Soil borne plant pathogens cause annual economic losses in most of the crops. In nature microbial interactions involve competition, hyper parasitism or antibiosis and these phenomena play an important role in striking ecological balance and keeping several plant pathogens in check. It is observed that plant growth promoting rhizobacteria (PGPR) influence the growth and yield of many plants. In this study, isolates of Bacillus, one of the important PGPR, were isolated from different rhizosphere soils. Seven isolates of B. megaterium JUMB1, JUMB2, JUMB3, JUMB4, JUMB5, JUMB6 and JUMB7 were screened in vitro for their plant growth promoting traits like production of indole acetic acid (IAA), ammonia, HCN, phosphate, siderophore and evaluated for the ability to suppress fusarial growth. All the isolates were able to produce IAA, ammonia, HCN and siderophore but none of the isolates solubilized phosphorous. Production of IAA and siderophore was highest in the isolate JUMB3 (127 µg/ml and 124% respectively) and lowest in JUMB7 (35µg/ml and 44% respectively). In-vitro screening for antagonism against F. oxysporum revealed significant inhibitory effects on mycelial radial growth by all the seven isolates. Among seven isolates JUBM5 showed highest inhibition of 3.25, 0.22 and 0.21 cm in well diffusion, streak and point inoculation method respectively.
This study was carried out to determine the influence of cuprous oxide nanoparticles (Cu2O NPs) biosynthesised from leaf extracts of Flacourtia montana on the tomato Lycioersicum esculentum seed germination, seedling growth and vigour index. Here we examined the promotory and phytotoxic effect of Cu2O NPs (0-160ppm) on tomato seeds resulted in dosage dependent response. The highest germination percentage (95%) was observed at 20ppm Cu2O NPs, however, above 20ppm Cu2O NPs, there is a reduction in the seed germination. The tomato seedlings showed increased root and shoot elongation up to 20ppm Cu2O NPs concentration, further increase in NPs concentration caused the negative effect on plants growth and development. The leaf pigments showed increasing trend in tomato plants after treatment with Cu2O NPs up to 20ppm as compared to control. Phytotoxicity of Cu2O NPs in tomato seedlings demonstrated by lower contents of chlorophyll a, b and carotenoid pigments. The study of effect on antioxidant enzymes showed increases in activity with increase in Cu2O NPs concentration for two enzymes, Super oxide dismutase (SOD) and Glutathione Peroxidase (GPX) out of five enzymes treated. High antioxidant activity of enzymes is followed by the increased lipid peroxidation and decrease in free radical scavenging activity by the DPPH. The activity of Catalase, Pheny Alanine Aminolyase and Poly Phenol Oxidase enzymes were found to increase up to 20ppm as compared to control and above this, all three enzymes showed decrease in activity. Uptake of Cu2O NPs nanoparticle by tomato seedlings was confirmed by atomic absorption spectroscopy.
Key words: Nano-Cuprous Oxide, Flacourtia montana, Tomato, antioxidant enzymes, lipid peroxidation
Ridge gourd (Luffa acutangula Roxb.) is important Cucurbitaceous vegetable and susceptible host crop facing considerable yield loss due to pest and diseases. The biochemical analysis was carried out in resistant, moderately resistant, susceptible and highly susceptible varieties of both healthy and root-knot nematode infested roots to know the accumulation and variations in biochemical constituents with regard to total phenols, total amino acids, reducing sugar and total sugar. The infested roots of variety Arka Sumeet (830 mg/g, 0.097mg/g) recorded significantly higher amount of total phenol and amino acids compared to healthy roots and all other varieties studied. Whereas, reducing sugar content was more in infested roots of variety Ridge gourd PN (15.00 mg/g) when compared to healthy roots (10.00 mg/g). Wherein, non-reducing sugar content was maximum in healthy roots of variety Ridge gourd PN (12 mg/g) compared to that of infested roots (9.00 mg/g) of same variety. Whereas healthy roots of Ridge gourd PN (9.50 mg/g) recorded more of non reducing sugar compared to (6.75 mg/g) in infested roots of same variety.
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