Spatiotemporal mapping of rice acreage and productivity growth in Bangladesh

Technological advancements have long played crucial roles in rice productivity and food security in Bangladesh. Seasonal variation over time and regional differences in rice production, however, pose a threat to agricultural sustainability but remain unexplored. We performed a spatial-temporal mapping of rice cultivation area, production, and yield from 2006-2007 to 2019-2020 using secondary data for disaggregating 64 districts in Bangladesh. Growth and multivariate approaches were employed to analyze time-series data. Results showed that Mymensingh had the highest rice cultivated area and production, while Bandarban had the lowest. The 14 years highest average rice yield was found in Gopalganj and Dhaka (3.63 tons/ha), while Patuakhali (1.73 tons/ha) had the lowest. For the Aus, Aman, and Boro, the rice cultivation area in 19 districts, 11 districts, and 13 districts declined significantly. The overall rice production increased significantly in most districts. For the Aus, Aman, and Boro seasons, the rice yield in 54, 50, and 37 districts demonstrated a significant upward trend, respectively. The adoption rate of modern varieties has risen dramatically. However, there are notable variances between regions and seasons. A significant increasing trend in Aus (0.007% to 0.521%), Aman (0.004% to 0.039%), and Boro (0.013% to 0.584%) were observed in 28, 34, and 36 districts, respectively, with an increase of 1% adaptation of HYV. Predictions revealed that rice cultivation area and production of Aus, Aman, and Boro seasons will be increased in most of the regions of Bangladesh by 2030. Based on spatiotemporal cluster analysis, the five identified cluster groupings illustrated that clusters lack spatial cohesion and vary greatly seasonally. This suggests increasing rice production by expanding cultivable land, adopting high-yielding varieties, and integrating faster technological advancement in research and extension. The findings will assist scientists in developing region-specific production technologies and policymakers in designing decentral region-specific policies to ensure the future sustainability of rice production.

Exploring the antioxidant and antimicrobial potential of three common seaweeds of Saint Martin's Island of Bangladesh

Antioxidants, which have long been deemed an indispensable guardian of human health, play a pivotal role in bolstering the body's defense against a plethora of diseases. Three well-recognized seaweeds in Bangladesh, including Caulerpa racemosa, Padina tetrastromatica, and Hypnea musciformis, were subjected to meticulous analysis to reveal their phytochemical composition, antioxidant activity, and antimicrobial efficacy using advanced spectroscopic and disc diffusion methods. Intriguingly, we observed that C. racemosa emerges as frontrunners, possessing a substantial arsenal of phenol (143.08 ± 18.51 mg gallic acid equivalent g─1) and flavonoid (63.79 ± 2.16 mg rutin equivalent g─1). More fundamentally, C. racemosa exhibits a notable enrichment in the content of tannin (73.58 mg RE g─1) and chlorophyll (13.50 mg g─1), as well as, antioxidant capacity (4457.67 μg g─1). P. tetrastromatica, on the other hand, displayed commendable effectiveness in scavenging the DPPH radical, with percentages ranging from 53.98 to 62.17%. In terms of hydroxyl radical (OH•) scavenging activity, C. racemosa exhibited the highest efficacy at 400 g mL─1. Fascinatingly, C. racemosa exhibited an impressive antioxidant potential, as evidenced by its exceptionally low IC50 value of 5.58 μg mL-1 for OH• scavenging, whereas P. tetrastromatica showed impressively low value of 0.96 μg mL-1 for DPPH scavenging. Although the three seaweeds demonstrated limited efficacy against a spectrum of five human pathogenic bacteria, their potential as abundant sources of antioxidants remains unscathed. Notably, heatmap and PCA analysis revealed that C. racemosa and P. tetrastromatica emerge as the leading contender for studied antioxidant compounds, demonstrating their proclivity for antioxidant extraction, a trait that could be exploited for large-scale production of these valuable compounds.

Identification of influential weather parameters and seasonal drought prediction in Bangladesh using machine learning algorithm

Droughts pose a severe environmental risk in countries that rely heavily on agriculture, resulting in heightened levels of concern regarding food security and livelihood enhancement. Bangladesh is highly susceptible to environmental hazards, with droughts further exacerbating the precarious situation for its 170 million inhabitants. Therefore, we are endeavouring to highlight the identification of the relative importance of climatic attributes and the estimation of the seasonal intensity and frequency of droughts in Bangladesh. With a period of forty years (1981-2020) of weather data, sophisticated machine learning (ML) methods were employed to classify 35 agroclimatic regions into dry or wet conditions using nine weather parameters, as determined by the Standardized Precipitation Evapotranspiration Index (SPEI). Out of 24 ML algorithms, the four best ML methods, ranger, bagEarth, support vector machine, and random forest (RF) have been identified for the prediction of multi-scale drought indices. The RF classifier and the Boruta algorithms shows that water balance, precipitation, maximum and minimum temperature have a higher influence on drought intensity and occurrence across Bangladesh. The trend of spatio-temporal analysis indicates, drought intensity has decreased over time, but return time has increased. There was significant variation in changing the spatial nature of drought intensity. Spatially, the drought intensity shifted from the northern to central and southern zones of Bangladesh, which had an adverse impact on crop production and the livelihood of rural and urban households. So, this precise study has important implications for the understanding of drought prediction and how to best mitigate its impacts. Additionally, the study emphasizes the need for better collaboration between relevant stakeholders, such as policymakers, researchers, communities, and local actors, to develop effective adaptation strategies and increase monitoring of weather conditions for the meticulous management of droughts in Bangladesh.

Exploring of bacterial blight resistance in landraces and mining of resistant gene(s) using molecular markers and pathogenicity approach

Bacterial blight, one of the oldest and most severe diseases of rice poses a major threat to global rice production and food security. Thereafter, sustainable management of this disease has given paramount importance globally. In the current study, we explored 792 landraces to evaluate their disease reaction status against three highly virulent strains (BXo69, BXo87 and BXo93) of Xanthomonas oryzae pv. oryzae (Xoo). Subsequently, we intended to identify the possible candidate resistant (R) genes responsible for the resistant reaction using six STS (Sequence Tagged Site) markers correspond to Xa4, xa5, Xa7, xa13, Xa21 and Xa23 genes and finally, we evaluated morphological variability of the potential bacterial blight resistant germplasm using quantitative traits. Based on pathogenicity test, a single germplasm was found as highly resistant while, 33 germplasm were resistant and 40 were moderately resistant. Further molecular study on these 74 germplasm divulged that 41 germplasm carried Xa4 gene, 15 carried xa5 gene, 62 carried Xa7 gene, 33 carried xa13 gene, and 19 carried Xa23 gene. Only a single germplasm found to carry Xa21 gene. Interestingly, we found a wide range of gene combinations ranged from 2 to 4 genes among the germplasm, where 10 germplasm carried 4 genes, 15 germplasm carried 3 genes and 38 germplasm carried 2 genes of various combinations. Notably, G3 genotype (Acc. No. 4216; highly resistant) having Xa4, Xa7, xa13, Xa21 and G43 genotype (Acc.No. 1523; resistant) having Xa4, xa5, xa13 and Xa23 gene combination being the most effective against all the Xoo strains. Nonetheless, UPGMA dendrogram and heatmap analysis based on quantitative traits identified two clusters viz. cluster-III and cluster-VIII with multiple desired traits. The outcome of this study would enrich and diversify the rice gene pool and would be useful for the development of durable bacterial blight resistant varieties.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12298-022-01139-x.

Linkage of SSR markers with rice blast resistance and development of partial resistant advanced lines of rice (Oryza sativa) through marker-assisted selection

Rice blast disease is one of the major bottlenecks of rice production in the world including Bangladesh. To develop blast resistant lines, a cross was made between a high yielding but blast susceptible variety MR263 and a blast resistant variety Pongsu seribu 2. Marker-assisted backcross breeding was followed to develop F₁, BC₁F₁, BC₂F₁, BC₂F₂, BC₂F_3, BC₂F₄ and BC₂F₅ population. DNA markers i.e., RM206, RM1359 and RM8225 closely linked to Pb1, pi21 and Piz blast resistant genes, respectively and marker RM276 linked to panicle blast resistant QTL (qPbj-6.1) were used in foreground selection. Calculated chi-square (χ²) value of phenotypic and genotypic segregation data of BC₂F₁ population followed goodness of fit to the expected ratio (1:1) (phenotypic data χ² = 1.08, p = 0.701; genotypic data χ² = range from 0.33 to 3.00, p = 0.08-0.56) and it indicates that the inheritance pattern of blast resistance was followed by a single gene model. Eighty-nine advanced lines of BC₂F₅ population were developed and out of them, 58 lines contained Piz, Pb1, pi21, and qPbj-6.1 while 31 lines contained Piz, Pb1, and QTL qPbj-6.1. Marker-trait association analysis revealed that molecular markers i.e., RM206, RM276, and RM8225 were tightly linked with blast resistance, and each marker was explained by 33.33% phenotypic variation (resistance reaction). Morphological and pathogenicity performance of advanced lines was better compared to the recurrent parent. Developed blast resistance advanced lines could be used as donors or blast resistant variety for the management of devastating rice blast disease.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12298-022-01141-3.

Growth and trend analysis of area, production and yield of rice: A scenario of rice security in Bangladesh

Bangladesh positioned as third rice producing country in the world. In Bangladesh, regional growth and trend in rice production determinants, disparities and similarities of rice production environments are highly desirable. In this study, the secondary time series data of area, production, and yield of rice from 1969-70 to 2019-20 were used to investigate the growth and trend by periodic, regional, seasonal and total basis. Quality checking, trend fitting, and classification analysis were performed by the Durbin-Watson test, Exponential growth model, Cochrane-Orcutt iteration method and clustering method. The production contribution to the national rice production of Boro rice is increasing at 0.97% per year, where Aus and Aman season production contribution significantly decreased by 0.48% and 0.49% per year. Among the regions, Mymensingh, Rangpur, Bogura, Jashore, Rajshahi, and Chattogram contributed the most i.e., 13.9%, 9.8%, 8.6%, 8.6%, 8.2%, and 8.0%, respectively. Nationally, the area of Aus and Aman had a decreasing trend with a -3.63% and -0.16% per year, respectively. But, in the recent period (Period III) increasing trend was observed in the most regions. The Boro cultivation area is increasing with a rate of 3.57% per year during 1984-85 to 2019-20. High yielding variety adoption rate has increased over the period and in recent years it has found 72% for Aus, 73.5% for Aman, and 98.4% for Boro season. As a result, the yield of the Aus, Aman, and Boro seasons has been found increasing growth for most of the regions. We have identified different cluster regions in different seasons, indicating high dissimilarities among the rice production regions in Bangladesh. The region-wise actionable plan should be taken to rapidly adopt new varieties, management technologies and extension activities in lower contributor regions to improve productivity. Cluster-wise, policy strategies should be implemented for top and less contributor regions to ensure rice security of Bangladesh.