Rice Ecosystem Research Articles

Viability of zooplankton resting eggs in rice field sediment after pesticide applications.

Many herbicide products are commonly used in agricultural areas to prevent and eliminate weeds. Contamination from these toxicants in water might affect aquatic organisms not only in the active stage, but also in the diapause stage. To test the effect of herbicide on the resting eggs of zooplankton, we prepared two rice fields: one field without the application of pesticides (RF-NPA) and one with the application of pesticides (RF-PA) in a sampling year. We conducted a hatching experiment for 30 days. Twenty-four taxa of zooplankton were found. Sixteen species of these were rotifers, seven species were cladocerans and one taxon was an unidentified nauplius copepod. The species richness of zooplankton between RF-NPA (17 taxa) and RF-PA (16 taxa) was close, but species compositions between RF-NPA and RF-PA were different, indicated by the similarity index of 0.545. Lecanidae was the most diverse family of rotifers in both rice fields with nine species, while Chydoridae was the most diverse family of cladocerans (four species). The total abundance of zooplankton of RF-NPA was higher than RF-PA with 1,897 and 1,286 individuals, respectively. The Shannon-Wiener diversity index (H´) and Pielou's evenness (J) in RF-NPA were higher than in RF-PA. The high species richness of zooplankton in both rice fields occurred on days 18 to 30. On the other hand, the highest abundance was recorded on day 18 for RF-NPA and on day 24 for RF-PA. The non-metric multidimensional scaling (NMDS) demonstrated significant differences in zooplankton community composition between RF-NPA and RF-PA (p < 0.05; ANOSIM test). According to the diversity indices, the RF-NPA has more diversity than the RF-PA, which might be a result of herbicide application in the sampling year. This study suggests that the toxicity of glyphosate should be a concern in terms of the biodiversity of rice field ecosystems.

Growth Performance of Photoperiod-Sensitive Rice (Oryza sativa L.) Varieties in Different Soil Types under Rainfed Condition in Cambodia

In Cambodia, rice is predominantly produced in areas with rainfed lowland conditions where photoperiod-sensitive varieties are cultivated. A number of varieties have been released for rainfed lowland areas, and the rice grain yield has reportedly increased by approximately 12% over the past ten years. Moreover, great fluctuations in yield performance have been observed across different soil types of the rainfed ecosystems of Cambodia. Therefore, the present study aimed to analyze the grain yield and stability among ten popular varieties that were released for rainfed lowland ecosystems across the four different soil types in Cambodia in two years. The grain yield varied 566 g m−2 as the highest in clay soil and about 220 g m−2 as the lowest in sandy soil. A combined ANOVA revealed significant differences for the main effect of genotype, environment, and genotype-by-environment interaction (GEI) for all yield-related traits and grain yield per square meter. The principal component test results showed that the heterogeneity of grain yield was mainly attributable to the effect of environment, followed by the effect of genotype. In fertile conditions, a higher percentage of filled grains was supported by higher leaf N until the late stage with a wider flag leaf. In conditions of moderate fertility, larger numbers of panicles were supported by a higher percentage of productive culms with higher leaf N until the late stage. In conditions of poor fertility, a higher percentage of filled grains was supported by higher leaf N until the late stage, which is considered to be important for higher grain yield. The variety Phka Rumduol showed these preferable traits and produced higher yields in fertile to poor natural soil fertility conditions with moderate variation. This variety is considered to be more desirable and ideal due to its stability and higher grain yield. The other varieties, namely, Phka Mealdei, Phka Rumdeng, and CAR4, were identified as above-average yielders. Therefore, those varieties potentially may be recommended for cultivation in rainfed lowland rice ecosystems in Cambodia due to their high yields. CAR4 showed moderate variation at the same level as Phka Rumduol. From the point of stability, Phka Rumduol and CAR4 can be expected to excel.

Critical weather limits for paddy rice under diverse ecosystems of India.

Rice yields are largely influenced by variability in weather. Here, we demonstrate the effect of weather variables viz., maximum and minimum temperatures, rainfall, morning and evening relative humidity, bright sunshine hours on the yield of rice cv. Swarna, grown across five rice ecologies of India through field experiments during kharif (wet) season (Jun-Sept.). Critical thresholds of weather elements were identified for achieving above average, average and below average yield for each ecology. The investigation could determine how different weather elements individually and collectively affect rice yield in different rice ecosystems of India. While a sudden increase in minimum temperature by 8-10 °C (> 30 °C) during reproductive period resulted in 40-50 per cent yield reduction at Mohanpur, a sudden decrease (< 20 °C) caused yield decline at Dapoli. The higher yields may be attributed to a significant difference in bright sunshine hours between reproductive phases of above-average and below-average yield years (ranging from 2.8 to 7.8 hours during P5 stages and 1.7 to 5.1 during P4 stages). Rice cultivar Swarna performed differently at various sowing dates in a location as well as across locations (6650 kg ha-1 at Dapoli to 1101 kg ha-1 at Samastipur). It was also found that across all locations, the above average yield could be associated with higher range of maximum temperature compared to that of below average yield. Principal component analysis explained 77 per cent of cumulative variance among the variables at first growth stage, whereas 70 per cent at second growth stage followed by 74 per cent and 66 per cent at subsequent growth stages. We found that coastal locations, in contrast to inland ones, could maximize the yield potential of the cultivar Swarna, due to the longer duration of days between panicle initiation to physiological maturity. We anticipate that the location-specific thresholds of weather factors will encourage rice production techniques that are climate resilient.

Biochar amendment reassembles microbial community in a long-term phosphorus fertilization paddy soil.

This study investigates the effect of biochar amendment on microbial community structure and soil nutrient status in paddy soil that has been fertilized for an extended period of time, shedding light on sustainable agricultural practices. A 90-day incubation period revealed that biochar amendment, as opposed to long-term fertilization, significantly influenced the physicochemical properties and microbial composition of the soil. The microcosm experiment conducted using six treatments analyzed soil samples from a long-term rice ecosystem. We employed microbial biomarkers (phospholipid fatty acids, PLFAs; isoprenoid and branched glycerol dialkyl glycerol tetraethers, iGDGTs and brGDGTs; DNA) to assess microbial biomass and community structure. Biochar addition led to a decrease in PLFA biomass (15-32%) and archaeal iGDGT abundance (14-43%), while enhancing bacterial brGDGT abundance by 15-77%. Intact biochar increased archaeal and bacterial diversity, though fungal diversity remained unchanged. However, acid-washed biochar did not result in a uniform microbial diversity response. The abundance of various microbial taxa was changed by biochar amendment, including Crenarchaeota, Proteobacteria, Nitrospira, Basidiomycota, Halobacterota, Chloroflexi, Planctomycetota, and Ascomycota. Soil NH4+-N was found as the primary environmental factor impacting the composition of archaea, bacteria, and fungus in this study. These findings imply that the addition of biochar has a quick influence on the structure and activity of microbial communities, with fungi possibly having a critical role in acid paddy soil. This study contributes valuable knowledge for developing sustainable agricultural practices that promote healthy soil ecosystems. KEY POINTS: • Biochar type and phosphorus fertilization demonstrated an interactive effect on the diversity of archaea, but no such effect was observed for bacteria and fungi. • Soil fungi contribute to approximately 20% of the total phospholipid fatty acid (PLFA) content. • Biochar, especially acid-washed rice straw biochar, increases glucose metabolism in bacteria and archaea and decreases saprophytic fungi.

Organic Management Approaches of Stem Borer in Rice Ecosystem of Assam

Stem borer is the only insect pest which attacks the rice plant starting from tillering upto maturity stage and is of great challenge to manage due to its cryptic behavior and nocturnal habit. The experiment was laid out in the experimental field of AAU-Assam Rice Research Institute, Assam Agricultural University, Titabar both in kharif and rabi season during 2019-2022 taking three popular rice varieties of Assam, Ranjit, Ranjit Sub-1 and Gitesh. Seeds were treated with a solution of Pseudomonas florescense (10 g/liter of water /kg of seed for 12 hrs in organic and with Chlorantraniliprole 18.5 SC @ 30 g/a.i in chemical treatment and without treating the seeds in farmers’ practice plot and sown both in kharif season and rabi season. The foliar application of Beauveria bassiana (5gm/l/ha), Pseudomonas florescense (20g/l/ha) and neem product (5g/liter/ha) in organic plot and insecticide application with Chlorantraniliprole 18.5 SC @ 30 g/a.i. in the chemical plot was done at 45 days after transplanting (DAT) without application of any biopesticide or insecticide in farmers’ practice plot. The dead heart incidence drastically reduced both in chemical (6.19%) and organic treatment (7.23%) without significant difference at 65 DAT in Ranjit. The benefit cost ratio was 2.32 and 2.06 in chemical and organic approach respectively, but it was 1.78 in farmers’ practice. The use of B. bassiana, P. florescense and neem products were found to be safer to the predators as the spider and coccinellid beetle population in organic treatment (10.59 and 9.49 number/hill) was at par with farmers’ practice (12.83 and 11.67 number/hill), respectively.

Biochar Implementation in Rice Paddies for Addressing Greenhouse Gas Emissions and Nutrient Loss: A Review

Eco-challenges like greenhouse gas (GHG) emissions and nutrient depletion are key threats to the health of rice field ecosystems. Biochars (BCs) - porous, carbon-dense materials with substantial surface areas and an abundance of surface functional groups - are emerging as a viable solution for these issues, offering a way to increase rice production and address environmental concerns. Despite this potential, there is still a need for a comprehensive understanding of BCs' performance characteristics and their environmental interactions with rice paddy soils. The beneficial outcomes of using BCs, including enhanced rice growth and yield, decreased nutrient loss, and reduced GHG emissions. Factors like biomass type, pyrolysis temperature, and modification process significantly influence BCs' performance. The use of BCs can boost rice production while mitigating emissions of CO2, N2O, and CH4. They do this by improving soil properties, encouraging microbial diversity, supplying nutrients, and minimizing nutrient losses. However, the potential ecological hazards related to the use of BCs in rice paddies. These hazards include inconsistent research outcomes and the possibility of secondary pollution. Future research must address these challenges to ensure the sustainable application of BCs.

Mapping, temporal dynamics, and assessment of agricultural ecosystem services: evidence from eastern India

The study of ecosystem services (ES) has been gaining momentum for two main reasons-first to quantify the ES that the humans are enjoying; second, to incentivize the people or institutions that contribute to the improvement of ES. Agriculture, as the dominant form of land management, acts as both a provider and consumer of ES. The present study is an attempt to map the ecosystem services and assess the agricultural ecosystem services in the village landscape of eastern India. The study aims to understand the various ES, linkages, and trade-offs that have affected the welfare of households in an area of eastern India over time. We found that Jamujhari, the village investigated, had a diverse ecosystem that produced over 60 ecosystem goods, and provided over 200 ecosystem services to the villagers. Moreover, the village’s four ecosystems, viz., forest, water, grassland, and agricultural ecosystems, along with human resources, are integrated and interdependent. However, the ES and the dependence of households on nature’s services have undergone substantial changes over time. The valuation of agroecosystem services (paddy and fallow land ecosystems) was done using the benefit transfer method. The value of the ES for the rice ecosystem was estimated to be US $ 37892.3 year-1, while under fallow land it was US$ 9667.8 year-1. resulting in a total value of US $ 47560.1 year-1 of total agroecosystem services. We suggest comprehensive research to develop context-specific tools to identify and measure ES. Further, we recommend an appropriate policy mix by considering synergies and trade-offs among different ES.

Distribution and population density of plant parasitic nematodes in Kallakurichi, Vedaranyam and Bargur blocks of Tamil Nadu

India contribute 9 per cent share in world production and one of the main vegetables grown in Tamil Nadu. Major production area of Tamil Nadu is Coimbatore, Dharmapuri, Salem and Krishnagiri districts. In India an average, a national loss of Rs. 21,068.73 millions has been estimated due to plant parasitic nematodes. An overall average annual yield loss in major horticultural crops due to nematodes goes upto 60% under protected cultivation. Protected cultivation is an emerging technology for raising vegetable and flower crops under controlled environmental condition and continuous growing of crops. Plant parasitic nematodes has emerged as a major problem, causing enormous yield loss. The maximum population of Pratylenchus spp in soil and root (300.54 and 275.50) were recorded in Veerasolapurammadur village, Kallakurichi block in sugarcane eco system and maximum lesion index 5.0 was recorded in same location and no incidence for root knot nematode was recorded. In Vaedharanyam block, The maximum population of Melodogyne graminicola in soil and root (300.25 and 325.65) were recorded in Neivellakku village, Vedharanyam block in rice eco system and maximum root knot index 5.0 was recorded in same location and no incidence for Aphelenchoides besseyi was recorded. In Barugur block ,The maximum population of lesion nematode, Radopholus similis in soil and root (450.20 and 410.25) were recorded in Santhur village, burgur block in banana eco system and maximum root lesion index 5.0 was recorded in same location and minimum population of root knot nematode (110.20 and 120.54) was recorded in Errapatty village of Burgur block.

Assessing Stakeholders’ Preferences for Future Rice Farming Practices in the Mekong Delta, Vietnam

Rice farming is the dominating agriculture activity in the Mekong Delta and has been of significant importance for the region’s economic development, but it has also had an impact on the environment. Recent governmental policies emphasize the need for sustainable and climate-resilient agriculture; however, policy reforms pushing for transformation towards sustainable socio-agricultural systems are compounded by a lack of coherent and shared visions. Gaps between policy making and implementation and stakeholders’ divergent visions of what is meant by sustainable agriculture and how that can be achieved hinder progress. To address this, the Q-methodology was used to elucidate and integrate different perspectives from 41 stakeholders on 35 statements related to agriculture developments in the Mekong Delta. Under the theoretical lens of sustainability, and ecosystem services, the results unveiled four major development schemes, namely production through intensification, sustainable intensification, production through nature, and people and nature in balance. The majority of the stakeholders in this study believed that future agriculture strategies in the Mekong Delta should be designed to promote more diverse and integrated farming methods, emphasizing the environmental and social dimensions of sustainable development. They acknowledged the multifunctional benefits of rice field ecosystems and emphasized the importance of supporting, regulating, and cultural ecosystem services for a long-term and healthy production of food and increased resilience of the Delta’s social-ecological systems.

Faunistic and diagnostics of predaceous spiders in rice ecosystem under Terai region of West Bengal

Aim: Analyzing the community structure of predatory spider fauna in rice ecosystems to facilitate conservation biological control and sustainable pest management programmes. Methodology: The spiders were collected from rice field with cultivated variety (MTU-7029) during both Kharif and Rabi seasons at different rice growth stages. The spiders collected by various sampling methods such as direct catch in polythene carry bags, ground collection and foliage collection were kept in collection bottles and killed by inserting a strip of cotton dipped in chloroform and transferred separately on a white sheet of paper. Thereafter, using a stereo zoom microscope (ZEISS Stemi 508), the spiders were sorted, separated, counted, identified based on the available keys and literature described by Tikader (1987) and Barrion and Litsinger (1995). The unidentified samples were sent to the Zoological Survey of India, Kolkata for authorized identification. Results: In total, sixteen different species of predatory spiders belonging to six families of order Araneae and representing four functional/foraging guilds were identified in the rice ecosystem of Sub-Himalayan Terai region of West Bengal. These included Lycosa pseudoannulata Boesenberg &amp; Strand and Arctosa tanakai Barrion &amp; Litsinger; Oxyopes lineatipes C.L. Koch, Oxyopes javanus Thorell and Oxyopes salticus Hentz; Bianor sp. and Hasarius adansoni Audouin, while the family Thomisidae was represented by a single species Thomisius sp. All these eight species constituted the non web former group of spiders. The web weaving spiders recorded were Tetragnatha maxillosa Thorell, Tetragnatha mandibulata Walckenaer. Tetragnatha javana Thorell, Leucage decorate Walckenaer, Leucage celesbesiana Walckenaer and Neoscona theisi Walckenaer, Neoscona mukerjei Tikader, Araneus sp. Interpretation: The lynx spiders (Oxyopidae) were found to be the most dominant group by individual numbers, followed by the wolf spiders (Lycosidae), however, considering the species richness, the long jawed spiders (Tetragnathidae) were in large number with five different species. Good agricultural practices along with habitat diversification of landscapes are imperative for enhancing the predation by rice field spiders. Key words: Dominance, Foraging guilds, Predatory spiders, Rice, Species richness, Terai region

First-hand Report of False Smut in Coastal Rice Ecosystem at Naira, Andhra Pradesh

First-hand Report of False Smut in Coastal Rice Ecosystem at Naira, Andhra Pradesh

Period of effective catching of insect pests and natural enemies in light traps

Light trap helps to protect natural enemies and manage destructive insect pests in rice farming ecosystem. Light trapping time at night is not identified, for organic farming in farmers level its essential to identified proper timing at night. The experimental light trap was set up at Sagordi rice farm, Bangladesh Rice Research Institute, Barishal, during T. Aman rice season in 2019-2020. The time of catching insects by light trap were divided in six different times in a night and defined as treatments (T1= 17.20 to 18.20, T2= 18.20 to 19.20, T3= 19.20 to 20.20, T4 =20.20 to 21.20, T5=21.20 to 22.20, T6= 22.20 to rest of night insects caught at light trap) in this study. Each treatment has had four replications. Yellow sticky trap used to catch and trapped insect and natural enemyRice insect pests and their natural enemies were counted and recorded manually. The caught of yellow stem borer increased and green leafhopper were decreased from treatment, T1 to treatment, T6. During dusk to first four hours, the percentage of caught was approximately 69.28% insect pests. Overall, the percentages of insect pests trapping were 89.65% and natural enemies were 10.35% during the experimental period. The ratio of destructive insect pests caught was highest compared to that of natural enemies in light trap of rice ecosystem.

Severity and distribution of bacterial leaf blight of rice in different rice growing ecosystems of Karnataka state of India

Bacterial leaf blight of rice caused by Xanthomonas oryzae pv. oryzae has posed a major threat to production-oriented farming in recent years. The yield losses caused by this pathogen are as high as 70 to 80 per cent based on the severity of the disease. A random survey was carried out in the major rice-growing ecosystem of Karnataka viz., Bhadra, Coastal, Hilly, Kaveri, Tunga Bhadra project (TBP) and Upper Krishna project (UKP) ecosystems of Karnataka during Kharif 2019. Among all the surveyed ecosystems, the highest mean per cent disease index (PDI) of 52.60 was observed in the Bhadra ecosystem, followed by 43.67 PDI in the TBP ecosystem, and the lowest PDI of 31.08 was observed under the Kaveri ecosystem. However, moderate disease severity in the range of 31.82 to 33.79 was observed under the UKP and Hilly ecosystems of Karnataka. Among the surveyed districts, the highest disease severity (62.04 PDI) was observed in Shivamogga, followed by Gadag (52.17 PDI) and Ballari (52.87 PDI) districts, and the least severity of 20.72 PDI was observed in Raichur district. However, there was no disease severity in the Coastal ecosystem of Karnataka. The disease was severe in commercial rice-growing regions compared to those where the traditional varieties were grown. The moderate rainfall areas like Bhadra and TBP ecosystem were more severely infected with BLB than the severe rainfall area like the coastal ecosystem. The present study has identified the risk-prone areas of BLB in different rice ecosystems of Karnataka.

Aquatic Hemiptera inhabiting rice fields in Karaikal, Puducherry, India

The present investigation was taken up to record the diversity and abundance of aquatic hemipterans in an irrigated rice ecosystem during kharif 2019 and rabi 2019–2020. The aquatic hemipterans were collected using a D-frame dip net at weekly intervals. This study revealed 21 species under 13 genera and nine families of Hemiptera in irrigated rice fields during kharif 2019 and rabi 2019–2020. Micronecta scutellaris (Stål, 1858) and Anisops sardeus Herrich-Schäffer, 1850 were the dominant species in both seasons. Corixidae and Notonectidae were the most abundant families. Species diversity was maximum in kharif 2019, while species richness was maximum during rabi 2019–2020. Multiple linear regression indicated that all the physicochemical characteristics and weather parameters together were responsible for significant variation in the occurrence of Corixidae (53.60%) and Notonectidae (82.40%). Based on our research, we found that rice fields serve as suitable habitats and play a crucial role in supporting diverse range of aquatic hemipterans.

Infestation by the Piercing-Sucking Herbivore Nilaparvata lugens Systemically Triggers JA- and SA-Dependent Defense Responses in Rice.

It has been well documented that an infestation of the piercing-sucking herbivore, brown planthopper (BPH), Nilaparvata lugens, activates strong local defenses in rice. However, whether a BPH infestation elicits systemic responses in rice remains largely unknown. In this study, we investigated BPH-induced systemic defenses by detecting the change in expression levels of 12 JA- and/or SA-signaling-responsive marker genes in different rice tissues upon a BPH attack. We found that an infestation of gravid BPH females on rice leaf sheaths significantly increased the local transcript level of all 12 marker genes tested except OsVSP, whose expression was induced only weakly at a later stage of the BPH infestation. Moreover, an infestation of gravid BPH females also systemically up-regulated the transcription levels of three JA-signaling-responsive genes (OsJAZ8, OsJAMyb, and OsPR3), one SA-signaling-responsive gene (OsWRKY62), and two JA- and SA- signaling-responsive genes (OsPR1a and OsPR10a). Our results demonstrate that an infestation of gravid BPH females systemically activates JA- and SA-dependent defenses in rice, which may in turn influence the composition and structure of the community in the rice ecosystem.

Soil and microbial C:N:P stoichiometries play vital roles in regulating P transformation in agricultural ecosystems: A review

Stoichiometry plays a crucial role in biogeochemical cycles and can modulate soil nutrient availability and functions. In agricultural ecosystems, phosphorus (P) fertilizers (organic or chemical) are often applied to achieve high crop yields. However, P is readily fixed by soil particles, leading to low P use efficiency. Therefore, understanding the role of carbon:nitrogen:P stoichiometries of soil and microorganisms in soil P transformation is of great significance for P management in agriculture. This paper provides a comprehensive review of the recent research on stoichiometry effect on soil P transformation in agricultural ecosystems. Soil microorganisms play an important role in the transformation of soil non-labile inorganic P to microbial biomass P by regulating microbial biomass stoichiometry. They also mobilize soil unavailable organic P into available P by changing ecoenzyme stoichiometry. Organic materials, such as manure and straw, play an important role in promoting the transformation of insoluble P into available P as well. Additionally, periphytic biofilms can reduce P loss from rice field ecosystems. Agricultural stoichiometries are different from those of natural ecosystems and thereby should receive more attention due to the influences of anthropogenic factors. Therefore, it is necessary to conduct further stoichiometry research on the soil biochemical mechanisms underlying P transformation in agricultural ecosystems. In conclusion, understanding stoichiometry impact on soil P transformation is crucial for P management in agricultural ecosystems.

Soil and Plant Enzymes Responses to Zinc Oxide Nanoparticles in Submerged Rice (Oryza sativa L.) Ecosystem

In the present study, the effects of zinc oxide nanoparticles (ZnO NPs) on rice (Oryza sativa L. cv. PB1509) plant growth were assessed in hydroponics (5, 10, 25, 50 mg L−1) and soil microcosm (5, 10, 25 50 mg kg−1) experiments. In both hydroponics and soil experiments, Zinc (Zn) accumulation in plant parts (roots, shoots and grains) was found to increase with increasing doses of ZnO NPs. Grains accumulated 29 mg kg−1 Zn at 50 mg kg−1 ZnO NPs in the soil experiment. In the hydroponics experiment, growth and photosynthetic pigments were induced by ZnO NPs up to 10 mg L−1, while higher doses of 25 and 50 mg L−1 were toxic to plant growth. Antioxidant enzyme activities (SOD, CAT, APX and GPX) were mostly increased or unaffected by all ZnO NPs doses. In soil experiments, acid and alkaline phosphatase activities were increased at 5 mg kg−1 followed by a declining trend. However, a significant decrease occurred only at 50 mg kg−1. Urease activity in soil was significantly increased at all doses of ZnO NPs, while the activity of dehydrogenase did not show any significant change up to 25 mg kg−1. The length of plants and photosynthetic pigments did not show much toxicity except root length beyond 10 mg kg−1; however, the biomass of plants including grains was significantly lower than control beyond 5 mg kg−1 dose. The activity of antioxidant enzymes (GPX, APX and CAT) showed a significant increase at all doses of ZnO NPs. The DTPA extractable Zn concentration in the soil was significantly elevated with increasing exposure concentrations of ZnO NPs. Based on hydroponics and soil experiments, this study suggests a dose of up to 10 mg L−1 or 10 mg kg−1 would be an appropriate dose for augmenting the growth of rice plants and Zn accumulation, and this can be practically utilized for rice plants growing in submerged conditions. HIGHLIGHTS Rice plants exposed to ZnO nanoparticles in hydroponics and soil Zinc accumulation increased significantly in roots, shoots and grains Lower dose of ZnO NPs (10 mg/L or mg/kg) augmented plant growth Antioxidant enzymes showed a significant increase in activity in ZnO NPs treatment GRAPHICAL ABSTRACT

Straw management effects on global warming potential and yield-scaled greenhouse gas emissions in a subtropical rice ecosystem

Global warming potential (GWP) of rice paddies depends on straw management. This study evaluated methane (CH4) and nitrous oxide (N2O) emissions and soil C stocks to determine GWP and yield-scaled GWP under different strategies and intensities of rice straw management in a subtropical climate. We hypothesized that decreasing soil management intensity and straw incorporation in the soil would reduce GWP. Methane fluxes were substantially higher during the rice growing season than in the off-season, while the opposite was observed [...]

Yield Evaluation of Upland Rice Varieties (Oryza sativa L.) in Several Levels of Soil Water Content

Production and productivity of upland rice is still very low due to limited water in the upland rice ecosystem. The objective of this study was to evaluate the yields of upland rice varieties at several levels of soil water content. The experiment was conducted at the Growth Centre LLDIKTI Wilayah I Medan from March to July 2013. This research used a factorial randomized block design with two factors and replicated three times. Five upland rice varieties as the first factor, namely Batutegi, Inpago 4, Limboto, Situbagendit, and Situpatenggang. Second factor was four levels of soil water content, namely: 80% of field capacity (FC), 60% of FC, 40% of FC, 20% of FC. The main effect of upland rice varieties and soil water content significantly affected (p&lt;0.05) the productive tiller number, percentage of empty and filled grain, the panicle length, 1000 grain weight, and weight grain per clumps. The interaction effect between upland rice varieties and soil water content showed significant interaction on the panicle length, 1000 grain weight, and weight grain per clumps. Situpatenggang variety showed the best yield characters like productive tiller number, percentage of empty and filled grain than the other four varieties. Combination treatment of Situpatenggang variety with 80% FC showed the highest panicle, 1000 grain weight, and weight grain per clumps. The smallest percentage decreased in grain yield per clumps due to decreased the level of soil water content was found in the Inpago 4 variety, so it can be recommended to plant Inpago 4 on soil which had low level of soil water content.

Weed management with Triafamone herbicide in transplanted rice ecosystem

Field experiments were conducted during Rabi 2018-19 (September to January) and Kharif 2019 (May to September). Medium duration rice cv. CO(R) 51 was used as a test variety at Tamil Nadu Agricultural University, Coimbatore, India to study the effect of Triafamone on broad spectrum weed control in transplanted rice. Triafamone was applied at two times. First set of treatments (30, 40,50 and 100 g/ha) applied two to three leaf stage of weeds and second set treatments imposed (30, 40,50 and 100 g/ha) at three days after transplanting of the rice crop. These treatments were compared with Pyrazosulfuron ethy 10% WP @ 15 g/ha, Pretilachlor 5% EC @ 750 g/ha, hand weeding @ 20 and 40 days after transplanting and unweeded control. The major grasses were Echinochloa crus-galli (L.) and E. colonum (L.) while the sedge weed included Cyperus nutans (L.). Among the broad leaved weeds Eclipta alba (L.) and Bergia ammanioides were the dominant species. In both the seasons of the study, lesser population of grass was recorded with the pre and early post emergence application of triafamone herbicide 40 g a.i. ha-1 (1.41 and 1.41 per m-2 at 28 and 42 DAA for both the seasons respectively) and it was closely followed by application of triafamone herbicide 50 g a.i. ha-1 and application of PE Pretilachlor at 0.75 kg a.i. ha-1 and EPOE Pyrazosulfuron ethyl at 15 g a.i. ha-1. The same trend was observed for broad leaved weeds and their weed dry weights. Application of triafamone herbicide at 40 g a.i. ha-1 as pre emergence and early post emergence application recorded highest weed control efficiency of 100, 97.7 and 99.6 % and 97.8% at 42 DAA during both years of experimentation and also resulted in higher grain yield (8052 and 8182 kg ha-1 during rabi 2018-19 and 9018, 9175 kg ha-1 during Kharif 2019). Further, it is noticed that, there was no residual toxicity of herbicide to the succeeding crops. Hence, application of Triafamone 40 g a.i. ha-1 either pre or early post emergence herbicide has higher productivity and no residues in transplanted rice ecosystem.&#x0D; Key words: Triafamone, efficacy, weeds and transplanted rice ecosystem