Adoption of the right rice variety and water-saving irrigation method could reduce greenhouse gas (GHG) emissions in lowland rice cultivation. A study was conducted at the research farm of Bangladesh Agricultural University, Mymensingh, Bangladesh, in 2019 during the Boro (dry) season to determine the impacts of different rice varieties (BRRI dhan29, BRRI dhan47, BRRI dhan69, Binadhan-8, Binadhan-10, and Binadhan-17) on methane (CH₄) emissions under two irrigation methods, i.e., alternate wetting and drying (AWD) and continuous flooding (CF). The treatments were laid out in a split-plot design, considering water regime as the main plots and rice variety as the sub-plots. The emission rates of CH₄ were determined by collecting air samples using the closed chamber technique and measuring the concentrations using a gas chromatograph. CH₄ emission rates varied with the growth and development of the rice varieties. The lowest cumulative CH₄ emission rate was observed in Binadhan-17, particularly under AWD irrigation. Across the rice varieties, AWD irrigation significantly reduced the cumulative CH₄ emissions by about 35% compared with CF. No significant variation in rice yield was observed between AWD (5.38 t ha⁻¹) and CF (5.16 t ha⁻¹). This study suggests that the cultivation of Binadhan-17 under AWD irrigation could be effective at reducing the carbon footprint of lowland rice fields.

Rice is a major crop in Bangladesh that supports both food security and livelihoods. However, a need remains for improved productivity and adaptation to the risks associated with climate change. To accomplish this, the increased adoption of climate-resilient and high-yielding rice varieties can be beneficial. Therefore, we conducted a study in Bangladesh over three consecutive years: 2016, 2017, and 2018. The scope of the study included the major cropping season (wet), Aman. The yield advantages of climate-resilient rice varieties were evaluated and compared with those of the varieties popular with farmers. We included new stress-tolerant varieties, such as submergence-tolerant rice (BRRI dhan51 and BRRI dhan52) and drought-tolerant rice (BRRI dhan56 and BRRI dhan71), along with farmer-chosen controls, in the study. We conducted the evaluation through on-farm trials to compare the varieties in both submergence- and drought-affected environments. The seasonal trials provided measured results of yield advantages. The participating farmers were also studied over the three-year-period to capture their varietal adoption rates. We calculated both the location estimated yield advantages (LEYA) and the location observed yield advantages (LOYA). The results revealed that, under non-stress conditions, the grain yields of climate-resilient varieties were either statistically similar to or higher than those of the farmer-chosen controls. Our study also revealed a year-to-year progressive adoption rate for the introduced varieties. The study suggests that the wide-scale introduction and popularization of climate-resilient varieties can ensure higher productivity and climate risk adaptation. The close similarity between LOYA and LEYA indicated that the observational and experiential conclusions of the host farmers were similar to the scientific performance of the varieties. We also found that comparison performed through on-farm trials was a critical method for enhancing experiential learning and obtaining an accurate estimation of yield advantages.

Traditional public extension worker-farmer cooperation in rice production demonstration is not working efficiently, therefore, private partnership-based demonstration has been attempted to introduce as its alternative very recently involving dealer-customer farmer. The study evaluated the private extension services rendered through dealer-customer farmer cooperation in Bangladesh. Thirty-three rice seed dealers and ninety-two customer farmers formed the samples for the study. Face-to-face interviews were employed as a quantitative method while focus group discussion was used as a qualitative method in the present study. Involving in the private rice production demonstration approach, customer farmers indicated high profit, greater involvement in decision-making, and improved marketing skills as the major advantages; while the dealers stressed the benefit received by the small farmers, improvement in their decision-making capacity and increased local rice production. However, the slow distribution of inputs during the production period was a weakness in the arrangement, which was mostly because of the dealers' lack of understanding of the customer farmers’ needs. The private extension system being a new concept in the country may be observed over a period and gradually extended to the nooks and crannies of the country.

Arsenic (As) contamination of rice remains a major human health issue in Asia. Most research has been on irrigated rice. However much of the projected increase in global rice demand over coming decades must be met by rainfed lowland systems, for which As relations are poorly understood. We present the most comprehensive survey to date of As in rice in farmers' fields across Bangladesh, covering both irrigated and rainfed systems. We collected rice grain and soil at 943 sites in the three rice growing seasons: irrigated Boro, rainfed Aus, and longer-duration rainfed Aman. Grain As concentrations increased in the order Aman ≪ Boro < Aus with 2, 25 and 41 % of the sites exceeding permitted thresholds, respectively. The greater concentration in Aus than Boro challenges the accepted wisdom that contaminated irrigation water is the main source of As. The main growth and grain filling periods, when most As is taken up, coincide in Aus with the peak of the monsoon rains, suggesting a link between rainfall and high grain As. We suggest this is due to stronger soil reducing conditions and hence As solubility during peak rainfall. We discuss implications for rainfed lowland rice across Asia and mitigation options.

This paper measures the impact of a micronutrient training among women farmers with young children on the demand for zinc-enhanced varieties. We conducted a randomized control trial by providing micronutrient training in randomly selected villages in May–June 2017. These farmers were also given information on the biofortification of rice with zinc. One week after the training, we conducted a phone-based bidding for high-zinc rice seeds among trainees and their counterparts in control villages. More than 70% of the treated female farmers participated in the bidding for high-zinc rice seed, but only 23% of the women in the control group participated in the bidding. Female farmers who self-reported that they had input into most or all decisions on the use of income generated from rice bid a higher price than other female farmers. The results suggest the effectiveness of the micronutrient training, at least in a short period immediately after the training.