Agro-ecological Zones Of Bangladesh Research Articles

Determination of critical limit of soil phosphorous for mustard (<i>Brassica napus</i> L.) and maize (<i>Zea mays</i> L.) in different agroecological zones of Bangladesh

The idea of a critical limit (CL) of nutritional elements distinguishes deficiency from adequacy, which could suggest fertilizer administration. The critical limit can be used to distinguish between responsive (deficiency) and non-responsive (sufficiency) sites. The study aims to estimate the critical limit of phosphorus (P) for mustard and maize in different Agro-ecological Zones (AEZs) of Bangladesh. In this context, the study was conducted in 20 types of soil and two crops (maize and mustard) both in pot and field experiments. Twenty soils from different places were used as experimental materials, among them 12 soil samples had inadequate soil fertility, 4 had low fertility, and the remaining 4 had medium levels of fertility. The treatments were two crops: BARI Hybrid Maize 7 (Maize) and BINA Sharisha 9 (Mustard) and two levels of phosphorus (P): 0 and 15 ppm. Dry matter (DM) yield was calculated and the nutritional content of plant samples was determined. Depending on the chemical properties of the soil, the results ranged from extremely low to very high levels. Reading the mustard crop, the estimated critical levels of P were found to be 14.8 ppm (graphical) and 18.9 ppm (statistical). Regarding the maize crop, the estimated critical P levels were found to be 14.5 ppm (graphical) and 12.3 ppm (statistical). When soil P is less than the CL, plants respond to P-based fertilizer effectively. The results of the trials will assist in managing P fertilizer for the sustainability of maize and mustard production in diverse soil types in different agroecological zones of Bangladesh.

Variations in Morpho-Cultural Characteristics and Pathogenicity of Fusarium moniliforme of Bakanae Disease of Rice and Evaluation of In Vitro Growth Suppression Potential of Some Bioagents

Bakanae is one of the important diseases of rice in Bangladesh that causes substantial yield loss every year. We collected thirty isolates of Fusarium spp. from bakanae-infected rice plants from different agroecological zones of Bangladesh and investigated the variations in cultural and morphological characteristics and pathogenicity. Diversity was found in cultural characteristics, viz., colony features, phialide, chlamydospore formation, shape, and size of macro- and microconidia. Three variants of Fusarium species such as F. moniliforme, F. fujikuroi, and F. proliferatum were identified on PDA media based on their cultural and morphological characteristics. Isolate FM10 (F. moniliforme) exhibited the highest disease aggressiveness in developing elongated plants (26.50 cm), the highest number of chlorotic leaves (5.75), and a lower germination percentage. We evaluated different bioagents against the virulent isolate of F. moniliforme to develop a rice bakanae disease management approach. Four bioagents, viz., Trichoderma spp., Bacillus subtilis, Pseudomonas fluorescens, and Achromobacter spp., were evaluated for growth suppression of F. moniliforme. Among the bioagents, Achromobacter spp. and B. subtilis (BS21) showed 73.54% and 71.61% growth suppression, respectively. The investigation revealed that the application of Achromobacter spp. and B. subtilis (BS21) would be a potential candidate for effective and eco-friendly management of the bakanae disease of rice.

Critical Limit of Manganese for Soybean in Soils of Three Agro-Ecological Zones of Bangladesh

Manganese (Mn) is an essential micronutrient for plants, which influences multiple physiological systems. Determination of the critical limit (CL) of Mn in the soil is necessary for Mn fertilizer application as this limit delineates the deficiency, optimum, and toxicity ranges of Mn. A pot experiment was performed in the winter season with 20 soils collected from three Agro-Ecological Zones (AEZs) of Bangladesh to determine the CL of Mn for soybean (Glycine max L.). Manganese was applied in soil @ 0, 1, 2, and 4 ppm, and the experiment was laid out in a factorial and completely randomized design with three replications. The CL of Mn was determined by the Cate-Nelson graphical and statistical approach and was found 3.60 and 3.55 µg g−1, respectively. Applying 1 µg g−1 Mn in soil significantly enhanced root and shoot weight, as well as seed yield of soybean compared to no Mn application. In field conditions, a significant positive response of soybean yield was found up to the CL of Mn. The findings of the study could help predict possible Mn deficiency in soil and soybean response to Mn fertilizer, which is important in decision-making for efficient fertilizer management practices to ensure the yield potential of soybeans.

Determination of Critical Limit of Zinc for Lentil (Lens culinaris L.) in Diverse Soils under Intensive Cropping Systems

Determination of the critical limit (CL) for nutritionally essential zinc (Zn) is very important in developing fertilizer recommendations for crops and soils. However, the CL of Zn for the lentil crop has not been determined yet in Bangladesh, leading to the use of a fertilizer rate for the crop estimated on the basis of old critical limit generalised for all crops. A study was conducted in the Greenhouse facilities of the Soil Science Division of BARI, Gazipur, from October to April (Rabi season) of 2018/2019 and 2019/2020, to determine Zinc CL for soils and lentil crop in soils collected at twenty locations encompassing the six Agro-Ecological Zones (AEZs) of Bangladesh. For extraction of available Zn concentrations from soils and lentil biomass, a diethylene triamine penta acetic acid (DTPA) (0.005 M) solution was used. The DTPA-extractable Zn (mg kg-1) in the soils were from 0.43 to 4.10 and from 0.52 to 4.20 in 2018/2019 and 2019/2020, respectively. In all seasons, accessible Zn had negative but substantial correlations with soil pH, soil P, Ca, and Mg in available forms, but the association between available Zn and lentil dry matter was positive and significant (DM). Soil Zn had also a positive significant correlation with Zn concentration of lentil tissue Zn (0.501**). In 2018-2019 and 2019-2020, the CL of EDTA-extractable Zn was determined to be 0.75 mg kg-1 and 0.68 mg kg-1 in soils for lentil crop (0.72 mg kg-1 on an average), respectively, while it was 48.6 mg kg-1 for lentil tissue. The revised CL can be used for fertilizer recommendation for the lentil crop in the entire Gangetic Plains and other Agro-Ecological Zones of Bangladesh. Keywords: Pulse crop, Nutrient management, Micronutrient, Dryland crop, Sustainable agriculture

Development of Short Duration, Tolerance to High Temperature and Bipolaris Leaf Blight, and Moderately Susceptible to Blast Disease of Wheat Genotype with Trials in Various Agroecological Zones in Bangladesh

Wheat production in Bangladesh faces to the detrimental effects of biotic and abiotic stresses that have been exacerbated by climate change. The development of short duration, high temperature and disease tolerant wheat variety is the most importance to produce higher yield combating the deleterious effects of the stresses. Some wheat lines (line was expressed by E) were evaluated at the different research stations of Bangladesh Wheat and Maize Research Institute (BWMRI) and farmers’ fields in consecutively three years under irrigated timely sowing (ITS) and irrigated late sowing (ILS) conditions. The days to heading (DH), days to maturity (DM), plant height (PH), spikelet spike-1 (SPS), grain spike-1 (GPS), thousand grain weight (TGW), and grain yield were depicted comparatively higher in ITS and ILS than ITS, but the severity of Bipolaris leaf blight (BpLB) and blast diseases were exhibited lower in BAW 1194 (E9) line than check varieties and other lines same conditions (BAW = Bangladesh Advanced Wheat). Those phenotypic and yield contributing characters, and BpLB and blast diseases were also observed lower in ILS than other genotypes. Further, E9 exhibited the lower percentage of yield loss in the ILS compared to ITS than check and other genotypes indicated its high temperature tolerance. In addition, E9 exhibited relatively higher grain yield than other genotypes in the candidate variety demonstration and multiplication yield trials. Therefore, BAW 1194 line may be released as a short duration, tolerance to high temperature and BpLB, and moderately tolerance to blast disease wheat variety to accelerate wheat production.

Carcass and meat quality attributes of native sheep in Bangladesh: A review

Three native sheep breeds like Jamuna basin, Barind tract and Coastal belt that used to rear in semi-intensive systems in three agro-ecological zones of Bangladesh. The quality of meat is a multifactorial trait dependent on the perspective and goals of the link in the production chain. In this review an attempt has been made to present detail carcass traits and meat quality attributes of native sheep in relation to other sheep breeds. Some factors that influence carcass traits and the quality of lamb meat namely proximate component, physicochemical traits, sensory attributes and instrumental color values were considered in this review.

Effect of Sowing Date and Phosphorus on Growth, Seed Yield and Quality of Fenugreek

The effect of sowing date (three sowing dates viz., S1= 01 November, S2= 15 November and S3= 30 November) and phosphorus levels (four phosphorus fertilizer levels viz., P0= Control, P1= 35 kg P ha-1, P2= 45 kg P ha-1 and P3= 55 kg P ha-1) on growth, seed yield and quality of fenugreek was investigated at Horticulture Farm, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh, during 10 October 2020 to April 2021. Growth-related data was maximum on S1 (01 November) treatment but S2 (15 November) treatment showed the best result in case of seed yield. In case of growth characters, P3 (55 kg ha-1) revealed the best result but in case of seed yield, P2 (45 kg ha-1) treatment showed the best effect. Under this investigation, it was revealed that the maximum growth was obtained by S1P3 (01 November with 55 kg P ha-1) and the minimum growth was obtained by S3P0 (30 November with control) treatment combination. The maximum pods per plant (52.61), seeds per pod (12.87), weight of individual pod (147.11 mg), the weight of seeds per plant (7.67 g) and weight of 1000-seed (13.86 g), seed yield per plot (306.72 g), seed yield per hectare (2.13 t) and vigor index (570.27) was observed from the treatment combination S2P2 (15 November with 45 kg P ha-1). It was concluded that the combination of sowing date S2 (15 November) along with phosphorus application P2 (45 kg P ha-1) were given the better performance of all the yield contributing parameters and seed yield of fenugreek. So, S2P2 (15 November with 45 kg P ha-1) treatment combination can be repeated in different agro-ecological zones of Bangladesh.

Weather parameters largely regulate the outbreak of rice bacterial blight: an endemic disease poses a threat for food security in Bangladesh

Bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae is a destructive disease of rice causing significant yield losses. Surveys were conducted to know the influence of weather parameters on epidemic development of BB in the thirty agroecological zones of Bangladesh. The maximum (55.11%) bacterial blight incidence and severity were recorded Mymensingh division (AEZs 8 and 9) while the minimum (3.25%) incidence was observed in Barishal division (AEZ 13) in both rainfed and irrigated seasons. In rainfed conditions, the maximum BB incidence and severity were recorded in hybrid varieties Aloron from Netrokona (AEZ 9) and the minimum incidence was observed in the local variety Sughondi from Jalhokhati (AEZ 13). On the other hand, in irrigated conditions, the highest BB incidence was recorded in the hybrid variety Hera-2 from Netrokona (AEZ 9) and the lowest incidence was observed in the local variety from Hobiganj (AEZ 20, 21, 22). Swarna, Puja, BRRIdhan28, BRRIdhan29, and BRRIdhan49 showed intermediate levels of infection, while hybrid Hera-2, Arize TejGold, Partex, Agrodhan, Aloron, ACI-2, and Dhani Gold showed higher level of infection (susceptibility) to BB. The data analysis on BB incidence with the weather parameters of rice growing seasons from 2015 to 2017 revealed that the rainfall distribution varied greatly within rice growing seasons over the years. The results indicated that weather parameters, viz. temperature (25-34°C), relative humidity (70-84%), and rainfall (>200mm), largely affected the prevalence, incidence and severity of BB. The correlation studies revealed that, among the climate variables, minimum temperature exhibits a negative correlation. However, rainfall, maximum temperature, morning relative humidity and evening relative humidity were found positively correlated, while wind velocity imparted a significant positive correlation with BB infection. The regional outbreak of BB indicated a considerable yield loss of rice and give rise a threat for food security of the country.

Genetic variation of Meloidogyne spp. of brinjal reveals their difference in pathogenicity and hatching

Brinjal (Solanum melongena L.) is an important vegetable worldwide and its production is hampered by the infestation of root-knot nematodes (Meloidogyne spp.). In an attempt to identify the Meloidogyne species involved in causing root-knot disease of brinjal by using molecular tools, plants showing knots/galls were collected from 22 brinjal growing locations that belong to different agro-ecological zones in Bangladesh. Nematode populations were maintained in a susceptible brinjal variety by inoculating with egg-masses developed on different varieties of brinjal roots collected from different locations. For molecular identification, DNA was extracted directly from galls developed in the roots of the inoculated plants. Randomly selected three galls from each location were crushed together in order to get DNA from mixed species of root-knot nematodes. Sequence Specific Amplified Region (SCAR) primers specific for Meloidogyne incognita, M. javanica or M. arenaria were used for PCR amplification. For 18 of the 22 locations, M. javanica was identified. At two locations M. incognita was found as a mixed population with M. javanica. M. arenaria was not found. PCR products were sequenced bi-directionally and their analysis revealed genetic variation among the populations. M. javanica was the predominant root-knot nematode species of brinjal in Bangladesh. Intra-specific variation of the SCAR suggested six phylogenetic groups of M. javanica. They showed significant differences in reproduction on brinjal and in their effect on root and shoot weight, while differences in hatching dynamics over five weeks were not significant. This population-dependent aggressiveness of the dominant root-knot nematode M. javanica on brinjal in Bangladesh should be considered for a more efficient management.

Prevalence of the Alternaria blight of cumin (Cuminum cyminum L.) in Bangladesh: Morphology, phylogeny and pathogenic variation of Alternaria spp.

Cumin (Cuminum cyminum L.) is an important spice crop worldwide and its production is hampered by the infection of Alternaria blight. Cultivation of cumin in Bangladesh is very limited due to the lack of appropriate germplasm and adequate scientific information regarding the prevalence of Alternaria blight. Field trials were conducted with four advanced lines of cumin viz. CN026, CN028, CN031 and CN038 in five agro-ecological zones (AEZ) to know the adaptation possibility of these lines against the incidence and severity of Alternaria blight of cumin in Bangladesh. Among all lines, CN026 was found as the best in germination capacity and other yield parameters in all locations. The incidence and severity of the disease was observed as high as 98% and 88%, respectively, however, out of the five locations, the incidence and severity of the disease was the lowest in Bogura for the line CN026. In an attempt to identify the causal organism of the Alternaria blight of cumin by using molecular tools, a total of twenty three isolates were collected from the plants showing Alternaria blight symptoms from different AEZ in Bangladesh. Based on the molecular analysis, the isolates were identified as Alternaria alternata, A. burnsii, A. gaisen and A. tenuissima. A. alternata was the most prevalent species followed by A. tenuissima. The isolates of the identified species were found to have genetic, morphological and pathogenic variation. An isolate of A. alternata was observed as the most virulent among the isolates. This is the first report of A. alternata causing Alternaria blight disease of cumin in Bangladesh. The findings of this experiment will help in selecting suitable cumin germplasm and designing proper management strategies against Alternaria blight of cumin in Bangladesh.

Quantity-to-intensity (Q/I) relationships can efficiently characterize intensively cultivated agricultural soils in Bangladesh for better potassium supplying capacity

Aim of the study: Firstly, to evaluate the K dynamics of soils through a quantity-intensity isotherm study; and secondly, to characterize the soils on the basis of quantity-intensity (Q/I) parameters.Area of study: Gazipur, BangladeshMaterial and methods: Eleven soils collected from major agro-ecological zones in Bangladesh were evaluated for their varying K dynamics parameters, and K supplying capacities of these soils were described.Main results: The Q/I plot showed both linear and polynomial relationships for soils in the study. The eleven soils had labile K ranging from 0.022 in Palashbari clay loam to 1.35 cmol kg-1 in Barisal clay. The latter soil had the highest equilibrium K activity ratio (0.003 mol L-1)1/2 and potential buffering capacity (PBC) (460.4 (cmol kg-1) (mol L-1)1/2). The PBC of soils for non-exchangeable pool (PBCne) was much higher than that of exchangeable pool (PBCe) in most soils. The largest amount of PBCne and PBCe occurred in Barisal clay, Gopalpur clay, Jhalokathi clay and Nachol loam which had a higher K desorption rate than all the other soils. The equilibrium exchangeable K, critical exchangeable K and equilibrium solution K of the soils varied widely (0.0006-0.035, 0.06-0.61 and 0.06-0.604 cmol kg-1, respectively). The added K was converted almost equally for the respective soils, with specific reference to the respective exchangeable and non-exchangeable pool for Barisal clay and Nachol loam.Research highlights: All the studied parameters revealed wide variations among the soils. The linear and polynomial relationships for soils can efficiently characterize intensively cultivated soils in Bangladesh.

Potassium Fractions and Rice Yield in Different Agro-ecological Zones of Bangladesh

Response of Potassium (K) is boosted due to the introduction of high-yielding varieties and cropping intensity. So, a pot experiment was done to see the allocation of native and added K in soils and the response of this on rice. Seven soil samples from seven AEZs. An amount of 1-kilogram soil was taken in each of 28 earthen pots of which 14 pots for cultivation rice and 14 pots for without cultivation as a control. Potassium and other fertilizers applied as follows Fertilizer Recommendation Guide-1012. Two replicate plots were used per treatment. Then the soils were saturated with water so that the soils could be soaked well. The pots were kept in this condition for one day to allow the soils to settle in the pots properly. The rice variety used for the experiment was BRRI dhan28. All forms of K were found to remarkable decrease due to cultivation. The depleted non-exchangeable K sum was the largest, this was followed by exchangeable and then, in control plots, water-soluble K. The depleted amount of exchangeable and non-exchangeable K was almost similar but higher than water-soluble K in treated pots. A significant variation was found among the yields ranging from 3.77 to 5.48 g pot-1. The average dry matter yield of treated pots 4.75 g pot-1 was significantly higher than non-treated pots 3.10 g pot-1.

Adaptation of Promising Rice Genotypes for Broadcast Aus Season

Rice cultivation in Aus season is eco-friendly and essential for sustainable food security of Bangladesh utilizing rain water rather than extracting underground water. Four rice genotypes (BR6855-3B-12, BR6855-3B-13, BR6848-3B-12 and BR6976-2B-11-1) along with check variety BRRI dhan43 were evaluated at farmers’ field during broadcast Aus season. The objectives were to investigate the adaptability of the rice genotypes and find out promising genotype(s) for Broadcast Aus rice. The experiment was conducted at farmers’ field in eight agro-ecological zones of Bangladesh. Randomized complete block design (RCB) was used with three replications. Standard and uniform management practices were followed for all the locations. Data were taken on grain yield, days to 80% maturity, plant height, panicles m-2, 1000-grain weight, grains panicle-1, spikelet sterility (%), Phenotypic acceptance at vegetative and maturity stage, pest incidence; feedback of farmers and extension personnel. Genotypes, environments and interaction of genotypes by environments had significant effect on grain yield, yield components and agronomic parameters. Analysis of variance indicated that there were significant differences between the check (control) and improved genotypes except the genotype BR6976-2B-11-1 which was similar with the check BRRI dhan43 for all parameters. Correlation analysis was also performed to establish extent of association between yield and major yield components. Grain yield positively and significantly correlated with the agronomic parameters except spikelet sterility. Across the locations, BR6848-3B-12 produced significantly the highest grain yield (4.88 t ha-1) at Feni while the lowest grain yield (1.58 t ha-1) was obtained in BR6976-2B-11-1 followed by BRRI dhan43 (1.64 t ha-1) at Kushtia. BR6848-3B-12 showed yield advantage of 1.0 t ha-1 over the check variety BRRI dhan43 with similar growth duration (104 day). AMMI stability value, yield stability index and GGE Bi-plot model indicated that BR6855-3B-12 is the most adaptable, suitable and stable genotype for broadcast Aus rice across the locations, and finally it is released in 2017 as BRRI dhan83 for broadcast Aus season.
 Bangladesh Rice j. 2019, 23(2): 35-48

Climate change impacts on farmland value in Bangladesh

Many studies have examined the effects of climate change on farmland value in developed countries, but our understanding of the impact of climate change on farmland value is still very limited, especially in developing countries. In this study, we aimed to assess the effects of climate change on farmland value in Bangladesh using the Ricardian model. Household-level data collected from seven selected agroecological zones in Bangladesh were used to estimate the relationships among farmland value and long-term climate, farm household, and policy variables. The results showed that the current land values of farmers are sensitive to climate. A new variable called “flooding” was added to the Ricardian model, and the results indicated that floods are responsible for reductions in farmland value, especially in lowland areas. Among the socio-economic variables, the availability of extension services and access to irrigation facilities were positively correlated with farmland value. The estimated marginal impact results suggested that increases in temperature were associated with losses in small farmland value, whereas the precipitation levels in both seasons positively influenced farmland value. Selected global climate models predicted that climate change would have a negative impact on land value depending on the climate model and source of farm income. The empirical findings obtained from this study are expected to contribute to the formulation of sustainable adaptation strategies to maintain farm productivity and farmland value in Bangladesh in the context of climate change.

Performance of Boro rice cv. BRRI dhan28 as influenced by different plant establishment methods and weeding regimes

At present time food safety is a precedence issues in Bangladesh and it is essential to increase the production level of rice to address this mission. The study was undertaken to evaluate the yield performance of boro rice cv. BRRI dhan28 under different plant establishment methods and weeding regimes. The experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during December 2017 to June 2018.It was a two factor experiment that comprehended three plant establishment methods viz. sprouted seeds in line, sprouted seeds in broadcasting and transplanting of seedlings in line; five weeding regimes viz. no weeding, one hand weeding at 20 day after planting (DAP), two hand weeding at 20 and 40 DAP, three hand weeding at 20, 40 and 60 DAP, and application of herbicide (Sathi 10WP @ 185 g ha-1). The experiment was set up following randomized complete block design with three replications. Yield contributing characters and yield of Boro rice were exerted significantly by plant establishment methods and the highest results were recorded in transplanting of seedlings in line method in which the number of total tiller hill-1 (6.39), number of effective tiller hill-1 (5.93), grains panicle-1 (99.28), 1000 grain weight (24.16 g) and grain yield (4.19 t ha-1). And the lowest results were found in sprouted seeds in broadcasting method. Considering weeding regimes, the highest number of total tillers hill-1 (6.03), effective tillers hill-1 (5.28), grains panicle-1 (101.4), grain yield (4.12 t ha-1) and straw yield (5.74 t ha-1) were recorded with application of herbicide method. Contrariwise, no weeding showed the lowest values. In interaction effect, maximum grain yield (4.48 t ha-1) was obtained in transplanting of seedlings in line method with application of herbicide and Sprouted seeds in broadcasting method with no weeding was performed the lowest grain yield (2.86 t ha-1). From the overall results, the growers can be recommended to cultivate boro rice cv. BRRI dhan28 in transplanting of seedlings in line method with application of herbicide at different Agro-ecological zones of Bangladesh.

Factors influencing adoption of crossbred cattle in different agro-ecological zones of Bangladesh

Crossbred cattle farming by small farm holders are one of the promising agricultural activities to enhance financial and nutritional status of the rural people of Bangladesh. Several factors influence the rural farmers to raise the crossbred cattle farming. Thus, the research investigates the demographic, socioeconomic and agro-ecological factors and farming assets and facilities of the small farm holders that influence the adoption of crossbreds. Multistage random sampling technique was used to random selection of 300 cattle households in four agro-ecological zones. Chi-square tests were carried out to assess the association between cattle breeds and levels of variables. Also, the binary logistic regression model was used to determine the effects of the factors. Age group, level of education, occupation, household income, farming experience and reception of extension services were significantly (p<0.01) associated with the adoption of crossbred cattle. Extension services (OR=128.82, 95%CI=27.74-598.2) and higher income group (OR=6.138, 95%CI=1.352-27.87) were significant and more likely to adopt crossbred cattle compared to no extension services and low-income group respectively. Secondary educated farmers were 3.64 times more likely (OR=3.642, 95%CI=1.24-10.67) and higher than secondary educated farmers were 7.58 times more likely (OR=7.579, 95%CI=2.45-23.40) to adopt crossbred cattle compared to illiterate or primary educated farmers. Industrial zone was more likely and other two zones were less likely to adoption of crossbred cattle compare to river basin zone. Youths should be trained and educated and also extension services should be provided to the farmers to raise crossbred cattle for increased milk production and household poverty alleviation.

Molecular Identification and Evaluation of Indigenous Bacterial Isolates for Their Plant Growth Promoting and Biological Control Activities against Fusarium Wilt Pathogen of Tomato

In search of an effective biological control agent against the tomato pathogen Fusarium oxysporum f. sp. lycopersici, rhizospheric soil samples were collected from eight agro-ecological zones of Bangladesh. Among the bacteria isolated from soil, 24 isolates were randomly selected and evaluated for their antagonistic activity against F. oxysporum f. sp. lycopersici. The two promising antagonistic isolates were identified as Brevundimonas olei and Bacillus methylotrophicus based on morphological, biochemical and molecular characteristics. These two isolates were evaluated for their biocontrol activity and growth promotion of two tomato cultivars (cv. Pusa Rubi and Ratan) for two consecutive years. Treatment of Pusa Rubi and Ratan seeds with B. olei prior to inoculation of pathogen caused 44.99% and 41.91% disease inhibition respectively compared to the untreated but pathogen-inoculated control plants. However, treatment of Pusa Rubi and Ratan seeds with B. methylotrophicus caused 24.99% and 39.20% disease inhibition respectively. Furthermore, both the isolates enhanced the growth of tomato plants. The study revealed that these indigenous bacterial isolates can be used as an effective biocontrol agent against Fusarium wilt of tomato.

Productivity, nutrient balance, and economics of monsoon rice under different nutrient management practices in two agro-ecological zones of Bangladesh

Abstract Inherently poor soil fertility and non-adoption of fertilizer recommendations based on soil test and yield targets by farmers limit the productivity and profitability from monsoon rice in Bangladesh and much of South Asia. In the Level Barind Tract (LBT; AEZ-25) and the High Ganges River Floodplain (HGR; AEZ-11) agro-ecological zones (AEZs) of Bangladesh, monsoon (aman/kharif) season transplanted rainfed rice (known as T. aman rice) is grown in large areas after maize, wheat and/or mungbeans, with residues of each crop removed from the field after grain harvest. This results in lower grain yield and lower profits in these AEZs as compared with other AEZs. Nutrient management, based on soil test, yield targets, or integrated use of inorganics and organics for each AEZ together with retention of crop residue, has the potential to increase rice yield, reduce production cost and increase income. With this hypothesis, this study was conducted to determine the optimum nutrient management practices for achieving higher yield, maintaining apparent soil nutrient balance, and obtaining high profits from monsoon rice. Twelve nutrient management options were evaluated, of which the first six were: (i) 80-16-44-12-2 kg ha-1 of N, P, K, S, Zn respectively for a high yield goal (T1; ‘HYG’); (ii) 56-12-32-8- 1.5 kg ha-1 respectively for a medium yield goal (T2; ‘MYG’); (iii) 65-13-32-9-2 kg ha-1 respectively plus 5 t ha-1 cowdung as integrated plant nutrient management system (T3, ‘IPNS’); (iv) 67-14-41-9-2 kg ha-1 respectively as a soil test-based fertilizer management strategy (T4; ‘STB’); (v) 40-9-11-0-0 kg ha-1 respectively as per farmers’ practice (T5; ‘FP’) and (vi) 0-0-0-0-0 kg ha-1 as a control (T6; ‘CON’). The remaining six treatments were the same as above but each also included the crop residue incorporation (CRI), i.e., (vii) T7, ‘HYG+CRI’; (viii) T8, ‘MYG+CRI’; (ix) T9, ‘IPNS+CRI’; (x) T10, ‘STB+CRI’; (xi) T11 ‘FP’+CRI’; and (xii) T12, ‘CON+CRI’. In both AEZs, STB plus CRI resulted in the highest rice yield (p≤0.05) followed by ‘STB’ and ‘IPNS+CRI’. In comparison with ‘FP’ and ‘CON’, each without CRI, balances were positive (p≤0.05) for P, S, Zn and B but were negative for N and K in ‘HYG’, ‘MYG’, ‘IPNS’ and ‘STB’ with or without CRI. In both AEZS, STB nutrient management had the highest (p≤0.05) net returns (526 &amp; 487 US$ ha-1, respectively), highest benefit cost ratio (BCR; 3.54 &amp; 3.36) and highest marginal benefit cost ratio (MBCR; 10.47 &amp; 10.19). These were followed by STB+CRI’ and ‘IPNS’, while they were lowest (p≤0.05) for CON and FP. We recommend that nutrient application, based on soil test with incorporation of mungbean residue, followed by IPNS, could be the best strategies for achieving high yield, improving soil fertility and for fetching a higher profit from monsoon rice in Bangladesh and similar soils and growing environments of South Asia.

Stability of hybrid rice genotypes for grain yield and maturity

An experiment was conducted using nine hybrid rice genotypes along with two inbred standard check varieties in five different locations of Bangladesh to assess their stability in terms of grain yield and maturity in diverse environments. For this, adaptability, stability, genotype × environment (G×E) interaction effect for grain yield and maturity of 11 rice varieties in five agro ecological zones in Bangladesh were assessed during T. Aman season of 2015. The analysis of variance for growth duration and grain yield (t/ha) for genotypes, environment and genotype-environment interaction were highly significant at 1% level of probability indicating the variable response of genotypes and environments. The hybrid genotypes IR79156A/BRRI20R, BRRI hybrid dhan3, BRRI33R/BRRI26R, BRRI hybrid dhan4, standard check variety BRRI dhan49 and BR11 had high yield performance and widely adapted to all environments and these were non sensitive to environmental interactive forces, while the hybrids BRRI7A/BRRI31R, IR79156A/BasmatiR and SL-8 were sensitive to environmental interaction. Environment such as Gazipur (E1) and Faridpur (E3) having positive IPCA1 score and positive interaction with the hybrids BRRI7A/BRRI13R, SL-8H and IR79156A/BasmatiR were considered as the favourable environments for these hybrids.Bangladesh J. Agril. Res. 43(1): 99-108, March 2018

Coping with flashflood under changing climate in north-eastern haor areas of Bangladesh: potentials of promising crop production practices

Haors are large bowl shaped fl oodplain depressions and one of the most important agro-ecological zones in Bangladesh. However, rice production in this area has been severely impacted by recent events of frequent early fl ashfl oods. Many experts have linked the changes of fl ooding time and duration in haor area to global climate change. Farmers need short duration, relatively tall, lodging tolerance and non-shattering rice varieties to cope with the fl ashfl ood. With this contrast, this study is conducted in Tahirpur and Biswambarpur upazila of Sunamganj district to examine occurrence time and duration of fl ashfl ood; identify fl ashfl ood coping crop production practices; and fi nally investigate relationship between socio-economic characteristics of farmers and their fl ashfl ood coping crop production practices. Hence, this study utilizes a set of approaches viz. structured questionnaire survey, key informants interview with stakeholders and focus group discussions to get primary data and secondary data also collects to conceptualize the problems. Results reveal that short duration, varietal diversifi cation, tall plant type of rice varieties are found popularly used practices in haor area. Although other coping practices like harvesting of rice at 80 percent maturity, early transplanting, aged seedling and rabi crops have substantial impact in coping fl ashfl ood but they are not extensively practiced. Study also reveals that education levels of farmers have highly positive and signifi cant relationship with fl ashfl ood coping crop production practices; high coping practices are observed in educated farmers. In order to increase coping ability of farmers of farm practices, it is utmost important to link between government and development agencies to provide adequate technical support, extension service, education, income generating opportunity and water conservation measures.