Selection Pressure, Cropping System, and Rhizosphere Proximity Affect Atrazine Degrader Populations and Activity ins-Triazine–Adapted Soil

Weed Science ◽  
2012 ◽  
Vol 60 (3) ◽  
pp. 516-524 ◽  
Author(s):  
L. Jason Krutz ◽  
Robert M. Zablotowicz ◽  
Krishna N. Reddy
Keyword(s):  
Selection Pressure ◽  
Crop Production ◽  
Rhizosphere Soil ◽  
Cropping System ◽  
Bulk Soil ◽  
Most Probable Number ◽  
Probable Number ◽  
Continuous Corn ◽  
Mineralization Kinetics ◽  
Time Required

A field study was conducted on ans-triazine–adapted soil to determine the effects ofs-triazine exclusion interval (1, 2, 3, or 4 yr), crop production system (continuous corn or continuous soybean), and rhizosphere proximity (bulk or rhizosphere soil) on atrazine degrader populations and activity. Atrazine degrader populations were quantified by a radiological Most Probable Number technique, while degrader activity was assessed via mineralization of ring-labeled14C-atrazine. As thes-triazine exclusion interval increased, atrazine degrader populations declined exponentially, regardless of crop or rhizosphere proximity. Crop and exclusion interval interacted to affect degrader populations (P = 0.0043). Pooled over rhizosphere and bulk soil, degrader populations were 1.5-fold higher and declined 2.8-fold faster in soybean than corn. An interaction between rhizosphere proximity and exclusion interval was also noted (P = 0.0021), whereby degrader populations were 1.9-fold higher and declined 2.8-fold slower in rhizosphere compared with bulk soil, regardless of crop. The time required for 50% mineralization of ring-labeled14C-atrazine (DT50) following exclusion ofs-triazine herbicides increased linearly at a rate of 2.2 d yr−1. In contrast, the DT50for this site prior to a knowns-triazine application was 85 d and declined exponentially over 5 yr of successive atrazine applications: 24.5 d after 1 yr, 10.8 d after two successive years, and 3.8 d after five successive atrazine applications. Omittings-triazines can reduce degrader populations and activity in adapted soils, but more than 4 yr is required to return mineralization kinetics to nonadapted levels, regardless of crop or rhizosphere proximity.

Culturable Populations of Sporomusa spp. and Desulfovibrio spp. in the Anoxic Bulk Soil of Flooded Rice Microcosms

1999 ◽  
Vol 65 (8) ◽  
pp. 3526-3533 ◽  
Author(s):  
Dirk Rosencrantz ◽  
Frederick A. Rainey ◽  
Peter H. Janssen
Keyword(s):  
Ethylene Glycol ◽  
Bulk Soil ◽  
Most Probable Number ◽  
Culturable Bacteria ◽  
Soil System ◽  
Probable Number ◽  
Selective Enrichment ◽  
Methanospirillum Hungatei ◽  
Dry Soil ◽  
Different Strains

ABSTRACT Most-probable-number (MPN) counts were made of homoacetogenic and other bacteria present in the anoxic flooded bulk soil of laboratory microcosms containing 90- to 95-day-old rice plants. MPN counts with substrates known to be useful for the selective enrichment or the cultivation of homoacetogenic bacteria (betaine, ethylene glycol, 2,3-butanediol, and 3,4,5-trimethoxybenzoate) gave counts of 2.3 × 103 to 2.8 × 105 cells per g of dry soil. Homoacetogens isolated from the terminal positive steps of these dilution cultures belonged to the genus Sporomusa. Counts with succinate, ethanol, and lactate gave much higher MPNs of 5.9 × 105 to 3.4 × 107 cells per g of dry soil and led to the isolation of Desulfovibrio spp. Counting experiments on lactate and ethanol which includedMethanospirillum hungatei in the medium gave MPNs of 2.3 × 106 to 7.5 × 108 cells per g of dry soil and led to the isolation of Sporomusa spp. The latter strains could grow with betaine, ethylene glycol, 2,3-butanediol, and/or 3,4,5-trimethoxybenzoate, but apparently most cells of Sporomusa spp. did not initiate growth in counting experiments with those substrates. Spores apparently accounted for 2.2% or less of the culturable bacteria. It appears that culturableDesulfovibrio spp. and Sporomusa spp. were present in approximately equal numbers in the bulk soil. Multiple, phylogenetically-distinct, phenotypically-different, strains of each genus were found in the same soil system.

scholarly journals Enhanced Mineralization of [U-14C]2,4-Dichlorophenoxyacetic Acid in Soil from the Rhizosphere of Trifolium pratense

2004 ◽  
Vol 70 (8) ◽  
pp. 4766-4774 ◽  
Author(s):  
Liz J. Shaw ◽  
Richard G. Burns
Keyword(s):  
Plant Species ◽  
Trifolium Pratense ◽  
Rhizosphere Soil ◽  
Most Probable Number ◽  
Dichlorophenoxyacetic Acid ◽  
Polymorphism Analysis ◽  
Alternative Mechanism ◽  
Probable Number ◽  
Enhanced Biodegradation ◽  
2,4 Dichlorophenoxyacetic Acid

ABSTRACT Enhanced biodegradation in the rhizosphere has been reported for many organic xenobiotic compounds, although the mechanisms are not fully understood. The purpose of this study was to discover whether rhizosphere-enhanced biodegradation is due to selective enrichment of degraders through growth on compounds produced by rhizodeposition. We monitored the mineralization of [U-14C]2,4-dichlorophenoxyacetic acid (2,4-D) in rhizosphere soil with no history of herbicide application collected over a period of 0 to 116 days after sowing of Lolium perenne and Trifolium pratense. The relationships between the mineralization kinetics, the number of 2,4-D degraders, and the diversity of genes encoding 2,4-D/α-ketoglutarate dioxygenase (tfdA) were investigated. The rhizosphere effect on [14C]2,4-D mineralization (50 μg g−1) was shown to be plant species and plant age specific. In comparison with nonplanted soil, there were significant (P < 0.05) reductions in the lag phase and enhancements of the maximum mineralization rate for 25- and 60-day T. pratense soil but not for 116-day T. pratense rhizosphere soil or for L. perenne rhizosphere soil of any age. Numbers of 2,4-D degraders in planted and nonplanted soil were low (most probable number, <100 g−1) and were not related to plant species or age. Single-strand conformational polymorphism analysis showed that plant species had no impact on the diversity of α-Proteobacteria tfdA-like genes, although an impact of 2,4-D application was recorded. Our results indicate that enhanced mineralization in T. pratense rhizosphere soil is not due to enrichment of 2,4-D-degrading microorganisms by rhizodeposits. We suggest an alternative mechanism in which one or more components of the rhizodeposits induce the 2,4-D pathway.

scholarly journals Agroclimatic classification for assessment Of the crop potential of Karnataka

MAUSAM ◽  
2021 ◽  
Vol 43 (1) ◽  
pp. 91-98
Author(s):  
Dr. (SMT.) N.N. KHAMBETE
Keyword(s):  
Crop Production ◽  
Most Probable Number ◽  
Cropping Pattern ◽  
Probable Number ◽  
Dry Spells ◽  
Agricultural Potential ◽  
Climatic Classification ◽  
Availability Index ◽  
Dry Farming ◽  
Made In

To plan cropping pattern and to bring out agricultural potential of a region, it is essential that the agro climatic classification is made on an objective and rational basis. Such an attempt has been made in this paper by devising an index called Water Availability Index (WAI). This index takes into account the distribution of the minimum water required by the crop. It utilizes the most probable number of the wet weeks for three threshold values of weekly rainfall and probability of dry spells of more than three weeks. The methodology developed is applied to dry farming tracts of Karnataka State. Using these information along with the information of the soil types and water requirement of different crops, cropping pattern can be assessed in each agro climatic zone, so that optimum use of the available moisture is made in stabilizing the crop production in the State.  

scholarly journals The Reaction of Cellulolytic and Potentially Cellulolytic Spore-Forming Bacteria to Various Types of Crop Management and Farmyard Manure Fertilization in Bulk Soil

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 772
Author(s):  
Jakub Dobrzyński ◽  
Paweł Stanisław Wierzchowski ◽  
Wojciech Stępień ◽  
Ewa Beata Górska
Keyword(s):  
Farmyard Manure ◽  
Crop Management ◽  
Total Carbon ◽  
Bulk Soil ◽  
Most Probable Number ◽  
Cellulolytic Bacteria ◽  
Probable Number ◽  
Microbiological Methods ◽  
The Impact ◽  
Spore Forming Bacteria

The ecology of cellulolytic bacteria in bulk soil is still relatively unknown. There is still only a handful of papers on the abundance and diversity of this group of bacteria. Our study aimed to determine the impact of various crop management systems and farmyard manure (FYM) fertilization on the abundance of cellulolytic and potentially cellulolytic spore-forming bacteria (SCB). The study site was a nearly 100-year-old fertilization experiment, one of the oldest still active field trials in Europe. The highest contents of total carbon (TC) and total nitrogen (TN) were recorded in both five-year rotations. The abundances of SCB and potential SCB were evaluated using classical microbiological methods, the most probable number (MPN), and 16S rRNA Illumina MiSeq sequencing. The highest MPN of SCB was recorded in soil with arbitrary rotation without legumes (ARP) fertilized with FYM (382 colony-forming units (CFU) mL−1). As a result of the bioinformatic analysis, the highest values of the Shannon–Wiener index and the largest number of operational taxonomic units (OTUs) were found in ARP-FYM, while the lowest in ARP treatment without FYM fertilization. In all treatments, those dominant at the order level were: Brevibacillales (13.1–43.4%), Paenibacillales (5.3–36.9%), Bacillales (4.0–0.9%). Brevibacillaceae (13.1–43.4%), Paenibacillaceae (8.2–36.9%), and Clostridiaceae (5.4–11.9%) dominated at the family level in all tested samples. Aneurinibacillaceae and Hungateiclostridiaceae families increased their overall share in FYM fertilization treatments. The results of our research show that the impact of crop management types on SCB was negligible while the actual factor shaping SCB community was the use of FYM fertilization.

Legumes: Their potential role in agricultural production

1987 ◽  
Vol 2 (2) ◽  
pp. 69-73 ◽  
Author(s):  
James F. Power
Keyword(s):  
Crop Production ◽  
Production Systems ◽  
Economic Value ◽  
Cropping System ◽  
Primary Source ◽  
N Availability ◽  
Total Production ◽  
Physical Conditions ◽  
Continuous Corn ◽  
N Use

AbstractThe energy crisis of the late 1970's has raised the question of the wisdom of depending upon fertilizer nitrogen as the primary source of N input into crop production systems. While present and past price structures have favored fertilizer-N over biologically fixed N, there are a number of other benefits of legumes in a cropping system in addition to their effects on N availability. Among these are less potential for environmental degradation and improved soil physical conditions and water relations, but it is difficult to assign economic value to many such benefits. In addition to the economics of the present price structure, disadvantages of using legumes could include reduced total production and increased need for livestock in a farming enterprise (these could be considered assets from some aspects). Legumes are presently used in shortterm rotation, such as corn-soybean, or in continuous corn with a legume winter cover crop. These systems are finding widespread use and offer the producer many benefits, as well as helping to solve several major environmental problems associated with N use in agriculture.

Analysis of Coliform and Colifecal Total Pollution Test on Various Types of Drinking Water Using the MPN (Most Probable Number) Method

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Wanda Aulya ◽  
Fadhliani Fadhliani ◽  
Vivi Mardina
Keyword(s):  
Drinking Water ◽  
Fecal Coliform ◽  
Pathogenic Bacteria ◽  
Microbiological Quality ◽  
Coliform Bacteria ◽  
Most Probable Number ◽  
Inspection Method ◽  
Sample Number ◽  
Probable Number ◽  
Fecal Coliform Bacteria

Water is the main source for life and also the most severe substance caused by pollution. The mandatory parameters for determining microbiological quality of drinking water are total non-fecal Coliform bacteria and Coliform fecal (Escherichia coli). Coliform bacteria are a group of microorganisms commonly used as indicators, where these bacteria can be a signal to determine whether a water source has been contaminated by bacteria or not, while fecal Coliform bacteria are indicator bacteria polluting pathogenic bacteria originating from human feces and warm-blooded animals (mammals) . The water inspection method in this study uses the MPN (Most Probable Number) method which consists of 3 tests, namely, the presumption test, the affirmation test, and the reinforcement test. The results showed that of 15 drinking water samples 8 samples were tested positive for Coliform bacteria with the highest total bacterial value of sample number 1, 15 (210/100 ml), while 7 other samples were negative. From 8 positive Coliform samples only 1 sample was stated to be negative fecal Coliform bacteria and 7 other samples were positive for Coliform fecal bacteria with the highest total bacterial value of sample number 1 (210/100 ml).

Cemaran Eshericia coli dalam makanan laut yang beredar di pasar tradisional Kota Pontian

2015 ◽  
Vol 1 (1) ◽  
pp. 44
Author(s):  
Rafika Sari ◽  
Pratiwi Apridamayanti
Keyword(s):  
Most Probable Number ◽  
Probable Number

Latar Belakang: Makanan laut merupakan salah satu jenis makanan yang banyak dikonsumsi oleh masyarakat selain sebagai komoditi ekspor. Mengkonsumsi makanan laut yang telah terkontaminasi bakteri hidup atau toksin yang dihasilkannya dapat menyebabkan keracunan makanan. Tujuan penelitian ini adalah untuk mengetahui adanya kontaminasi bakteri koliform E.coli sebagai indikator pencemaran pada makanan laut dan memberikan informasi kelayakan dan keamanan konsumsi dari makanan laut di dua pasar tradisional terbesar di daerah Pontianak. Metode: Sampel yang digunakan adalah ikan, sotong dan udang. Penelitian terhadap sampel dilakukan menggunakan uji Most Probable Number (MPN) yang dilengkapi dengan uji biokimia untuk mengidentifikasi jenis bakteri pada sampel melalui penanaman bakteri pada media agar Lactose Broth (LB) dan Briliant Green Lactose Bile Broth (BGLB). Hasil: Hasil penelitian menunjukkan bakteri koliform E.coli terdeteksi pada 100% sampel dengan nilai MPN yang tidak memenuhi kriteria kelayakan konsumsi, yakni >3/g. Kesimpulan: Makanan yang ada tidak memenuhi kriteria kelayakan konsumsi.

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