Rice Field Conditions Research Articles

Modeling and Analysis of Rice Root Water Uptake under the Dual Stresses of Drought and Waterlogging

The development of an accurate root water-uptake model is pivotal for evaluating crop evapotranspiration; understanding the combined effect of drought and waterlogging stresses; and optimizing water use efficiency, namely, crop yield [kg/ha] per unit of ET [mm]. Existing models often lack quantitative approaches to depicting crop root water uptake in scenarios of concurrent drought and waterlogging moisture stresses. Addressing this as our objective; we modified the Feddes root water-uptake model by revising the soil water potential response threshold and by introducing a novel method to calculate root water-uptake rates under simultaneous drought and waterlogging stresses. Then, we incorporated a water stress lag effect coefficient, φWs, that investigated the combined effect of historical drought and waterlogging stress events based on the assumption that the normalized influence weight of each past stress event decreases with an increase in the time interval before simulation as an exponential function of the decay rate. Further, we tested the model parameters and validated the results obtained with the modified model using data from three years (2016–2018) of rice (Oryza sativa, L) trails with pots in Bengbu, China. The modified Feddes model significantly improved precision by 9.6% on average when calculating relative transpiration rates, particularly post-stress recovery, and by 5.8% on average when simulating soil moisture fluctuations during drought periods. The root mean square error of relative transpiration was reduced by 60.8%, and soil water was reduced by 55.1%. By accounting for both the accumulated impact of past moisture stress and current moisture conditions in rice fields, the modified model will be useful in quantifying rice transpiration and rice water use efficiency in drought–waterlogging-prone areas in southern China.

Population Dynamics of Dragonflies at The Paddy Field Ecosystem, Sidorejo, Central Bengkulu

The rice fields of Sidorejo Village have the potential for dragonfly diversity. This study aims to analyze fluctuations in the diversity and abundance of dragonflies in three ecosystem conditions of rice fields in Sidorejo Village, Bengkulu Tengah. Sampling using purposive sampling with the cruising method. Data analysis was carried out descriptively through the identification of characteristics to obtain the name of the species. After the species name was obtained, the relative abundance, Shannon Wienner diversity index, and species evenness index were calculated. The results of the study found that the harvest ecosystem had the highest diversity and abundance of dragonflies (13 species and 45 individuals). The species that were consistently found in three types of ecosystems were Orthetrum sabina, O. testaceum, and Pantala flavescens. The species with the highest relative abundance was O. sabina with 32%. The diversity index ranged from 1.32 (post-harvest) to 2.25 (harvest). The highest evenness index was in the post-harvest ecosystem at 0.95, and the lowest was in the harvest ecosystem at 0.87. The results of this study are expected to show that the diversity and abundance of dragonflies fluctuate depending on seasonal ecosystem conditions in the rice fields.

Effects of Organic and Inorganic Fertilizers on Soil Nutrient Conditions in Rice Fields with Varying Soil Fertility

The majority of crop-growing areas in China have low or medium fertility levels, which limits the yield of crops grown in those areas. Fertilizer application can improve soil quality, but the effects of such treatments vary depending on the base soil fertility. However, the specific differences associated with the application of different fertilizer types to soils of varying fertility levels have yet to be clearly delineated. Here, the influences of several fertilizer types on physical, chemical, and biological soil indicators were assessed in rice fields in the red soil area of Hunan Province with varying base fertility levels: Hehua (low fertility), Dahu (medium fertility), and Longfu (high fertility). Four treatments were applied to these fields: no fertilizer, standard fertilizer, 60% chemical fertilizer + 40% organic fertilizer, and 100% chemical fertilizer. Across the three sites and treatment groups, the largest increases in total nitrogen and phosphorus contents were in Hehua and Longfu, respectively. Soil organic matter content increased most significantly in Hehua. Application of any type of fertilizer increased the total and fast-acting nutrient content in the low-yielding fields, whereas organic fertilizers increased the nutrient content and soil biological indicators more than chemical fertilizer alone did; the effect of organic fertilizer application on the combined enzyme activity of the soil was also higher than that of chemical fertilizers alone. Overall, these experiments provide a theoretical basis and technical support for rational fertilizer application and improvement of Hunan’s red soil quality based on the natural soil fertility levels.

Adaptive Sliding Mode Path Tracking Control of Unmanned Rice Transplanter

To decrease the impact of uncertainty disturbance such as sideslip from the field environment on the path tracking control accuracy of an unmanned rice transplanter, a path tracking method for an autonomous rice transplanter based on an adaptive sliding mode variable structure control was proposed. A radial basis function (RBF) neural network, which can precisely approximate arbitrary nonlinear function, was used for parameter auto-tuning on-line. The sliding surface was built by a combination of parameter auto-tuning and the power approach law, and thereafter an adaptive sliding controller was designed. Based on theoretical and simulation analysis, the performance of the proposed method was evaluated by field tests. After the appropriate hardware modification, the high-speed transplanter FLW 2ZG-6DM was adapted as a test platform in this study. The contribution of this study is providing an adaptive sliding mode path tracking control strategy in the face of the uncertainty influenced by the changeable slippery paddy soil environment in the actual operation process of the unmanned transplanter. The experimental results demonstrated that: compared to traditional sliding control methods, the maximum lateral deviation was degraded from 17.5 cm to 9.3 cm and the average of absolute lateral deviation was degraded from 9.1 cm to 3.2 cm. The maximum heading deviation was dropped from 46.7° to 3.1°, and the average absolute heading deviation from 10.7° to 1.3°. The proposed control method not only alleviated the system chattering caused by uncertain terms and environmental interference but also improved the path tracking performance of the autonomous rice transplanter. The results show that the designed control system provided good stability and reliability under the actual rice field conditions.

The PERFORMANSI PADI GREEN SUPER RICE YANG ADAPTIF PADA LAHAN SAWAH TADAH HUJAN

Green Super Rice (GSR) is a rice plant that can be cultivated on land that is nutrient efficient, has high yields and is resistant to biotic and abiotic stresses. GSR planting is expected to have adaptability and good yields in conditions of infertile rice fields, often experiencing drought, uncertainty in air supply, low fertility, and disease attacks. The aim of the study was to see the performance of adaptive Green Super Rice in rainfed rice fields. The GSR rice lines will be planted in Bireun, Indonesia. This study used a one-factor Randomized Block Design (RAK) with 3 replications. The treatment factors that were tried were 6 GSR rice lines, the F8 line, from a cross between the Sikuneng variety from Bireun and IRBB27. As a comparison, the national superior variety Inpari 42 was used. There were 21 experiments and each experiment consisted of 2 plant units, one plant as the sample plant. GSR lines which were selected at the Aceh Rice Research Center in the previous planting season. The comparison variety used was Inpari 42. Seedlings aged 21 days after sowing from each line and comparison varieties were planted 1-3 seedlings per hole in a plot measuring 2m x 5m with a spacing of 20 cm x 20 cm. Irrigation relies on rain and water pumps from rainwater reservoirs. variables of plant height (cm), number of productive tillers, heading date or 50% flowering age (HSS), number of filled grain, percentage of filled grain(%), weight of 1,000 grains(g), and yield(t/ Ha).

Biochar Amendment and Nitrogen Fertilizer Contribute to the Changes in Soil Properties and Microbial Communities in a Paddy Field.

Biochar amendment can influence the abundance, activity, and community structure of soil microbes. However, scare information is present about the effect of the combined application of biochar with synthetic nitrogen (N) fertilizer under paddy field condition. We aimed to resolve this research gap in rice field conditions through different biochar in combination with N fertilizers on soil nutrients, soil microbial communities, and rice grain yield. The present study involves eight treatments in the form of biochar (0, 10, 20, and 30 t ha–1) and N (135 and 180 kg ha–1) fertilizer amendments. The soil microbial communities were characterized using high-throughput sequencing of 16S and Internal transcribed spacer (ITS) ribosomal RNA gene amplicons. Experiential findings showed that the treatments had biochar amendments along with N fertilizer significantly advanced soil pH, soil organic carbon (SOC), total nitrogen (TN), soil microbial carbon (SMBC), soil microbial nitrogen (SMBN), and rice grain yield in comparison to sole N application. Furthermore, in comparison with control in the first year (2019), biochar amendment mixed with N fertilizer had more desirable relative abundance of microorganism, phyla Acidobacteria, Actinobacteria, Proteobacteria, and Verrucomicrobia with better relative abundance ranging from 8.49, 4.60, 46.30, and 1.51% in T7, respectively. Similarly, during 2020, bacteria phyla Acidobacteria, Actinobacteria, Bacteroidetes, Gemmatimonadetes, Planctomycetes, and Verrucomicrobia were resulted in higher and ranging from 8.69, 5.18, 3.5, 1.9, 4.0, and 1.6%, in biochar applied treatments, respectively, as compared to control (T1). Among the treatments, Sphingopyxis and Thiobacillus bacterial genus were in higher proportion in T7 and T3, respectively, as compared to other treatments and Bacillus was higher in T6. Interestingly, biochar addition significantly decreased the soil fungi phyla Ascomycota, Basidiomycota, Chytridiomycota, and Rozellomycota, in 2020 as compared to 2019. Whereas biochar addition to soil decreased Echria, Kohlmeyeriopsis, and Westerdykella fungal genus as compared to non-biochar treatments. The redundancy analysis showed that soil biochemical traits were positively correlated with soil bacteria. In addition, correlation analysis showed that soil bacteria including Acidobacteria, Actinobacteria, Bacteroidetes, Planctomycetes, and Proteobacteria strongly correlated with rice grain yield. This study demonstrated that soil nutrients and bacteria contribute to an increase in rice yield in combined biochar amendment with lower N treatments.

Biochemical characteristics and inoculation effects of multi-trait plant growth-promoting rhizobacteria on upland rice (Oryza sativa L. cv PSB Rc23) seedling growth.

Plant growth-promoting rhizobacteria (PGPR) are known to stimulate plant growth because of their versatility in nutrient transformation. However, the success of PGPR inoculation depends not only on their ability to promote plant growth but also on their capacity to metabolize substrates that can be used as energy for the development and survival of the crops. Given the important influence of seed germination and vigor on crop yield, this study investigated the biochemical characteristics and effectiveness of multi-trait PGPR isolates in enhancing upland rice seedling growth and vigor. Biochemical identification was done using Biolog GEN III Microbial Identification System. Isolates were characterized based on their ability to metabolize all major classes of biochemicals in the carbon source utilization and chemical sensitivity assays. Identified rhizobacterial isolates were tested in vitro to evaluate their inoculation effects on the growth of PSB Rc23 upland rice seedlings. Biochemical identification results showed that rhizobacterial isolates have extensive metabolic activities in a wide range of carbon sources. Inoculation effects revealed that isolate IBBw1a was the most effective in enhancing root length and vigor index of rice seedlings in vitro, yielding a significant increase of 60% and 53%, respectively, over the uninoculated control. This study suggests that rhizobacterial isolates from upland rice may have commercial significance to improve seedling growth and vigor. These isolates will undergo a further assessment of their effectiveness in actual upland rice field conditions as they were already proven effective growth promoters in laboratory and screenhouse conditions. Such future activity can uncover their efficacy as potential biofertilizers in the actual soil environment.

Composition of pests and predators in the early generative phase of rice cultivation in two different conditions

The early phase of growth is the most vulnerable for the survival of rice plants. However, this is influenced by many factors, such as the presence of pests and predators as natural enemies. This study aimed to determine the composition of pests and predators in the vegetative phase of rice plants in rice fields close to forests, and rice fields close to urban areas. The research location was determined by purposive random sampling method. Arthropod species and populations were observed directly from 8 am to 11 am. Data on safety results were processed and calculated. Based on the results of the observations in initial generative phase, there were 687 Arthropods. At the species level, the most abundant main pest was Nilaparvata lugens (11.76%) and Gesonula mundata (10.07%). The most abundant predator was Lycosa pseudoannulata (25.89%). Based on the overall calculation, predatory Arthropods have largest composition (72.36%), while pests were 27.04%. Based on the type of rice field conditions, Arthropods in the rice fields bordering the mountains have higher composition in both pests (15.99%) and predators (41.18%) compared to rice fields that are near settlement/urban areas, namely 11.25% pests and predators 31.18%.

TRANSFORMASI KARAKTERISTIK TANAH SAWAH PADA LAHAN BEKAS PENAMBANGAN EMAS DI KABUPATEN SIJUNJUNG SUMATERA BARAT

The process of physical and chemical properties of the former gold mining soil which is caused by the transformation of different land conditions in natural rice fields, reclaimed rice fields, and mine fields. This study aims to determine the differences in the characteristics of the former gold mining soil in natural rice fields, reclaimed rice fields and mining fields in Sijunjung Regency. There were three sampling locations with three sample points each and the samples were analyzed physically and chemically. Results of this study showed that natural paddy soil has optimal conditions for the growth of rice plants followed by reclaimed lowland soil and the worst was in mining paddy soil based on soil physical and chemical properties. The difference in soil physical properties in the form of natural paddy soil texture was smoother compared to land conditions in reclaimed rice fields and mining rice fields. This was due to intensive inundation processes, which created a plough tread layer, low volume weight accompanied by a moderate total pore space. The difference in chemical properties was in the stable pH of natural paddy soil due to inundation and high organic carbon accompanied by rice reclamation and very low organic carbon in mining soils, which would affect the growth of rice plant.

Mapping of the Denitrification Pathway in Burkholderia thailandensis by Genome-Wide Mutant Profiling

Burkholderia thailandensis is a soil saprophyte that is closely related to the pathogen Burkholderia pseudomallei, the etiological agent of melioidosis in humans. The environmental niches and infection sites occupied by these bacteria are thought to contain only limited concentrations of oxygen, where they can generate energy via denitrification. However, knowledge of the underlying molecular basis of the denitrification pathway in these bacteria is scarce. In this study, we employed a transposon sequencing (Tn-Seq) approach to identify genes conferring a fitness benefit for anaerobic growth of B. thailandensis Of the 180 determinants identified, several genes were shown to be required for growth under denitrifying conditions: the nitrate reductase operon narIJHGK2K1, the aniA gene encoding a previously unknown nitrite reductase, and the petABC genes encoding a cytochrome bc 1, as well as three novel regulators that control denitrification. Our Tn-Seq data allowed us to reconstruct the entire denitrification pathway of B. thailandensis and shed light on its regulation. Analyses of growth behaviors combined with measurements of denitrification metabolites of various mutants revealed that nitrate reduction provides sufficient energy for anaerobic growth, an important finding in light of the fact that some pathogenic Burkholderia species can use nitrate as a terminal electron acceptor but are unable to complete denitrification. Finally, we demonstrated that a nitrous oxide reductase mutant is not affected for anaerobic growth but is defective in biofilm formation and accumulates N2O, which may play a role in the dispersal of B. thailandensis biofilms.IMPORTANCE Burkholderia thailandensis is a soil-dwelling saprophyte that is often used as surrogate of the closely related pathogen Burkholderia pseudomallei, the causative agent of melioidosis and a classified biowarfare agent. Both organisms are adapted to grow under oxygen-limited conditions in rice fields by generating energy through denitrification. Microoxic growth of B. pseudomallei is also considered essential for human infections. Here, we have used a Tn-Seq approach to identify the genes encoding the enzymes and regulators required for growth under denitrifying conditions. We show that a mutant that is defective in the conversion of N2O to N2, the last step in the denitrification process, is unaffected in microoxic growth but is severely impaired in biofilm formation, suggesting that N2O may play a role in biofilm dispersal. Our study identified novel targets for the development of therapeutic agents to treat meliodiosis.

Flexible Behavior of the Black-Tailed Godwit Limosa limosa is Key to Successful Refueling during Staging at Rice Paddy Fields in Midwestern Korea.

Successful refueling at staging sites is essential for the survival and reproduction of migratory birds. Understanding their staging ecology is therefore crucial for the conservation of migrant species. Rice fields in the mid-western region of the Korean Peninsula serve as staging habitats for the black-tailed godwit (Limosa limosa). We examined the behavior of staging black-tailed godwits in rice fields located in the East Asian-Australasian Flyway during their northward migration. Specifically, we tested the effect of flock size and water level on the foraging, vigilance, and resting behaviors of black-tailed godwits. Our observations revealed that as flock size increased, stepping rate, pecking rate, and vigilance duration decreased, while probing rate, preening duration, and foraging efficiency increased. Stepping and pecking rates increased at low water levels, compared with high water levels. We determined that the behavior of black-tailed godwits at the staging site is influenced by flock size and water level. These observations suggest that black-tailed godwits form larger flocks to increase foraging efficiency by lowering individual-level vigilance, and to spend more time on preening, which is critical for flight and survival. It can be also inferred, based on the shift in primary foraging mode between probing and pecking depending on the water level, that they obtain higher foraging efficiency by flexibly adapting their foraging mode to the conditions in rice fields that are subject to agricultural activities. Our results are expected to serve as basic data for establishing efficient management strategies for anthropogenic habitats for the conservation of migratory shorebirds such as black-tailed godwit.

Assessment of Rhizospheric Arbuscular Mycorrhizae Spores in Relation to Soil Characters in the Rice Fields of Malda District, India

Arbuscular mycorrhizal fungi (AMF) show symbiotic associations with the roots of plants and facilitates nutrients uptake through the hyphae-plant root-soil interface. Many edaphic and anthropogenic activities greatly influence this mutualistic association. Among which soil parameters are of great importance. The major objective of this study is to assess the soil colonization of AM fungi in different textural and nutritional conditions in agricultural rice fields of different locations of Malda district, West Bengal, India. Fifty rhizospheric soil samples of rice fields were collected from Jadupur (25.080° N, 88.1255° S) and Mohadipur (24.8525° N, 88.1255° E) areas of Malda district, India and the mycorrhizal spores were isolated and quantified according to adhesion and floatation techniques and identified morphometrically through the INVAM database. Soil texture was determined by conventional pipette method and soil pH, conductivity, nitrogen, potassium, phosphorus, and organic carbon contents were quantified according to standard methods. It was observed that the soil samples had a wide diversity of genera of mycorrhizal spores such as Aculospora sp., Entrophospora sp., Gigaspora sp., Glomus sp., and Scutellospora sp. The texture of the sample sites are mostly sandy loamy to loamy and have variations in soil chemical properties. The clay and phosphorous contents are inversely proportional to mycorrhizal spore content whereas it was directly proportional to the organic carbon and nitrogen content in the soil. The AM fungal diversity was more in Jadupur soil while it was less in Mohadipur. The study concludes that low nutrient content soil had more spore numbers than high nutrient content, reflecting their role in mineral acquisition for better plant nutrient supply.

Influence of pH and Divalent Metals Relevant to California Rice Fields on the Hydroxide-Mediated Hydrolysis of the Insecticide Chlorantraniliprole

The hydrolysis of chlorantraniliprole (3-bromo-N-[4-chloro-2-methyl-6-(methylcarbamoyl)phenyl]-1-(3-chloro-2-pyridine-2-yl)-1H-pyrazole-5-carboxamide; CAP) was investigated over the pH range of 6-10, reflective of California rice field conditions, with variable additions of Cu2+, Zn2+, Mn2+, or Ni2+. Dissipation accelerated as pH increased with half-lives ranging from 26.9 to 2.2 days with slight inhibition in rice field water. The addition of divalent metals was not observed to catalyze the hydrolysis of CAP at pH 6, indicating that the insecticide is likely to remain recalcitrant to hydrolysis in neutral or acidic surface waters. However, Mn2+ and Ni2+ were observed to inhibit hydrolysis at pH 8 and 9. Attenuated total reflectance Fourier transform infrared analysis supports the conclusion that divalent metals may withdraw electron density from the amide nitrogen via interaction with the amide oxygen, though additional quantum chemical modeling is necessary to provide further mechanistic insights. Overall, the hydrolysis of CAP in California rice fields and their surrounding surface waters will be dominated by pH and inhibited by dissolved metal species.

Crop rotation sequencing to minimize yield losses of summer-irrigated lowland rice in Myanmar caused by the rice root-knot nematode Meloidogyne graminicola

The effect of different rice-based crop rotation sequences on the population densities of Meloidogyne graminicola and on the yield of rice was evaluated in a microplot experiment under lowland rice field conditions. Ten treatments of cropping sequences were grown in four successive growing seasons: continuous growing of the susceptible rice cultivar Thihtatyin (rice-rice-rice-rice), four treatments of 1- season crop rotation sequences (rice-rice-chickpea-rice, rice-rice-black gram-rice, rice-rice-soybean-rice, rice-rice-cowpea-rice), and five treatments of 2-season crop rotation sequences (groundnut-rice-chickpea-rice, green gram-rice-black gram-rice, cowpea-rice-soybean-rice, sesame-rice-cowpea-rice, sunflower-rice-sesame-rice). Population densities of M. graminicola recovered from the rice plants and the nematode multiplication factors (Mf) in the soil in the continuous rice cropping sequence (rice-rice-rice-rice) was the highest among the ten cropping sequences. Lowest nematode Mf in the soil was observed in the 2-season crop rotation sequence sunflower-rice-sesame-rice and the highest was observed in the 1-season crop rotation sequence rice-rice-cowpea-rice among the nine crop rotation sequences. Highest rice yield was obtained in the 2-season crop rotation sequences green gram-rice-black gram-rice, sesame-rice-cowpea-rice and sunflower-rice-sesame-rice, which were about 2 times higher compared with the 1-season crop rotation sequences and about 3 times higher compared with the continuous rice cropping sequence.

Genetic variants of the oppA gene are involved in metabolic regulation of surfactin in Bacillus subtilis

BackgroundBacillus subtilis 916 has been identified as an effective biocontrol agent against Rhizoctonia solani, the causal pathogen of rice sheath blight, under greenhouse and field conditions. HPLC analysis showed that surfactin, a member of the lipopeptide family produced by B. subtilis, was the major antimicrobial substance.ResultsPreviously, we obtained a mutant strain of B. subtilis 916, Bs-H74, which produced significantly more surfactin than the wild type and presented 10% stronger inhibitory activity against R. solani. To explore the molecular mechanism underlying the higher surfactin productivity in the mutant, high-throughput proteomic analysis was carried out to analyze the differential protein expression. Our results showed that several differentially expressed proteins are involved in OppA, DegU and Carbon Catabolite Repression (CCR) regulatory pathways, which could be positively or negatively associated with surfactin biosynthesis. At both transcriptional and translational levels, we suggested that OppA may play a key role in surfactin synthesis regulation. Based on the above findings, we proposed the hypothesis that a point mutation in the oppA gene may lead to changes in oligopeptides acquisition in B. subtilis, and then the changed oligopeptides may activate or suppress the global regulatory protein, CcpA in the CCR pathway, and ComA and DegU may indirectly regulate surfactin synthesis in Bs-H74. To further explore the regulatory mechanisms in Bs-H74, metabolomics analysis was performed in this study. Interestingly, only 16 metabolites showed changes in abundance in Bs-H74 compared to Bs-916. Neohesperidin, a type of natural flavanone glycosides from citrus with a range of biological activities, increased by 18 times over the wild type Bs-916. This result implied exciting findings in regulatory mechanisms by OppA protein.ConclusionsIn summary, this study has revealed the mechanisms underlying the improved antagonistic property with increased surfactin production in Bs-H74 at the gene, protein and metabolic levels, which may help to comprehend the map of the regulatory networks in B. subtilis. Findings from our work have provided a solid physical and theoretical basis for practically applying metabolic and genetic engineering to achieve improved and high-yielding biocontrol strains.

Variation in lowland rice yield and its determinants in a rainfed area in Savannakhet Province, Laos

Irrigated areas in the Lao People’s Democratic Republic (Laos) constitute only 12% of the total agricultural land. Most of the lowland rice is cultivated under rainfed conditions. The rice yield in rainfed fields is lower and more unstable than that in irrigated fields. Most of the lowland rice fields in Savannakhet Province, which is the main rice-producing region, cover not only lowlands but also gradual hilly terrain, with sandy soils. The water and nutrient conditions of the lowland rice fields likely differ with location and geological conditions, and rice production may be insufficient in some areas. The objectives of this study are (1) to assess rice yield and water and soil conditions in the rainfed rice fields of Savannakhet Province and (2) to identify the determinants of variation in rice yield. We selected a village with rainfed rice fields as the research site. Sixty plots were set in the rice fields, from the lowland to middle and upper positions of the terrain. The rice grain yield varied from 0.6 to 3.6 t ha−1, averaging 1.9 t ha−1, and the yield in the lower positioned fields was significantly higher than that in the upper positioned fields. Surface water in the observed fields was mostly maintained above ground level throughout the planting period, and the average surface water depth in the lower position fields was deeper than that in the upper and middle position fields. The total carbon (TC), total nitrogen, available phosphorus, and exchangeable potassium were extremely poor, while the exchangeable calcium (ExCa) and exchangeable magnesium were relatively rich, and the ExCa in the lower positioned fields was higher than that in the upper and middle positioned fields. ExCa was the main determinant of difference in rice grain yield, followed by TC.

The Role of Local Communities in the Development of Taro Tourism Village Gianyar

This research is located in Taro Village, Gianyar Regency, which has a lot of natural potential to be developed. The characteristics of the population are mostly farmers supported by the geographical conditions of rice fields and forests which become its own strength. It has been proclaimed to be a tourism village since 2017 because of the natural potential spread in four villages, namely Banjar Let, Patas, Taro Kaja, and Pakuseba. Agro tourism, Lembu Putih tourism, tracking and cycling, and monkey conservation are the potential which are being develop. Geographical conditions which are plateau with paddy and forest structure strongly support the development of this potential. The management enthusiasm consisting of heads of village, tourism conscious groups (pokdarwis) and local communities hailed the development of the village which has the concept of community empowerment.   The purpose of this research is to find out how the role of the local community in the development of Taro tourism villages and the constraints faced in the development. This research is a qualitative research by collecting data through in-depth interviews with key informants consisting of heads of village, village secretaries, Pokdarwis members, and the people who also manage homestays. From the results of the interviews, it was found that the role of the community in the development of Taro tourism villages are in various ways, including: in the field of social culture; the rise of local art which is a hereditary cultural heritage begin to be encouraged and acquired enthusiasm from the local community such as eat together (megibung), and drama gong art show. In the field of management; the involvement of local communities as members of Pokdarwis, using people's houses to become homestays shows community-based tourism management. In the field of education and training; homestay management training, English language, seven charm and beauty (Sapta Pesona) which are all followed by high enthusiasm from the community.   However, as a new established tourism village, there are some obstacles faced in its development, including: the lack of skilled people in tourism, the involvement of facilities in attractions, and unintegrated online marketing.  However, various active and organized efforts done by the manager are believed can overcome those obstacles.

Sensitivity Analysis of Alisma plantago-aquatica L., Cyperus difformis L. and Schoenoplectus mucronatus (L.) Palla to Penoxsulam

Determining the intra-specific variability of response to a given herbicide is important for monitoring the possible shifts in the sensitivity of weed populations. This study describes the responses of populations of Alisma plantago-aquatica, Cyperus difformis, and Schoenoplectus mucronatus from Italy, Greece, Portugal, and Spain to penoxsulam, an acetolactate synthase (ALS) inhibitor widely used in rice. To evaluate previously evolved resistance to ALS inhibitors, sensitivity to azimsulfuron and bensulfuron-methyl was assessed. Dose-response experiments with penoxsulam were performed in a greenhouse simulating paddy rice field conditions. Log-logistic dose-response curves were used to estimate the ED50, ED80, ED90 and GR50, GR80, and GR90. To calculate the average ED and GR and assess the intra-specific variability, an artificial resampling method was performed. Populations ALSPA 0364, 0365, 0469, 0470, 0471; SCPMU 0371, 0475, 0267; CYPDI 0013, 0431, 0432, 0433 appeared to be resistant to sulfonylureas, while a higher sensitivity to penoxsulam was observed, while populations ALSPA 0363, CYPDI 0223 and SCPMU 9719 proved to be cross-resistant. Regardless of species, ED90 of susceptible populations were below penoxsulam label dose (40 g ai ha−1) while they reached values higher than 320 g ai ha−1 for resistant populations. Average GR50 were generally lower than ED50. Sensitivity variability among susceptible populations is relatively low, allowing for discrimination between susceptible and resistant populations, and previously evolved resistance to sulfonylureas can influence sensitivity to penoxsulam.

Decay of Quinclorac in Acidic Paddy Soil and Risk Evaluation to the Subsequent Crop, Tobacco (Nicotiana tabacum L.).

Quinclorac is a selective herbicide commonly used in China to control monocotyledonous weeds in paddy fields. A field experiment was conducted to quantify the environmental behavior of quinclorac in acidic paddy soil under rice (Oryza sativa L.) field conditions, and to evaluate the risk of its residues to the subsequent crop of tobacco (Nicotiana tabacum L.). Rice was sprayed once with quinclorac 50% WP at 562.5, 375.0, or 187.5g a.i. ha-1 at 7 days after transplanting the seedlings. Decay of quinclorac in paddy field soil followed first-order kinetics, with a half-life of 28.29-30.27days. At harvest time, 0.090, 0.074 and 0.034mg kg-1 of quinclorac were found in soils following the above-described treatments, respectively. Leaves of the subsequent crop, tobacco, sown the year after the quinclorac treatments, exhibited different dose-dependent degrees of visible phytotoxicity symptoms.

Impact of Simulated California Rice-Growing Conditions on Chlorantraniliprole Partitioning.

Chlorantraniliprole (3-bromo-N-[4-chloro-2-methyl-6-(methylcarbamoyl)phenyl]-1-(3-chloro-2-pyridine-2-yl)-1H-pyrazole-5-carboxamide, CAP; water solubility 1.023 mg·L-1) was recently registered for application on California rice fields. Air- and soil-water partitioning of CAP were investigated under simulated California rice field conditions through calculation of KH and ΔawH and a batch equilibrium method following OECD 106 guidelines, respectively. KH and ΔawH were determined to be 1.69 × 10-16 - 2.81 × 10-15 atm·m3·mol-1 (15-35 °C) and 103.68 kJ·mol-1, respectively. Log(Koc) ranged from 2.59 to 2.96 across all soil and temperature treatments. Log(KF) ranged from 0.61 to 1.14 across all soil, temperature, and salinity treatments. Temperature and salinity increased sorption significantly at 35 °C (P < 0.05) and 0.2 M (P < 0.0001), respectively, while soil properties impacted sorption across all treatments. Overall results, corroborated using the Pesticides in Flooded Applications Model, indicate that volatilization of CAP is not a major route of dissipation and sorption of CAP to California rice field soils is moderately weak and reversible.