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Rice is a major grain crop in numerous countries. In lowland areas, high iron levels in the soil severely hinder its cultivation. The current study explored high-yielding and Fe-toxicity-tolerant irrigated lowland rice (340 lines) among a population derived from a cross between Suakoko 8 and Bao Thai in Edozighi and Ibadan, Nigeria. In contrast to Ibadan, the soils in Edozighi contain a significant amount of iron. For the stated purpose, we carried out a two-year experiment using an alpha lattice design. The data showed significant differences between genotypes for the days to heading, plant height, number of tillers per plant, number of panicles per plant, panicle length, and grain yield. The results revealed that multiple characteristics had both direct and indirect effects on cultivated rice yields. There was a direct and positive influence on the number of days in the 50% heading period (0.31), a direct and negative effect on plant height (−0.94), a direct and positive effect on tiller and panicle numbers, and a direct but negative effect on panicle length (−0.56). The leaf bronzing score was adversely correlated with yield, panicle length, and plant height, while it was positively correlated with the number of panicles, tillers, and days to heading. The findings showed significant changes in yield and yield characteristics between genotypes. Grain yields ranged from 283 to 11,700 kg/ha in the absence of iron in the soil, contrary to 0 to 8230 kg/ha in soil with iron toxicity, with losses estimated between 6 and 94%, demonstrating the resulting disaster. In contrast to the elite parents and varieties used in this study, the ten top genotypes exhibited smaller losses in yield. The authors strongly recommend using these lines for further studies as donors or releasing them in farmer fields in Africa. [ABSTRACT FROM AUTHOR]

The resilience of rice production to floods is a crucial aspect of agricultural development in flood-prone regions. However, little is known about the farming practices and challenges of rice farmers in two river basins in Tanzania: Lower-Rufiji and Kilombero, where rice is the main crop grown. This study aimed to investigate the experiences of farmers in these two rice-growing floodplains regarding the impact of floods on lowland rice production and farmer livelihoods, and the strategies they use to cope with floods. The study used a mixed-methods approach that involved household surveys, key informant interviews, and transect walks to collect data from 180 rice farmers and 14 experts and community leaders. The data analysis revealed that floods were the dominant stressor affecting rice production, occurring mostly during the long rainy season and experienced by all farmers in both locations. Floods not only caused significant crop losses, especially in Lower- Rufiji where farmers reported losing between 75 and 100% of their yield in cases of extreme floods, but also made it difficult to establish and manage crops, leading to crop land abandonment. Floods also affected the livelihoods of rice farmers by forcing them to abandon, rent, or sell their farms. Coexistence of floods with other biotic and abiotic stresses such as crop diseases and droughts also limited the use of short maturing high yielding rice varieties. Farmers have adopted on-farm strategies such as adjusting planting schedules, using different varieties of rice, changing to other crops or activities after the floods to cope with floods, but these practices face numerous challenges. The study recommends the development of early warning systems, breeding for flood-tolerant rice varieties, introgression of tolerance traits to multiple stresses and improving crop establishment methods to enhance the resilience of farmers to floods and other extreme climate events. [ABSTRACT FROM AUTHOR]

Alternate wetting and drying irrigation (AWD) has been shown to decrease water use and trace gas emissions from paddy fields. Whereas genotypic water use shows little variation, it has been shown that rice varieties differ in the magnitude of their methane emissions. Management and variety‐related emission factors have been proposed for modelling the impact of paddy production on climate change; however, the magnitude of a potential reduction in greenhouse gas emissions by changing varieties has not yet been fully assessed. AWD has been shown to affect genotypic yields and high‐yielding varieties suffer the greatest loss when grown under AWD. The highest yielding varieties may not have the highest methane emissions; thus, a potential yield loss could be compensated by a larger reduction in methane emissions. However, AWD can only be implemented under full control of irrigation water, leaving the rainy seasons with little scope to reduce methane emissions from paddy fields. Employing low‐emitting varieties during the rainy season may be an option to reduce methane emissions but may compromise farmers' income if such varieties perform less well than the current standard. Methane emissions and rice yields were determined in field trials over two consecutive winter/spring seasons with continuously flooded and AWD irrigation treatments for 20 lowland rice varieties in the Mekong Delta of Vietnam. Based on the results, this paper investigates the magnitude of methane savings through varietal choice for both AWD and continuous flooding in relation to genotypic yields and explores potential options for compensating farmers' mitigation efforts. [ABSTRACT FROM AUTHOR]

The limited Nitrogen availability in most Nigerian soils is why poor rice yields are observed. The cost of inorganic fertilizers, especially in the post-COVID-19 era, tends to increase. Systems of Rice Intensification (SRI) principles utilize integrated nutrient management systems for growing lowland rice in order to reduce the negative effects of climate change. This study focused on evaluating the effects of six different nutrient source combinations on the development of NERICA (New Rice for Africa) L-34 and ARICA (Advanced Rice Varieties for Africa) 3 in Abeokuta Nigeria, between the years of 2017 and 2019. The treatment arrangements were split-plot, randomized complete block design, and triple replication. The nutrient sources and varieties were allocated a subplot and the main plot. The data pertaining to rice yield and its constituent parts were subjected to a two-way Analysis of Variance. In 2017, NERICA L-34 outperformed ARICA 3 in terms of grain yield. The longest panicle, heaviest panicle, and largest grain yield in 2018 were generated by combining 25 kg N per hectare (inorganic) and 75 kg N per hectare (organic). The most grains per panicle were observed by combining 25 kg N per hectare (inorganic) and 75 kg N per hectare (organic). The study concluded that enhancing the 1000 grain-weight and grain yield of ARICA 3 and NERICA L-34 by combining 25 kg N per hectare (inorganic) and 75 kg N per hectare (organic) is advantageous. [ABSTRACT FROM AUTHOR]

Lowland rice flooding, while consuming considerable water, has adverse environmental effects, including releasing methane into the atmosphere, aggravating climate change. Several drawbacks can be attributed to water-saving alternatives, such as aerobic rice, whereas rice drip irrigation techniques have been evaluated primarily under aerobic conditions. This study investigated drip tape irrigation technique with different lateral spacings for transplanted rice in puddled paddy soil at the Rice Research Institute of Iran in Rasht over two years (2020 and 2021), compared to intermittent irrigation. In twelve isolated concrete basins, three treatments with lateral spacings of 40 (T40), 60 (T60), and 80 cm (T80), were compared with a fixed five-day period intermittent irrigation (INT). In 2020 and 2021, the INT treatment produced the highest grain yield (3814 and 4758 kg ha−1, respectively) and among drip tape treatments, T40 demonstrated the highest grain yield (3613 and 4020 kg ha−1, respectively), comparable with INT’s yield but with the highest sterile spikelets ratio. In contrast, T80 resulted in the lowest grain weight (2892 and 3653 kg ha−1, respectively) and yield characteristics values, while producing the highest weeds population. Drip tape irrigation significantly reduced water application by 27% and 36% in 2020 and 2021, respectively and T40 achieved the highest water productivity, at 0.68 kg m−3. The economic water productivity estimation of drip tape irrigation can range from 0.11 to 0.51 US$ m−3 in various scenarios, while that of intermittent irrigation remains at 0.25 US$ m−3.

Rice is a staple food source for the Indonesian population. Rice commodity is an agricultural commodity that has a high enough risk and poses a threat to the welfare of rice farmers. The Badak river village is one of the villages that has superior agricultural commodities in Mesuji Regency in the form of rice plants. This research aims to identify the sources of risk faced by farmers in Sungai Badak Village, Mesuji District, Mesuji Regency and analyze the magnitude of the risk impact. The results of the analysis showed that the main sources of risk during planting season 1 were Plant Pest Organisms (OPT) and plant diseases, while the main risk sources in planting season 2 were weather / climate factors. Meanwhile, using the Z-Score shows a risk probability of 30 percent in planting season 1 and 26 percent in planting season 2, while the analysis using the VaR method, the resulting risk impact in planting season 1 is IDR 3,646,801 per hectare, while the risk impact on planting season 2 amounting to IDR 4,030,634, - per hectare.

Rice is a major grain crop in numerous countries. In lowland areas, high iron levels in the soil severely hinder its cultivation. The current study explored high-yielding and Fe-toxicity-tolerant irrigated lowland rice (340 lines) among a population derived from a cross between Suakoko 8 and Bao Thai in Edozighi and Ibadan, Nigeria. In contrast to Ibadan, the soils in Edozighi contain a significant amount of iron. For the stated purpose, we carried out a two-year experiment using an alpha lattice design. The data showed significant differences between genotypes for the days to heading, plant height, number of tillers per plant, number of panicles per plant, panicle length, and grain yield. The results revealed that multiple characteristics had both direct and indirect effects on cultivated rice yields. There was a direct and positive influence on the number of days in the 50% heading period (0.31), a direct and negative effect on plant height (−0.94), a direct and positive effect on tiller and panicle numbers, and a direct but negative effect on panicle length (−0.56). The leaf bronzing score was adversely correlated with yield, panicle length, and plant height, while it was positively correlated with the number of panicles, tillers, and days to heading. The findings showed significant changes in yield and yield characteristics between genotypes. Grain yields ranged from 283 to 11,700 kg/ha in the absence of iron in the soil, contrary to 0 to 8230 kg/ha in soil with iron toxicity, with losses estimated between 6 and 94%, demonstrating the resulting disaster. In contrast to the elite parents and varieties used in this study, the ten top genotypes exhibited smaller losses in yield. The authors strongly recommend using these lines for further studies as donors or releasing them in farmer fields in Africa.

The resilience of rice production to floods is a crucial aspect of agricultural development in flood-prone regions. However, little is known about the farming practices and challenges of rice farmers in two river basins in Tanzania: Lower-Rufiji and Kilombero, where rice is the main crop grown. This study aimed to investigate the experiences of farmers in these two rice-growing floodplains regarding the impact of floods on lowland rice production and farmer livelihoods, and the strategies they use to cope with floods. The study used a mixed-methods approach that involved household surveys, key informant interviews, and transect walks to collect data from 180 rice farmers and 14 experts and community leaders. The data analysis revealed that floods were the dominant stressor affecting rice production, occurring mostly during the long rainy season and experienced by all farmers in both locations. Floods not only caused significant crop losses, especially in Lower-Rufiji where farmers reported losing between 75 and 100% of their yield in cases of extreme floods, but also made it difficult to establish and manage crops, leading to crop land abandonment. Floods also affected the livelihoods of rice farmers by forcing them to abandon, rent, or sell their farms. Coexistence of floods with other biotic and abiotic stresses such as crop diseases and droughts also limited the use of short maturing high yielding rice varieties. Farmers have adopted on-farm strategies such as adjusting planting schedules, using different varieties of rice, changing to other crops or activities after the floods to cope with floods, but these practices face numerous challenges. The study recommends the development of early warning systems, breeding for flood-tolerant rice varieties, introgression of tolerance traits to multiple stresses and improving crop establishment methods to enhance the resilience of farmers to floods and other extreme climate events.

This study aims to determine: (1) the effect of the nature of innovation, the nature of potential users, innovation decision-making, communication channels and PPL qualifications simultaneously on the speed of adoption of PTT innovations in the lowland rice SL-PTT program, and (2) the effect of the nature of innovation, the nature of potential users, innovation decision making, communication channels and PPL qualifications partially on the speed of adoption of PTT innovations in the lowland rice SL-PTT program. The research design used in this study is a quantitative research with a quantitative descriptive survey technique. The sampling method used was the census technique, meaning that 20 members of the farmer group working on lowland rice farming were taken as samples. To determine the effect of the independent variables, namely the influencing factors (nature of innovation, nature of prospective users, decision-making, communication/media channels and PPL qualifications) on the speed of adoption of the SLPTT program of lowland rice cultivation, a multiple linear regression model test was used. The results showed that: (1) The nature of innovation, the nature of potential users, innovation decision-making, communication channels and PPL qualifications simultaneously had a significant effect on the speed of adoption of PTT innovations in the lowland rice SL-PTT program, and (2) The nature of innovation, the nature of candidates users, innovation decision making, communication channels and PPL qualifications partially have a significant positive effect on the speed of adoption of PTT innovations in the lowland rice SL-PTT program. [ABSTRACT FROM AUTHOR]

Abstract. A field experiment was conducted in 2018 and 2019 in Lafia, Nigeria to determine the effects of single and tank-mix of seven selected herbicides (bispyribac-sodium; cyhalofop-butyl; penoxsulam; pendimenthalin; propanil; thiobencarb) and their mixtures in lowland rice (Oryza sativa L.). Rice grain yield following the single application of bispyribac-sodium post emergence (POST), cyhalofop-butyl POST and penoxsulam POST averaged 30% and 47% greater than the nontreated control in 2018 and 2019, respectively. The application of cyhalofop-butyl plus bispyribac-sodium or thiobencarb plus bispyribac-sodium POST reduced weed density over nontreated control, ranging 98 to 100% in 2018 compared to 88 – 91% reduction in weed density achieved with the application of cyhalofop-butyl alone and the sequential application of PRE pendimenthalin fb POST propanil. Bispyribac-sodium plus cyhalofop-butyl application resulted in the highest rice yield (5.13 and 5.60 t.ha−1) in 2018 and 2019, respectively. Mixtures of bispyribac–sodium with chyhalofop-butyl showed no injury on rice, whereas increased efficacy on weed control as compared with the single application of bispyribac–sodium. We recommend bispyribac-sodium and tank-mixed combination with cyhalofop-butyl to provide a broad spectrum of weed control in lowland rice system in Nigeria.

Rice stands as an important staple crop in Indonesia and Asia, prompting endeavors to enhance its production. One such technology, aimed at intensifying rice cultivation, involves optimizing plant density utilizing the "jajar legowo" system. This research was conducted within community rice fields located in Pasar Ambacang, Kuranji District, Padang City, West Sumatra, Indonesia, spanning from February 2020 to June 2020. The primary objective of this study was to assess the potential of the jajar legowo planting system, in conjunction with varying dosages of kieserite, to increase lowland rice yields. The study employed a two-factor experiment in a completely randomized design. The first factor is the jajar legowo types: A (25 cm x 12.5 cm x 50 cm) and B (25 cm x 25 cm x 50 cm). The second factor involved different kieserite dosages, comprising three levels (0, 150, 300 kg.ha-1). Each treatment combination was replicated four times. Our investigation unveiled that rice panicle length reached 27.20 cm under the influence of jajar legowo type A with a kieserite dosage of 150 kg.ha-1. Conversely, with the application of jajar legowo type B alongside a kieserite dose of 300 kg.ha-1, the rice panicle length increased to 27.88 cm. The highest yield was obtained with jajar legowo type A at a dose of 300 kg.ha-1, producing 5.35 tons.ha-1. It is recommended to implement the jajar legowo type A cropping pattern with the addition of 150 kg.ha-1 of kieserite, or jajar legowo type B with the addition of 300 kg.ha-1 of kieserite.

IN LOWLAND rice areas, the presence of barnyardgrass weed (Echinochloa crusgalli) is disadvantageous to Indonesian farmers and requires an initial assessment and identification of characteristics for management. Therefore, this study aimed to obtain the characteristics and similarities of barnyardgrass accessions from lowland rice fields based on the morphological characteristics of the seed. A descriptive-analytical method was used to determine the barnyardgrass characteristics of 45 accessions from nine sub-districts in Serdang Bedagai and one accession from Medan City (MDN), Indonesia, as a comparison. This study was conducted from May to August 2022 and the data were analyzed using one-way ANOVA, followed by Tukey's test at P<0.05. The hierarchical cluster and constellation plot were generated using Ward's method. The results showed that 45 accessions of barnyardgrass from lowland rice fields had sizes of upper glume, lower glume, upper lemma, flag leaf length, and flag leaf width ranging from 2.93 to 4.33mm, 1.45 to 1.96mm, 0.03 to 17.10mm, 22.77 to 45.40cm, and 0.53 to 1.13cm, respectively. Among all accessions, only PG4 accession was nearest (1.825) to MDN. Furthermore, there were five clusters with 13 accessions including SB4; PC1; PC5; PG3; PG4; BK1; BK3; BK5; PB1; PB2; TB2; TB1; and TT2, classified in the same cluster as MDN. This information is very important as an initial reference for farmers in the management of barnyardgrass weeds in their lowland rice fields. [ABSTRACT FROM AUTHOR]

Bulukumba Regency is one of the major rice-producing areas in South Sulawesi, Indonesia and has experienced frequent climate disasters over the past decade. Several downstream villages within the Bettu River irrigation area have been affected by the drought, culminating in reduced lowland rice production and increasing the vulnerability of farmers’ livelihoods. This study aims to evaluate the vulnerability of the livelihood system among rice farmers in the Bettu River irrigation area by classifying the area into two zones based on the distance from the main irrigation canal, namely the upstream area and downstream area. The livelihood vulnerability index (LVI) framework and livelihood vulnerability index-Intergovernmental Panel on Climate Change (LVI-IPCC) approach were applied by selecting geographic and socio-demographic indicators that affected the farmer households, including 8 major components and 26 sup-components. The data for LVI-IPCC estimation were collected by randomly selecting 132 households from villages in the two areas. The empirical results showed that farmers in the downstream area were more vulnerable to climate change than farmers in the upstream area. The major components causing the livelihood vulnerability of the downstream farmers were livelihood strategy, food, water, land, health, as well as natural disasters and climate variability. In particular, the sub-components of agricultural livelihood diversification, consistent water supply for farming, and drought events were important in the downstream area. Farmers in the upstream area were vulnerable to socio-demographic profile and social network components. The LVI-IPCC findings suggested that the government should prioritize farmers in the downstream area to develop resilience strategies, particularly by increasing irrigation infrastructure and the number of reservoirs and drilling holes. Furthermore, to increase their adaptive capacity in terms of diversification of agricultural livelihood systems, the government and donor agencies need to provide trainings on the development of home food industries for poor farmers and vulnerable households that were affected by disasters.

A field experiment was conducted in 2018 and 2019 in Lafia, Nigeria to determine the effects of single and tank-mix of seven selected herbicides (bispyribac-sodium; cyhalofop-butyl; penoxsulam; pendimenthalin; propanil; thiobencarb) and their mixtures in lowland rice (Oryza sativa L.). Rice grain yield following the single application of bispyribac-sodium post emergence (POST), cyhalofop-butyl POST and penoxsulam POST averaged 30% and 47% greater than the nontreated control in 2018 and 2019, respectively. The application of cyhalofop-butyl plus bispyribacsodium or thiobencarb plus bispyribac-sodium POST reduced weed density over nontreated control, ranging 98 to 100% in 2018 compared to 88 - 91% reduction in weed density achieved with the application of cyhalofop-butyl alone and the sequential application of PRE pendimenthalin fb POST propanil. Bispyribac-sodium plus cyhalofopbutyl application resulted in the highest rice yield (5.13 and 5.60 t.ha-1) in 2018 and 2019, respectively. Mixtures of bispyribac--sodium with chyhalofop-butyl showed no injury on rice, whereas increased efficacy on weed control as compared with the single application of bispyribac--sodium. We recommend bispyribac-sodium and tank-mixed combination with cyhalofop-butyl to provide a broad spectrum of weed control in lowland rice system in Nigeria. [ABSTRACT FROM AUTHOR]

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Grain yield is a complex trait that is determined by direct and indirect traits. To improve grain yield, it is important to determine the relationships between these traits. To further explain the source-sink concept, fifteen genotypes were evaluated to explore not only the variation and association of primary and secondary traits of the main crop but also of the ratoon crop. Aboveground parts are cut at harvest leaving only stubbles and roots as sources of assimilates for the growth and development of ratoon crops. Results of this study indicated significant interactions in the grain yield and dry matter production between the main crop and ratoon crop with opposing tendencies of associations. This information is very useful in developing varieties with the breeding objective of increasing the grain yield potential of the ratoon crop. This may include advancing the grain partitioning in ratoon rice since the low grain yield of the ratoon crop was not the result of limited biomass production but rather a poor translocation and partitioning of assimilates into grains. The ratoon crop yield potential of genotypes identified with good ratooning ability in this study ranged from 1.8-2.4 tons/ha. Halay Palawan, Cuevas, and NSIC Rc216 were identified to have significantly higher ratoon grain yield than the other genotypes evaluated. However, NSIC Rc216, NSIC Rc222, and NSIC Rc480 were the best genotypes if the selection criteria should include shorter crop growth duration. If cultivars with good ratooning ability have similar crop duration and yield potential with the long-maturing varieties, the use of long-maturing varieties may be more practical in taking advantage of the residual water in areas with moisture and climate limitations instead of increasing crop intensity using ratoon strategy. [ABSTRACT FROM AUTHOR]

The yield of irrigated paddy rice in Sri Agung Village has decreased. In the last four years, the increase in the addition of input units (fertilizers) has not been followed by an increase in economic yields. This study aims to analyze the effect of organic fertilizers on soil fertility, such as pH, total N, organic C, available P and available K. The research was conducted in the rice fields of Sri Agung Village. Batang Asam area, West Tanjung Jabung Regency - Jambi. The research was conducted from April to September 2020. The study used a randomized block design with six treatments and five replications. The treatments tried were: Recommended Fertilizer (R), five types of organic fertilizer with a dose of 10 t ha-1 each, namely, Petroganik+R ( P1), Compost Solid Decanter + R (P2), Chicken Manure + R (P3 ), Cow Manure +R (P4) and Industrial Waste Compost + R (P5). The results showed that organic fertilizers significantly increased available K content of paddy soil but they did not significantly increase soil pH, total N, organic C and available P. The highest yield of dry milled grain (7.52 t ha-1) was obtained at +R (P1) Petroganic treatment.

Rice (Oryza sativa L.) production is globally impacted by salinity stress, since it is a salt-sensitive plant species. This study aimed to determine the effect of exogenous trehalose to reduce the salinity stress at the tillering stage in three lowland rice varieties: Chai Nat 1 (CNT1), Pathum Thani 1 (PT1) and Inpari 35 (IN35). Salinity stress was induced by watering the plants with four concentrations (0, 50, 100 and 150 mM) of sodium chloride (NaCl). Thereafter, exogenous trehalose with the same concentration was applied through foliar spray to reduce the salinity stress. The induced salinity in the rice plants affected various physiological parameters, such as relative water content, chlorophyll content and chlorophyll a/b ratio. Salinity also affected the levels of soluble sugar, starch content and other eight agronomic traits. At the concentration of 50 mM, the impact of trehalose was significantly observed on the physiological, biochemical and other agronomic traits of the plant. However, the 100-grain weight of the rice did not improve with the use of trehalose, what may have been influenced by the duration of the trehalose exposure during the tillering stage. The physiological, biochemical (excluding starch content) and agronomical traits of the rice plants also varied with the varieties. The salt-tolerant variety (IN35) showed a higher content of relative water (12.98 %), chlorophyll (8.33 %), soluble sugars (12.25 %), reproductive tillers per plant (12.4 %), grains per panicle (18.81 %), 100-grain weight (10.71 %), percentage of filled grains per panicle (22.39 %) and grain yield per plant (23.49 %), in comparison to CNT1 and PT1.

This study aimed to determine the ratooning ability of lowland rice to production management practices. It assessed the profitability of rice ratooning to the abovementioned objectives. The experiment was set out in a split-plot organized in a Randomized Complete Block Design with production management practices as the main plot and cutting heights of ratoon crop as the subplot treatment. Production management practices notably affected all agronomic characteristics, yield, and yield component parameters evaluated except the grain yield. Cutting height remarkably influenced all growth and yield parameters tested except panicle weight. Economic analysis revealed that the improved method achieved a higher gross margin (PHP21,321.60) than the farmer’s practice (PHP15,419.40) because of the former’s high productivity (1.64 t ha-1). A cutting height of 45.0 cm under the improved method obtained the highest gross margin (PHP28,677.00). Moreso, this approach is considered a good measure in adapting to the problematic scenario relative to climate change.

Rice is still a strategic commodity in the economy and national food security. Improvement efforts to rice production can be impelemented and one of them is through the intensification of rice plants. The aim of this study was to analyze the contribution and trend of rice production in development areas to rice production in South Sulawesi. This study uses secondary time series data for rice production in South Sulawesi and central areas for a period of 15 years (2004 - 2018). For development areas in South Sulawesi, there are 12 regencies : Selayar, Sinjai, Bulukumba, Bantaeng, Jeneponto, Takalar, Gowa, Maros, Pangkep, Barru, Enrekang and Tator. Descriptive and quantitative methods and analyzes were used to determine the contribution and trend of rice production in development areas to rice production in South Sulawesi. For the analysis of rice production trends in the development area of South Sulawesi is the least square method. The results of the research on the contribution of development area rice production to South Sulawesi rice production for 15 years (2004 - 2018) showed an increase. The trend of rice production in the development area of South Sulawesi has increased with the assumption that the current situation is the same as that in the future.

Reducing methane emissions and water use is critical for combating climate change and declining aquifers on food production. Reductions in irrigation water use and methane emissions are known benefits of practicing alternate wetting and drying (AWD) over continuous flooding (CF) water management in lowland rice (Oryza sativa L.) production systems. In a two-year (2020 and 2021) study, methane emissions from large farm-scale (∼50 ha) rice fields managed under CF and AWD in soils dominated by Sharkey clay (Sharkey clay, clay over loamy, montmorillonitic non-acid, thermic Vertic halauepet) were monitored using the eddy covariance method (EC). In the EC system, an open-path laser gas analyzer was used to monitor air methane gas density in the constant flux layer of the atmosphere over the rice-crop canopies. Total water pumped into the field for floodwater management was higher in CF compared to AWD by 24 and 14% in 2020 and 2021, respectively. Considerable variations between seasons in the amount of methane emitted from the CF and AWD treatments were observed: CF emitted 29 and 75 kg ha−1 and AWD emitted 14 and 34 kg ha−1 methane in 2020 and 2021, respectively. Notwithstanding, the extent of reduction in methane emissions due to AWD over CF was similar for each crop season (52% in 2020 and 55% in 2021). Rice grain yield harvested differed by only ±2% between AWD and CF. This investigation of large-scale system-level evaluation, using the EC method, confirmed that by practicing AWD floodwater management in rice, water pumped from aquifers could be reduced by about a quarter and methane emissions from rice fields could be cut down by about half without affecting grain yields, thereby promoting sustainable water management and greenhouse gas emission reduction during rice production in the Lower Mississippi Delta.

𝘐𝘯𝘵𝘳𝘰𝘥𝘶𝘤𝘵𝘪𝘰𝘯: 𝘊𝘩𝘢𝘯𝘨𝘦𝘴 𝘪𝘯 𝘭𝘢𝘯𝘥 𝘧𝘶𝘯𝘤𝘵𝘪𝘰𝘯, 𝘦𝘪𝘵𝘩𝘦𝘳 𝘱𝘢𝘳𝘵𝘪𝘢𝘭𝘭𝘺 𝘰𝘳 𝘤𝘰𝘮𝘱𝘭𝘦𝘵𝘦𝘭𝘺 𝘧𝘳𝘰𝘮 𝘪𝘵𝘴 𝘰𝘳𝘪𝘨𝘪𝘯𝘢𝘭 𝘧𝘶𝘯𝘤𝘵𝘪𝘰𝘯, 𝘢𝘳𝘦 𝘪𝘯𝘵𝘦𝘳𝘱𝘳𝘦𝘵𝘦𝘥 𝘢𝘴 𝘭𝘢𝘯𝘥 𝘶𝘴𝘦 𝘤𝘩𝘢𝘯𝘨𝘦𝘴. 𝘏𝘪𝘨𝘩 𝘥𝘦𝘮𝘢𝘯𝘥 𝘧𝘳𝘰𝘮 𝘱𝘳𝘰𝘥𝘶𝘤𝘦𝘳𝘴 𝘰𝘳 𝘤𝘰𝘯𝘴𝘶𝘮𝘦𝘳𝘴 𝘧𝘰𝘳 𝘧𝘳𝘶𝘪𝘵 𝘱𝘭𝘢𝘯𝘵 𝘴𝘦𝘦𝘥𝘴 𝘩𝘢𝘴 𝘭𝘦𝘥 𝘮𝘢𝘯𝘺 𝘧𝘢𝘳𝘮𝘦𝘳𝘴 𝘵𝘰 𝘱𝘳𝘰𝘥𝘶𝘤𝘦 𝘭𝘢𝘳𝘨𝘦 𝘲𝘶𝘢𝘯𝘵𝘪𝘵𝘪𝘦𝘴 𝘰𝘧 𝘧𝘳𝘶𝘪𝘵 𝘱𝘭𝘢𝘯𝘵 𝘴𝘦𝘦𝘥𝘴. 𝘛𝘩𝘦𝘳𝘦𝘧𝘰𝘳𝘦, 𝘪𝘳𝘳𝘪𝘨𝘢𝘵𝘦𝘥 𝘳𝘪𝘤𝘦 𝘧𝘪𝘦𝘭𝘥𝘴 𝘸𝘩𝘪𝘤𝘩 𝘢𝘳𝘦 𝘨𝘦𝘯𝘦𝘳𝘢𝘭𝘭𝘺 𝘱𝘭𝘢𝘯𝘵𝘦𝘥 𝘸𝘪𝘵𝘩 𝘧𝘰𝘰𝘥 𝘤𝘳𝘰𝘱𝘴 𝘩𝘢𝘷𝘦 𝘣𝘦𝘦𝘯 𝘤𝘰𝘯𝘷𝘦𝘳𝘵𝘦𝘥 𝘵𝘰 𝘧𝘶𝘯𝘤𝘵𝘪𝘰𝘯. 𝘛𝘩𝘦 𝘳𝘦𝘴𝘦𝘢𝘳𝘤𝘩 𝘰𝘣𝘫𝘦𝘤𝘵𝘪𝘷𝘦𝘴: (1) 𝘵𝘰 𝘥𝘦𝘵𝘦𝘳𝘮𝘪𝘯𝘦 𝘵𝘩𝘦 𝘪𝘯𝘤𝘰𝘮𝘦 𝘰𝘧 𝘭𝘰𝘸𝘭𝘢𝘯𝘥 𝘳𝘪𝘤𝘦 𝘧𝘢𝘳𝘮𝘪𝘯𝘨 𝘢𝘯𝘥 𝘧𝘳𝘶𝘪𝘵 𝘴𝘦𝘦𝘥𝘭𝘪𝘯𝘨 𝘣𝘶𝘴𝘪𝘯𝘦𝘴𝘴, (2) 𝘵𝘰 𝘧𝘪𝘯𝘥 𝘰𝘶𝘵 𝘸𝘩𝘢𝘵 𝘧𝘢𝘤𝘵𝘰𝘳𝘴 𝘪𝘯𝘧𝘭𝘶𝘦𝘯𝘤𝘦 𝘧𝘢𝘳𝘮𝘦𝘳𝘴' 𝘥𝘦𝘤𝘪𝘴𝘪𝘰𝘯𝘴 𝘪𝘯 𝘤𝘩𝘢𝘯𝘨𝘪𝘯𝘨 𝘵𝘩𝘦 𝘧𝘶𝘯𝘤𝘵𝘪𝘰𝘯 𝘰𝘧 𝘭𝘢𝘯𝘥 𝘧𝘳𝘰𝘮 𝘳𝘪𝘤𝘦 𝘧𝘪𝘦𝘭𝘥𝘴 𝘵𝘰 𝘯𝘶𝘳𝘴𝘦𝘳𝘪𝘦𝘴 𝘧𝘰𝘳 𝘧𝘳𝘶𝘪𝘵 𝘵𝘳𝘦𝘦𝘴. 𝘔𝘦𝘵𝘩𝘰𝘥: 𝘛𝘩𝘦 𝘮𝘦𝘵𝘩𝘰𝘥 𝘶𝘴𝘦𝘥 𝘪𝘴 𝘢 𝘴𝘶𝘳𝘷𝘦𝘺. 𝘛𝘩𝘦 𝘴𝘢𝘮𝘱𝘭𝘦 𝘤𝘰𝘯𝘴𝘪𝘴𝘵𝘦𝘥 𝘰𝘧 104 𝘧𝘢𝘳𝘮𝘦𝘳𝘴 𝘤𝘰𝘯𝘴𝘪𝘴𝘵𝘪𝘯𝘨 𝘰𝘧 38 𝘧𝘢𝘳𝘮𝘦𝘳𝘴 𝘢𝘯𝘥 66 𝘳𝘪𝘤𝘦 𝘴𝘦𝘦𝘥 𝘧𝘢𝘳𝘮𝘦𝘳𝘴 𝘴𝘦𝘭𝘦𝘤𝘵𝘦𝘥 𝘣𝘺 𝘴𝘪𝘮𝘱𝘭𝘦 𝘳𝘢𝘯𝘥𝘰𝘮 𝘴𝘢𝘮𝘱𝘭𝘪𝘯𝘨 𝘮𝘦𝘵𝘩𝘰𝘥. 𝘋𝘢𝘵𝘢 𝘢𝘯𝘢𝘭𝘺𝘴𝘪𝘴: (1) 𝘪𝘯𝘤𝘰𝘮𝘦 𝘢𝘯𝘢𝘭𝘺𝘴𝘪𝘴 𝘢𝘯𝘥 𝘙/𝘊 𝘳𝘢𝘵𝘪𝘰, (2) 𝘭𝘰𝘨𝘪𝘴𝘵𝘪𝘤 𝘳𝘦𝘨𝘳𝘦𝘴𝘴𝘪𝘰𝘯 𝘢𝘯𝘢𝘭𝘺𝘴𝘪𝘴. 𝘙𝘦𝘴𝘶𝘭𝘵𝘴: (1) 𝘛𝘩𝘦 𝘪𝘯𝘤𝘰𝘮𝘦 𝘰𝘧 𝘧𝘳𝘶𝘪𝘵 𝘤𝘳𝘰𝘱 𝘯𝘶𝘳𝘴𝘦𝘳𝘪𝘦𝘴 𝘪𝘴 𝘙𝘱. 36.214.234,21 (𝘙/𝘊 𝘳𝘢𝘵𝘪𝘰 2,25) 𝘢𝘯𝘥 𝘪𝘯𝘤𝘰𝘮𝘦 𝘧𝘰𝘳 𝘭𝘰𝘸𝘭𝘢𝘯𝘥 𝘳𝘪𝘤𝘦 𝘪𝘴 𝘙𝘱. 6.746.722,00 (𝘙/𝘊 𝘳𝘢𝘵𝘪𝘰 2,07)., 𝘢𝘯𝘥 (2 ) 𝘓𝘰𝘨𝘪𝘴𝘵𝘪𝘤 𝘳𝘦𝘨𝘳𝘦𝘴𝘴𝘪𝘰𝘯 𝘳𝘦𝘴𝘶𝘭𝘵𝘴: 𝘵𝘩𝘦 𝘷𝘢𝘳𝘪𝘢𝘣𝘭𝘦𝘴 𝘰𝘧 𝘢𝘨𝘦, 𝘭𝘢𝘯𝘥 𝘢𝘳𝘦𝘢, 𝘪𝘯𝘤𝘰𝘮𝘦 𝘢𝘯𝘥 𝘪𝘳𝘳𝘪𝘨𝘢𝘵𝘪𝘰𝘯 𝘸𝘢𝘵𝘦𝘳 𝘤𝘰𝘯𝘴𝘵𝘳𝘢𝘪𝘯𝘵𝘴 𝘩𝘢𝘷𝘦 𝘢 𝘴𝘪𝘨𝘯𝘪𝘧𝘪𝘤𝘢𝘯𝘵 𝘪𝘯𝘧𝘭𝘶𝘦𝘯𝘤𝘦 𝘰𝘯 𝘧𝘢𝘳𝘮𝘦𝘳𝘴' 𝘥𝘦𝘤𝘪𝘴𝘪𝘰𝘯𝘴 𝘵𝘰 𝘤𝘩𝘢𝘯𝘨𝘦 𝘵𝘩𝘦 𝘧𝘶𝘯𝘤𝘵𝘪𝘰𝘯 𝘰𝘧 𝘳𝘪𝘤𝘦 𝘧𝘪𝘦𝘭𝘥𝘴 𝘵𝘰 𝘧𝘳𝘶𝘪𝘵 𝘯𝘶𝘳𝘴𝘦𝘳𝘪𝘦𝘴. 𝘊𝘰𝘯𝘤𝘭𝘶𝘴𝘪𝘰𝘯: 𝘛𝘩𝘦 𝘪𝘯𝘤𝘰𝘮𝘦 𝘰𝘧 𝘧𝘳𝘶𝘪𝘵 𝘯𝘶𝘳𝘴𝘦𝘳𝘪𝘦𝘴 𝘪𝘴 𝘮𝘰𝘳𝘦 𝘱𝘳𝘰𝘧𝘪𝘵𝘢𝘣𝘭𝘦 𝘵𝘩𝘢𝘯 𝘭𝘰𝘸𝘭𝘢𝘯𝘥 𝘳𝘪𝘤𝘦 𝘧𝘢𝘳𝘮𝘪𝘯𝘨 𝘴𝘰 𝘵𝘩𝘢𝘵 𝘵𝘩𝘦 𝘷𝘢𝘳𝘪𝘢𝘣𝘭𝘦𝘴 𝘰𝘧 𝘪𝘯𝘤𝘰𝘮𝘦 𝘢𝘯𝘥 𝘢𝘨𝘦, 𝘭𝘢𝘯𝘥 𝘢𝘳𝘦𝘢, 𝘢𝘪𝘳 𝘤𝘰𝘯𝘴𝘵𝘳𝘢𝘪𝘯𝘵𝘴 𝘩𝘢𝘷𝘦 𝘢 𝘴𝘪𝘨𝘯𝘪𝘧𝘪𝘤𝘢𝘯𝘵 𝘦𝘧𝘧𝘦𝘤𝘵 𝘰𝘯 𝘧𝘢𝘳𝘮𝘦𝘳𝘴' 𝘥𝘦𝘤𝘪𝘴𝘪𝘰𝘯𝘴 𝘵𝘰 𝘤𝘩𝘢𝘯𝘨𝘦 𝘵𝘩𝘦 𝘧𝘶𝘯𝘤𝘵𝘪𝘰𝘯 𝘰𝘧 𝘳𝘪𝘤𝘦 𝘧𝘪𝘦𝘭𝘥𝘴 𝘪𝘯𝘵𝘰 𝘧𝘳𝘶𝘪𝘵 𝘯𝘶𝘳𝘴𝘦𝘳𝘪𝘦𝘴.

Farmer groups have an important role in agricultural activities, such as learning classes and vehicles for cooperation and production units. However, in practice there are still some obstacles, such as the infrequency of farmer groups to carry out farming activities and carry out farming activities together. The purpose of this study was to analyze the performance of rice farming, process innovation, the effectiveness of the farmer groups role ant its role on the performance of rice farming directly and through process innovation. The data sources used are primary processed descriptively qualitatively and quantitatively using the SEM-PLS approach. The results of the analysis show that the performance of rice farming, process innovation is in the high category and the effectiveness of the role of farmer groups is in the effective category. Analysis of the influence of the effectiveness of farmer groups on the performance of rice farming yielded negative results but not significant. While the indirect effect states that the role of farmer groups has a positive and significant effect on the performance of rice farming through process innovation. Based on a comparison of direct and indirect effects, process innovation is the biggest contributor to improve the performance of rice farming. With these results, farmer groups must still be able to improve the realization of their role so that farmers as members of farmer groups can still improve farming performance and farmer groups must be more active in overcoming various farming problems.

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Farmers in Indonesia are beginning to understand the importance of biofertilizers with standardized quality and effectiveness required by the Indonesian Ministry of Agriculture. So that many biological fertilizers circulating in the market need to be researched to test their quality and effectiveness. The purpose of this study was to test the quality and effectiveness, as well as farm business analysis of liquid biological fertilizers on lowland rice (Oryza sativa). The treatments were arranged in 5 levels of fertilization, namely: without application of fertilizer or control (P0), 1.00 dose of NPK (P1), 1.00 dose of NPK + 1.00 dose of biological fertilizer (P2), 0.75 dose of NPK + 1.00 dose of biological fertilizer (P3), 0.50 dose NPK + 1.00 dose of biofertilizer (P4). The experiment was carried out with 4 replications so that there were 20 experimental units. Each experimental unit is a plot of land with an area of 25 m2 . The results showed that the quality test met the criteria of Ministry of Agriculture No. 1 of 2019, also the application of biological fertilizers in the field in general resulted in the growth and yield of lowland rice plants that were the same as the comparison, and better than the control treatment. The treatment of 0.75 doses of NPK + 1.00 doses of biological fertilizers is the most effective and beneficial treatment agronomically with an RAE value of 100%, and economically with an R/C value of 1.83. [ABSTRACT FROM AUTHOR]

Methane is a major greenhouse gas that contributes to climate change. Methanogen and methanotrophic group microbes play a role in methane emissions in lowland rice fields. Methane is produced by methanogenic bacteria that decompose organic matter in anaerobic conditions. These bacteria will be active if the soil is inundated for an extended period of time. Some of this methane will be oxidized by methanotrophic bacteria in the rhizosphere. The researchers aimed to isolate, screen, and characterize methane-utilizing bacteria in lowland rice sediment from several Indonesian provinces. 27 methane- utilizing bacteria were isolated from rice field sediments in Lampung, West Java, and East Nusa Tenggara Province. Six of them had the potential to reduce methane emissions by more than half. A pmoA-like gene could be found in all of the selected isolates. The bacterial isolates were identified as Mycobacterium senegalense, Bacillus marisflavi, Bacillus methylotrophicus, Flavobacterium tirrenicum, Providencia stuartii, and Rhizobium rhizoryzae after characterization and identification with the Biolog OmniLog® ID system. These were all capable of nitrogen fixation, phosphorus solubilization, and IAA production. These isolates have the potential to be used as biofertilizers and methane mitigation agen [ABSTRACT FROM AUTHOR]

Rice grain yields in irrigated areas of Agusan del Norte/Sur provinces ranged at only 3.3–3.8 t/ha in 2010–2019 – hence the need to study the yield potential of varieties, appropriate water management, and optimum fertilizer rates to improve such yields. This study assessed the effects of rice varieties, water management, and fertilizer rates on grain yield and agronomic parameters. It also recommended variety, water management, and fertilizer rate for improving grain yields in Agusan soil. Screenhouse experiment was done using lowland rice soils collected from Remedios T. Romualdez, Agusan del Norte, Philippines. The experiment was laid out in unbalanced randomized complete block design with three factors: [1] PSB Rc 18, NSIC Rc 122, and PSB Rc 82 for the variety factor; [2] continuous submergence (CS) and alternate wetting and drying (AWD) for the water management factor; and [3] PalayCheck (PFR) and farmers’ fertilizer rates (FFR) for the fertilizer rate factor. Three replications each for PSB Rc 18+CS+PFR, PSB Rc 18+CS+FFR, PSB Rc 18+AWD+FFR, NSIC Rc 122+CS+FFR, NSIC Rc 122+AWD+FFR, PSB Rc 82+CS+PFR, PSB Rc 82+CS+FFR, and PSB Rc 82+AWD+FFR plus four replications each for PSB Rc 18+AWD+PFR, NSIC Rc 122+CS+PFR, NSIC Rc 122+AWD+PFR, and PSB Rc 82+AWD+PFR were employed. Data on chlorophyll (chl) levels, plant height, tiller count, and number of healthy and unhealthy leaves were gathered weekly. Yield component data, including panicle lengths and dry weight of all filled grains or grain yields, were determined before and after harvesting. Dry weight of straw and roots were also assessed. Compared with PSB Rc 82, PSB Rc 18 had a significantly higher grain yield by 9% due to enhanced protection of chloroplast structure, leading to longer leaf area duration and higher chl contents across growth stages (GSs). These contributed to an improved “sink” or significantly greater number of grains per panicle by 19% and enhanced “source” or better health status of leaves. Improved “source” increased the grain filling efficiency, resulting in a significantly higher number of filled grains per panicle by 18%, grain weight per panicle by 21%, and harvest index by 6%. In contrast with AWD, CS had a significantly higher grain yield by 7% due to higher soil nitrogen availability leading to better yield-contributing plant traits. These traits include a significantly longer vegetative stage by 3%, greater straw biomass by 9%, higher leaf chl levels, and better health status of leaves from grain filling until harvesting. Moreover, the lower number of small, unproductive tillers in CS allowed more plant resources to be used for improving the health of large, panicle-bearing tillers. Compared with FFR, PFR had a significantly higher grain yield by 18% due to a closer-tothe- optimum fertilizer rate leading to an improved “source.” Improved “source” includes the following statistically significant parameters: [1] higher number of tillers by 7–18%, greater number of healthy leaves, and higher total number of leaves throughout GSs; [2] greater biomass by 15%; [3] higher chl content from booting until grain filling stage; and [4] better health status of leaves from booting until harvesting. The closer-to-the-optimum fertilizer rate also improved the “sink,” which was the significantly higher number of productive panicles by 16% and longer panicles by 2%. The study implies that certain management practices – employing a more adapted variety, CS or PFR in Agusan soil – provides a better genetic or environmental factor, which enhances plant traits and improves grain yields. Management recommendations are as follows: [1] PSB Rc 18 should be selected over PSB Rc 82 because it is more adapted in Agusan soil, [2] CS should be preferred over AWD in a non-zinc-deficient Agusan soil, and [3] the 74-28-43-24 kg N-P2O5-K2O-S/ha PFR should be selected over the 42.0-4.5-10.5-3.8 kg N-P2O5-K2O-S/ha FFR. Variety, water management, and fertilizer rate do not have significant two- and three-way interaction effects on grain yield; hence, no specific combination of the three factors can be recommended. [ABSTRACT FROM AUTHOR]

During the course of evolution, different ecotypes of rice (Oryza sativa L.) have evolved distinct strategies to cope with submergence stress. Such contrasting responses are mediated by plant hormones that are principle regulators of growth, development and responses to various biotic and abiotic stresses. These hormones act cooperatively and show extensive crosstalk which is mediated by key regulatory genes that serve as nodes of molecular communication. The presence or absence of such genes leads to significant changes in hormone signalling pathways and hence, governs the type of response that the plant will exhibit. As flooding is one of the leading causes of crop loss across all the major rice‐producing countries, it is crucial to deeply understand the molecular nexus governing the response to submergence to produce flood resilient varieties. This review focuses on the hormonal signalling pathways that mediate two contrasting responses of the rice plant to submergence stress namely, rapid internode elongation to escape flood waters and quiescence response that enables the plant to survive under complete submergence. The significance of several key genes such as Sub1A‐1, SLR1, SD1 and SK1/SK2, in defining the ultimate response to submergence has also been discussed. [ABSTRACT FROM AUTHOR]

In Indonesia, rice was produced by small-scale farmers where yields were still generally low. This was because small-scale farmers still used poor quality seeds and unbalanced fertilizers. Therefore, this research aimed to analyze the socio-economic factors that affected the adoption of quality seeds in lowland rice farming and the use of fertilizers on quality seeds. This research used a double-hurdle model to answer the objectives of research and used 329 farmings which were selected randomly in Central Sulawesi Indonesia. The results show that the gender variable only affected the use of fertilizer on quality seeds. Education, access to credit, sources of income (income diversification), access to extension, meetings with farmer groups were found to be positively correlated with the decision to adopt quality seeds in lowland rice farming and use of fertilizers to quality seeds, while the number of dependents of the household head was negatively correlated. The land area of lowland rice was positively correlated with the adoption of quality seeds in lowland rice farming but negatively correlated with the number of fertilizers used for quality seeds. Based on these findings, the role of extension workers and farmer groups was needed in disseminating quality seeds, and through credit institutions, it was necessary to provide credit facilities to rice producers (farmers) so that rice productivity could be increased. [ABSTRACT FROM AUTHOR]

This study seeks to determine the effect of N fertilization method on ratoon lowland rice performance, to choose a fertilization method that provides high ratooned yield, and to assess its profitability adopting N fertilization method. The experiment lays out in a Randomized Complete Block Design with three replications and five N fertilization methods as treatments. Method of N application significantly affected the number of days to heading and maturity, plant height, leaf area index (LAI), number of productive tillers hill-1, panicle length and weight, number of filled and unfilled grains panicle-1. This method compensates cost of production of growing ratoon crop than those of the main crop. In fact, the highest profit (PhP25,564.80) was obtained in ratooned plants, which received 60 kg ha-1 N basal + 30 kg ha-1 N topdress application (T3) due to higher grain yield. Thereby, this is an appropriate option that provides high productivity and income for the ratoon growers.

Currently, most rice farmers in the central highlands of Madagascar do not apply mineral fertilizer in their fields and we investigated whether a fertilizer micro-dose applied to the seedling nursery could serve as an entry point for intensification. Effects of nursery applications of a micro-dose of mineral (P and NPK) or locally produced sources of fertilizers (Guanomad, Vermicompost) on seedling vigour were evaluated, as was final grain yield after transplanting to main fields that were either not fertilized (farmers’ practice) or received combinations of mineral N, P and K fertilizer. Applying only P to the nursery had minor effects and we conclude that early seedling vigor is more limited by N than P, while grain yield in the main field was more limited by P than N. Carry-over effects of the nursery application of NPK and of guano on final grain yield were observed under farmers’ practice and when only urea was applied. The nursery NPK application significantly increased agronomic nitrogen use efficiency of urea application. We conclude that the low cost of micro-dosing NPK in the nursery makes this a profitable option for small-scale farmers cultivating rice on poor-fertility soils. Sole urea application in the main field is not a profitable option but would at least need additional nursery NPK application as an insurance against losing investments in N fertilization. Longer-term sustainability would require direct nutrient inputs into the main plot and additional low-cost nutrient management options should therefore be considered.

Cropping calendar optimization contributes to an increase in rice yield. Information on the seasonal variation in grain yield and climate conditions is necessary to determine an appropriate cropping calendar. We sought to find the optimal cropping calendar in Mwea, Kenya, in a tropical highland in equatorial East Africa. We conducted a series of 58 experiments using a local popular rice variety, Basmati 370, between 2013 and 2016, using a secured water supply and adequate blast control, sowing every 15 days. The grain yield was 0–2 t ha−1 when the variety was sown between March and June. This poor grain yield was attributable to the low temperature and low solar radiation from May to September. In contrast, the grain yield was always more than 3 t ha−1 when the variety was sown between July and February. Sowing Basmati 370 between March and June is not recommended, because it may lead to a suboptimal yield due to cold stress. The current cropping calendar (July–December or August–January) is acceptable even under abundant year-round water supply, but sowing between October and February is a good alternative sowing period for single rice cropping. Rice production per year is expected to increase to >100% with the introduction of double cropping by adding cultivation from between January and February before the current cropping calendar. These findings serve as useful references for considering and determining the appropriate calendar options for single and double cropping of rice in tropical highlands in equatorial East Africa.

Merauke Regency is the main rice-producing center in the southern region of Papua and the largest rice contributor for the provinces of South Papua and Papua, with 55,674.75 hectares of paddy field area, 76 percent (42,387 hectares) of which located in three districts, namely Kurik, Semangga and Tanah Miring District. This study aims to inventory and estimate Green House Gas (GHG) emissions and scenarios for reducing GHG emissions in order to find the mitigation and adaptation methods. The sources of GHG emissions include CH4, CO2, and N2O. The data used for GHG estimation in the paddy field agricultural sector comes from primary and secondary data. The data analysis to determine the value of potential GHG emissions generated by the 2006 IPCC calculation method, based on the guidelines for GHG Calculation of the Ministry of Environment and Forestry of the Republic of Indonesia. The analysis results shows that the total value of potential emissions (CH4 ) from the management of paddy fields produces 9,35 Gg CO2eq/year (264,5 Emisi CO2 e/tahun (Gg) CO2eq/year. The total potential value of carbon dioxide gas (CO2) emissions from the application of urea fertilizer on paddy fields produces 4.10 Gg CO2eq/year. Meanwhile, the total potential value of direct and indirect nitrous oxide gas (N2O) from soil management activities in paddy fields produces 39,15 and Emissions from incinerated straw 0,295 Gg CO2eq/year. Mitigation efforts can be applied by choosing the right and low emissions rice varieties, appropriate land and fertilizers management systems. Adaptation strategy can be carried out with innovative technology, namely a development system in the form of an integrated land management system.

Intensive agricultural land with a limiting factor of acidity often has a great degree of phosphate elements but is not accessible to plants. The utilization of bio-phosphate fertilizer (Bio-P) is an effort to enhance the available P for plants to support sustainable agricultural development. This research evaluated the effectiveness of Bio-P on the growth performance and production of irrigated lowland rice. The research was accomplished in Gemolong District, Sragen Regency, Central Java, Indonesia, from May to October 2021. The research was set in a randomized block design corresponded of ten treatments and four replications. The treatment corresponded of fertilization according to the recommended dose, fertilization according to the recommended dose + Bio-P, existing farmers' fertilization + Bio-P, and without fertilization. The data observed included plant growth, yield components, production, and agronomic and economic feasibility assessments. The findings revealed that fertilization treatment according to the recommended dose + Bio-P and the existing farmers' fertilization + Bio-P did not significantly affect plant growth and yield. The extension of 10 kg ha-1 Bio-P with existing farmers' fertilization produced the highest effectiveness value of 3.56 with a profit of IDR 25,400,400 ha-1 and the highest RAE value of 110.25%.

Potassium is one of the primary macro nutrients along with N and P nutrients, which plants need in large quantities. Lack of K nutrients, one of which can inhibit photosynthetic transport to plant seeds. The availability of K nutrients in paddy soil varies greatly depending on the chemical properties of other soils. This paper aims to evaluate the nutrient K characteristics of paddy fields, the K contribution from irrigation water and harvested straw, and the response of fertilization to rice yields. The availability of K nutrients, apart from being influenced by clay mineral composition, clay content, organic C and soil CEC, is also influenced by N fertilization, soil pH, exchangeable of Ca and Mg, and N-total. The content of potential K and exchangeable of K increases in paddy fields which are further east of Java Island because they have soil with parent material that is rich in potassium minerals. The content of exchangeable K is very closely related to the potential K with R2 = 0.53 (n = 73). Based on the map of the nutrient status of K rice fields with a scale of 1:250,000 in 23 provinces in Indonesia, it is known that most of the paddy fields have moderate K status at 37% and high 48%. The K content in paddy soil can be contributed by irrigation water as much as 7-74 kg K/ha/season. If all of the remaining rice straw from crop yields is returned to the field, the K nutrient requirements for rice plants in the medium and high K nutrient status fields have been fulfilled. The response to K fertilization in rice plants was only visible when the exchangeable K content < 0.10 cmol(+)/ kg. The policy implication of this paper is that K fertilization is focused on paddy fields with low K content, the effectiveness of K fertilization can be increased by returning rice straw from crop residues and proper N fertilization.

Accurate measurements of actual evapotranspiration (ETa) and crop coefficients (Kc) are essential to know crop water requirements and to improve irrigation scheduling. The eddy covariance (EC) technique is increasingly being used to do so. Precise information on Kc for lowland rice is essential for local- and regional-scale irrigation planning but it is lacking for tropical humid climates such as those found in eastern India. We used the EC technique to measure ETa and Kc—the ratio of ETa to reference potential evapotranspiration (ET0)—of tropical lowland rice in eastern India over 2 years. ET0 was estimated by four different approaches—the Food and Agriculture Organization-Penman–Monteith (FAO-PM) method, the Hargreaves and Samani (HS) method, the Mahringer (MG) method, and pan evaporation (Epan) measurements. Measurements were taken when rice was grown in the dry season (January–May) and wet season (July–November) and in between growing seasons when the field was kept fallow. The magnitude of average ETa during dry seasons (2.86 and 3.32 mm d−1 in 2015 and 2016, respectively) was higher than that of the wet seasons (2.3 and 2.2 mm d−1) in both the study years. Of the four methods tested for ET0 estimation, the FAO-PM method best-represented ET0 in this region of India. The energy balance was found to be more closed in the dry seasons (75–84%) and dry fallow periods (73–81%) as compared to the wet season (42–48%) and wet fallow (33–69%) periods of both years of study, suggesting that lateral heat transport was an important term in the energy balance. The estimated Kc values for lowland rice in dry seasons by the FAO-PM method at the four crop growth stages, namely, initial, crop development, reproductive, and late-season, were 0.23, 0.42, 0.64, and 0.90, respectively, in 2015 and 0.32, 0.52, 0.76, and 0.88, respectively, in 2016. The FAO-PM, HS, and MG methods produced reliable estimates of Kc values in the dry seasons, whereas Epan performed better in wet seasons. The actual Kc values derived for tropical lowland rice in eastern India are different from those suggested by the FAO implying revision of Kc values for regional-scale irrigation scheduling. [ABSTRACT FROM AUTHOR]

Characterization of carbon dioxide (CO2) fluxes was investigated in tropical lowland flooded rice ecology using open path eddy covariance (EC) technique during dry season of 2009–2010. Select environmental variables like air and soil temperatures, soil moisture, net radiation, photosynthetically active radiation, vapour pressure deficit and soil heat flux were monitored throughout the season and correlated with half hourly CO2 fluxes. The study was conducted to gain insight of environmental impact in terms of carbon (C) budget in a submerged soil of tropical region planted to rice. Total C budget integrated over dry season expressed in terms of net ecosystem CO2 exchange (NEE) was − 392 g C m−2, while the gross primary production (GPP) and ecosystem respiration (RE) were 731 and 339 g C m−2, respectively. Seasonal daily mean NEE, GPP and RE were − 3.73, 6.96 and 3.23 g C m−2 d−1, respectively. The ratio of RE/GPP in flooded rice field was 0.46. The NEE was negative during daytime and positive during nighttime, i.e. rice paddy ecosystem acted as a CO2 sink and source during daytime and night hours, respectively. Lowest negative NEE was found during heading to flowering stage (− 26.93 µmol CO2 m−2 s−1) of crop growth due to estimated highest values of GPP (32.34 µmol CO2 m−2 s−1) and RE (5.42 µmol CO2 m−2 s−1). On seasonal basis flooded rice ecology behaved as net sink for CO2. This was attributed to higher photosynthetic capacity of lowland rice to convert atmospheric C into organic compounds and slow organic matter decomposition in flooded soils. [ABSTRACT FROM AUTHOR]

Agricultural soil acts as a source and sink of important greenhouse gases (GHGs) like methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2). Rice paddies have been a major concern to scientific community, because they produce the threatening and long-lasting GHGs mainly CH4 and N2O. Around 30% and 11% of global agricultural CH4 and N2O, respectively, emitted from rice fields. Thus, it is urgent to concurrently quantify the fluxes of CH4 and N2O to improve understanding of both the gases from rice fields and to develop mitigation strategies for upcoming climate change reduction. An effort is being made in this review to discuss exclusively the emission of CH4 and N2O under normal and controlled conditions in different locations of India and also addresses the current synthesis of available data on how field and crop management activities influence CH4 and N2O emissions in rice fields. Making changes to conventional crop management regimes could have a significant impact on reducing GHG emissions from rice field. Environmental and agricultural factors related to soil could be easily altered by management practices. So, knowing the mechanism of CH4 and N2O production and release in the rice field and factors controlling the emissions is fundamental to develop well-organized strategies to reduce emissions from rice cultivated soil. This will help the regulatory bodies or policy makers to formulate adequate policies for agricultural farmers to refine the GHG emissions as well as minimize the global climate change. [ABSTRACT FROM AUTHOR]

Currently, most rice farmers in the central highlands of Madagascar do not apply mineral fertilizer in their fields and we investigated whether a fertilizer micro-dose applied to the seedling nursery could serve as an entry point for intensification. Effects of nursery applications of a micro-dose of mineral (P and NPK) or locally produced sources of fertilizers (Guanomad, Vermicompost) on seedling vigour were evaluated, as was final grain yield after transplanting to main fields that were either not fertilized (farmers' practice) or received combinations of mineral N, P and K fertilizer. Applying only P to the nursery had minor effects and we conclude that early seedling vigor is more limited by N than P, while grain yield in the main field was more limited by P than N. Carry-over effects of the nursery application of NPK and of guano on final grain yield were observed under farmers' practice and when only urea was applied. The nursery NPK application significantly increased agronomic nitrogen use efficiency of urea application. We conclude that the low cost of micro-dosing NPK in the nursery makes this a profitable option for small-scale farmers cultivating rice on poor-fertility soils. Sole urea application in the main field is not a profitable option but would at least need additional nursery NPK application as an insurance against losing investments in N fertilization. Longer-term sustainability would require direct nutrient inputs into the main plot and additional low-cost nutrient management options should therefore be considered. [ABSTRACT FROM AUTHOR]

Lowland rice flooding, while consuming considerable water, has adverse environmental effects, including releasing methane into the atmosphere, aggravating climate change. Several drawbacks can be attributed to water-saving alternatives, such as aerobic rice, whereas rice drip irrigation techniques have been evaluated primarily under aerobic conditions. This study investigated drip tape irrigation technique with different lateral spacings for transplanted rice in puddled paddy soil at the Rice Research Institute of Iran in Rasht over two years (2020 and 2021), compared to intermittent irrigation. In twelve isolated concrete basins, three treatments with lateral spacings of 40 (T40), 60 (T60), and 80 cm (T80), were compared with a fixed five-day period intermittent irrigation (INT). In 2020 and 2021, the INT treatment produced the highest grain yield (3814 and 4758 kg ha−1, respectively) and among drip tape treatments, T40 demonstrated the highest grain yield (3613 and 4020 kg ha−1, respectively), comparable with INT's yield but with the highest sterile spikelets ratio. In contrast, T80 resulted in the lowest grain weight (2892 and 3653 kg ha−1, respectively) and yield characteristics values, while producing the highest weeds population. Drip tape irrigation significantly reduced water application by 27% and 36% in 2020 and 2021, respectively and T40 achieved the highest water productivity, at 0.68 kg m−3. The economic water productivity estimation of drip tape irrigation can range from 0.11 to 0.51 US$ m−3 in various scenarios, while that of intermittent irrigation remains at 0.25 US$ m−3. • Drip tape irrigation of transplanted rice compared to intermittent irrigation (INT). • Drip irrigation saved water by up to 36% compared to INT. • WP ranged between 0.44 and 0.68 kg m−3, an increase of up to 22% compared to INT. • 40 cm lateral spacing is the most yielding and profiting drip irrigation formation. [ABSTRACT FROM AUTHOR]

Since Rice is indispensable to almost all Filipinos as their primary food, it is necessary to aim for an additional greater harvest as an ultimate objective. The study was conducted to determine if there were significant differences in growth performance and on the yield of lowland rice applied with zinc sulfate at different levels. The experimental area was divided into four blocks for the number of replications and each block was further divided into 5 plots for the number of treatments adopting the Randomized Complete Block Design (RCBD). The following treatments were: T0-control-without application of zinc sulfate, T1-5kg of zinc sulfate, T2-10kg of zinc sulfate, T3-15kg of zinc sulfate, and T4 -20kg of zinc sulfate. Results showed significant differences in the plant height, the number of tillers, percentage of bearing culm, length of the panicle, percentage of filled and unfilled grains, grain yield per hill, grain yield per treatment, the weight of 1000 grains, except the number of grains per panicle. Maximum paddy yield was achieved in Treatment 4 (20kg zinc sulfate) and the minimum paddy yield was noted in treatment control (no zinc sulfate application). Zinc application increases the crop growth rate and yield of rice.

Abstract Objectives This study was conducted to establish a method for early, quick and cheap screening of iron excess tolerance in rice (Oryza sativa L.) cultivars. Results Based on the experiments, iron excess leads to reduction in shoot length (SL) and this can be a useful characteristic for adequate screening of tolerant genotypes. The sensitive genotypes Nipponbare and BR-IRGA 409 indicated higher accumulation of iron in their tissues while BRS-Agrisul and Epagri 108 also accumulated iron, but at lower concentrations. BR-IRGA 410 displayed an intermediate phenotype regarding iron accumulation. No changes in shoot Cu content can be observed when comparing treatments. On the other hand, an increase was seen for Zn and Mn when shoots are subjected to Fe2+ excess. Fe stress at a lower concentration than 7 mM increased Zn but decreased Mn contents in shoots of BR-IRGA 409. Strong positive correlations were found here for Fe × Zn (0.93); Fe × Mn (0.97) and Zn × Mn (0.92), probably due to the Fe-induced activation of bivalent cation transporters. Results show that genotypes scored as sensitive present higher concentration of Fe in shoots and this is an efficient method to characterize rice cultivars regarding iron response.

Fertilizers and fertilization technology have important roles in increasing crop production including lowland rice. In response to the issue, a field experiment was conducted to study the effects of micronutrients on growth and yield of lowland rice. The experiment was carried out at Cihideung Ilir Village, Dermaga Sub-district, Bogor Regency from November 2015 until March 2016. The experiment consisted of 8 treatments, namely control (without fertilization), NPK-standard, NPK-standard + ¼ dosage of Hortigro Rice fertilizer, and ¾ NPK + ¼ until 11/4 dosages of Hortigro Rice fertilizer as a source of macronutrients N, P, K and micronutrients of Mn, Cu, Zn, B, and Mo. The treatments were arranged in a Randomized Block Design with 3 replications. Parameters observed during the research were plant height, tiller number, and yield of grain and straw of INPARI-32 lowland rice as crop indicator. The results showed that among other treatments, the highest plant height was resulted from the application of ¾ NPK-standard + ¼ Hortigro Rice, i.e. around 124 cm at 60 days after planting. The highest harvesting dry weight of grain and straw were observed in NPK-standard + 1/4 of Hortigro Rice fertilizer treatment, i.e. around 9.0 Mg ha-1 and 25.9 Mg ha-1, respectively. This yield showed a significant difference with ¾ NPK-standard combined with ¾ -11/4 dosages of Hortigro Rice. The highest dry weight of milled grains was resulted in the application of ¾ NPK-standard + 1/2 Hortigro Rice, i.e. around 7.3 Mg ha-1, which is significantly different from that in ¾ NPK-standard combined with 1.0 - 11/4 dosages of Hortigro Rice treatments, while the highest dry weight of straw was provided by NPK-standard, i.e. around 14.0 Mg ha-1. The highest dry weight of 1000 milled grains and ratio of dry weight of milled grain to straw were provided by ¾ NPK-standard + 1/2 Hortigro Rice around 32.0 gram and 0.63, respectively. The results indicated that the application of micronutrient fertilizer of Hortigro Rice in combination with NPK fertilizers can potentially increase lowland rice productivity due to the micronutrients content of Mn, Cu, Zn, B, and Mo in it.

One of the potential ways of increasing rice production to cater for ever increasing population of Malaysia is to extend the production area of lowland rice through its production as upland rice. Therefore, this research was conducted to determine the effects of seed priming in alleviating water deficit stress in lowland rice produced as upland rice. The treatments used were 100mM calcium chloride dihydrate for duration of 48hours and temperature of 25oC, 40% w/v polyethylene glycol (PEG) 6000 for a duration of 48hours and temperature of 25oC, 100ppm kinetin for a duration of 24hours and temperature of 4oC, 200ppm methyl jasmonate for a duration of 24hours and temperature of 4oC, stressed control (unprimed seeds) and the unstressed control (unprimed seeds with adequate irrigation). The experiment was laid out in randomized complete block design (RCBD) with three replications. Data were collected on classical growth parameters, germination pattern, gas exchange characteristics, yield and yield components. It was found that priming MR219 rice with PEG could enable the variety to be produced as upland rice with little yield reduction because PEG priming was the best in individual seed mass, final yield, harvest index and water use efficiency. It is, therefore, concluded that 48hours of priming with 40%w/v polyethylene glycol at 25oC be used for MR219 rice seeds whenever MR219 rice variety is to be cultivated as upland rice. [ABSTRACT FROM AUTHOR]

This study describes the socioeconomic characteristics of rice farmers, identifies the production system used by the farmers, compares the profitability of rice production systems, identifies the factors influencing the choice of production systems among the farmers as well as the constraints to rice production systems. A three-stage random sampling procedure was used to select 120 rice farmers on whom a set structured questionnaire was administered. Data was analysed using descriptive statistics and multinomial logistic regression model. Results show that 48.3%, 35% and 16.7% of the farmers cultivate rice using the upland, lowland and the combined production systems respectively. The findings also reveal variability in yield, profit and income across the rice production systems. The gross margins for lowland, upland and combined rice production systems were N65,735.73, N67,900.89 and N78,015.57 per hectare respectively. The factors that influenced the choice of upland production system relative to combined production system were age, household size, farming years and extension visits while the factors that influenced the choice for combined rice production system relative to lowland rice production system was income. Inadequate finance to purchase inputs, problem of pests and diseases, and unfavorable climatic conditions are the constraints faced by rice farmers in the upland, lowland and combined production systems. The combined production systems had the highest return per hectare. Therefore, the study recommends that farmers should be encouraged to choose the combined rice production system for optimum profitability of rice production. [ABSTRACT FROM AUTHOR]