Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Paddy field”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2024

Transfer of antibiotic resistance genes from soil to rice in paddy field.

The global spread and distribution of antibiotic resistance genes (ARGs) has received much attention whereas knowledge about the transmission of ARGs from one matrix to another is still insufficient. In this study, the paddy fields fertilized with chemical fertilizer, swine compost, and no fertilizer were investigated to assess the transfer of ARGs from soil to rice. Soil and plant samples were collected at day 0, 7, 30 and 79 representing various stages of paddy growth. High throughput qPCR was applied to quantify ARGs using a set of 144 primers. Gene copy number of ARGs measured in soil initially decreased and then increased in soil with no fertilizer and chemical fertilizer, indicating that crop planting and flooding conditions did influence the ARGs profiles in soil. Application of swine compost significantly enhanced the relative abundance and gene copy number of ARGs in paddy soil. Rice seedlings contained substantial amount of ARGs and their relative abundance continually decreased after transplant. Compared with initial stage, detection frequencies of ARGs increased in soil without swine compost at harvest time (day 79), indicating the transmission of ARGs from irrigation water to soil. Detection frequencies of ARGs increased in soil and rice root with swine compost at harvest time, indicating the transfer of ARGs from swine compost to soil and rice root. There was no significant difference in abundance and diversity of ARGs in rice grains with these three different fertilizations. The source of the ARGs in rice grain still needs further exploration.

Oryza↗
PubMed1990

Heavy metal contents of paddy fields of Alcácer do Sal, Portugal.

Recent claims of metal contamination in the lower reaches of the Sado River, in the Alcácer do Sal region, Portugal, a major rice-producing area were investigated by carrying out metal surveys in the area. The elements Fe, Mn, Zn, Cu and Pb were measured in the soil and in rice plant parts--roots, shoots and grain--as well as in some weeds growing in the Sado banks, near the paddy fields. Results showed that the metal contents of paddy soils were similar to background concentrations, with the exception of Zn and Cu, which were above those concentrations and reached their highest levels at Vale de Guizo, the monitored station located furthest upstream in the Sado River. At some sites, plant roots accumulated relatively large amounts of Fe, Mn, Zn and Cu, but the shoot levels of these metals were within the normal range for rice plants. It is possible that varying, but significant, amounts of Fe associated with the roots were in the form of ferric hydroxide plaque covering their surfaces. Copper levels in the shoots of rice were below the normal contents cited for this plant in the literature. Metal levels of river sediments collected near Vale de Guizo seem to corroborate the possibility of some metal contamination in the Sado River, most probably derived from pyrites mining activity in the upper zone of the Sado basin.

Copper↗
PubMed1990

Interspecific associations among anophelines in different breeding habitats of Kheda district, Gujarat. Part I: Canal irrigated area.

In a study covering two years, 1306 samples of immatures were collected from 7 different breeding habitats of canal irrigated villages of Kheda district in Gujarat. Out of the samples belonging to 8 anopheline species, 14396 adults emerged. Breeding of An. culicifacies was associated with An. annularis in ponds, paddy fields, small pools and with An. stephensi in paddy fields. Maximum association was observed between An. barbirostris and An. nigerrimus in irrigation canals and An. culicifacies and An. subpictus in intradomestic containers. An. annularis, An. stephensi and An. subpictus were strongly associated in paddy fields. Strong interspecific repulsion was observed between An. subpictus and An. stephensi in intradomestic containers and An. barbirostris and An. subpictus in ponds.

Animals↗
PubMed1991

Pattern of rice cultivation and anopheline breeding in Koraput district of Orissa state.

The potentiality of rice fields in anopheline vector breeding in Koraput district was studied in two agricultural seasons--rubi and kharif. Altogether, 17 species were recorded from the rice fields. The terraced stream bed paddy-fields with a perceptible water flow in top-hill areas support heavy breeding of the principal vector A. fluviatilis at all stages of paddy growth. A. culicifacies and A. annularis breeding became scarce when the paddy plants reached a height of 80 cm. Vector species formed 2 per cent in rabi and 32 per cent in kharif of the anopheline fauna from the paddy fields and the maximum production was during early stage of paddy growth or after harvesting.

Agriculture↗
PubMed1979

Salinity adaptation in the snake eel Pisoodonophis boro (Ham-buch).

The snake eel Pisoodonophis Boro (Family Ophichthidae) burrows, causing leaks in the bunds and damaging the salterns and paddy fields adjoining estuaries. The animal's capability to withstand brine in salterns and fresh water in paddy fields was determined from laboratory experiments. The eel tolerated salinities ranging from deionized water to 75%. Adaptation to fresh water as well as full strength seawater was completed within 24 h. The concentration of sodium and chloride in the blood varied by 10--20% on transfer from seawater to fresh water. P. boro can survive in paddy fields but not in salterns. However, their occurrence in both is described as a rare phenomenon and not obligatory.

Adaptation, Physiological↗
PubMed1991

Observations on the breeding of anophelines in rice fields of Shahjahanpur district, Uttar Pradesh.

Studies on ecological succession and association of anophelines in selected paddy fields of Dadraul PHC were carried out in 1988 during the paddy cultivation period from June to October. Breeding of five anophelines was observed in paddy fields. Out of the adults that emerged from larval collections the percentage of An. subpictus was the highest followed by An. nigerrimus, An. culicifacies, An. annularis and An. barbirostris. Further, An. culicifacies and An. subpictus breeding occurred in the early stage of rice cultivation and stopped before the breeding of An. nigerrimus started i.e., nearly 30 days after rice transplantation. An. nigerrimus breeding continued till harvesting. An inverse correlation between larval density of both An. culicifacies and An. subpictus and the height of the rice plants was observed.

Animals↗
PubMed1990

Breeding habitats of malaria vectors: A. fluviatilis, A. annularis and A. culicifacies, in Koraput district, Orissa.

Anopheline breeding habitats were studied in two different geoclimatic zones. The vectors A. fluviatilis, A annularis and A. culicifacies breed in all types of habitats. Streams were most productive for the main vector, A. fluviatilis and breeding was intense during winter and early summer. In the rainy season, breeding occurred in terraced paddy fields. A. culicifacies were produced in large numbers in rivers in summer and in paddy fields in rainy and cold seasons. Considering the vastness of these breeding habitats, vector control measures by larviciding or any other bioenvironmental means will not be a feasible alternative even though house spraying poses serious problems in this area due to several reasons. The use of personal protection methods is suggested.

Animals↗
PubMed1989

Feasibility of wing beat sound trap for the control of mosquito vectors.

Early observations suggested that the female sound was a possible cause of mating. Attempts had been made for introduction of female wing beat sound for removal male mosquitoes from the population for the control purpose. The traps emitted female wing beat sound, were set on black clothes as a swarm marker, could collect a large number of male Cx. tritaeniorhynchus in Japan. Those traps were later improved with introduction of two attractants, hamster and dry ice. Consequently, two systems were adopted for efficiency trapping of males and females. A cylinder trap with 350 Hz of wing beat frequency was introduced for male Cx. tritaeniorhynchus collection, while the cage trap with 530 Hz was for female collection. The traps were set every other days after sun set for three weeks in a paddy field. Although there was no decrease of population density, the reduction of parous rate was evident. For future effective control, it may suggest the need to distribute more wing beat sound traps to cover all larva breeding paddy field and near by blood sources. On the other hand, other control methods should be integrated.

Animals↗
PubMedDate not supplied

Pesticide selection pressure on Anopheles subpictus in Sri Lanka: comparison with two other Sri Lankan anophelines.

Adult Anopheles subpictus from Sri Lanka show a broad spectrum of resistance towards organophosphate insecticides but not to carbamates in contrast to the broad resistance to organophosphates and carbamates reported earlier for An. nigerrimus. In both species the frequency of resistance to malathion and fenitrothion increased between 1980 and 1987, despite the ban on agricultural use of these two compounds and the restriction of malathion to indoor residual spraying in malaria control since 1977. In contrast, An. culicifacies shows only low level specific resistance to malathion at a very low frequency. As An. subpictus breeds to a large extent in paddy fields which are highly contaminated by agricultural pesticides, and is highly endophilic, selection for resistance theoretically could occur through both agricultural and anti-malarial pesticide use. However, the anti-malarial use of malathion may have been less important, taking into consideration the low level of resistance of An. culicifacies which is also highly endophilic but breeds to a negligible extent in paddy fields.

Animals↗
PubMed1989

Breeding habitats of mosquitoes in Goa.

Studies carried out in Goa from 1986 to 1987 revealed immature stages of 43 species of mosquitoes. Breeding habitats were divided into three categories, viz., (i) Ground water habitats consisting of ground pools and tanks, rocky pools, paddy fields and stream beds, yielding 30 species; (ii) Plant habitats consisting of tree holes and fallen coconut shells and leaf sheaths yielding 20 species; and (iii) Domestic/peridomestic habitats consisting of cement tanks, glass, earthen, metallic containers and tyres yielding 11 species. Five species viz., Anopheles subpictus, Aedes albopictus, Armigeres subalbatus, Culex quinquefasciatus and Cx. pallidothorax were found in all three types of habitats. Cx. tritaeniorhynchus preferred to breed in ground pools and paddy fields but was found in domestic cement tanks and ground tanks in adverse season. Majority of the anophelines and culicines were found in ground water habitats. Five out of 11 species of Aedes were found in tree holes. Aedes aegypti and Toxorhynchites splendens were found only in discarded tyres. Three species of the genus Uranotaenia, viz., U. bicolor, U. stricklandi and U. campestris were recorded from stream beds and plant containers.

Aedes↗
PubMed2025

Synergic impact mechanisms of cover crop residue on Cd and As availability and native organic carbon mineralization in Cd and As co-contaminated paddy soil.

The synergic impacts of cover crop residue on heavy metal and metalloid availability and soil organic carbon (SOC) mineralization in contaminated paddy soil and the underlying microbial mechanism remain unclear. This study investigated the availability of cadmium (Cd) and arsenic (As) and mineralization of native SOC in paddy soil treated with 0, 0.4 %, 0.8 % and 1.2 % of δ13C-labeled cover crop residue (Astragalus sinicus L.) via 90-day incubation experiments, the related functional genes and functional microbial communities were analyzed using metagenomic binning assembly. Cover crop residue with addition rate from 0.4 % to 1.2 % significantly decreased available Cd by 56 %-85 % but increased available As by 39 %-66 % compared to the control treatment. Cover crop residue resulted in a positive priming effect on native SOC mineralization but benefited SOC sequestration. Cover crop residue increased the abundance of genes encoding iron reductase (mtrABC, pilA, omcB), sulfate reductase (sir, fpr), As(V) reductase (ArsC), organic carbon hydrolases, methanogenesis, and methylotrophy. Genomes associated with Chloroflexota and Bacteroidota encoded all these key pathways, and their abundance increased with cover crop residue application. Cover crop residue decreased soil Eh, dissolved crystalline iron oxides, enriched specific microorganisms, including Chloroflexota and Bacteroidota, and then synergistically promoted the decrease in Cd availability and the increase in As availability and native SOC mineralization in the examined paddy soil. These findings provided practical and feasible guidance for achieving both safe production and carbon sequestration in contaminated paddy fields, highlighting the requirement to cautious utilization of cover crop residue in As-contaminated paddy fileds.

Soil Pollutants↗
PubMed1989

Toxicity of three herbicides to some nitrogen-fixing cyanobacteria.

The effects of some common rice field herbicides, such as 2,4-dichlorophenoxyacetic acid (2,4-D), Machete, and Saturn, on the paddy field nitrogen-fixing cyanobacteria Nostoc linckia, Nostoc calcicola, Nostoc sp., and Anabaena doliolum were studied. These cyanobacteria were found to be more tolerant to 2,4-D (lethal doses 1500-2000 micrograms/ml) than to Machete and Saturn (lethal doses 6-8 micrograms/ml). The effects of these three herbicides on some physiological processes of N. linckia were studied. The 2,4-D stimulated the growth and nitrogen fixation up to 100 micrograms/ml concentration (a dose higher than the field dose, i.e., about 40 micrograms/ml), recommended for field application. However, with Machete and Saturn this type of stimulation was not observed even at lower concentrations. Similarly, the uptake of nutrients, such as NO3- and NH+4, was also inhibited by Machete and Saturn. However, 100 micrograms/ml 2,4-D stimulated the uptake of NO3- but not of NH+4; higher doses of 2,4-D inhibited the uptake of both nutrients. Factors such as pH, organic carbon sources (glucose and acetate), and amino acids were found to regulate the toxicity of all three herbicides to N. linckia. Lower pH enhanced the toxicity of all three herbicides, whereas higher pH (up to 9.0) lowered it. Glucose and acetate (each 500 micrograms/ml) protected against the toxicity of 2,4-D and Saturn, but not against Machete. Whereas glutamine, arginine, serine, and tryptophan conferred upon N. linckia a greater protection against the toxicity of all three herbicides, methionine did not do so, and the presence of methionine with herbicide in the culture medium resulted in greater toxicity to N. linckia than that in the presence of the herbicide alone.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1975

Degradation of organophosphorus pesticides in soils with special reference to unaerobic soil conditions.

Organophosphorus pesticides are generally transformed by the reactions including oxidation, reduction, hydrolysis, hydroxylation, dehydrochlorination, dealkylation, methylation, isomerization, and conjugate formation. Although the degradation process of pesticides in soils is complicated, main factors may be soil constituents, soil microflora, and chemical structures of pesticides. Chemical structures are especially important for soil metabolism of organophosphorus pesticides, because the priority of the reactions mentioned above is decided. Although organophosphorus pesticides are generally hydrolyzable, the order of hydrolysis varies with chemical structures. It might be said that the slower the hydrolysis rate of the molecule, the more the possibility to be attacked by reactions other than hydrolysis. In such cases, oxidation and reduction are primarily important for the degradation of organophosphorus pesticides. Flooded soils in paddy fields give a favourable environment for the reduction of organophosphorus pesticides having labile substituents such as nitro groups. The threshold of reduction in-flooded soil is expressed as redox potential. Eh, the Eh of paddy soil fluctuates to a great extent, depending on seasons and soil types, especially organic matter content. The result of laboratory experiments with fenthion, disulfoton, Kitazin P (0,0-diisopropyl S-benzyl phosphorothiolate), edifenphos (0-ethyl S,S-diphenyl phosphorodithiolate) and amiprophos (0-ethyl 0-(2-nitro-p-tolyl) N-isopropyl phosphoramidothionate) suggested the participation of several factors mentioned above in the degradation of organophosphorus pesticides.

Anaerobiosis↗
PubMed1979

Field assessment of B-2 as a new molluscicide for the control of Oncomelania nosophora.

Sodium 2,5-dichloro-4-bromophenol named B-2 was evaluated for application in the field as a molluscicde against Oncomelania nosophora. A dosage of 10 g/m2 as 25% liquid form or 25 g/m2 as 10% granular form of B-2 was suggested as a standard dose for the control of O. nosophora. The residual concentration of B-2 in the soil after application was observed to decrease more rapidly than did that of NaPCP. The residual level of B-2 in the rice grains harvested from the paddy field in which the chemical was applied at most 4 times during the planting season did not exceed 0.03 ppm.

Animals↗
PubMed1991

Small-scale field trials of Bacillus sphaericus (strain 2362) formulations against Mansonia mosquitoes in Malaysia.

Five formulations of Bacillus sphaericus (strain 2362) including aqueous suspension BSP 1, BSP 2, technical powder ABG 6184, corncob granules ABG 6185 (potencies 2 x 10(10), 2 x 10(7), 9.5 x 10(10), 5 x 10(10), 5 x 10(10) spore/g, respectively) and wettable powder ABG 6232 (1,000 BS ITU/mg) were tested against laboratory-cultured late third/early fourth instar larvae of Mansonia uniformis in floating screened cages in small plots at swampy ditches on Penang Island, Malaysia. Mean dosage/response values at 90% mortality levels were 6.93, 95.32, 1.45, 11.92 and 2.86 liters or kg per ha, respectively, for the formulations tested. There were practically no residual effects for the formulations tested with larvae introduced at 48, 96, and 168 h post-treatment. In trials of BSP 1, ABG 6184 and ABG 6185 (1 liter or 1 kg per ha) against immature Mansonia spp. in impounded paddy field ditches, improved efficacy and residual effects were obtained with mean reductions of 93.1, 91.9 and 80.4% at days 3, 7 and 14 posttreatment, respectively.

Animals↗