Yield stability among potato varieties suitable for different agroecological regions of Bangladesh.

Multilocation trials are usually performed in breeding and variety evaluation programs to identify stable genotype(s) with similar crop performance in various environments. The present study evaluated the stability of six selected potato varieties (BARI Alu-7, BARI Alu-8, BARI Alu-25, BARI Alu-28, BARI Alu-36, and BARI Alu-41) suitable for multiple locations (Barishal, Bogura, Cumilla, Jamalpur, Jashore, Munshiganj, Mymensingh, and Rajshahi) in Bangladesh from 2014 to 2019. The study considered genotype and environment as treatments, year as replications and used a randomized complete block design (RCBD) with to construct the genotype plus genotype-vs-environment interaction (GGE) model. The joint analysis of variance revealed significant differences among the genotypes and environments (GE). The scores of PC1 (principal component 1) and PC2 (principal component 2) cumulatively explained approximately 63 % of the total variation in GE interactions and were used to construct the GGE biplot. BARI Alu-8 and BARI Alu-28 were the best genotypes, with high average yields and high stability across the locations. Jamalpur and Munshiganj was identified as the desired locations among the tested environments for growing all the genotypes. This study will help potato growers select highly stable high-performance varieties for a particular environment to achieve maximum tuber production.

Emission factors and global warming potential as influenced by fertilizer management for the cultivation of rice under varied growing seasons.

Greenhouse gas (GHG) emissions from paddy fields are intensified during rice production, and are generally reported based on single or double cropping. It needs to be known how emission factors, GHG emission patterns, and global warming potential are affected by growing three rice crops yearly under the principle of integrated plant nutrient system fertilization (IPNSF). Cowdung and vermicompost were used as IPNSF and compared with commercial fertilization alone. A static close chamber technique was used to measure GHG emissions. The peak periods of CH4 emissions were 20-37, 22-42, and 19-38 days after transplanting during dry, wet, and premonsoon seasons, respectively. The use of cow dung significantly enhanced total N2O, CH4, and CO2 fluxes by 5-10%, 15-23%, and 9-20%, respectively, compared to vermicompost. CH4 emissions for each kg grain production were 39-80, 45-63, and 43-57 gm in the dry, premonsoon, and wet seasons, respectively. Vermicompost significantly reduced CH4, CO2, and N2O fluxes by 13-19%, 17-21%, and 4-9%, respectively, along with a reduction in GHG emission factors by 8-17% and global warming potential by 13-17% compared to cow dung. Moreover, vermicompost and cow dung significantly improved rice grain yields in all three growing seasons compared to commercial fertilizer alone. In conclusion, the use of vermicompost as an IPNSF could be a viable technique for improving grain yield and for reducing GHG emissions from paddy fields during year-round rice cultivation.

Bio-Organic Fertilizer: A Green Technology to Reduce Synthetic N and P Fertilizer for Rice Production.

Decomposed organic materials, in combination with plant growth-promoting bacteria (PGPB), are environmentally friendly and reduce synthetic fertilizer use in rice production. A bio-organic fertilizer (BoF) was prepared using kitchen waste (79%), chita-dhan (unfilled rice grain) biochar (15%), rock phosphate (5%), and a consortium of 10 PGPB (1%) to supplement 30% nitrogen and to replace triple superphosphate (TSP) fertilizer in rice production with an improvement of soil health. PGPB were local isolates and identified using 16S ribosomal RNA partial gene sequences as Bacillus mycoides, Proteus sp., Bacillus cereus, Bacillus subtilis, Bacillus pumilus, Paenibacillus polymyxa, and Paenibacillus spp. Isolates could fix N2 by 0.7-1.4 g kg-1, solubilize 0.1-1.2 g kg-1 phosphate, and produce 0.1-40 g kg-1 indoleacetic acid. The performance of BoF was evaluated by 16 field experiments and 18 farmers' field demonstration trials during the year 2017-2020 in different parts of Bangladesh. Performances of BoF were evaluated based on control (T1), full synthetic fertilizer dose of N, P, and K (T2), BoF (2 t ha-1) + 70% N as urea + 100% K as muriate of potash (T3), 70% N as urea + 100% P as TSP + 100% K as muriate of potash (T4), and 2 t ha-1 BoF (T5) treatments. At the research station, average grain yield improved by 10-13% in T3 compared with T2 treatment. Depending on seasons, higher agronomic N use efficiency (19-30%), physiological N use efficiency (8-18%), partial factor productivity (PFP)N (114-150%), recovery efficiency (RE)N (3-31%), N harvest index (HIN) (14-24%), agronomic P use efficiency (22-25%), partial factor productivity of P (9-12%), AREP (15-23%), and HIP (3-6%) were obtained in T3 compared with T2 treatment. Research results were reflected in farmers' field, and significant (P < 0.05) higher plant height, tiller, panicle, grain yield, partial factor productivity of N and P were obtained in the same treatment. Application of BoF improved soil organic carbon by 6-13%, along with an increased number of PGPB as compared with full synthetic fertilizer dose. In conclusion, tested BoF can be considered as a green technology to reduce 30% synthetic N and 100% TSP requirements in rice production with improved soil health.

Nitrous oxide and nitric oxide emissions from lowland rice cultivation with urea deep placement and alternate wetting and drying irrigation.

Urea deep placement (UDP) and the alternate wetting and drying (AWD) irrigation method are two promising rice production technologies. However, studies on the impact of UDP under AWD irrigation on nitrous oxide (N2O) and nitric oxide (NO) emissions are limited. In this study, the effects of UDP with AWD irrigation on these emissions, nitrogen use efficiency (NUE), and rice yields are investigated, compared to conventional broadcast application. N2O and NO emissions from three fertilizer treatments - no nitrogen, UDP, and broadcast application of prilled urea (PU) - were measured. Measurements were taken using an automated gas sampling and analysis system continuously for two consecutive Boro (dry) rice seasons. N2O emission peaks were observed after broadcast application of PU but not after UDP. In contrast, large spikes in N2O emission were observed after UDP, compared to broadcast application, during dry periods. Despite differences in emission peaks, seasonal cumulative N2O emissions from UDP and broadcast treatments were similar. However, NO emissions were minimal and unaffected by UDP or AWD. UDP increased rice yields by 28% and N recovery efficiency by 167%, compared to broadcast urea. This study demonstrates that UDP with AWD irrigation can increase yields and NUE without increasing N2O and NO emissions.