Soil microbial communities and enzymes as affected by herbicides of rice-wheat and soybean- wheat cropping system

A field study was conducted to study the long term impact of continuous use of herbicide on microbial activity in rice-wheat and soybean- wheat cropping system. In the present investigation, non herbicide treatments such as hand weeding and weedy check showed higher activity as compared with herbicide receiving treatments. In rice, among the two herbicides, application of butachlor had less adverse effect when compared to the application of anilophos on soil microorganisms. Actinomycetes population maintained stable after the application of herbicides. Among the different herbicide application practices, maximum dehydrogenase activity (27.7µg TPF/g soil/24hrs) and urease activity (44.5µg NH4/g soil/24hrs) was observed in anilophos and butachlor treatment respectively. The treatment preceding wheat crop did not influence the microbial and enzyme activities. In soybean, highest population of total bacteria (3.34×106cfu/g) and actinomycetes (2.47×103 cfu/g) were observed in one hand weeding treatment. The treatment preceding wheat crop did not influence the basic microbial activities. However, it positively influenced dehydrogenase activity in all the three rabi season herbicides. This study clearly indicated that herbicide application had not significant effect on the soil microbial population and soil enzymes

A review on weeds as source of novel plant growth promoting microbes for crop improvement

In the context of increasing international concern for food security and environmental quality, the use of bioinoculants like diazotrophs and plant growth-promoting rhizobacteria (PGPR) for reducing chemical inputs in agriculture is a potentially important issue. The improvement in agricultural sustainability requires optimal use and management of soil fertility and soil physical properties, where both rely on soil biological processes and soil biodiversity. Biological nitrogen fixation by plant-associated bacteria is eco-friendly and has been effectively exploited for crop plants including legumes. Although associations of rhizobacteria with non-leguminous plants such as grasses have been known for decades, they have been poorly - studied. Weedy grass species normally thrive in adverse conditions and act as potential habitats for the diverse groups of elite bacteria with multiple beneficial characters remains unexplored. A more complete understanding of the diversity and functioning of rhizobacterial microorganisms, especially those that have symbiotic relationships with grass species is of great value for agricultural research and application

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Not AvailableThe study explores the antioxidant activity, volatile chemical profile and antifungal potential of Pi menta dioica leaf essential oil (EO) against toxin producing Aspergillus flavus. GC–MS analysis of EO revealed the presence of 41 compounds with eugenol (54%), as the major compound followed by myrcene (16.0%) and chav icol (12.5%). It exhibited the strong antioxidant activity with IC50 value of 19.40 lg/ml and polyphenolic content of 526.9 mg g-1 gallic acid equivalent. The aflatoxin producing IISRaf1strain from nutmeg (Myristica fragrans) was identified by 18S rRNA sequencing as Aspergillus flavus (MH345939). MIC of P. dioica leaf EO against A. flavus was found to be at 0.04%. The changes in hyphae growth and architecture after treatment with EO were observed under light microscopy. Antifungal compounds eugenol which got separated at the particular spot caused the clear zone at the TLC plate by agar overlay bioassay. The mode of action of antifungal activity of EO was recorded in terms of its effect on ergosterol content of plasma membrane and malate dehydrogenases activity (MDH) of A. flavus. Thus P. dioica leaf EO might be viable alternative as plant based preservative in perspective on its antioxidant, antifungal activity and efficacy in food systemNot Availabl

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Not AvailableIn this study, plant growth-promoting potential isolates from rhizosphere of 10 weed species grown in heavy metal-contaminated areas were identified and their effect on growth, antioxidant enzymes, and cadmium (Cd) uptake in Arundo donax L. was explored. Plant growth-promoting traits of isolates were also analyzed. These isolates were found to produce siderophores and enzymes such as 1- aminocyclopropane-1-carboxylate (ACC) deaminase, and aid in solubilization of mineral nutrients and modulate plant growth and development. Based on the presence of multiple plant growth-promoting traits, isolates were selected for molecular characterization and inoculation studies. Altogether, 58 isolates were obtained and 20% of them were able to tolerate Cd up to 400 ppm. The sequence analysis of the 16S rRNA genes indicates that the isolates belong to the phylum Firmicutes. Bacillus sp. along with mycorrhizae inoculation significantly improves the growth, the activity of antioxidants enzymes, and the Cd uptake in A. donax than Bacillus alone. Highly significant correlations were observed between Cd uptake, enzymatic activities, and plant growth characteristics at 1% level of significance. The synergistic interaction effect between these organisms helps to alleviate Cd effects on soil. Heavy metal-tolerant isolate along with arbuscular mycorrhizae (AM) could be used to improve the phytoremedial potential of plants.ICAR-NFBSFARA schem

Domestic quarantine: An introspection and future perspectives on biosecurity interventions to contain pathogen spread in vegetatively propagated spices in India: Domestic quarantine in vegetatively propagated spices

Safeguarding biodiversity poses a major challenge that warrants preventive legislative and regulatory frameworks to ensure biosecurity, preserve intrinsic biodiversity and mitigate risks from the invasion of exotic pathogenic microbes thereby sustaining agricultural productivity and food safety. The anthropogenic activities contribute enormously towards transboundary movement of invasive alien pathogens through trade and transport of seeds/propagation materials that need to be regulated by enacting appropriate laws and policy guidelines. Black pepper, cardamom, ginger, turmeric and vanilla are the major vegetatively propagated spices cultivated in India. Since primary spread of the major pathogens in these spices are mediated through planting materials, it is imperative to formulate guidelines for flawless and meticulous implementation of quarantine measures which are otherwise not adopted. This review discusses the significance of domestic quarantine in major vegetatively propagated spices with a comprehensive background on plant biosecurity and invasive plant pathogens which could pose threat to spice cultivation in India. It further illustrates the constraints and possible strategies to annihilate the cryptically disseminated pathogens through vegetative planting materials ultimately to safeguard our self-sustaining agricultural systems

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Not AvailableIn this study, experiments were designed to isolate, characterize and evaluate an array of bacteria isolates for their Zn solubilization potential. Out of the six promising Zn solubilizing bacteria (ZnSB), ZnSB2 (B. megaterium, KY687496) was found to be the most potential strain owing to its enhanced Zn solubilization in vitro. In the quantitative study, the net Zn solubilized by ZnSB2 was significantly higher than those solubilized by the other ZnSB at all days of sampling. Similar effects of ZnSB2 was observed in the soil per se, wherein the rate of release of available Zn by ZnSB2 was markedly higher at all days of incubation (25.6%–40.7% of added Zn), with a peak on the 8th day. Such enhanced rates of Zn release by ZnSB2 were attributed to marked decrease in pH owing to enhanced gluconic acid production. In fact, gluconic acid production by ZnSB2 was 1884.7 ± 413.4 μgmL−1, which was 35.3–69.7% greater than the other shortlisted ZnSB isolates. Further evaluation of ZnSB2 was done in the green house using turmeric as the test crop. ZnSB2 was applied either alone or in combination with chemical Zn (75% and 100% of recommended Zn). The results revealed that soil available Zn level in the treatment with 75% Zn+ZnSB2 (12.69 ± 2.96 mg kg−1) was on par with the level in the treatment with 100% Zn (12.74 ± 2.63 mg kg−1) at 120 days after planting, while at harvest the treatment with 75% Zn+ZnSB2 maintained 65.0% higher available Zn levels than 100% Zn. The positive effect of ZnSB2 was also manifested on rhizome yield, which was at par in the treatments with ZnSB2+75% Zn (154.2 g ± 36.0 pot−1) and 100% Zn (177.2 ± 36.7 g pot−1). Besides, the Zn concentration in the rhizome was significantly higher (P < 0.05) in the treatment with ZnSB2+75% Zn (40.5 ± 3.5 mg kg−1), which was at par with 100% Zn, but was greater by 98.5% compared to control. The study indicated that ZnSB2 strain was a potential candidate for enhanced Zn dissolution in soil, which would allow reduced inorganic Zn application rates. Nonetheless, in vitro interaction studies (dual culture) suggested that this strain was seriously lacking in disease suppressing traits. But its compatibility with several plant growth promoting rhizobacteria enhanced the possibility of co-inoculation or applying ZnSB2 in a consortium mode especially in condition wherein both soil Zn solubilization and disease suppression becomes imperative.Not Availabl

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Not AvailableIn this study, experiments were designed to isolate, characterize and evaluate an array of bacteria isolates for their Zn solubilization potential. Out of the six promising Zn solubilizing bacteria (ZnSB), ZnSB2 (B. megaterium, KY687496) was found to be the most potential strain owing to its enhanced Zn solubilization in vitro. In the quantitative study, the net Zn solubilized by ZnSB2 was significantly higher than those solubilized by the other ZnSB at all days of sampling. Similar effects of ZnSB2 was observed in the soil per se, wherein the rate of release of available Zn by ZnSB2 was markedly higher at all days of incubation (25.6%–40.7% of added Zn), with a peak on the 8th day. Such enhanced rates of Zn release by ZnSB2 were attributed to marked decrease in pH owing to enhanced gluconic acid production. In fact, gluconic acid production by ZnSB2 was 1884.7 ± 413.4 μgmL−1, which was 35.3–69.7% greater than the other shortlisted ZnSB isolates. Further evaluation of ZnSB2 was done in the green house using turmeric as the test crop. ZnSB2 was applied either alone or in combination with chemical Zn (75% and 100% of recommended Zn). The results revealed that soil available Zn level in the treatment with 75% Zn+ZnSB2 (12.69 ± 2.96 mg kg−1) was on par with the level in the treatment with 100% Zn (12.74 ± 2.63 mg kg−1) at 120 days after planting, while at harvest the treatment with 75% Zn+ZnSB2 maintained 65.0% higher available Zn levels than 100% Zn. The positive effect of ZnSB2 was also manifested on rhizome yield, which was at par in the treatments with ZnSB2+75% Zn (154.2 g ± 36.0 pot−1) and 100% Zn (177.2 ± 36.7 g pot−1). Besides, the Zn concentration in the rhizome was significantly higher (P < 0.05) in the treatment with ZnSB2+75% Zn (40.5 ± 3.5 mg kg−1), which was at par with 100% Zn, but was greater by 98.5% compared to control. The study indicated that ZnSB2 strain was a potential candidate for enhanced Zn dissolution in soil, which would allow reduced inorganic Zn application rates. Nonetheless, in vitro interaction studies (dual culture) suggested that this strain was seriously lacking in disease suppressing traits. But its compatibility with several plant growth promoting rhizobacteria enhanced the possibility of co-inoculation or applying ZnSB2 in a consortium mode especially in condition wherein both soil Zn solubilization and disease suppression becomes imperative.ICAR Network Project on micronutrient management in horticultural crops for enhancing yield and quality headed by ICAR-Indian Institute of Horticultural Research, Bengaluru, Karnataka State, India