Rice Crop Production Research Articles

Irrigation Management and Greenhouse Gas Emissions in Uruguayan Rice Production Systems

Environmental impact and sustainability of agricultural systems and management practices leading to climate change mitigation are one of the most relevant issues to agricultural production nowadays. Mitigation is the process of reducing emissions or enhancing sinks of greenhouse gases (GHG), to limit global warming potential and restrict future climate change. The most relevant GHG are Carbon dioxide (CO2), Methane (CH4) and Nitrous Oxide (N2O). The steady increase of its concentrations in the atmosphere over several decades has led to enhance global warming. CH4 and N2O are the most relevant GHG emitted mainly in the agricultural sector. It is well known that water management has great impact on GHG emissions from rice paddy fields. One of the most important tools for rice crop production and mitigation of CH4 emission is the controlled irrigation. However, it could result in a N2O emission increase and reduced rice yields. For these reasons, it is remarkably important to assess the tradeoff relationship between both GHG and the effect on rice productivity. A 3 year field experiment with two different irrigation systems was set at southeast of Uruguay. Conventional water management (continuous flooding after 30 days of emergence, CF30) and an alternative irrigation system (controlled deficit irrigation allowing wetting and drying, AWDI) were compared. The objective was to study the effect of water management on GHG emission, water productivity and rice yields in order to identify strategies for further progress in sustainable intensification of Uruguayan rice. Results showed that mean cumulative CH4 emission values for AWDI were 55% lower than CF30 systems; on the other hand, there were no significant differences in N2O emission among systems. Significant yield differences were not observed in two of the rice seasons, while AWDI recorded a significant yield reduction in one of them. Total irrigation water applied and irrigation water productivity did not showed differences in two of the rice seasons, while CF30 reported a higher amount of water applied and lower water productivity in one of the seasons. It can be concluded that AWDI could be an option to enhance water productivity and GHG emission mitigation. However, grain yield can be compromised in AWDI systems. The adoption of these technology is based on the indispensable assess of an overall tradeoff between the risk of possible yield losses, total water used and GHG emissions.

Raised and sunken bed land configuration for crop diversification and crop and water productivity enhancement in rice paddies of the north eastern region of India

The crop and water productivity (WP) of monocropped rice in lowland of north-eastern region of India is low mainly due to cultivation of long duration variety, meagre use of fertilizer and manure, and inefficient water management, which needs to be improved for sustaining food security. Raised and sunken bed (RSB) land configuration (removing the surface soil layer from an area and depositing on the adjacent area to a height of about 50 cm by cutting and filling method) was demonstrated in a participatory research mode in farmers’ field during 2010–2012 for promoting crop diversification, enhancing crop and WP, and improving livelihood. The results indicated significant improvement in cropping intensity, productivity, employment, and income of farmers due to adoption of RSB land configuration compared to farmers’ practice (FP) of rice monocropping. The average rice equivalent yield (REY) of RSB land configuration was 16.20 t ha−1 compared to 3.24 t ha−1 under FP. The enhancement in employment and water-use efficiency were 445 and 291 % due to RSB over FP, respectively. The WP enhanced by four times due to RSB (0.69 kg m−3 water) compared to FP (0.18 kg m−3 water). In raised beds, the highest gross (USD 7,346 ha−1) and net returns (USD 4,524 ha−1) were recorded under tomato–okra–broccoli sequence, while in sunken beds, the highest gross and net returns were obtained under rice–pea (USD 2,633 and 1,590 ha−1, respectively) and these were substantially higher than those observed under FP (USD 775 ha−1 and USD 383 ha−1, respectively). Multiple cropping index, cultivated land utilization index, and diversity index also increased substantially due to RSB land configuration.

A decision-making model for rice paddy cropping in an urbanizing area of the Lao PDR

In Southeast Asia, economic and population growth are expected in the near future. Rapid change is anticipated especially in the Lao PDR. Concern has been expressed that population growth will lead to an increased demand for food and economic growth to changes in the use of land. For food production to keep pace with the growth of population, it is very important to understand decision-making in rice paddy cultivation in urbanizing areas; for this reason, this study with the SEM model was conducted. The original data were collected by a questionnaire survey in some Lao villages; the survey included questions on various conditions, such as the availability of water in the dry season (irrigation), the access to a city, and job opportunities other than farming. The findings of the study demonstrate that the planting of a second rice crop was related to such factors as the productivity of rain-fed rice and cash crops and, most importantly, job opportunities other than farming.

Potential impacts on climate change on paddy rice yield in mountainous highland terrains

Crop models are suitable tools to assess the potential impacts of climate change on crop productivity. While the associated assessment reports have been focused on major rice production regions, there is little information on how climate change will impact the future rice crop production in mountainous highland regions. This study investigated effects of climate change on yield of paddy rice (Oryza sativa) in mountainous highland terrains of Korea using the CERES-Rice 4.0 crop model. The model was first calibrated and validated based on observed data and then applied to simulations for the future projections of rice yield in a typical mountainous terrain which borders North and South Korea, the Haean Basin in Kangwon Province, Republic of Korea. Rice yield in the highland terrain was projected to increase by 2050 and 2100 primarily due to elevated CO2 concentration. This effect of CO2 fertilization on yield (+10.9% in 2050 and +20.0% in 2100) was also responsible for increases in water-use efficiency and nitrogen-use efficiency. With management options, such as planting date shift and increasing nitrogen application, additional yield gains were predicted in response to the future climate in this area. We also found that improving genetic traits should be another option to get further yield increases. All in all, climate change in mountainous highland areas should positively influence on paddy rice productivity.

PERANCANGAN SISTEM INFORMASI GEOGRAFIS SEBARAN TANAMAN PANGAN BERBASIS SPASIAL DAN MULTI TIER MENGGUNAKAN MAP SERVER

The province of Central Java is one of the important national crop producers, therefore its productivity of rice and other crops are always at the highest priority (Central Java in Numbers, 2009). To achieve this, all efforts must be arranged systematically and correctly, and one of the efforts is making an accurate inventory of crop fields and production centres which distributed across the province, to provide a good mapping of produce. The research designs a system which capable to create spatially based crops distribution maps, which in turn helps the planning, operation, monitoring, and evaluation of crop production by departments in charge. The mapping is presented using the multi-tier architecture. The distribution map will include crops produce capacity for each year over the whole province. Implementation results are the system performs successfully, and the process time is reasonable, therefore it is applicable.

Development of a microarray for two rice subspecies: characterization and validation of gene expression in rice tissues

BackgroundRice is one of the major crop species in the world helping to sustain approximately half of the global population’s diet especially in Asia. However, due to the impact of extreme climate change and global warming, rice crop production and yields may be adversely affected resulting in a world food crisis. Researchers have been keen to understand the effects of drought, temperature and other environmental stress factors on rice plant growth and development. Gene expression microarray technology represents a key strategy for the identification of genes and their associated expression patterns in response to stress. Here, we report on the development of the rice OneArray® microarray platform which is suitable for two major rice subspecies, japonica and indica.ResultsThe rice OneArray® 60-mer, oligonucleotide microarray consists of a total of 21,179 probes covering 20,806 genes of japonica and 13,683 genes of indica. Through a validation study, total RNA isolated from rice shoots and roots were used for comparison of gene expression profiles via microarray examination. The results were submitted to NCBI’s Gene Expression Omnibus (GEO). Data can be found under the GEO accession number GSE50844 (http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE50844). A list of significantly differentially expressed genes was generated; 438 shoot-specific genes were identified among 3,138 up-regulated genes, and 463 root-specific genes were found among 3,845 down-regulated genes. GO enrichment analysis demonstrates these results are in agreement with the known physiological processes of the different organs/tissues. Furthermore, qRT-PCR validation was performed on 66 genes, and found to significantly correlate with the microarray results (R = 0.95, p < 0.001***).ConclusionThe rice OneArray® 22 K microarray, the first rice microarray, covering both japonica and indica subspecies was designed and validated in a comprehensive study of gene expression in rice tissues. The rice OneArray® microarray platform revealed high specificity and sensitivity. Additional information for the rice OneArray® microarray can be found at http://www.phalanx.com.tw/index.php.

An Analysis of Share Cropping in Rice Cultivation-A Case Study in Karimganj District of Assam

Share cropping is an important age old agrarian phenomenon in Assam. There is still vast scope to boost rice production in the study area through increasing the productivity of crops with the adoption of improved and economic methods of crop cultivation in due space and time on a sustainable basis. Share cropping in the study area is established as supplementary source of farm income to those farmers who undertake share cropping by hiring lands from others. It also act as a complementary source of income and employment for both the group of farmers that is one who undertake share cropping on others lands and others who let their land for share cropping to other farmers. Thus, Share cropping in the study area is found as both supplementary and complementary source of farm income. Of course, in the study area, there is still great scope to make share cropping more profitable as the productivity of rice crop is 481 kg less than the productivity of Punjab and 3202 kg less than the productivity of Egypt which is highest in the world.

Mapping QTLs Related to Salt Tolerance in Rice at the Young Seedling Stage using 384-plex Single Nucleotide Polymorphism SNP, Marker Sets

Salinity is one of the most serious factors limiting the productivity of rice crops, with adverse effects on germination, plant vigor and crop yield. A population of 300 F 5:6 recombinant inbred lines (RILs), which was derived from a cross between IR29 (indica sensitive to salinity) and Hasawi (Saudi cultivar showing salt tolerance), was evaluated at a young seedling stage under hydroponic conditions at an EC of 12 dsm -1 . Such RIL population when fixed can be repeatedly used for investigating QTLs of various phenotypes under different environments. Transgressive segregation was noted for all traits in the RILs; In all 31 RILs (10% of the 300 RILs) had tolerance level similar or better than Hasawi as determined by their standard evaluation system (SES) score of 4 or less, performance under both saline and non-saline conditions for plant height, root length, shoot dry weight and shoot fresh weight; suggesting these RILs can be rated as tolerant to salinity and are been advanced in our breeding program Quantitative trait loci (QTL) related to salt tolerance were detected using 142 F 5 RILs and single nucleotide polymorphisms (SNPs) chip composed of 384 SNP markers for indica x indica background. There were seven significant QTL related to 4 different traits associated to salt tolerance at young seedling stage. They were mapped on chromosomes 1, 2 and 6. The QTL qDW1.1, qDW2.1, qDW2.2 and qDW6.1 co-segregated with shoot dry weight and accounted between 10.6 and 42.3% of its phenotypic variation, while qPH1.1 and qPH1.2 were associated with plant height (explaining between 12.7 and 13.8% of its phenotypic variation), and qF2.1 co-segregated with shoot fresh weight (10.6% of trait variation) was accounted by SNP marker (id2007526). These QTLs had positive additive effects confirming that Hasawi alleles contributed to enhance traits related to salt tolerance at young seedling stage. The SNP markers associated with the QTLs identified in this study could be useful for further marker-aided breeding aiming at developing new rice cultivars for saline-prone agro-ecosystems

EFFECT OF DIFFERENT DRAIN DEPTHS ON SOIL HYDROLOGY AND CROP PRODUCTION OF RICE AND WHEAT CROPS

The present work was carried out during summer and winter seasons on rice and wheat crops cultivated in an open field at Zankalon area, Sharkia Governorate, Egypt, to study the effect of drain depth on soil hydrology, salinity and crop production of rice and wheat crops. Three drainage treatments were used i.e. conventional drainage depth (drain depth 1.20 m, T120), controlled drainage depth (drain depth 0.60 m, T60) and without drainage depth ( drain depth 0.0 m , T0 where the drain outlet was completely blocked) to achieve this target. The obtained results reveal that, the total amounts of irrigation water applied to different treatments during the growing season were arranged in a descending order: conventional drainage depth (T120) > controlled drainage depth (T60) > without drainage depth (T0) for both rice and wheat crops. Using T60 and T0 treatments for rice crop saved 32.7 and 49.7 % of the applied water as compared with the T120 treatment, respectively. The irrigation intervals were 2.0, 3.0 and 5.0 days for T120, T60 and T0 treatments, respectively. This means that, using T60 reduced the number of irrigations by 40 % which reduces the irrigation cost. On the other hand, there is a little difference between the total amounts of irrigation water applied to the different treatments cultivated with wheat crop. The total amounts of drainage water drained from the soil cultivated with rice crop at T120, T60 and T0 treatments were 2069.6, 1065.0 and 0.0 m3/fed, respectively, but at wheat crop they were 305.9, 292.1 and 0.0 m3/fed., respectively. Concerning the fluctuation of water table for wheat crop, the results emphasized that at T120 treatment, 80% of the measured water table levels were fluctuated within the depths of 50-75 cm, to >100 cm below soil surface. While, it never reached the depth of 0-20 cm below soil surface. Under T60 and T0 treatments about 90% of the measurements were fluctuated within the depths of 0-50 cm below soil surface during rice cultivation. On the other hand, 63% of the measured water table during the wheat growing season fluctuated at the depth less than 100 cm at T0 treatment. While, 85 % and 66 % from measured water table levels during the growing season were fluctuated at depth more than 1.0 m for T120 and T60 treatments, respectively. The values of relative ground water depths (RGWD) at rice were 1.3, 0.3 and 0.4 for T120, T60 and T0 treatments, respectively. Whereas, under wheat crop, they were 2.0, 1.8 and 1.4 for the same above mentioned treatments, respectively. It is clear that (RGWD) values were more than one at all wheat treatments, and also in case of T120 treatment cultivated with rice. This may be attributed to the fact that the fluctuating water table rises to the soil surface after irrigation but soon it falls down to the drain depth. The highest grain yield of both rice and wheat were obtained from plant grown under the T120 treatment. This means the effect of drain depth on grain yield was positive. Crop water productivity (CWP) values for rice grain were 0.75, 1.34 and 1.68 kg/m3 for conventional, T60 and T0 treatments, respectively. Whereas, the (CWP) values for the wheat grain, were 1.01, 0.9 and 0.90 kg/m3 for the above mentioned treatments respectively. Using the T120 treatment, the obtained results proved that more salts were leached from the soil to drainage water followed by T60 for both crops under the study. On the other hand, more salts were accumulated in soil layers during the growing season in both crops in the soil of T0 treatment.

Climatic characteristics and their relationship to the cultivation and production of rice crop in Najaf Governorate

Rice is one of the most important summer grain crops in Iraq, and comes second in nutritional importance after wheat.Because of the nutritional and economic importance of rice in Iraq, and given that Najaf governorate comes at the forefront of Iraqi governorates in terms of the cultivated area and the amount of production, and what its production can lead to achieving a reasonable amount of food security, which today has become a preoccupation for many researchers.The researchers influenced his study by examining the most important climatic characteristics affecting the cultivation and production of rice, and identifying the levels of its production at the level of Iraq, as well as the geographical distribution of the main production areas in the province.

Cover Crop Termination Timing on Rice Crop Production in a No‐Till System

ABSTRACTMeasuring shikimic acid accumulation in response to glyphosate applications can be a rapid and accurate way to quantify and predict glyphosate‐induced damage to sensitive plants. The objective of this paper was to evaluate the effect of cover crop termination timing by glyphosate application on rice (Oryza sativa L.) yield in a no‐till system. A factorial experiment, arranged in a split‐plot design, was conducted for 2 yr. Treatments consisted of cover crops (main plots) and timed herbicide applications (subplots) to these cover crops (30, 20, 10, and 0 d before rice planting). There was a decrease in rice yield from 2866 kg ha−1 to 2322 kg ha−1 when the herbicide was applied closer to the rice planting day. Glyphosate application on cover crops increased shikimate concentrations in rice seedlings cultivated under palisade grass (Brachiaria brizantha), signal grass (B. ruziziensis), guinea grass (Panicum maximum), and weedy fallow (spontaneous vegetation) but not under millet (Pennisetum glaucum), which behaved similarly to the control (clean fallow, no glyphosate application). Glyphosate applications in the timing intervals used were associated with stress in the rice plants, and this association increased if cover crops took longer to completely dry and if higher amounts of biomass were produced. Millet, as a cover crop, allowed the highest seedling dry matter for upland rice and the highest rice yield. Our results suggest that using millet as a cover crop, with glyphosate application far from upland rice planting day (10 d or more), was the best option for upland rice under a no‐tillage system.

The Impact of El Niño/Southern Oscillation on Hydrology and Rice Productivity in the Cauvery Basin, India: Application of the Soil and Water Assessment Tool

This study was performed to further understanding of the variations in hydrology and rice crop productivity during different El Niño/Southern Oscillation (ENSO) events in the Cauvery River Basin of Tamil Nadu, India using the Soil and Water Assessment Tool (SWAT). The entire Cauvery Basin was divided into 301 sub-basins and further subdivided into 3,601 Hydrological Response Units (HRU). Based on the National Oceanic and Atmospheric Administration (NOAA) official website, information on El Niño (1972, 1982, 1987, 1991, 1997, 2002 and 2004) and La Niña (1970, 1971, 1973, 1974, 1975, 1988, 1998, 1999 and 2000) years were obtained. The SWAT model was continuously run from 1970 to 2008, and a composite for El Niño, La Niña and normal years was constructed to understand their influence on hydrology and rice crop productivity in the study area. From the analysis, it was clear that an El Niño episode is correlated with rainfall, hydrology and rice productivity in the Cauvery river basin. The validation of the SWAT model indicated the capability of SWAT to accurately predict stream flow and rice productivity. It was evident from the investigation that the quantum of rainfall was more during El Niño years with high inter-annual rainfall variability (809.3mm to 2,366mm) compared with La Niña and normal years. As a result, the soil water recharge, including percolation and soil water availability in the surface layers, was increased in the El Niño years. Simulated rice productivity over 39 years in the Cauvery Basin ranged between 1,137 and 7,865kgha−1 with a mean productivity of 3,955kgha−1. The coefficient of variation in rice productivity was higher during La Niña (21.4%) years compared with El Niño (14.7%) and normal years (14.6%). The mean rice productivity was increased in both El Niño and normal years, indicating the possibility of higher yields than those in La Niña years. An analysis of the hydrological data and rice productivity showed that the risk of failure was low during El Niño years compared with normal or La Niña years. This behavior could be utilized for forecasting rice crop productivity under different ENSO conditions and can provide information for policy makers when deciding on water allocation and import / export policies.

Spectral Characteristics of High-Yielding Varieties of Rice Plants Using Landsat 8 Data

In applying remote sensing technology for inventory, evaluation and estimation of rice crop production, required the data of spectral characteristics changing of the plants during its growth phase. By identifying spectral characteristics, it will be recognized the objects in the images. This study identifies the spectral characteristics of high-yielding varieties of rice plants during their growth in Malang regency. Based on the results of field survey, the high yielding varieties that are commonly planted consist of IR64, Ciherang and Membramo. Then, from the identification of vegetation index is known that all these three varieties have different growth patterns, where the most distinct pattern found in IR64.

Effect of Integrated Nutrient Management on Rice Yield, Soil Nutrient Profile, and Cyanobacterial Nitrogenase Activity under Rice–Wheat Cropping System

We assessed the cyanobacterial inoculation, green manure (GM) application, and chemical nitrogen (N) fertilization on grain/straw yield, nutrient balance, and nitrogenase activity under individual and integrated nutrient management mode in a rice–wheat cropping sequence. Individual and integrated application of cyanobacterial biofertilizer (CB) and GM with chemical fertilizer improved the soil health and production of rice crop. Integration of cyanobacterial and green manure resulted in a savings of 50 kg N ha−1. Functional relationships (R2, –83.5 to 95.7%) between the different sources of nutrients revealed that the maximum positive contribution of cyanobacteria was on final available N (45.2%) and available phosphorus (P, 18.5%). Green manure had the greatest contribution to total N, total P, zinc, iron, and manganese (Mn). However, cyanobacteria had a negative relationship with Mn and sodium (Na, –30.19%). A negative relationship with Na indicates the possibility of using cyanobacteria as an ameliorating agent for salt-affected soil.

Evaluation of global warming effects on the geographical distribution of weeds in paddy fields by characterizing germination time and morphological factors

Global warming, a consequence of climate change, alters rice-paddy ecosystems, especially through the changes of both growth rate of plants and the occurrences of pests, and affects both rice crop production and biodiversity. In this study, factors related to the germination temperatures of 80 weed species in paddy fields were analyzed to elucidate the effect of warming on morphological (leaf size), phenological (germination time), and population (distribution) responses. A self-organizing map (SOM) was used to classify the weed species on the basis of 5 factors related to germination temperature: the minimum, maximum, and optimum temperatures and the minimum and maximum optimal range. Climate data for the Korean Peninsula during 4 different decades (1990s, 2020s, 2050s, and 2080s) were obtained from a regional climate change model following the A1B emission scenario of the Intergovernmental Panel on Climate Change. Changes in the germination time and range of potential habitable areas for the weed species were estimated on the basis of the patterns of the SOM. The species associated with relatively lower germination temperatures tended to have smaller leaves, shorter stems, and earlier flowering and germination times than the species associated with higher germination temperature. The potential germination area increased progressively with rising temperature. The degree of potential increase in germination area was the greatest in the 2080s when the weeds could germinate in most of the southern Korean Peninsula. These results suggest that studying the patterns of germination temperature through SOM could provide necessary information for characterizing the germination of weeds on the basis of various characteristics (e.g., morphology, phenology, and distribution) and would be useful for maintaining agricultural productivity and agroecosystem biodiversity under global warming.

Integrated Agricultural Development in High-Altitude Tribal Areas

A high-altitude (&gt; 1,500 m asl) integrated participatory watershed development programme was implemented between 2004 and 2008 in the West Khasi Hills, Meghalaya, North-Eastern Indian Himalaya. The aim was to assess and refine practices for integrating crop, fish and livestock production systems. Soil and water conservation measures, with the active participation of local inhabitants, included the construction and renovation of ponds, jalkunds (micro rainwater-harvesting structures) and bench and half-moon terraces. Impact analysis revealed that 4.3 million litres of water were harvested and enhanced potato and rice crop productivity by 30% to 40% and 45% to 50% respectively. Farmers are now able to earn net incomes of around $56.8 and $8.9 per month from community dairy units and fish ponds respectively.

Change in net global warming potential of a rice–wheat cropping system with biochar soil amendment in a rice paddy from China

Soil amendment of biochar produced via pyrolysis of waste biomass had been proposed as a potential countermeasure to mitigate climate change in agriculture. An overall accounting of net greenhouse gas balance (NGHGB) and greenhouse gas intensity (GHGI) was conducted of a whole rice–winter wheat rotation year of 2010–2011 in a paddy soil under biochar soil amendment at different rates from Southeast China. Fluxes of soil carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) were measured using a static chamber method, and the net ecosystem exchange of CO2 (NEE) was estimated by the difference between net primary production (NPP) and soil CO2 emissions (RH) for both rice and winter wheat growing seasons. While no change observed in RH, NPP of both rice and winter wheat was similar between the treatments except for an increase under BSA at 10tha−1 over the control. However, seasonal total N2O emission was significantly and greatly decreased by 45.1% and 39.5% of rice growing season, and by 37.6% and 41.2% of winter wheat growing season under BSA treatment of 20tha−1 and 40tha−1 respectively over the control. Whereas, a 30.6% increase in seasonal total CH4 emission was observed only under BSA of 20tha−1 of the rice growing season. However, BSA both at 20tha−1 and 40tha−1 exerted a great reduction in both NGHGB and GHGI of wheat cropping season but of the rice season. As an overall effect, a net reduction in GHGI by 10–20% with BSA was significant across all the biochar treatments. And this reduction could be accounted mainly by the consistent decrease in N2O emission across rice and wheat growing cycles with insignificant changes in soil respiration and CH4 flux during rice season. Whereas there could be variable changes in crop yield and net ecosystem GHGs balance with biochar rates and with crop cycles, biochar soil amendment (BSA) could have a great potential to reach a low carbon intensity production with sustaining crop productivity of a whole rice and wheat rotation system in rice-based agriculture of China.

Constraints of Rainfed Rice Production in India: An Overview

Rice is one of the most important crops in eastern India and it will continue to enjoy its leading position so long as it remains the staple food of almost entire of the population of this region. Under the influence of increasing population pressure the demand for rice is expected to rise persistently in coming years. As the land frontier has already been exhausted the future source of growth in this region lies in raising the productivity of rice crop. Even to sustain in food grains production, it is important to give due attention to the eastern India in general and to accord high priority to the constraints of rice production in this region in particular. This can be achieved if rice research helps to reduce production losses due to various biotic and abiotic constraints in rainfed rice ecosystems. Since elimination or partial solution of these constraints would have a major impact on rice production in eastern India because the yield gaps are very high, the major constraints to rice production in eastern India require more objectivity and concerted efforts while addressing them. The major rice production constraints and priority research problem areas of rainfed rice production in eastern India are drought and submergence, bacterial blight, leaf blast, weeds, brown plant hopper and poor soil fertility. Hence, it would be logical to prioritize rice research on the basis of prevailing constraints under rainfed areas of eastern India. Besides, low input use, inappropriate plant spacing, late sowing and selection of wrong cultivars are some of the other technical constraints, which can be effectively reduced through the diffusion of relevant technologies among ultimate users or farmers. It requires further strengthening of linkages between ‘Research & Extension’ that facilitates feed-backs and disseminates technical information.

MASALAH-MASAIAH DAN SOLUSI BUDIDAYA PADI SAWAH

The main factor causingtownational rke production is the km productivity ofricecrops in Indonesiathat is less than 4.66 ton/ha in mineral soil. Efforts to expand rice cultivation is very limited, because thefertile hnd has no longer available while marginal land still has obstacles (o develop cultivation of paddies.Some of tiie proUenis encountered in wedand development in Indonesiatekm pU so3 which shouM be improvedand limited soil nutrient availability, increase in the solubiiity of Fe and Fe toxklty problem, lack of potassiumdement because ail crops were tramiported oat; goieral fertilizerrecommendationis applied for each tocatktn/diirereot land; lack of research on h>cat)on-specifk fertilizer recsommendatiott; much water is needed (o moistsoil; and land productK'ity is still low. Optimal management of wetland win affect some aspects such as: soilnutrient status of fidds needs to be tested as a baus for determining fertilizer recommendation: microbialfertilizer technology to improve the efTiciency of fertilization, irrigation and leaching processes on wetlandmanagement can change tbe chemical properties of soil, crop ntaiugement development in traditional Indonesianrice cultivation should be done with SRI, because it can increase the productivity ofriceand of sustainableagriculture.

Use of time-of-flight mass spectrometry for large screening of organic pollutants in surface waters and soils from a rice production area in Colombia

The irrigate district of Usosaldaña, an important agricultural area in Colombia mainly devoted to rice crop production, is subjected to an intensive use of pesticides. Monitoring these compounds is necessary to know the impact of phytosanitary products in the different environmental compartments. In this work, surface water and soil samples from different sites of this area have been analyzed by applying an analytical methodology for large screening based on the use of time-of-flight mass spectrometry (TOF MS) hyphenated to liquid chromatography (LC) and gas chromatography (GC). Several pesticides were detected and unequivocally identified, such as the herbicides atrazine, diuron or clomazone. Some of their main metabolites and/or transformation products (TPs) like deethylatrazine (DEA), deisopropylatrazine (DIA) and 3,4-dichloroaniline were also identified in the samples. Among fungicides, carbendazim, azoxystrobin, propiconazole and epoxiconazole were the most frequently detected. Insecticides such as thiacloprid, or p,p′-DDT metabolites (p,p′-DDD and p,p′-DDE) were also found. Thanks to the accurate-mass full-spectrum acquisition in TOF MS it was feasible to widen the number of compounds to be investigated to other families of contaminants. This allowed the detection of emerging contaminants, such as the antioxidant 3,5-di-tertbutyl-4-hydroxy-toluene (BHT), its metabolite 3,5-di-tert-butyl-4-hydroxy-benzaldehyde (BHT-CHO), or the solar filter benzophenone, among others.