Department of Agricultural Chemistry

Phosphorus (P) fixation limits availability of P to plants in tropical soil, which is a major constraint for crop production. The aim of our research was to isolate, screen and characterize phosphate solubilizing bacteria (PSB) from wheat and evaluate their efficacy in P nutrition in wheat. Upon screening, 9 isolates showing varying level of phosphate solubilizing activity in both agar plate and broth assays using Pikovskaya's medium were obtained. The pH of the culture media was decreased with increased bacterial growth suggesting that they might secrete organic acids to solubilize insoluble phosphorus. In vitro wheat seedling bioassay with two superior PSB isolates (PSB1 and PSB8) and varying sources of P revealed that both isolates significantly enhanced seedling growth (shoot and root length, shoot and root dry weight) and nutrient contents (%N, %P and %K) in plant tissue compared to control (no PSB). The performance of PSB8 was superior to PSB1 in respect of all the parameters studied. The PSB8 was tentatively identified as Pseudomonas sp. through 16S rRNA gene sequencing. Our results suggest that Pseudomonas sp. PSB8 isolated from wheat might be useful for improving P nutrition in wheat in soils with low available P.

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The effect of supplemental calcium (Ca) on the growth of three rice genotypes PVSB9, NS15, and Pokkali were assessed. Different morphological characters were studied among which the percent relative-plant height, total tillers, root dry weight (RDW), shoot dry weight (SDW), and total dry matter (TDM) were higher in Pokkali and PVSB9, but lower in NS15 under different salinity and supplemental Ca levels. These morphological characteristics significantly decreased with increasing salinity levels grown at different Ca levels, but significantly increased with increasing supplemental Ca levels. The interaction effect of genotypes and salinity levels, and genotypes and Ca levels were significant, where a negative relationship with increasing salinity levels and a positive relationship with increasing supplemental Ca levels were found. The interaction effect of salinity and Ca levels on all morphological parameters was significant, where these characteristics increased due to increasing the supplemental Ca levels at all the levels of salinity.

Aromatic rice has great potential to attract rice consumer for its taste and deliciousness, and high price to boost up the economic condition of the rice grower in the developing countries. A field experiment was conducted to evaluate the morpho-physiological and biochemical attributes in relation to yield potentials of fine aromatic rice varieties in Bangladesh. Two aromatic fine rice cultivars, Ukunmadhu and Kataribough (local land races), one hybridized variety BRRIdhan32 and one mutant variety Binasail were used in the experiment. The results revealed that rice varieties BRRIdhan32 and Binasail showed the greater number of branches of panicle, grain size, grain yield and harvest index as compared to aromatic varieties. On the other hand, aromatic rice showed taller plant stature, more tiller, plant biomass and larger panicle but lower number of primary and secondary branches, grain size, yield and harvest index. The biochemical attributes namely chlorophyll and soluble protein content were higher at vegetative stage as compared to panicle initiation and flowering stages. The aromatic rice Kataribhough and Ukonmondhu contained higher amount of total free amino acid as compared to that of Binasail and BRRIdhan32. Other biochemical parameters namely nitrate reductase activity (NRA), total sugar and free amino acid contents were higher at flowering stage compared to those contained at tillering and panicle initiation stages. Physico-chemical properties of grain viz. length, breadth, L/B ratio, nitrogen (%) and protein (%) were significantly higher in fine rice as compared to aromatic rice. From the results it may be concluded that the high yielding varieties were more efficient in transfer of photosynthate to the grain i.e. economic yield and that is why BRRIdhan32 recorded the highest yield. Poor yield in Ukonmodhu and Kataribhough was due to low harvest index indicating minimum translocation of assimilates to the grains.

Abstract
A pot experiment was conducted in the house of the Agricultural Chemistry Department, Bangladesh Agricultural University, Mymensingh during July to November 2003 to assess the morphological features of some naturally grown boron hyperaccumulating weed species as influenced by boron contamination in soil. The pot experiment was laid out in a Completely Randomized Design (CRD) with 13 treatments and three replications. The treatments were 0, 0.5, 0.75, 1.0, 1.5, 2, 4, 8, 12, 20, 30, 50 and 100 mg BL-1. Nine weed species namely, Barnyard grass (Echinochloa crus-galli), Joina (Fimbristylis miliacea), Chisra (Scirpus juncoids), Panikachu (Monochoria hastata), Panilong (Luduwigia hyssopifolia),  Malancha (Alternanthera philoxeroides), Topapana (Pistia stratiotes) and Water cress (Enhydra fluctuans) were used in the experiment. Plant height, number of leaves per plant and biomass of each plant were gradually decreased with the application of increasing levels of boron. Considering the characteristics of the nine weed species Mutha water cress and Joina seem to have better enduring capacity to higher levels of boron.
Keywords: Boron, phytoremediation, hyperaccumulating weeds, morphological characters

ABSTRACT
A pot experiment was conducted in the net house of the Agricultural Chemistry Department Bangladesh Agricultural University, Mymensingh during July to November 2003 to identify naturally grown boron hyper accumulating weed species from boron contaminated soil and assessment of boron accumulation by naturally grown weeds for the development of phytormediation technology. Boron and phosphorus were determined in Barnyard grass, Joina, Water cress, Malancha, Panikachu, Panilong, Chisra and Topapana. The pot experiment was laid out in a completely Randomized Design (CRD) with 13 treatment and two replications. The treatments were 0, 0.5, 0.75, 1.0, 1.5, 2, 4, 8, 12, 20, 30, 50 and 100 mg BL-1. Nine weed species namely; Barnyardgrass (Echinochloa crus-gullia), Joina (Fimbristylis miliacea), Chisra (Scirpus juncoids), Panikachu (Monochoria hastate), Panilong (Luduwigia hyssopifolia), Malancha (Alternanthera philoxeroides), Topapana (Pistia stratiotcs) and water cress (Enhydra  fluctuans) accumulate boron in a increasing level of boron treatment except Mutha (Cyperus  rotundus). Out of nine weeds water cress absorbed the highest amount (398.88 g pot-1), of boron followed by Malancha (188.67  g pot-1), Panikachu (154.15  g pot-1), Jonia (105.90  g pot-1), Barnyard grass (93.02  g pot-1), Chisra (74.68  g pot-1), Panilong (29.373  g pot-1) and Topapana (25.46  g pot-1). Although maximum accumulation of boron was found in Water cress, it is not abundant in the rice pattern, biomass and toxicity tolerance, Joina and Barnyard grass are the best performer and can be considered for the mitigation of  boron contaminated soil due to irrigation water while water cress and Malancha can be used for remediation of stagnant boron contaminated water as a means of phytoremediation technology.
Key words: Boron concentration, weeds, assessment of Boron accumulation, phytoremediation technology.

Four edible mushroom species (Pleurotus ostreatus, Agaricus bisporus, Volvariella volvacea, Ganoderma lucidum) from different locations of Bangladesh, were analysed for their protein and metal content profile (K, Na, Fe, Cu, Zn, Mn, Cr, Pb, As and Cd). Trace metals were determined by atomic absorption spectrophotometer, Na and K by flame emission spectrophotometer and protein by micro Kjeldhal method. All element concentrations were determined on a dry weight basis. The protein content of mushrooms varied from 13.8%–34.3% and the metal content of samples ranged from 0.54–2.25% for K and 12.6–81.6, 69.5–626.2, 39.2–163.4, 30.1–75.5, 52.9–104.5, 0.20–0.30, 0.13–0.59 µg g-1 for Na, Fe, Cu, Zn, Mn, Cd, Pb, respectively. Arsenic and cadmium concentrations were below the detection limit of the method used. The detection limits of the method for As and Cd are 0.01 µg g-1 for each element. In general, K and Fe content were higher than other metals in all mushroom species. The levels of Cu and Zn in some mushroom samples were found to be higher than legal limits.

The aim of the present study was to evaluate the degree of metal contamination of the Turag River water and its suitability for irrigation. Twenty water samples were analyzed for physicochemical parameters and metals viz., calcium, magnesium, potassium (K), sodium, copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), lead (Pb), cadmium (Cd), chromium (Cr), and nickel (Ni). All water samples were slightly alkaline to alkaline. Regarding electrical conductivity (EC), all samples were suitable for crop in soils with moderate permeability and leaching. Water samples were medium salinity and low alkalinity hazard classes. In terms of total dissolved solids (TDS), all samples were classified as freshwater. As per sodium adsorption ratio (SAR) and soluble sodium percentage (SSP), all samples were classified as excellent. No residual sodium carbonate (RSC) was detected in any of the samples, indicating suitability for irrigation; and all samples were considered very hard. Cr and Mn contents in all samples were above FAO guideline values and, therefore, these metals were considered toxic. Zn, Cu, Pb, Cd, and Ni concentrations were below acceptable limit for irrigation and do not pose a threat to soil environment. Significant relationships were found between EC and TDS, SAR and SSP, SAR and RSC, and SSP and RSC. The combinations of ions such as K–Zn, K–Fe, K–Cu, K–Mn, K– Pb, Zn–Fe, Zn–Cu, Zn–Mn, Fe–Mn, Cu–Mn, Cu–Pb and Mn–Pb exhibited significant correlation. This study revealed that Turag River water samples are contaminated with Cr and Mn. This fact should not be ignored because water contamination by metals may pose a threat to human health through food chain.

Effects of arsenic (As) on seed germination, root and shoot length and biomass of rice varieties were investigated to
elucidate the toxicity of As. Nine rice varieties viz. BR 11, BR 22, BRRI dhan29, BRRI dhan33, BRRI dhan39, BRRI dhan40, BRRI dhan47, BRRI dhan49 and BRRI dhan53 were grown with different levels of As (0, 15, 40, 70, 100 and 150 ppm). The experiment was laid out in a complete block design with three replications. Results showed that the germination percentage, root and shoot length and biomass of all rice varieties were gradually decreased with the increasing concentration of As solution. Among the rice varieties, BR 11, BR 22 and BRRI dhan49 showed highest degree of tolerance while BRRI dhan29 was the most susceptible to As toxicity.

The study was conducted to assess the level of Cu, Zn, Pb, Cr, Fe, Mn, Cd and Ni contamination in the water samples of the Buriganga river. Total 14 water samples were collected from different areas of upstream of the Buriganga river to determine the physicochemical properties, concentration of different metallic constituents and assess the heavy metal pollution load. Atomic Absorption Spectrometer was used for analyzing the heavy metals of the samples. The mean concentration of Ca, Mg, Na, K in water samples were 0.779, 0.889, 140.39, 26.9 µg mL-1 , respectively. The mean concentration of Cr, Pb, Fe, Cu, Zn and Mn in the water samples were 0.17, 0.05, 0.67, 0.22, 0.55 and 0.17 µg mL-1 , respectively. The amount of Cd in all samples and Pb in 10 samples was below detectable limit of the instrument (0.01 µg mL-1). Water pH ranged from 4.09 to 7.41 and EC was 346 to 7720 S cm-1. Magnitude of heavy metal pollution in the Buriganga river system implies that the condition is very alarming and may severely affect the aquatic ecology of the river. To minimize the severe impact on city dwellers and aquatic ecology of the Buriganga river, sustainable steps and continuous monitoring on pollution prevention and cleanup operation is suggested.

This study was carried out to isolate, screen and characterize arsenic (As) resistant bacteria from As contaminated soils of Dumrakandi and Matlab under Faridpur and Chandpur districts and to evaluate their efficiency in reducing As toxicity against rice seedlings during germination. Thirteen strains were isolated from the soils which showed resistance to different levels of sodium arsenite (viz. 5, 10, 20 and 40 mM) in both agar plate and broth assay using BSMY I media. Among the isolates, BTL0011, BTL0012, BTL0015 and BTL0022 showed highest resistance to 40 mM sodium arsenite. Gram staining and KOH solubility test revealed that five strains were gram positive and rest eight was gram negative. They grew well in the liquid media at pH 5.5 to 8.5. In-vitro rice seedling bioassay with two superior isolates (BTL0011 and BTL0022) revealed that As resistant strains significantly enhanced seed germination of BRRI dhan29 and BRRI dhan47 at 60 ppm As. This study was laid out in CRD with three replications. The performance of BTL 0022 was superior to BTL0011. The overall results suggest that BTL0011 and BTL0022 can be used for bioremediation of As contaminated soils and to increase the germination and seedling growth of rice in As contaminated soils.

In a quantitative assessment of water collected from the midstream of Karatoa river in Bangladesh, 31 water samples were analyzed to assess heavy metals, major ionic constituents and suitability parameters for irrigation usage. The electrical conductivity of all collected samples were within the range of 450 to 1653 µS cm -1 indicating medium to high salinity. Total dissolved solids ranged from 247 to 789 mg L -1 and the samples were rated as fresh water (<1000 mg L -1 ). The anion chemistry in the Karatoa river water was dominated by HCO 3 and Cl -, which contributed 66 and 31%, respectively of the total anionic mass balance. On the other hand, the cation chemistry indicated that 8 samples showed dominance sequence as Ca > Mg > Na > K, 8 samples as Ca > K > Na > Mg, 7 samples as Ca > Mg > K > Na, 6 samples as Ca > Na > K > Mg and only 2 samples as Ca > K > Mg > Na. Among the studied heavy metals (Fe, Mn, Cu, Zn, Pb, Cr and Ni), the most dominant metal was Fe and Mn. The concentration of Mn in 13 water samples exceeded the surface water quality standard (0.10 mg L -1 ) indicating Mn toxicity. Considering hardness, 6 water samples were graded as moderately hard while the rest 25 samples were graded as hard. As regards to permeability index, 65% of the water samples collected from the midstream of Karatoa river belongs to the unsuitable category.

In a quantitative analysis, a total of 28 sediment samples were collected from midstream of the river Karatoa, Bangladesh to assess Cd and Pb pollution level. The concentration of heavy metals in sediment samples were determined by using an Atomic Absorption Spectrophotometer (AAS) after digestion with aqua regia. The mean concentration of organic matter in sediment samples was 3.29%. The average concentration of Cu, Zn, Pb, Cd, Ni and Cr in the sediment samples were 20.72, 82.27, 69.46, 10.85, 9.48 and 8.37 µgg-1, respectively. The investigation revealed that the average Pb concentration (69.46 µgg-1) in sediments collected from the midstream of the river Karotoa was higher compared with several other rivers of Bangladesh and it was more than twice compared to geochemical background and toxicity reference value. The distribution of Cd in the study area was more than hundred times higher compared to standard continental crust, while it was almost twenty times greater compared to tox...

The effects of root-zone temperature (RZT) on the ion uptake, distribution and interactions of 21 (11 essential and 10 non-essential) elements using Lotus japonicus were studied. After acclimation in hydroponics at ambient (25 C) RZT for three weeks, seedlings were exposed to sub-optimal (15 C and 20 C) and ambient RZTs. After one week, plants were harvested and then growth and mineral elements were analyzed. The highest shoot and root biomass was at 25 C and lowest at 15 C RZT. In shoots, the highest concentrations of all elements, except for nickel (Ni), were at 25 C RZT. At lower RZTs, the reductions in concentrations were more evident especially for trace elements and heavy metals. Except for magnesium (Mg), the highest root concentrations were at 15 C RZT for all essential elements. Unlike other non-essential elements, the highest cadmium (Cd) and cobalt (Co) concentrations in roots were at 25 C RZT. The shoot/root ratios of almost all elements were affected by sub-optimal RZTs. Only manganese (Mn) and Co showed increased shoot/root ratio at sub-optimal RZTs; and this ratio decreased for other elements. Nickel in shoots and Mn, Co and Cd in roots tended to be negatively correlated with most other elements (either, essential or non-essential) in each respective organ. The present study showed that RZT significantly changed the ion profile of L. japonicus and suggests possible connection between global warming and phytoaccumulation of heavy metals, especially in temperate regions, since most metals tended to accumulate in shoots at higher RZT.

The objectives of the research were to isolate phosphate solubilizing bacteria (PSB) from the rhizoplane of rice (Oryza sativa L.) cv. BRRIdhan 29 cultivated in acidic soils of Tangail in Bangladesh and evaluate their performances in phosphate solubilization in both in vitro and in vivo conditions. A total of 10 bacterial strains were isolated and purified by repeated streak culture on nutrient agar medium. Upon screening, five isolates (OS01, OS03, OS07, OS08 and OS10) showed varying levels of phosphate solubilizing activity in agar plate and broth assays. Among them, the strain OS07 (B1) and two previously isolated PSB strains B2 and B3 were selected for evaluation for their performances in rice alone or in combination of TSP (triple super phosphate: P1) and rock phosphate (P2). Plant height and the number of tillers per plant were significantly increased by all PSB isolates when used in combination with TSP but PSB alone did not influence much on plant height and the number of ti...

A pot culture experiment was conducted in the Department of Agricultural Chemistry, Bangladesh Agricultural University, Mymensingh, with acidic soil of the Madhupur upazila under Tangail district to evaluate the effect of three phosphate solubilizing bacteria (PSB) with the addition of three different phosphatic fertilizers (triple superphosphate, single superphosphate, and Moroccan rock phosphate) at the recommended dose on nutrient content of transplanted aus rice (Oryza sativa L.) cv. BR26. PSB significantly increased the N, P, K, Ca, Mg, Fe, and Mn content in rice grains, and while in straw, the content of N, P, K, Ca, Mg, Fe, Zn, Mn, and Cu increased. Application of different P fertilizers significantly increased all the nutrient content except Fe in grains and K, Fe, & Zn in straw studied. P fertilizers accentuated the performance of PSB in increasing the nutrient content of rice.