efficiency. Cucumber growth and development, and photosynthetic nutrient, water, and light use efficiency were significantly reduced with a nutrient deficiency. The sodium lignosulfonate application was not successful in eliminating the negative effects of nutrient deficit on cucumber seedlings.

Biochar and compost-based phytoremediation of crude oil contaminated soil

Objectives: To study the effect of compost and biochar on phytoremediation of crude oil-contaminated soil. Methods: An attempt was made to remediate crude oil contaminated soil, using the phytoremediation method. The soil was amended with biochar and compost. Initially, the pH, moisture content and C/N ratio of the soil and amendments were determined. A pot culture experiment was conducted to study the effect of the amendments on the degradation of the Total Petroleum Hydrocarbons (TPH) in the crude oil contaminated soil using the plant species nutgrass (Cyperus rotundus). To avoid seepage of water from the pots plastic pots were used. The initial concentration of TPH was found to be 17mg/kg soil. The experiment was conducted from January to March 2019. No microorganism was inoculated either to enhance the growth of the plant or degrade the hydrocarbon. The study was conducted with natural microflora. The pots were kept (open) under direct sunlight with 8 hours of photoperiodism. The plants were watered daily with tap water to maintain optimum moisture content. Once in 15 days, the soil samples collected from each treatment were analysed for pH, moisture content and C/N ratio. The TPH removal rate was determined for the 45th day and 60th day. Findings: The soil amended with compost (200 kg/soil) and biochar (50 kg/soil) enhanced the degradation of TPH by the plant species. The highest degradation percent of 62.2 and 77.1% was achieved on 45th and 60th day respectively in the treatment T5 (amended with biochar and compost). Further, there was an increase in shoot length (54.52 cm/plant), root biomass (0.74 g/plant) and shoot biomass (5.08g/plant) of the plants in the biochar and compost amended soil which was comparable with the results of the treatment T2 (Plants were grown in soil without crude oil contamination). Applications: Biochar and compost amendment improves the water holding capacity and nutrient status of the soil, thereby enhancing the growth of TPH degraders in soil. Hence, from the study, it is understood that biochar and compost could be used for phytoremediation of crude oil contaminated soils. Keywords: Amendments; degradation of TPH; nutgrass

Assessment of natural radionuclide transfer factors and partition coefficients in some Syrian soils

Transfer factors of radium 226(226Ra), lead 210(210Pb), polonium 210 (210Po), uranium 238 (238U) and thorium 234(234Th) from five different agricultural soils in Syria to coriander, parsley and mint were investigated in a pot culture experiment. Geometric means of transfer factors (TF)were226Ra (0.13),210Pb(0.03), 210Po (0.02) and 238U (1.76) were within worldwide values, while TF values for 234Th (1.35) were higher than those recorded globally. The available transfer factor (ATF) values ranged between 0.03 and 1.45, 0.33 and 3.2, 0.10 and 3.36, 1.30 and 16.2 and 1.0 and 6.95 for226Ra,210Pb,210Po, 238U and 234Th, respectively. However, it is worth mentioning that the data from pot experiments may not represent field conditions. Liquid/solid partition coefficients (Kd)of 226Ra, U, 210Pb and 210Po for55 soils representing the dominant types of soils in Syria were also determined. Geometric means of Kd values ranged from 280 to1200, 750 to1600, 350to 4800 and 100–120 L kg−1 for 226Ra, 238U, 210Pb and 210Po, respectively at pH = 4.0, and from 200 to 6700, 670 to 2400, 150 to 2100 and 100 to 160Lkg−1at pH = 5.5, and from 370 to 790, 130 to 550, 60 to 330 and370 to 920Lkg−1at pH = 7.0. The effects of soil mineral content, CEC, ECE, pH and soluble ions on the Kd values were investigated. In general, there were logarithmic relationships between the activity concentrations in soil and the Kd values (R2 ranged from 0.59 to 1.00 at pH 4.0). There were no relationships between the Kd values and soil pH.

Analysis of physiological and metabolite response of Celosia argentea to copper stress.

Copper-tolerant (Cu) plants with high ornamental value play an important role in the ecological restoration of the copper tail mining area. We first discovered Celosia argentea adaptability in a copper mine area in China; however, its resistance to Cu and the underlying mechanism are not clear. In this study, C.argentea was selected for pot culture experiments. Its heavy metal accumulation and translocation, physiological and metabolic products were analysed under different growth concentrations of Cu (0-2400 mg.kg-1 ) stress. Our results indicated that roots strongly accumulated Cu2+ . Oxidative stress defence mechanisms were activated in leaves under Cu treatment. Higher Cu concentrations triggered higher electrolyte leakage (EL), Malondialdehyde (MDA), superoxide dismutase (SOD) and peroxidase (POD) activity, and consequently a higher capacity to scavenge oxygen radicals and maintain cellular membrane integrity. In the citrate cycle, some amino acids and sugars related to biological pathways were altered in C. argentea exposed to Cu stress. Metabolomics data revealed that C. argentea used elevated sugar content as an antioxidant to regulate reactive oxygen species (ROS). Some organic acids and amino acids were up-regulated compared with the control, indicating that these may chelate Cu in cells to remove excess Cu2+ . The up-regulation of polyamines and some organic acids may mitigate oxidative stress. These results indicate that C. argentea could be used as a Cu-tolerant plant in Cu mine restoration. Its Cu tolerance mechanism also provides a basis for future plant improvement or breeding for use in mine restoration.

Phytoremediation of Soils Contaminated with Cadmium by Agave americana

ABSTRACT Agave americana was evaluated for its phytoremediation potential of the soils contaminated with Cd. This plant was selected because of its drought tolerance and high biomass. The pot culture experiment was carried with five levels of cadmium (0, 25, 50,100, and 200 mg Cd kg soil−1). Parameters, viz. uptake, translocation factor (TF), translocation efficiency (TE), bioconcentration factor (BCF), etc., were calculated to study the phytoremediation potential. The study indicated that the plant was highly tolerant to Cd at lower levels, i.e., up to 50 mg Cd kg soil−1, but there was a significant reduction in dry weight of root, leaf, and total at higher levels of, i.e.,, 100 and 200 mg Cd kg soil−1. Cd mainly accumulated in the roots, and exclusion was found to be the principal physiological tolerance mechanism. Based on the tissue concentration of Cd (<100 μg g−1 in the leaves; and TF and BCF <1), A. americana was classified as an excluder of Cd. However, since, the plant could establish an evergreen cover over the contaminated/polluted land surface because of its exponential reproductive capacity, it could be suitable for the phytostabilization of soils contaminated with Cd.

A Microcosm Study on Effect of Iron Nanoparticles on Paddy (Oryza sativa) Growth

Nanoparticles could be important in sustainable, environment friendly development of agricultural production. The objective of the present study was to synthesize iron nanoparticles (INPs) and examine their effect on growth of paddy plants. The INPs were synthesized by co-precipitation method and characterized by fourier transform infrared microscopy (FTIR), transmission electron microscopy (TEM) and particle size analysis (PSA). The synthesized particles were examined for their effect on growth of paddy plants using pot culture experiment. Various plant growth parameters like shoot length, root length, fresh and dry weight of plant and chlorophyll content was estimated in presence of various iron nanoparticle concentrations till 45 d. Interveinal chlorosis and iron content in plants also were examined. The data are suggestive of positive effects of INPs on paddy plants and confirm INPs as potential fertilizers for iron-deficient soils where paddy is grown.

Evaluation of foliar application of zinc nanoparticles on growth and yield parameters of maize (Zea mays L.) grown under greenhouse conditions

Maize is one of the important crop for human consumption both directly and indirectly. It is also used as major feed source for cattle. After the major nutrients (Nitrogen, Phosphorus and Potassium) micronutrient Zinc, plays critical role in growth and yield of Maize. By owing to zinc importance, the present investigation was conducted to find out the impact of foliar application of zinc nanoparticles. Microbial synthesized zinc nanoparticles (MNP’s) in the laboratory and chemically synthesized zinc nanoparticles (CNP’s) were foliar applied at 30 and 60 days after sowing in pot culture experiment. Experiment composed of twelve treatments, first treatment was control without any zinc application, second treatment was farmers practice of soil application of zinc sulfate, five treatments were with foliar spray of MNP’s (250, 500, 750, 1000 and 1250 ppm), and the other five with CNP’s (250, 500, 750, 1000 and 1250 ppm). Among the treatments, the treatments imposed with 750ppm of zinc nanoparticles foliar spray had shown significantly higher growth parameters, chlorophyll content and yield parameters. Application rate of 750 ppm put forward the maximum yield under application of microbial synthesized nanoparticles. Microbial synthesized nanoparticles possess a protein layer from the mother source which helps in improved dispersivity of nanoparticles and increase the active ingredient concentration available to the plant.

Interactive effects of potassium and saline water on yield, nutrient accumulation and uptake by rice

A pot culture experiment was conducted to assess the interaction effects of salinity and potassium nutrition on rice during 2018.A pot experiment was conducted in CRD with three replications and twelve treatments consist of four levels of saline water (0, 2, 4 and 8 dS m-1) and three doses of potassium (60, 120 and 180 kg ha-1). The crop received a common dose of N @ 120 kg ha-1 (in splits) and P @ 60 kg ha-1. The crop received saline water irrigation up-to saturation point at 30, 45, 60 and 80 DAP (days after planting). The study indicated that the cumulative application of saline water @ 4 and 8 dS m-1 decreased the grain yield and straw yield, yield components, potassium content and uptake by rice whereas, sodium content and uptake increased significantly at higher level of salinity (4 and 8 dS m-1). The adverse effect of Na was reduced with application of potassium. The grain and straw yield, yield component, potassium content and uptake by rice was increased with increasing the dose of potassium. The sodium content and uptake by rice was reduced significantly with higher dose of potassium (180 kg ha-1) application. Based on the present study, split application of potassium @ 180 kg ha-1 is recommended for rice in saline soil. The K+/Na+ ratio in soil and plant can be considered as a best indicator in evaluating crop performance in saline soil.

Effect of different Jeevamrut based liquid organic formulations on biochemical properties of soil and on plant growth of blackgram [Vigna mungo (L.) Hepper] under pot culture conditions

A pot culture experiment was conducted at organic farming unit, Rajasthan College of Agriculture, MPUAT, Udaipur, to study the effect of different jeevamrut based liquid organic formulations on biochemical properties of soil and on plant growth of blackgram during kharif 2019. The various types of liquid organic formulations were prepared from plant and animal origin wastes and are effective in the promotion of growth and fruiting in blackgram. Jeevamruth promotes immense biological activity in soil and enhance nutrient availability to crop. Similarly, beneficial effects of silicon, vermiwash and leaf extracts (of lemon grass and Aleo vera) have been reported to protect the crop from soil borne and seed borne pathogens and also improves seed germination. In the present study, significant highest plant growth and root length was recorded with the application of jeevamrut + lemon leaf extract (2.5%) + Aloe vera leaf extract (2.5%) + silica (1%) + vermiwash (5%) and it was found to be significantly superior over other treatments. The N, P, and K concentration of plants and microbial population and dehydrogenase activity of soil was significantly highest in the treatment given jeevamrut + lemon leaf extract (2.5%) + Aloe vera leaf extract (2.5%) + silica (1%) + vermiwash (5%).

Effect of levels of fulvic acid through foliar sprays on yield and quality of green chilli

A pot culture experiment was conducted with Chilli (cv. Phule Jyoti) at College of Agriculture, Pune (MS), during 2009-10. The soil used for experiment was alkaline in nature with medium in organic carbon, having low available N, medium available P and very high available K. The FYM used for extraction of fulvic acid had pH 7.63, EC 1.42 dSm-1 and C/N ratio 19.8 indicated good quality and maturity. The experiment was laid in completely randomized design (CRD) keeping water and fulvic acid sprays (water, 50, 100, 200, 300 and 400 mg L-1) with three replications. The recommended dose of fertilizers (100:50:50 kg ha-1N:P2O5:K2O) and FYM @ 20 t ha-1 were applied to all treatments. The water and fulvic acid sprays were applied at 30 and 45 days after transplanting of Chilli. The results of the experiment revealed that the application of 200 mg L-1 fulvic acid significantly increased yield of green Chilli and nutrient uptake over the other treatments. The significant increase in length of fruit (8.96 cm), girth of fruit (4.50 cm) number of fruits per plant (40.3), green fruit yield (89.9 g plant-1) and dry matter of stalk (39.6 g plant-1) and ascorbic acid content (109.8 mg 100-1 g) were reported under foliar spray of 200 mg L-1 fulvic acid with some few exceptions found at par with 100 mg L-1 FA. The results summarized that the application of 200 mgL-1 fulvic acid as foliar spray extracted from good quality FYM at 30 and 45 days after transplanting to Chilli along with recommended dose of fertilizers and 20 t FYM ha-1 found beneficial to improve the quality, yield and uptake of nutrients by chilli.

Efficacy of Biosynthesised Silver Nanoparticles From Entomopathogenic Fungi Metarhizium Rileyi Against Spodoptera Litura on Cabbage

There is lot of scope for applications of nanotechnology in agriculture. Nanobased insecticide formulations show less toxicity against non-target organisms due to absence of organic solvents. Hence, in this study silver nanoparticles were biosynthesized from Metarhizium rileyi Farl. and the synthesis confirmed initially by colour change from pale yellow to dark brown after seven days. Further, these were characterized using UV-visible spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and EDAX analysis. The surface plasmon resonance peaks were observed at 311 nm and 315 nm in 1.75 and 2.00 mM concentration, respectively. The particle size ranged from 64.11 to 99.08 nm in 1.75 mM and 64.11 to 128.2 nm in 2.00 mM concentration under SEM. In TEM analysis the particle size ranged from 12.80 to 22.20 nm in 1.75 mM and 11.00 to 19.00 nm in 2.00 mM concentration. The presence of elemental silver was confirmed by signals that ranged from 0 to 10 keV in EDAX analysis. The synthesized nanoparticles were effective in suppressing the Spodoptera litura F. both under laboratory and pot culture experiments. The maximum mortality of80.00 and 53.33% was observed at 1.75 and 2.00 mM under laboratory condition, in the 2nd and 3rd instar larvae, respectively. Whereas, in pot culture the mortality was 73.75 and 78.75% with 1.75- and 2.00-mM concentrations, respectively, as compared to the commercial formulation of M. rileyi and NSKE 4%.

Integrated Management of Root-Knot Nematode, Meloidogyne incognita (Kofoid and White) Chitwood in Cowpea

Pot culture experiment was carried out under glass house condition to evaluate the resistance/tolerance of seven varieties of vegetable cowpea against Meloidogyne incognita. The variety Kadakkal local found as resistant with gall index 1 and all other varieties were highly susceptible to M. incognita. A field experiment was carried out to study the comparative effect of bio agents (Purpureocillium lilacinum and Stenotrophomonas maltophilia) and organic amendment (neem cake) in comparison with chemicals fluopyram and carbosulfan for the management of M. incognita in cowpea. All the treatments increased yield and reduced nematode population compared to untreated. Among the treatments, P. lilacinum cfu 2x106 @ 10 g/m2 in combination with neem cake @ 50 g/m2 and fluopyram 400 SC @ 250 g a.i./ha were statistically on par in increasing yield (53.70-54.63 %) and reducing nematode population in soil (93.03-94.27 %) and root (86.94-88.31 %).

Exploration of Potential Bacterial Endophytes against Root Knot Nematode, Meloidogyne incognita in Banana

A field survey was conducted in 12 districts of Assam viz., Jorhat, Golaghat, Nagaon, Marigaon, Goalpara, Dibrugarh, Tinsukia, Lakhimpur, Dhemaji, Sivsagar, Kamrup and Barpeta. A total of 92 root samples were collected and 37 bacterial isolates were isolated from commercial banana cultivars. The culture filtrates extracted from 37 endophytic bacterial isolates, were screened against southern root-knot nematode, Meloidogyne incognita in vitro and under pot culture studies. The five bacterial isolates viz., EB4, EB8, BC1, BC11 and BC12 showed 100% inhibition of egg hatching and juvenile mortality of M. incognita with an exposure period of 48 and 72h. On seed bacterization, with these five promising isolates, two isolates viz.EB4, BC1 significantly enhanced germination percentage (33.33, 25.31%) and vigour index (75.5, 64.39%) of paddy, receptively. The potential bacterial isolates viz., BC1 and EB4 were identified as Lysinibacillus sp. and Pseudomonas sp., respectively , based on the morphological phenotypic and biochemical characterization. The pot culture experiment revealed that the bacterial endophytes viz., Lysinibacillus sp. (BC1) Pseudomonas sp. (EB4) significantly reduced the soil (61.64, 56.71%) and root nematode population (77.29, 68.87%), number of adult females (73.97, 69.89%), egg masses (85.63, 80.11%) and root-knot index (1.33, 1.67) of M. incognita compared to untreated control. The bacterial endophytes viz., Pseudomonas sp. (EB4), Lysinibacillus sp. (BC1) were also significantly increased the growth parameters viz., shoot length (43.33, 39.18%), and root length (78.24, 59.26%) and pesudostem girth (58.38, 52.13%).

Effect of Crop Cover and Stage of Crop Growth on Soil L-Glutaminase Activity

A pot culture experiment was conducted at glass house of Department of Soil Science and Agricultural Chemistry, College of Agriculture, Rajendranagar, Hyderabad. The aim of the present experiment was to study the influence of crop cover and stage of crop growth on soil L- glutaminase activity in an Alfisol and Vertisol. The experiment was under taken with six crops viz., two cereals (Rice, Maize), two legumes (Groundnut, Greengram), one oilseed (Sunflower) and one vegetable (Bhendi) crop. The experiment was conducted in Completely Randomized Block design with three replications along with the uncropped control. The results obtained with regard to the effect of these crops on soil L-glutaminase activity showed that there was an increase in enzyme activity with age of the crop upto 60 DAS and it varied with crops grown. The increased enzyme activity (μg of NH4+ released g-1 soil 4h-1) varied from 5.56 to 12.17 for groundnut, 5.58 to 11.25 for greengram, 5.43 to 10.87 for sunflower, 5.48 to 8.61 for rice, 5.39 to 8.23 maize and 5.31 to 7.92 for bhendi in Vertisol. In Alfisol the L-glutaminase activity (μg of NH4+ released g-1 soil 4h-1) under different crop cover found to vary from 6.72 to 13.59 (groundnut), 6.68 to 12.71 (greengram), 6.63 to 11.96 (sunflower), 6.61 to 10.25 (rice), 6.59 to 9.47 (maize), 6.62 to 9.26 (bhendi). A close perusal of the data indicates that the L-glutaminase activity followed the sequence groundnut &gt; greengram &gt; sunflower &gt; rice &gt; maize &gt; bhendi, in both Alfisol and Vertisol.