Thirty-Year Spatiotemporal Change Record of Sundarban Mangrove Forest in Bangladesh

Accurate and realistic forest cover change assessment is essential for the conservation and management of the Sundarban mangrove forest of Bangladesh. With these views, an integrated way of the vegetation cover assessment was conducted using time-series Landsat satellite imageries of 1991, 2001, 2011, and 2021. During the last 30-year (1991-2021), variations in four land cover classes viz. healthy vegetation, unhealthy vegetation, water body, and sandbar were recorded. It showed a decreasing trend of forest vegetation and a subsequent increase of water bodies during the study period. The healthy vegetation and unhealthy vegetation decreased at 1.33 and 1.66%, respectively, whereas water bodies increased 2.55% at the same time. The healthy vegetation consistently decreased over the decades, but unhealthy vegetation decreased during the 2001-2011 period. Conversion from healthy vegetation to unhealthy vegetation and unhealthy vegetation to healthy vegetation during 1991-2001 was similar. Such transform was much higher from unhealthy to healthy vegetation during 2001-2011. Transformation of healthy vegetation to unhealthy vegetation was remarkably higher during the 2011-2021 period. Further continuous change detection and classification algorithm (CCDC) showed a stable pattern over the study period without significant breakpoints. This study reveals the need for regular mangrove forest monitoring. The findings of this study can be used as a reference in the formulation and implementation of sustainable mangrove forest conservation and management. Ann. Bangladesh Agric. (2020) 24(2): 15-32

Inhibitory Effect of Trichoderma asperellum Isolate against Ralstonia solanacearum Causing Brinjal Wilt

A native Trichoderma isolate was collected from the agricultural soil of Gazipur. This isolate was identified as a Trichoderma asperellum through morphology and analysis of internal transcribed spacer (ITS) region of ribosomal RNA gene sequence and reconstruction of the phylogenetic tree. The antagonistic effects of the newly identified T. asperellum isolate were assessed against brinjal bacterial wilt caused by Ralstonia solanacearum both in vitro and in planta. Both qualitative and quantitative bioassays were conducted in vitro. For qualitative tests, dual culture and antibacterial activity were carried out, and pathogen growth was observed visually. The antagonism of T. asperellum cell free culture filtrate on the growth of R. solanacearum was conducted in a quantitative test. Successful antagonism was recorded after both in vitro qualitative tests. In addition, the lowest colony forming unit was recorded in 100% of CFC (2.4±0.51 ×103 cfu/ml) in quantitative test. The T. asperellum inoculated plant showed low disease incidence (13.33%) when seedlings were challenged with R. solanacearum in planta experiment. Disease incidence was 100% for seedlings when treated with only R. solanacearum. The results showed that the isolated and identified T. asperellum isolate suppressed R. solanacearum growth in vitro and protected the seedling from wilting in planta. Therefore, this isolate could be considered as a potential isolate. Ann. Bangladesh Agric. (2020) 24(2) : 107-120

Effect of Native Trichoderma asperellum Isolate on Phosphate Solubilization and Growth of Pea

Application of phosphorus solubilizing microbes is a promising tool for enhancing P uptake in plant. The aim of this study was to evaluate the phosphate solubilization potential and growth promotion of pea (Pisum sativum L.) by native Trichoderma asperellum isolate G3. Phosphate solubilization by T. asperellum strain was assessed in National Botanical Research Institute’s Phosphate (NBRIP) broth medium. Pea plants were inoculated by Trichoderma strain and grown in pot in phosphate deficit condition. The fungal strain was able to solubilize phosphate (from 188.95±2.04 to 262.50±3.80 mgL-1) in broth at different time periods and decreased solution pH. The Trichoderma inoculated pea plant increased the root growth, shoot growth, leaf number, shoot biomass, root biomass, total dry weight, chlorophyll a, chlorophyll b and carotenoid by 23.9%, 33.3%, 33%, 37.1%, 32.7%, 28.4%, 24.5%, 17.4% and 14.7% respectively over control after 5 weeks of post inoculation. The results showed that the native T. asperellum isolate G3 has great potential in the phosphorus solubilization. Ann. Bangladesh Agric. (2020) 24(2) : 121-124

Morphological and Molecular Characterization of Soybean (Glycine max L.) Genotypes undre Salt Stress

Three advanced lines (SB02, SB05, SB07) along with one tolerant (Lokon) and one susceptible check (Asswt) of soybean (Glycine max L.) were assessed for salt tolerance in terms of morpho-physiological traits and molecular markers (SSR). The experiment was conducted at seedling stage with four salinity treatments namely 0, 8, 12 and 16 dSm-1 following Completely Randomized design. All the genotypes displayed considerable reduction in their morphological traits, least affecting the tolerant one. None of the genotypes were survived at 12 and 16 dSm-1 stress condition. Among the lines tested, SB-02 and SB-05 were identified as salt tolerant at 8 dSm-1 based on salinity susceptibility index (SSI) scoring. These genotypes suffered less in reduction of leaf chlorophyll content (SPAD) and increase of Na+/K+ than the susceptible genotypes. For all the traits viz. shoot length, root length, total length, shoot fresh weiht, root fresh weight, shoot dry weight, root dry weight, total fresh weight, total dry weight, percent live leaves, chlorophyll content and Na+/K+ ratio, the phenotypic coefficient of variation (PCV) was higher than that of genotypic coefficient of variation (GCV). All the traits studied showed medium to high heritability ranging between 43.81% (SPAD) to 96.65% (shoot length). The genotypes were grouped into two clusters considering both Euclidian distance and Unweighted Pair Group Method with Arithmetic Mean analysis. Lokon, SB-02 and SB-05 are on the same cluster as tolerant, and SB-7 and Asset on the other as susceptible to salt stress. The molecular pattern using by SSR marker displayed an average number of 3.33 alleles per locus with PIC (Polymorphism Information Content) values ranged from 0.2688 (sat_655 and satt728) to 0.7680 (sat_210). The highest gene diversity was observed in sat_210 and satt237 and the lowest in sat_655 and satt728 with a mean diversity of 0.5733. The genotypes Lokon, SB-02 and SB-05 could be suggested as a potential germplasm source of QTL (Quantitative Trait Loci) analysis for the development of salt tolerant soybean variety. Ann. Bangladesh Agric. (2020) 24(2): 33-46

Pathology of Fowl Paratyphoid and Molecular Detection of Its Pathogen in Layer Chickens

The study was aimed to ascertain the pathology of fowl paratyphoid and molecular detection of its causal agent (Salmonella spp) in chickens. Pathological and swab samples were collected from layers in Gazipur district, Bangladesh. For observing the gross and microscopic lesions of different organs necropsy and histopathology were done, and to isolate and identify the Salmonella spp, different bacteriological tests and Polymerase Chain Reaction (PCR) were performed. Swabs from 150 chickens showed 66% of salmonellosis. Gram’s staining of isolated bacteria showed pink colored rod shaped bacilli. In biochemical tests, Salmonella fermented dextrose, maltose, xylose, arabinose, dulcitol, mannitol except lactose and sucrose. Investigation of gross lesions at necropsy revealed hemorrhage and congestion in intestine, liver, spleen and ovaries. Necrotic foci were found in liver and spleen, and button like ulceration in cecal tonsils as well. Microscopic lesions included hemorrhage and focal necrosis in liver and spleen. Congestion and infiltrations of inflammatory cells were observed in small intestine. Ovary was hemorrhagic and there was infiltration of heterophils. Biochemically positive and isolated Salmonella organisms were confirmed by PCR method using invA and IE1 primers. The final results showed that a total of 91.7% Salmonella suspected cultures were confirmed as Salmonella Enteritidis. Ann. Bangladesh Agric. (2020) 24(2) : 47-57

Evaluation of Growth and Yield of Sweet Pepper (Capsicum annuum) Varieties under Net Protected Conditions

An experiment was conducted at the experimental field of Horticulture Department, Sylhet Agricultural University, Bangladesh during winter season of 2013-2014 to evaluate growth and yield of sweet pepper varieties under net protected condition. The two-factor experiment was laid out in Randomized Complete Block Design with three replications. Three popular sweet pepper varieties viz. BARI Mistimorich-1, California Wonder and Yolo Wonder were grown under three protected systems viz. fine net (120 mesh), coarse net (40 mesh) and open field. Considering the effect of varieties, the highest value for all the parameters viz. fruit length (10.01 cm), fruit diameter (5.90 cm), number of fruits/plant (13.61), fruit yield per plant (0.77 kg), fruit yield (21.31 t/ha) were found in California Wonder followed by BARI Mistimorich-1 and Yolo Wonder. Again, considering the effect of net protection system, maximum values for parameters viz. early flowering, fruit length (10.58 cm), fruit diameter (6.29 cm), number of fruits/ plant (16.14), fruit yield/plant (0.94 kg) and per hectare (26.86 t/ha) were recorded under fine net protection system. Under fine net covering plants produced better quality fruit than open field condition. The earliest flowering (60.67 days), the highest number of fruits per plant (19.18) and the maximum fruit yield (35.71 t/ha) were observed in BARI Mistimorich-1grown under fine net system followed by California Wonder grown under coarse net protected system. Benefit cost ratio (BCR) for fine net (5.28) and coarse net (6.75) protected system were much higher than that of open field (1.64) condition indicating bright future for sweet pepper cultivation under net protected system. Ann. Bangladesh Agric. (2020) 24(2) : 85-94

Influence of Cage Shapes on Growth and Production of Silurid Catfish (Mystus cavasius) in Earthen Pond

Influence of three cage shapes viz (i) rectangular ii) square, and (iii) circular on growth and production of Mystus cavasius (local name: gulsha) was studied in earthen pond conditions for a period of 120 days. Each of nine cages, which were made of polyethylene nets, had same internal area (1.80 m3) and stocked with M. cavasius fry at the rate of 300 m-3, following a completely randomized design. Fishes were fed with a commercial floating pellet feed (Mega 002) initially at the rate of 25% of average body weight, with a gradual reduction to 8%. Significantly higher (P<0.05) average weight gain (AWG) of 13.49 ± 0.14 g, with specific growth rate (SGR) of 1.87% day-1, and the survival rate of 89.41% were recorded for gulsha reared in the circular cage compared to the other shapes. Rectangular and square cages resulted in a similar (P>0.05) AWG of 10.29 ± 0.10 and 10.43 ± 0.25 g with survival rate of 80 and 83.61%, respectively. A significantly higher (P<0.05) average total production of 4.05 ± 0.21 kg/m3 was obtained with circular cage compared to a similar production of 2.72 ± 0.28 and 3.08 ±0.29 kg/m3 (P>0.05) in rectangular and square cages, respectively. In case of lengthweight relationship (LWR), the coefficient of determination values (r2) was 0.86, 0.90, and 0.85 in square, circular and rectangular cages, respectively indicating a good linear regression between length and weight in circular cages than square and rectangular cages. Taken together, these results indicate that circular cage is the best for growth, survival and production of gulsha culture in pond condition. Ann. Bangladesh Agric. (2020) 24(2): 59-68

Determining Planting Window for Growing Upland Cotton (Gossypium hirsutum L.) during Dry Season in Bandarban, Bangladesh

Farmers in the Chattogram Hill Tracts, Bangladesh have been growing cotton (Gossypium hirsutum L.) in their traditional system of jhum cultivation which is undergoing transformation. Growing rainfed cotton as a monocrop in the uplands is constrained by farmers’ socio-economic conditions and erratic rainfall. Shifting growing season to post-monsoon dry monthscould be an option to sustain cotton production in hilly areas. An exploratory experiment was conducted for two seasons to explore the possibility of growing cotton in valley lands in Bandarban during dry season. Growth and yield potentials of dry season cotton were evaluated in relation to prevailing environmental conditions. Night temperature dropped to 9oC on several occasions in 2018-2019 season; but it remained higher than 11oC throughout the season in 2019-2020. In 2018-2019, day temperatures surged higher past March 15 occasionally exceeding 38oC. Variability in temperatures was more in 2018-19 while average temperatures were higher in 2019-20 season. Rainfall distribution was almost similar in both the growing seasons receiving total rainfall of 757 mm and 579 mm in two seasons, respectively. Higher seed cotton yield (2,047 kg per ha) was recorded for 15 November planted crop compared with 1 December planted crop (1,186 kg per ha). December 1 planted crop was affected more by low temperatures at seedling stage resulting in poor growth and fewer bolls per plant. Late planted crop was more vulnerable to rain damage at boll opening stage. Crops of both the seasons encountered high temperatures (>32oC) during boll development. Changing climate, shorter winter season and rising temperatures may allow cotton production in valley lands shifting growing season from rainy season to post-monsoon dry months. However, the window of dry season cotton growing in Bandarban, Bangladesh seems narrow. Rainfall pattern restricts planting seeds prior to mid-November. Again, high temperatures stress in March and April synchronizing boll development, and rainfall toward late April and May during boll opening may cause yield loss. Development and adoption of short duration, low temperature tolerant upland cotton varieties might be of advantage for adapting to climate change vulnerabilities. Ann. Bangladesh Agric. (2020) 24(2): 1-14

Effects of Artifical Substrate on Rearing of Macrobrachium Rosenbergii Post-larvae in Pond Net Cage

Two experiments were carried out to evaluate the effects of addition of net piece substrates in cages for nursery rearing of freshwater prawn, Macrobrachium rosenbergii post-larvae. In the first experiment, net piece substrates were added with an arrangement to increase the surface area of nursery cages to 50% and 75% and compared with cages without any substrate (control). In the second experiment, maintaining surface area increment at 75% in all cages, the net piece substrates were arranged in three different orientations of horizontal, vertical, and 45o angle sloping. Experiments were conducted in a pond of Faculty of Fisheries, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh for a period of 45 days in June –August of 2015 and 2016. A completely randomized design was followed to assign the treatments with three replications. The 75% area increment group showed significantly higher (P < 0.05) growth (1.02 ± 0.09 g) and survival rate (79.43 ± 1.63%), compared to 50% area increment (0.96 ± 0.05 g and 75.03 ± 2.45%) and control group (0.79 ± 0.06 g and 66.66 ± 3.57%). The vertically oriented substrate group showed significantly lower growth 0.95 ± 0.04 g) and survival (76.33 ± 1.15%), compared to the horizontal (1.06 ± 0.05 g and 77.12 ± 1.20%) and sloping (1.16 ± 0.10 g and 79.33 ± 0.57 %) substrate group. However, there were no differences between horizontal and sloping substrate groups regarding final length, final weight, specific growth rate (SGR), and survival rate except food conversion ratio (FCR). The overall results suggested that modification of net cage nursery structure of M. rosenbergii might have significant effects on growth and survival of post-larvae by the manipulation of their behaviour in culture system. Ann. Bangladesh Agric. (2020) 24(2) : 95-106

Influence of Organic and Inorganic Fertilizers on Growth, Yield and Physio-Chemical Properties of Papaya

A field experiment was conducted to investigate the effect of organic and inorganic fertilizers on growth, yield and physio-chemical properties of papaya (Carica papaya) from February to December 2019. The experiment was designed into twelve treatments [T1 = Control, T2 = 100% RDF (Recommended Dose of Fertilizers), T3 = 50% RDF+ 50% MOC (Mustard Oil Cake), T4 = 50% RDF+ 50% VER (Vermicompost), T5 = 50% RDF + 50% PM (Poultry Manure), T6 = 25% RDF+ 75% MOC, T7 = 25% RDF + 75% VER, T8 = 25% RDF+ 75% PM, T9 = 100% MOC, T10 = 100% VER, T11 = 100% PM and T12 = MOC + VER + PM] at the experimental field of Department of Horticulture, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur. The experiment was laid out in randomized complete block design with three replications. The effect of treatments varied significantly for most of the characters studied. Results showed that the plant growth, yield contributing traits, fruit yield and quality of papaya significantly increased in T10 treatment compared to other treatments. The maximum amount of dry matter of fruit (4.37%), TSS (18.17 %), total sugar (9.43 g/ 100g), reducing sugar (6.34 g/ 100g), β- carotene (0.24 mg/ 100g), mineral as Ca (0.39%), Mg (0.33%) and K (2.08%) were found in T10 treatment and the minimum amount were found in the control T1. The maximum amount of non-reducing sugar was obtained from T12 (3.93 g/ 100g) and the minimum from T3 (2.23 g/ 100g). Ascorbic acid was found maximum in T7 (24.99 mg/100g) and minimum from T11 (22.00 mg/100g). A significant influence of T10 treatment on growth, yield and physio-chemical characters was observed. The application of 100% vermicompost which influenced growth, yield and physio-chemical properties of papaya in Salna series of Red Brown-terrace soil is suggested. Ann. Bangladesh Agric. (2020) 24(2) : 69-83