Participatory evaluation guides the development and selection of farmers’ preferred rice varieties for salt- and flood-affected coastal deltas of South and Southeast Asia

Rice is the staple food and provides livelihood for smallholder farmers in the coastal delta regions of South and Southeast Asia. However, its productivity is often low because of several abiotic stresses including high soil salinity and waterlogging during the wet (monsoon) season and high soil and water salinity during the dry season. Development and dissemination of suitable rice varieties tolerant of these multiple stresses encountered in coastal zones are of prime importance for increasing and stabilizing rice productivity, however adoption of new varieties has been slow in this region. Here we implemented participatory varietal selection (PVS) processes to identify and understand smallholder farmers’ criteria for selection and adoption of new rice varieties in coastal zones. New breeding lines together with released rice varieties were evaluated in on-station and on-farm trials (researcher-managed) during the wet and dry seasons of 2008–2014 in the Indian Sundarbans region. Significant correlations between preferences of male and female farmers in most trials indicated that both groups have similar criteria for selection of rice varieties. However, farmers’ preference criteria were different from researchers’ criteria. Grain yield was important, but not the sole reason for variety selection by farmers. Several other factors also governed preferences and were strikingly different when compared across wet and dry seasons. For the wet season, farmers preferred tall (140–170cm), long duration (160–170 d), lodging resistant and high yielding rice varieties because these traits are required in lowlands where water stagnates in the field for about four months (July to October). For the dry season, farmers’ preferences were for high yielding, salt tolerant, early maturing (115–130 d) varieties with long slender grains and good quality for better market value. Pest and disease resistance was important in both seasons but did not rank high. When farmers ranked the two most preferred varieties, the ranking order was sometimes variable between locations and years, but when the top four varieties that consistently ranked high were considered, the variability was low. This indicates that at least 3–4 of the best-performing entries should be considered in succeeding multi-location and multi-year trials, thereby increasing the chances that the most stable varieties are selected. These findings will help improve breeding programs by providing information on critical traits. Selected varieties through PVS are also more likely to be adopted by farmers and will ensure higher and more stable productivity in the salt- and flood-affected coastal deltas of South and Southeast Asia

Crop and Residue Management Improves Productivity and Profitability of Rice–Maize System in Salt-Affected Rainfed Lowlands of East India

This study was conducted over 3 years in a salt-affected coastal rainfed lowland ecosystem. Farmers most commonly grow tall rice varieties in the wet season to cope with flash and/or stagnant floods, leading to large amounts of rice residue production. Most of the land remains fallow during the dry season because of increased salinity and scarcity of freshwater for irrigation. The study aims to provide options for increasing cropping intensity through management of crop residues (CR) and soil salinity, conservation of soil moisture, and reduction in production cost. The rice–maize rotation was assessed with rice as the main plot as (1) puddled transplanted rice (PTR) with CR of both rice and maize removed, (2) PTR and 40% CR of both crops retained, (3) dry direct-seeded rice (DSR) with CR of both crops removed, and (4) DSR with 40% CR of both crops retained. Maize in the dry season was supplied with different N levels as sub-plots—control (0 kg N ha−1), 80, 120, and 160 kg N ha−1. DSR, when combined with CR retention (DSR + R), reduced soil salinity. The increase in rice grain yield with CR retention (observed in second and third years) and crop establishment (higher in DSR versus PTR in the third year) was 16 and 24%, respectively. The cost of production increased by 17% (USD 605 ha−1) in PTR compared with DSR (USD 518 ha−1). CR retention reduced irrigation water requirement by 37% and N requirement by 40 kg ha−1 for hybrid maize. When CR was removed (−R), the N requirement for hybrid maize increased to 160 kg N ha−1 compared to when it was partially (40%) retained, where the requirement was 120 kg ha−1 with similar yields. Available N was highest under DSR + R (314 kg ha−1) and lowest under PTR − R (169 kg ha−1), and it also increased with increasing N application up to 120 kg ha−1 (+R) and 160 kg ha−1 (−R). The results of the study hold promise for increasing cropping intensity and farmers’ incomes, with broader implications for increasing productivity on about 2.95 million hectares currently under a rice–fallow system in eastern India, and in coastal areas affected by similar conditions in South and Southeast Asia

Optimum Sowing Date and Salt Tolerant Variety Boost Rice (Oryza sativa L.) Yield and Water Productivity during Boro Season in the Ganges Delta

Rice-fallow and rice-rice are major cropping systems in the salt affected region of the Ganges Delta covering West Bengal, India and Bangladesh. The dry season rice (Boro) is grown mostly by irrigation from ground water in this water scarce region. Boro encounters soil and water salinity, air temperature fluctuations and intense evaporative demand. We studied six sowing dates (1 October, 15 October, 1 November, 15 November, 1 December and 15 December) and three varieties (WGL 20471, Bidhan 2 and IET 4786) of rice to find an interacting effect on yield and water productivity. Soil and water salinity varied during the growing period with lower soil salinity during the month of November (2.20–2.53 dS m−1) and higher soil salinity towards the end of the growing season (4.30–5.23 dS m−1). The mean field water salinity was higher (1.78 dS m−1) during the Boro 2017–18 compared to that (1.65 dS m−1) during 2016–17, as about 49 mm rainfall was received in the month of March 2017. Sowing dates significantly affected the yield of Boro rice. Earliest sowing on 1 October is not feasible as it significantly reduced the grain and straw yields. Sowing of nursery up to 1 of November was found to be the best possible option, and it should not be delayed up to 15 December. The rice variety IET 4786 was found to be susceptible to salinity with the lowest grain yield 2.65–2.98 t ha−1, compared to Bidhan 2 (3.41–5.95 t ha−1) and WGL 20471 (3.40–5.81 t ha−1). Both irrigation and economic water productivity of Boro were affected by sowing dates and variety. Rice variety IET 4786 required less irrigation water (1320 mm) than the other two varieties (1350 mm). Higher (>0.5 kg m−3) irrigation water productivity of Boro can be achieved by selecting salt tolerant varieties (WGL 20471 and Bidhan 2) and optimum sowing window of 1–15 November

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Not AvailableAccurate measurement of flow depth in an open channel on a real-time basis is the prime factor leading to more accurate quantification of discharge by the flow measuring device. The aim of present study was to evaluate the ultrasonic sensors (viz. HC-SR04 and JSN-SR04T) for depth of flow and corresponding discharge rate measurement in irrigation channel of canal command. The effect of ambient temperature on ultrasonic sensors was also investigated for irrigation channel hydraulic response measurement. It was observed that the performance of calibrated and temperature compensated sensors was better than the uncalibrated ones. Moreover, the performance of JSN-SR04T was better with mean absolute deviation (MAD: 0.21 ± 0.01cm), root mean square error (RMSE: 0.82 ± 0.01) and mean absolute percentage error (MAPE: 0.46 ± 0.09) compared to HC-SR04 sensor with MAD (0.36 ± 0.07), RMSE (0.43 ± 0.08) and MAPE (1.54 ± 0.82), respectively. Hence, JSN-SR04T ultrasonic sensor was used in the developed sensing system for the measurement of flow depth. It was observed that the system measured flow rate when compared with the observed flow resulted in prediction error estimate MAD (0.13 ± 0.05 lps), RMSE (0.16 ± 0.05) and MAPE (2.09 ± 1.16) and coefficient of determination (R2: 0.99) for flow rate ranging from 2 to 20 lps. Overall, the study resulted in the development of a novel and economically viable open channel digital flow sensing system to measure discharge rate passing through the flume. The developed sensing system will assist stakeholders in enhancing surface irrigation water use efficiency in canal commands.Not Availabl

Evaluation of Ultrasonic Sensor for Flow Measurement in Open Channel

1091-1099Accurate measurement of flow depth in an open channel on a real-time basis is the prime factor leading to more accurate quantification of discharge by the flow measuring device. The aim of present study was to evaluate the ultrasonic sensors (viz. HC-SR04 and JSN-SR04T) for depth of flow and corresponding discharge rate measurement in irrigation channel of canal command. The effect of ambient temperature on ultrasonic sensors was also investigated for irrigation channel hydraulic response measurement. It was observed that the performance of calibrated and temperature compensated sensors was better than the uncalibrated ones. Moreover, the performance of JSN-SR04T was better with mean absolute deviation (MAD: 0.21 ± 0.01cm), root mean square error (RMSE: 0.82 ± 0.01) and mean absolute percentage error (MAPE: 0.46 ± 0.09) compared to HC-SR04 sensor with MAD (0.36 ± 0.07), RMSE (0.43 ± 0.08) and MAPE (1.54 ± 0.82), respectively. Hence, JSN-SR04T ultrasonic sensor was used in the developed sensing system for the measurement of flow depth. It was observed that the system measured flow rate when compared with the observed flow resulted in prediction error estimate MAD (0.13 ± 0.05 lps), RMSE (0.16 ± 0.05) and MAPE (2.09 ± 1.16) and coefficient of determination (R2: 0.99) for flow rate ranging from 2 to 20 lps. Overall, the study resulted in the development of a novel and economically viable open channel digital flow sensing system to measure discharge rate passing through the flume. The developed sensing system will assist stakeholders in enhancing surface irrigation water use efficiency in canal commands

Rice mechanization in India - key to enhance productivity and profitability

Long-term and seasonal variations in weather conditions, salt intrusion, waterlogging, and/or freshwater availability are some of the major factors that made coastal zones highly diverse, fragile, and vulnerable. Weather disturbances are common and are further aggravated by climate change. Competition among resource users usually leads to environmental and social challenges that need to be addressed at local and regional levels. These areas support dense human populations, with the prevalence of poverty and food insecurity, causing low and unstable agricultural productivity, driven by several abiotic stresses—floods in the wet season, soil salinization in the dry season, acidity, and high organic matter and nutritional toxicities or deficiencies throughout the year. Despite these challenges, these areas hold considerable opportunities for food production, though they still remain highly underutilized. Agriculture and aquaculture dominate the livelihood options in coastal tropical zones. Promising technologies together with access to knowledge had evolved considerably in the recent past, with packages of relevant technologies available to maximize the use of these areas. Major investments in infrastructure to control floods and salt intrusion demonstrated positive impacts in some areas, but this entails proper planning and policies for monitoring and adjustments, and large capital investments, beyond the reach of smallholder farmers. High rainfall during the wet season causes excessive wetting, positioning rice farming as the preferred agricultural activity. Several rice varieties with tolerance to salinity and floods or a combination of both have been developed and some deployed in affected areas over the past two decades, with remarkable impacts. These varieties provided opportunities for designing better stress- and variety-specific management options and more confidence and assurance for farmers to invest in input use and good crop husbandry, besides flexibility for higher cropping intensity and diversity to enhance their nutrition and household income. More efforts, however, are needed to fully exploit the potentials of these areas for food and nutrition security through large-scale adoption of validated technologies, human and infrastructure development, enabling and empowering policies, along with concomitant access to information via digital tools and to markets. Enhancing the productivity and profitability of rice-based cropping systems in these coastal areas with assured quality management services through proper harvest, postharvest processing, and value addition will significantly improve smallholder farmers’ livelihood, thereby contributing to national food security and to reach several of the targets of the United Nation’s Sustainable Development Goals

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Not AvailableRice (Oryza sativa) based cropping in the Asian region is considered as one of the most significant agricultural practices that contribute to climate change due to high energy use and carbon footprints (CF). To assess the contributions of rice-based cropping in lowland coastal ecosystems to environmental change, energy budgets, CF, exchange of CO2 and fluxes of non-CO2 greenhouse gases (GHGs) were determined for an array of conservation tillage practices under rice-rice (RR) and rice-cotton (Gossypium hirsutum) (RC) systems as main plot treatments, tillage intensity [zero tillage (ZT), reduced tillage (RT), conventional tillage (CT)] as sub-plot treatments, and residue (R) or no residue (NR) as sub-sub plot treatments. The energy use was calculated operation-wise and RT was recorded to be most efficient in terms of energy utilization. Rice-based cropping system enhanced soil organic carbon (SOC) at the rate of 0.22 to 0.69, and 0.09 to 0.45 Mg/ha/yr in rice-rice and rice-cotton systems, respectively, with the exception of RC-ZTNR which depleted SOC by 0.11 Mg/ ha/yr. Static chamber-gas chromatography-based methodology along with biometric data collection was used for the carbon and GHG budgeting. The evaluation of net ecosystem carbon budget (NECB, based on net ecosystem exchange of CO2 and non-CO2 carbon via crop harvest, CH4-C, C inputs to soils and C loss through runoff), and GHG budget (GHGB, adding CH4 and N2O fluxes, and emissions from inputs used to the NECB on CO2 equivalent basis) showed that the rice-based cropping systems in lowland coastal ecologies functioned as carbon sinks (NECB:1523 and 944 Kg C ha/yr in rice-rice and rice-cotton system, respectively) but GHG source except under reduced tillage with residue (RTR) management which was a GHG sink (-68 to -228 Kg CO2-eq /ha/yr). The treatment RTR also recorded the least CF, and highest ecosystem service values of climate regulation among all tillage practices.ICA

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Not AvailableSubmergence of lowland rice (Oryza sativa L.) fields during the wet season in coastal regions adversely affects survival and productivity of rice. A field experiment was conducted for two consecutive wet seasons in 2016 and 2017 at ICAR-Central Soil Salinity Research Institute, Regional Research Station, Canning Town, West Bengal to evaluate the performance of six varieties carrying the SUB1 gene (BR11-Sub1, Ciherang-Sub1, CR1009-Sub1, IR64-Sub1, Samba-Sub1, and Swarna-Sub1) along with two checks (DRR Dhan39 and Sabita) under stagnant and flash flooding situations. Sabita produced the highest grain yield (3.45 t/ha) followed by CR1009-Sub1 (3.27 t/ha) under stagnant flooding. Sabita is the local check under stagnant flooding. Under flash flooding, CR1009-Sub1 produced the highest grain yield of 4.11 t/ha, followed by Swarna-Sub1 (3.11 t/ha) and BR11-Sub1 (2.78 t/ha). Participatory varietal selection (PVS) was conducted during both the years to assess the preferences of farming communities for these varieties. Under stagnant flooding, the highest preference score was recorded for Sabita (0.62) followed by BR11-Sub1 (0.32) and CR1009-Sub1 (0.31). The lowest preference score was observed for IR64-Sub1 (-0.56), Samba-Sub1(-0.31), and Ciherang-Sub1 (-0.26). Under flash flooding, the highest preference score was recorded for CR1009-Sub1 (0.63) followed by BR11-Sub1 (0.38) and Swarna-Sub1 (0.20). The lowest preference score was observed for IR64-Sub1 (-0.62), Samba-Sub1 (-0.34), Ciherang-Sub1 (-0.29), and DRR Dhan39 (-0.27). Based on the results of field experiments and farmers’ preferences, CR1009-Sub1, BR11-Sub1, and Swarna-Sub1 could be recommended for cultivation in areas affected by flash floods in coastal areas of India.Not Availabl