Irrigated Rice Area Research Articles

Evaluation of multiple SAR speckling filter techniques performance in irrigated rice areas

Evaluation of multiple SAR speckling filter techniques performance in irrigated rice areas

Old Foe, New Host: Epidemiology, Genetic Diversity, and Pathogenic Characterization of Maize Streak Virus in Rice Fields from Burkina Faso

Rice is of critical significance regarding food security worldwide, including in Africa. Only two viruses impacting rice production in Africa have been deeply investigated for decades: the rice yellow mottle virus ( Solemoviridae) and the rice stripe necrosis virus ( Benyviridae). Using viral metagenomics, we aimed at broadening knowledge on interacting communities associated with plants in rice landscapes and exploring the diversity and epidemiological status of viruses circulating in rice fields from Burkina Faso. We performed an epidemiological survey in this country between 2016 and 2019 involving 57 small farmers’ rice fields under two production systems: rainfed lowlands and irrigated areas. More than 2,700 rice samples were collected without regard to disease symptoms following a regular scheme. Wild and cultivated Poaceae (maize and sugarcane) growing in nearby rice fields were also collected. Unexpectedly, metagenomics detected maize streak virus (MSV) ( Geminiviridae) in analyzed rice samples. Further molecular analyses using rolling circle amplification-polymerase chain reaction showed that MSV was widely distributed and highly prevalent in both rainfed lowlands and irrigated rice areas. MSV-A and MSV-G strains were identified. MSV-G, exclusively identified thus far in wild grasses, was the most prevalent strain, whereas MSV-A, known to cause severe symptoms in maize, was sporadically identified. Using infectious clones in experimental conditions, we confirmed the pathogenicity of both MSV strains in rice. Thus, in addition to contributing to the epidemiological surveillance of rice production in Africa, our results illuminate new epidemiological and pathogenic aspects of one of the most studied plant viruses with significant economic consequences in Africa. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Anthropogenic disturbance driving population decline of a dominant tree in East Asia evergreen broadleaved forests over the last 11,000years.

Current biodiversity loss is generally considered to have been caused by anthropogenic disturbance, but it is unclear when anthropogenic activities began to affect biodiversity loss. One hypothesis suggests it began with the Industrial Revolution, whereas others propose that anthropogenic disturbance has been associated with biodiversity decline since the early Holocene. To test these hypotheses, we examined the unique vegetation of evergreen broadleaved forests (EBLFs) in East Asia, where humans have affected landscapes since the early Holocene. We adopted a genomic approach to infer the demographic history of a dominant tree (Litsea elongata) of EBLFs. We used Holocene temperature and anthropogenic disturbance factors to calculate the correlation between these variables and the historical effective population size of L. elongata with Spearman statistics and integrated the maximum-entropy niche model to determine the impact of climate change and anthropogenic disturbance on fluctuation in its effective population size. We identified 9 well-defined geographic clades for the populations of L. elongata. Based on the estimated historical population sizes of these clades, all the populations contracted, indicating persistent population decline over the last 11,000years. Demographic history of L. elongata and human population change, change in cropland use, and change in irrigated rice area were significantly negatively correlated, whereas climate change in the Holocene was not correlated with demographic history. Our results support the early human impact hypothesis and provide comprehensive evidence that early anthropogenic disturbance may contribute to the current biodiversity crisis in East Asia.

Insect Diversity of Some Hybrid Rice Genotypes in Sleman-Yogyakarta Irrigated Agroecosystem

Diversity of insect at the rice field gives a main impact to the stability of ecosystem. Index of diversity reflects the relationship of species abundance in the community. This research was aimed to determine the diversity of insect at some hybrid rice varieties in irrigated rice agroecosystem. Research was conducted in Sleman, Yogyakarta Indonesia from April to August 2018. The experiment was conducted using purposive random sampling. Insect samples were obtained using swing net and visual observation. Diversity index was analysed using Shanon (H), while diversity and uniformity of insect was examined using Evennes index (E). Result showed pest insects found during vegetative stage of rice consist of more species, while lower numbers were found at generative stage with less species. They were belongs to 6 orders (more than 10 families) such as Diptera, Lepidoptera, Coleoptera, Orthoptera, Hemiptera and Hymenoptera. The dominant pest was Cicadellidae, followed by Delphacidae and Alydidae. Based on the diversity data analysis (H), pest insects and natural enemies were between moderate and high, with a range between 1.5 to 2.5. It indicates the rice field ecosystem planted with hybrid rice gave good impact and balance species diversity in the agroecosystem of irrigated rice area in Sleman Yogyakarta.

PHYSICO-CHEMICAL ASSESSMENT OF RICE SOILS IN QUIRINO PROVINCE, PHILIPPINES

Optimum crop production is achievable with scientific soil analyses. Thus, the study was conducted in Quirino province covering rainfed and irrigated rice fields. The purpose of this study is to establish an updated database on the physical and chemical properties of these soils which intends to guide farmers in their rice farming activities, particularly on soil management. Results of the soil physicochemical analysis revealed that irrigated rice soils from Aglipay are Loam to Sandy Loam with a pH of 5.7-6.1 (medium acidic to slightly acidic) while rainfed soils are clayey with a pH of 5.3-7.1 (with strongly acidic to very slightly alkaline found to be generally). Samples collected from irrigated rice areas of Cabarroguis are majority Silty Loam with a pH of 5.8 (medium acidic), and soil samples from rainfed areas are found to be Clay Loam with a pH of 5.7 (medium acidic). On the other hand, samples gathered from irrigated areas of Diffun are dominated by Silt Loam with pH ranges from 5.4-6.3 (medium to slightly acidic); while samples from rainfed areas Clay to Clay Loam and pH of 4-5.5 (strongly acidic). Irrigated soil samples collected from Maddela are Loamy to Sandy Clay Loam with a pH ranging from 5.4-6.3 (medium to slightly acidic); while samples from rainfed were revealed to be silty Loam with a pH of 4.6 (strongly acidic). Irrigated rice soils of Nagtipunan are sandy clay with a pH 0f 6.0 (slightly acidic) while rainfed areas are found to be Clay Loam and Sandy Clay with slightly acidic to very slightly alkaline pH.With this current status of rice soils in the area, it is suitable for rice production. Furthermore, the soils assessed are also suitable for other high-value crops to avoid a monocropping system of farming.

Revisiting yield gaps and the scope for sustainable intensification for irrigated lowland rice in Southeast Asia

CONTEXTRecent studies on yield gap analysis for rice in Southeast Asia revealed different levels of intensification across the main ‘rice bowls’ in the region. Identifying the key crop management and biophysical drivers of rice yield gaps across different ‘rice bowls’ provides opportunities for comparative analyses, which are crucial to better understand the scope to narrow yield gaps and increase resource-use efficiencies across the region. OBJECTIVEThe objective of this study was to decompose rice yield gaps into their efficiency, resource, and technology components and to map the scope to sustainably increase rice production across four lowland irrigated rice areas in Southeast Asia through improved crop management. METHODSA novel framework for yield gap decomposition accounting for the main genotype, management, and environmental factors explaining crop yield in intensive rice irrigated systems was developed. A combination of crop simulation modelling at field-level and stochastic frontier analysis was applied to household survey data to identify the drivers of yield variability and to disentangle efficiency, resource, and technology yield gaps, including decomposing the latter into its sowing date and genotype components. RESULTS AND CONCLUSIONThe yield gap was greatest in Bago, Myanmar (75% of Yp), intermediate in Yogyakarta, Indonesia (57% of Yp) and in Nakhon Sawan, Thailand (47% of Yp), and lowest in Can Tho, Vietnam (44% of Yp). The yield gap in Myanmar was largely attributed to the resource yield gap, reflecting a large scope to sustainably intensify rice production through increases in fertilizer use and proper weed control (i.e., more output with more inputs). In Vietnam, the yield gap was mostly attributed to the technology yield gap and to resource and efficiency yield gaps in the dry season and wet season, respectively. Yet, sustainability aspects associated with inefficient use of fertilizer and low profitability from high input levels should also be considered alongside precision agriculture technologies for site-specific management (i.e., more output with the same or less inputs). The same is true in Thailand, where the yield gap was equally explained by the technology, resource, and efficiency yield gaps. The yield gap in Indonesia was mostly attributed to efficiency and technology yield gaps and yield response curves to N based on farmer field data in this site suggest it is possible to reduce its use while increasing rice yield (i.e., more output with less inputs). SIGNIFICANCEThis study provides a novel approach to decomposing rice yield gaps in Southeast Asia's main rice producing areas. By breaking down the yield gap into different components, context-specific opportunities to narrow yield gaps were identified to target sustainable intensification of rice production in the region.

Induced mutations in crop plants at Instituto de Genética "Ewald A. Favret": mutants of scientific and/or agronomic interest: Induced mutations in crop plants at Instituto de Genética "Ewald A. Favret"

The use of induced mutations techniques in crop plants at Instituto de Genética "Ewald A. Favret" (IGEAF) INTA, started in 1949, with the pioneer work of Ewald Favret, who studied the effects of physical and chemical mutagens on barley (Hordeum vulgare) and wheat (Triticum aestivum). IGEAF contributed with several novel results about the effects of important chemical mutagens such as ethyl methane sulfonate (EMS) and sodium azide, and their interactions with X-rays, on barley and wheat. During several decades, a good deal of the research was directed to study the relationship between the different effects of mutagenic treatments on the M1 and subsequent generations, and its implications for efficient selection of induced mutants. Many original barley and wheat mutants have been isolated at IGEAF, which early on contributed to elucidate the genetic basis of characters like the hormonal control of growth, the grain protein content and diseases reactions. Besides, several other novel mutants were isolated and characterized including genetically unstable mutants, which are able to originate new heritable variability. One of these mutants is the barley chloroplast mutator (cpm) from which some interesting mutants have been isolated. Moreover, a high throughput strategy for the screening of plastome mutants originated by the cpm was developed (cpTILLING) that allowed the detection of 61 different mutational events, showing the cpm as an extraordinary source of plastome mutants. On the other hand, protocols for direct selection of wheat mutants tolerant to drought were developed and promising advanced lines are at present investigated. Furthermore, a mutant allele of the AHAS (acetolactate synthase) gene in wheat conferring imidazolinones herbicides tolerance, was isolated. The incorporation of this allele to other genetic backgrounds showed increased levels of tolerance, which in one family were observed in association with increased Fusarium tolerance. In addition to the work done in barley and wheat, interactions with several breeding programs in other crops were carried out. Finally, some commercial achievements of INTA obtained by using induced mutations techniques are briefly described; being the most important the case of the INTA rice (Oryza sativa) breeding program for developing imidazolinones tolerant commercial varieties that in recent years covered 70% of the irrigated rice area in Latin America.

Controlled Irrigation and Drainage Reduce Rainfall Runoff and Nitrogen Loss in Paddy Fields.

In southern China, the growing period of rice is synchronized with the rainy period, and the loss of nutrients (such as nitrogen) due to unreasonable irrigation and drainage, along with rainfall and runoff, has become the main source of agricultural nonpoint source pollution. The laws of runoff and nitrogen loss in paddy fields under different irrigation and drainage modes are not clear. In this study, field experiments were adopted to observe the runoff and nitrogen loss under typical rainfall and throughout the whole growth period. The results showed that, compared with the traditional irrigation and drainage mode, the controlled irrigation and drainage mode reduced the drainage of two typical rainfall processes by 47.5% and 31.3% and the peak drainage by 38.9% and 14.4%. Compared with those under the traditional irrigation and drainage mode, the average concentrations of total nitrogen, nitrate nitrogen, and ammonium nitrogen under the controlled irrigation and drainage mode were reduced by 22.2%, 22.7%, and 27.8%, respectively, during the whole rainfall process on July 21 and were decreased by 27.1%, 11.4%, and 25.6%, respectively, on August 25. In irrigated rice areas, under the controlled irrigation and drainage mode, drainage was reduced after two intercepts through paddy fields and drainage ditches. The nitrogen concentration in the drainage ditch decreased due to the increase in retention time and the effect of the ditch and field wetland. Compared with the traditional irrigation and drainage mode, the total nitrogen, nitrate nitrogen, and ammonium nitrogen loads of the controlled irrigation and drainage mode were reduced by 69.8%, 65.3%, and 69.7%, respectively.

A long‐term no‐tillage system can increase enzymatic activity and maintain bacterial richness in paddy fields

AbstractSoil management systems cause many changes in the microenvironment that directly affect activity and diversity of microorganisms. In lowlands, there is a gap in relation to the adoption of no‐tillage (zero‐tillage) and the impact it has on soil under cultivation of irrigated rice. This study, an in‐field experiment, evaluated the microbial enzymatic activity and diversity in an Entisol cultivated with rice under different managements for 22 years. The experiment started in the 1994/95 growing season, and the treatments were no‐tillage, conventional, and pregerminated management systems. After 22 years, the data obtained on most of the evaluation dates indicated that no‐tillage increased microbial biomass carbon (+45%), microbial biomass nitrogen (+54%), and basal respiration (+54%). No‐tillage compared to management under soil tillage (pregerminated and conventional tillage) increased the activity of β‐glucosidase (+43%), acid phosphatase (+68%), diacetate fluorescein (+34%), and urease (+96%). The enzyme activity was correlated with the soil organic carbon content and particulate fraction. Despite the relatively high enzyme activity with no‐tillage, bacterial richness was maintained in this soil management system. The Proteobacteria phylum has a greater abundance in the NT (43.2%) in relation to the CT (32.3%). Bacteroidetes phylum has a lower abundance in the NT (10.0%) in relation to the CT (15.2%). The Verrucomicrobia phylum has a greater abundance in NT (8.9%) in relation to CT (4.9%). The results suggest that no‐tillage is an important management tool in the recovery of irrigated rice areas whose soil has undergone microbiological degradation.

Development and Field Evaluation of Near-Isogenic Lines of GR2-EBRRI dhan29 Golden Rice.

Vitamin A deficiency remains a common public health problem among the rice-dependent poor people in the developing countries of Asia. Conventional milled rice does not contain provitamin A (β-carotene) in is edible part (endosperm) and is also deficient in essential minerals, such as iron and zinc. Transgenic Golden Rice event GR2E, which produces β-carotene in its endosperm, was used as a parent to introgress the transgene locus conferring β-carotene biosynthesis into a widely grown rice variety, BRRI dhan29, which covers around 26.1% of the irrigated rice area (4.901 Mha) of Bangladesh in the dry season. The current study reports the introgression process and field performance of GR2E BRRI dhan29 Golden Rice. The background recovery of GR2E BRRI dhan29 lines at BC5F2 generation was more than 98% with a 6K SNP-chip set. The transgenic GR2E BRRI dhan29 yielded 6.2 t/ha to 7.7 t/ha with an average of 7.0 ± 0.38 t/ha, while the non-transgenic BRRI dhan29 yielded 7.0 t/ha under confined field conditions in Bangladesh. Moreover, no significant difference between GR2-E BRRI dhan29 Golden Rice and non-transgenic BRRI dhan29 in any measured trait was observed in the multi-location trials conducted at five locations across the country. Furthermore, the appearance of cooked and uncooked rice was similar to that of BRRI dhan29 except for the yellow color indicating the presence of carotenoids. Total carotenoid content in the selected introgression lines ranged from 8.5 to 12.5 μg/g with an average of 10.6 ± 1.16 μg/g. This amount is sufficient to deliver approximately 66 and 80% of the recommended daily intake of vitamin A for children and women, respectively, assuming complete substitution of white rice in the diet with Golden Rice. However, the lead selected line(s) need further evaluation at open field conditions before deciding for commercial cultivation. A large-scale feeding trial among the malnourished community with this newly developed GR2-E BRRI dhan29 Golden Rice is also required to validate its efficacy in alleviating vitamin A deficiency.

The potential for expansion of irrigated rice under alternate wetting and drying in Burkina Faso

Achieving rice self-sufficiency in West Africa will require an expansion of the irrigated rice area under water-scarce conditions. However, little is known about how much area can be irrigated and where and when water-saving practices could be used. The objective of this study was to assess potentially irrigable lands for irrigated rice cultivation under water-saving technology in Burkina Faso. A two-step, spatially explicit approach was developed and implemented. Firstly, machine learning models, namely Random Forest (RF) and Maximum Entropy (MaxEnt) were deployed in ecological niche modeling (ENM) approach to assess the land suitability for irrigated rice cultivation. Spatial datasets on topography, soil characteristics, climate parameters, land use, and water were used along with the current distribution of irrigated rice locations in Burkina Faso to drive ENMs. Secondly, the climatic suitability for alternate wetting and drying (AWD), an irrigation management method for saving water in rice cultivation in irrigated systems, was assessed by using a simple water balance model for the two main growing seasons (February to June and July to November) on a dekadal time scale. The evaluation metrics of the ENMs such as the area under the curve and percentage correctly classified showed values higher than 80% for both RF and MaxEnt. The top four predictors of land suitability for irrigated rice cultivation were exchangeable sodium percentage, exchangeable potassium, depth to the groundwater table, and distance to stream networks and rivers. Potentially suitable lands for rice cultivation in Burkina Faso were estimated at 21.1 × 105 ha. The whole dry season was found suitable for AWD implementation against 25–100% of the wet season. Soil percolation was the main driver of the variation in irrigated land suitability for AWD in the wet season. The integrated modeling and water balance assessment approach used in this study can be applied to other West African countries to guide investment in irrigated rice area expansion while adapting to climate change.

Irrigated rice area mapping over Bangladesh with remotely sensed data from 2001 to 2018

Spatial information on irrigated area is very important for crops water requirements, agricultural planning, water management, and climate changes mitigation. It is challenging to map irrigated rice areas by images classification methods due to the spectral similarity between with and without irrigation. In this study, we developed an index for potential irrigated rice area map for three different seasons by using remote sensing-based evapotranspiration (MOD16A2), precipitation (GSMaP) data from 2001 to 2018 and local climate adjusted CROPWAT based rice crop coefficient data. By using the index, classified the rice are withing three different types of irrigated area; (i) irrigated, (ii) rainfed and (iii) supplementary irrigated rice area for three different rice growing season of Bangladesh. The result compared with the National statistical and others relevant irrigated area data. It’s found, the dry season irrigated rice (Boro) area shows a good relationship with the national statistical data, but the wet seasons amon and aus irrigated rice areas shows comparatively low agreement.

Development of Shading Tolerant Rice Varieties Suitable for Intercropping Cultivation in Agroforestry Systems

The Indonesian government continuously strives to increase rice production in an effort to meet the staple food needs of almost 270 million people and to turn Indonesia to become a rice exporter country. One of the strategic efforts is to expand the planted area of rice outside irrigated rice areas. Upland is one of the potential areas that continues to be developed to support the increase of national rice production. While upland is not an ideal ecosystem for rice plants to grow, the opportunity to produce rice in this ecosystem is promising, especially using rice as an intercropping in plantation. This effort requires the availability of adaptive varieties to low light intensity conditions. The breeding program to develop shade-tolerant rice varieties has been carried out by the Indonesian Center for Rice Research (ICRR) through the conventional breeding program. Breeding populations were produced by crossing local varieties, national leading varieties and introduced varieties. The selection of shading adaptive lines was carried out using both artificial shading and natural shading in the target plantation areas. New shade tolerant rice varieties have been recently released, namely Rindang 1 Agritan and Rindang 2 Agritan which have the potential to be utilized by farmers for intercropping rice cultivation in the agroforestry systems.

Can Brazil produce enough rice to meet demand in 2028?

The objectives of the study were estimate the additional yield that may be achieved by reducing the yield gap in actual rice area, evaluate if irrigated rice production meet future demand for rice without increase area and determine sowing date that allows maximum yield potential. The yield gap (Yg) was determined by the difference between yield potential (Yp) and actual yield (Ya). The Ya was obtained from surveys applied to the rice producers. The Ya was 51% of Yp, and the Yg was 49%. In a scenario of high demand, if the yields follow the historical rate of gain, the production should not be sufficient to meet projected demand without 6% expansion of the currently cultivated area, whereas for a scenario of low demand it should be sufficient. Moreover, for the low and high demand scenarios, if the national average yield reaches 80% of the rice Yp, a reduction until 29% in the current irrigated rice area can occur. Sowing between September and mid-November is a way of making it possible to obtain yields close to 80% of Yp without increasing production costs. This study can be used as an aid in the search for world food security.

Water management problems related major reservoirs and irrigation systems in Polonnaruwa District, Sri lanka

Water is a scarce resource in the dry zone of Sri Lanka and it is a major problem faced by the cultivators in the area. Since their cultivations totally depend on irrigation water every possible effort should be put in order to optimize the water usage to achieve increased crop production. Recent reports on water management activities of several irrigation schemes in the Dry Zone indicates, that the water distribution is not meeting the demands of farmers in terms of adequacy, reliability and timelines. Further it was said that there is considerable potential to increase paddy field in this system through improved irrigation water management, especially by efficient irrigation scheduling. The study intends to find out the annual statement of reservoir replenishment and behaviour is monthly analysed about reservoirs condition by Irrigation Department and recorded below data to statements for the water – year ending the month by month in orderly. It includes rainfall on catchment, area irrigated, water area, yield from catchment, issues from sluices, discharge over spills, change in reservoir storage, vapour-seepage loss, reservoir storage, depth at lowest sluice. And also this study identified above conditions and water management problems related ParakramaSamudraya, Giritale, Minneriya and Kaudulla major reservoirs in Polonnaruwa District. The greater part of the irrigated rice area is in the dry zone and the water availability there is less than that in others areas. Additionally, competition from domestic and industrial sectors will also increase. Therefore, water scarcities in the dry zone will have a severe impact on meeting the additional food requirements of the increasing population. In this respect, it is of vital importance to understand the regional scarcities of water and their impact on future food production.

Seeding furrow opening mechanisms and the soybean planting in lowland areas

ABSTRACT: The objective of this research was to evaluate the effect of seeder furrow opening mechanisms on soil physical characteristics, plant growth, and soybean yield in lowland areas with the presence of compacted layer near the surface. An experiment was conducted in the lowland experimental area of the Federal University of Santa Maria-RS, Brazil, during the 2015/16 and 2016/17 growing season. The experimental design was a randomized block with five replications and four treatments: Planter using shank (S) at 0.23 m depth; S at 0.13 m; Planter using double disk at 0.07 m depth and Raised-bed + S at 0.12 m depth. The use of S at 0.23 m depth allowed reduction of penetration resistance and increase of soil macroporosity in the layers 0-0.1 and 0.1-0.2 m depth in the seeding row. Sowing with S at 0.23 m depth and Raised-bed + S at 0.12 m depth allowed a better development of soybean plants in compacted irrigated rice area (higher nodulation, leaf area index and root growth), as well as higher grain yield.

Persistence of imazapyr+imazapic in irrigated rice area and effect on soybean due to soil moisture and phytoremediation in the off-season

ABSTRACT The residue of imidazolinone herbicides in soil can be detrimental to soybean cultivation in rotation with Clearfield® rice. Thus, this research aimed to evaluate the ryegrass phytoremediation capacity on the imazapyr+imazapic residue in the soil in two soil moisture conditions in the off-season, and the effect on soybean growth in the next growing season. Two experiments were conducted between 2016 and 2017 in Santa Maria, Rio Grande do Sul state, Brazil. It was used the randomized block design in a 3 × 2 factorial. The first factor being the residue in the soil of 0, 210 and 420 g c.p.·ha–1 of the formulated mixture of the herbicides imazapyr+imazapic(525 + 175 g a.i.·kg–1) applied to rice in the 2015/2016 growing season, and the second factor being the presence or absence of ryegrass in the off-season. One experiment was conducted under soil moisture above 70% of field capacity in the off-season, and the other under ambient condition of soil moisture. The soil residue of the application of 420 g c.p.·ha–1 of the imazapyr+imazapic herbicides performed129 days before planting caused phytotoxicity and reduced dry matter of ryegrass under high soil moisture condition in the off-season in irrigated rice areas. Soybean, when planted 359 days after application, has its initial root and shoot growth affected by the residue of 210 and 420 g c.p.·ha–1 rates in high soil moisture condition in the off-season, regardless of ryegrass cultivation during the same period. However, grain yield is not affected.

The association between child Schistosoma spp. infections and morbidity in an irrigated rice region in Mali: A localized study

BackgroundSchistosomiasis is one of the neglected tropical diseases endemic to Mali. There has been insufficient investigation of the morbidity burden in highly endemic irrigated rice areas with the ongoing mass drug administration with praziquantel. In February 2005, a year after an initial mass drug administration in 2004, we performed the first cross-sectional survey of schistosomiasis in the Kokry-Bozo village in the Office du Niger rice irrigation region. In the fourteen years since this survey, there has been almost no research into schistosomiasis morbidity in Mali due to lack of funding. Therefore, the 2005 survey supplies near-baseline data for any future research into the treatment impacts in the area. MethodsOne hundred and ninety-four children aged 6–14 years from two schools were assessed for bladder pathology by ultrasound, and for anaemia and micro-haematuria by laboratory tests. Schistosoma eggs were examined microscopically in fresh stool and urine samples. Multivariate logistic regression analysis quantified the association of Schistosoma infections with anaemia, bladder pathology and micro-haematuria. Akaike’s information criterion was used to test the assumption of linear effects of infection intensity classes and used to compare across models. ResultsThe overall prevalence of schistosomiasis in 189 school children was 97%; 17% (33/189) had a single infection (S. mansoni,13%, or S. haematobium, 4%) and 80% (156/189) were co-infected with S. mansoni and S. haematobium. The overall prevalence of S. mansoni with light infection was 27% (53/194), moderate infection was 24% (47/194) and heavy infection was 42% (81/194). Of the 194 of children investigated for S. haematobium 59% (114/194) had light infection and 26% (50/194) had heavy infection. No hookworm eggs were detected.The level of abnormal bladder pathology was 18% (35/189) with the highest found in 10–14 year old children. The prevalence of anaemia was 91% (172/189) and was twice as likely to be associated (OR 2.0, 95% CI 1.1–3.9) with S. mansoni infections than in children without infection. As infection intensity with S. mansoni increased the risk of anaemia (OR 2.0, 95% CI 1.1–3.9) also increased. As infection intensity with S. haematobium increased bladder pathology (OR 2.4, 95%CI 1.3–4.5), haematuria (OR 6.7, 95%CI 3.3–13.6) and micro-haematuria increased (OR 2.4, 95%CI 1.3–4.5). ConclusionOur research contributes an important micro-geographical assessment of the heavy burden of schistosomiasis and associated morbidity in children who live in the rice irrigation regions. Our literature review found that there has been very limited research conducted on the impact of the treatment to control morbidity in the ON. Therefore, there is a need to do a comparable, but more extensive, study to identify any changes in morbidity and to indicate current requirements for the control programme. Our results from 2005 called for routine integration of iron supplementation, food fortification and diet diversification into the deworming program.

High arsenic and low lead concentrations in fish and reptiles from Taim wetlands, a Ramsar site in southern Brazil

The pollution caused by heavy metals and metalloids represent an emerging threat to wetlands worldwide. Herein we examined the concentrations of arsenic (As) and lead (Pb) in fish and aquatic/semi-aquatic reptiles from Taim wetlands, a Ramsar site located at the southernmost Brazilian coastal plain. A total of 82 individuals from six fish and three reptile species from varied trophic levels were analysed through furnace graphite atomic absorption spectrophotometry. Mean As concentrations (μg·g−1 dry weight) were markedly high, ranging from 13.06 ± 3.18 to 19.4 ± 4.04 in fish and 3.51 ± 2.36 to 19.00 ± 10.45 in reptiles. Mean Pb concentrations were low, ranging from 0.00067 ± 0.00060 to 0.0040 ± 0.00045 in fishes and 0.00103 ± 0.0011 to 0.0271 ± 0.0353 in reptiles. The highest As mean level was detected in the herbivore-insectivore fish Astyanax aff. fasciatus, a species of low trophic level among the analysed taxa. The highest Pb mean level was found in the broad-snouted caiman Caiman latirostris, the highest trophic level species analysed. The present study warns for the contamination of As especially in edible fish, which constitute a threat to the communities that use this resource in systems connected to Taim wetlands. As concentrations in reptiles were also higher than those reported in previous studies concerning the groups herein addressed. It is possible that the high As burdens found in the analysed species could be attributed to the use of fertilizers and pesticides in extensive irrigated rice areas located in Taim wetlands surroundings, but natural sources cannot be dismissed.

Identification of A Major Quantitative Trait Locus for Grain Weight In Rice Using Microsatellite Marker

Rice is one of the major staple foods in the world, especially in Asia. Improving yield potential of superior cultivars is important to meeting the demand for rice production, which is increasing due to human population increase, climate change, and degradation of agricultural resources, such as land and water. In this study, a BC 3 F 2 population developed from an intraspecific cross between Ciherang and a new plant type line (B11143D) was used in a quantitative trait locus (QTL) analysis. Ciherang is a high yielding rice cultivar with good grain quality which has been planted in 37% of the irrigated rice area in Indonesia. The objective of this study was to identify QTL(s) for yield components on chromosome 12, which can be used to improve the elite cultivar Ciherang or other popular cultivars through marker-assisted breeding. A total of two hundred BC 3 F 2 lines were evaluated in the greenhouse during this study. The population was observed for eight agronomic traits including days to heading (dth), plant height (ph), flag leaf length (fll), panicles per plant (ppl), panicle length (pl), grains per panicle (gpp), 1000-grain weight (gw), and yield (yld). Four simple sequence repeats (SSR) markers (RM3472, RM28048, RM28195, and RM1986) were used for targeted mapping on chromosome 12. Linkage analysis identified a QTL for 1000-grain weight located on chromosome 12 at position 53.5 cM–73 cM.